This research work studies the impacts of irrigation and other agricultural practices on the soil along the bank of Tungan Kawo dam. The experimental analysis evaluates the soil physicochemical parameters and metal (Cd, Cu, Cr, Ni, Fe, Mn, Pb and Zn) concentrations using sequential extractions. The physicochemical parameters of the soils across the sites indicated values reported for less polluted soils. Also, analysis of total metals in the soils indicated lower concentration of all metals evaluated than recommended standard limits with exception of Cd. The results of sequen tial extraction of heavy metal in soil sample indicated that all metals were mainly associated with the residual, Fe-MnO and organic bound fractions. The residual fraction has the maximum concentration of metals especially in cool and dry season for Cr, Cu, Ni, Pb and Zn, whereas only a small fraction of all the heavy metal is extracted in water soluble, exchangeable and carbonate bound fractions. It indicates that the bioavailability index is low. Hence, mobility of the heavy metals by the surrounding plants grown on the soils is low.
Pollution of the environment is an important problem in human’s life that leads to a miserable condition. Environment usually affected include: air, soil, water and vegetations which have direct effect on human life. The soil being the repository of all pollutants is most affected because soil is used for vegetation of edible plants and plants are taken in as part of our food. Soil is a very important natural resource to man as it is a source of his life on this planet. Despite its importance, soil is often contaminated by human activities and this is reflected in the high horizontal and vertical variability brought about by the anthropogenic influence on soil formation and development [
A variety of human activities including municipal waste disposal, industrial emissions, and agricultural practices have left their impacts on soils in the form of elevated and high level of toxicants especially the heavy metals [
In Northern Nigeria, fadama is a common agricultural practice mostly located within the banks around rivers, dams and other major water sources that stay throughout the year and are often used for irrigation activities covering but not limited to the irrigation of assorted vegetables and other root crops [
The Tungan Kawo Dam is located State between latitude 10˚21"58.51˚N - 10˚23"28.50˚N of the equator and between longitude 5˚19"29.23˚E - 5˚20"59.23˚E in Tungan Kawo village, northwest of Kontagora, 7 km along Kontagora-Yauri road in Kontagora Local Government Area of Niger State. The dam has a catchments area of 143 km2 with a total storage capacity of 17.7 M Cubic meters, 20 m high and dam crest length of 1000 m. The dam was commission in May 1991. It is the largest source of water supply in Kontagora Township. The people of Tungan Kawo and its environs are predominantly farmers and have remained so for years. In this area, vegetables are irrigated with dam water and all kinds of available waste and polluted waters. Similarly, to enhance the yield of these vegetables, fertilizers and manures are occasionally added to the soil [
The farmland was divided into five sampling plots as shown in
Seasons
Cool and dry season: December-February
Hot and dry season: March-May
Warm and wet season: June-August
Warm and dry season: September-November
Soil samples for metal analysis were allowed to air-dried. Dry soils were ground into fine powder and homogenized using an acid-washed clean mortar and pestle and sieved to give 200 μm particle size. They were then stored in desiccators to attain constant weight before being stored in air-tight plastic bottles. All metallic determination from soil samples was based on the fine particles obtained.
Sequential extraction was carried out on the principle of selective extraction proposed by [
Quality control test was performed on soil and plant samples in order to validate the experimental procedures. This was done by spiking the pre-digested soil and plant samples with multielement metal standard solution (0.5 mgL−1 of Cd and Cr and 5 mgL−1 for Cu, Fe, Mn, Ni, Pb and Zn). The percentage recovery showed that 90% - 95% of the spiked metals were recovered, indication of reliability of the results obtained.
The efficiency of the digestion method was validated by a spiking experiment as described in the preceding chapter. The percentage recoveries of metals ranged from 99.0 - 108.0 in pepper and 90.0 - 100.0 in soils. The pattern of recovery efficiency in both pepper and soil were found to follow the decreasing order, Cd > Pb > Ni > Mn > Cu > Zn > Cr and Pb > Mn > Cd > Zn > Cu > Ni > Cr, respectively. However, high recoveries above 90% in this study could imply that the procedures used for treatment and analysis of sample is efficient.
The pH and electrical conductivity of sediment samples was measured with sediment: water ratio 1:2 using pH and electrical conductivity meters as described by [
The results of variation in physicochemical parameters from the study and control area in the four seasons are presented in Tables 1-4. The results of the pH for study site range from 5.77 (site 5) - 7.17 (site 1), 6.40 (sites 2 and 3) - 6.62 (site 1), 9.00 (site 4) - 10.23 (site 2), and 7.37 (site 3) - 7.49 (site 2) for cool and dry season, hot and dry season, warm and wet season, and warm and dry season respectively. For the control site, the pH fraction was 7.50, 6.20, 6.20 and 6.50 in the same order of seasons. pH in CaCl2(aq) for the study site showed 5.10 (site 3) - 5.27 (site 1), 5.27 (site 1) - 5.50 (site 3), 6.20 (site 5) - 6.67 (site 2) and 6.30 (sites 1 and 4) - 6.50 (site 3) for cool and dry season, hot and dry season, warm and wet season, and warm and dry season respectively. Also, for the control site, the pH in CaCl2(aq) was found to be 6.50, 5.10, 5.10 and 5.10 across the seasons in the
Site | pH | ECE (μS/cm) | OM (%) | TN (%) | AP (mg/100g) | Cl− (mg/L) | CEC (Cmol/kg) | |||
---|---|---|---|---|---|---|---|---|---|---|
1 | 7.17 ± 0.06 | 5.27 ± 0.06 | 0.05 ± 0.00 | 0.78 ± 0.01 | 0.05 ± 0.00 | 0.01 ± 0.00 | 7.81 ± 0.06 | 8.50 ± 0.05 | 0.46 ± 0.04 | 5.37 ± 0.06 |
2 | 6.67 ± 0.06 | 5.17 ± 0.06 | 0.03 ± 0.01 | 0.52 ± 0.01 | 0.04 ± 0.00 | 0.01 ± 0.00 | 13.13 ± 0.01 | 15.70 ± 0.10 | 0.34 ± 0.01 | 9.20 ± 0.10 |
3 | 6.30 ± 0.10 | 5.10 ± 0.10 | 0.01 ± 0.00 | 0.75 ± 0.01 | 0.05 ± 0.00 | 0.01 ± 0.00 | 7.82 ± 0.12 | 13.29 ± 0.01 | 0.25 ± 0.01 | 8.40 ± 0.10 |
4 | 5.80 ± 0.10 | 5.20 ± 0.10 | 1.31 ± 0.09 | 0.78 ± 0.01 | 0.08 ± 0.01 | 0.01 ± 0.00 | 8.74 ± 0.04 | 13.80 ± 0.10 | 0.45 ± 0.02 | 5.17 ± 0.15 |
5 | 5.77 ± 0.15 | 5.20 ± 0.10 | 1.30 ± 0.10 | 0.65 ± 0.02 | 0.05 ± 0.00 | 0.01 ± 0.00 | 9.31 ± 0.45 | 8.52 ± 0.08 | 0.25 ± 0.01 | 5.70 ± 0.10 |
Control | 7.50 ± 0.10 | 6.50 ± 0.10 | 0.05 ± 0.01 | 2.35 ± 0.05 | 0.18 ± 0.00 | 0.01 ± 0.00 | 136.40 ± 0.10 | 15.07 ± 0.02 | 2.23 ± 0.06 | 10.13 ± 0.06 |
EC: Electrical Conductivity; OM: Organic Matter; TN: Total Nitrogen; AP: Available Phosphorus; S: Sulphur; Cl−: Chloride; CEC: Cation Exchange Capacity.
Site | pH | ECE (μS/cm) | OM (%) | TN (%) | AP (mg/100g) | Cl− (mg/L) | CEC (Cmol/kg) | |||
---|---|---|---|---|---|---|---|---|---|---|
1 | 6.62 ± 0.03 | 5.27 ± 0.06 | 0.10 ± 0.00 | 1.00 ± 0.00 | 0.05 ± 0.00 | 0.02 ± 0.00 | 7.03 ± 0.06 | 9.06 ± 0.00 | 0.80 ± 0.00 | 8.40 ± 0.00 |
2 | 6.40 ± 0.00 | 5.40 ± 0.00 | 0.05 ± 0.01 | 1.60 ± 0.00 | 0.08 ± 0.01 | 0.01 ± 0.00 | 7.00 ± 0.00 | 20.53 ± 0.01 | 0.70 ± 0.00 | 7.83 ± 0.06 |
3 | 6.40 ± 0.00 | 5.50 ± 0.00 | 0.07 ± 0.01 | 0.87 ± 0.01 | 0.08 ± 0.00 | 0.01 ± 0.00 | 7.07 ± 0.06 | 9.65 ± 0.01 | 0.57 ± 0.06 | 8.60 ± 0.00 |
4 | 6.50 ± 0.00 | 5.30 ± 0.00 | 0.06 ± 0.01 | 1.49 ± 0.03 | 0.08 ± 0.00 | 0.01 ± 0.00 | 7.07 ± 0.12 | 9.77 ± 0.01 | 0.57 ± 0.06 | 8.57 ± 0.12 |
5 | 6.42 ± 0.03 | 5.37 ± 0.06 | 0.05 ± 0.01 | 0.97 ± 0.01 | 0.06 ± 0.00 | 0.01 ± 0.00 | 7.17 ± 0.15 | 10.23 ± 0.01 | 0.67 ± 0.06 | 8.63 ± 0.06 |
Control | 6.20 ± 0.00 | 5.10 ± 0.00 | 0.10 ± 0.00 | 1.14 ± 0.00 | 0.06 ± 0.00 | 0.01 ± 0.00 | 7.10 ± 0.10 | 9.84 ± 0.07 | 0.50 ± 0.00 | 6.20 ± 0.00 |
EC: Electrical Conductivity; OM: Organic Matter; TN: Total Nitrogen; AP: Available Phosphorus; S: Sulphur; Cl−: Chloride; CEC: Cation Exchange Capacity.
Site | pH | ECE (μS/cm) | OM (%) | TN (%) | AP (mg/100g) | Cl− (mg/L) | CEC (Cmol/kg) | |||
---|---|---|---|---|---|---|---|---|---|---|
1 | 9.72 ± 0.08 | 6.37 ± 0.06 | 0.30 ± 0.00 | 2.10 ± 0.00 | 0.07 ± 0.00 | 1.75 ± 0.01 | 7.77 ± 0.06 | 15.46 ± 0.01 | 0.97 ± 0.01 | 9.63 ± 0.06 |
2 | 10.23 ± 0.38 | 6.67 ± 0.38 | 0.07 ± 0.01 | 1.92 ± 0.01 | 0.08 ± 0.00 | 1.05 ± 0.01 | 8.07 ± 0.15 | 20.53 ± 0.01 | 0.90 ± 0.06 | 10.43 ± 0.04 |
3 | 9.87 ± 0.38 | 6.50 ± 0.00 | 0.08 ± 0.00 | 1.87 ± 0.01 | 0.09 ± 0.00 | 1.07 ± 0.01 | 7.80 ± 0.10 | 13.58 ± 0.11 | 1.46 ± 0.10 | 9.62 ± 0.01 |
4 | 9.00 ± 0.46 | 6.63 ± 0.49 | 0.07 ± 0.00 | 1.86 ± 0.06 | 0.09 ± 0.00 | 1.06 ± 0.01 | 8.33 ± 0.06 | 13.10 ± 0.59 | 0.95 ± 0.00 | 9.75 ± 0.01 |
5 | 9.63 ± 0.15 | 6.20 ± 0.36 | 0.08 ± 0.00 | 1.97 ± 0.01 | 0.09 ± 0.00 | 1.07 ± 0.01 | 7.80 ± 0.00 | 10.90 ± 1.15 | 0.96 ± 0.01 | 8.90 ± 0.11 |
Control | 6.20 ± 0.00 | 5.10 ± 0.00 | 0.10 ± 0.00 | 1.14 ± 0.00 | 0.06 ± 0.00 | 1.02 ± 0.00 | 5.17 ± 0.06 | 9.84 ± 0.01 | 0.40 ± 0.00 | 5.17 ± 0.06 |
Site | pH | ECE (μS/cm) | OM (%) | TN (%) | AP (mg/100g) | Cl− (mg/L) | CEC (Cmol/kg) | |||
---|---|---|---|---|---|---|---|---|---|---|
1 | 7.40 ± 0.18 | 6.30 ± 0.10 | 0.15 ± 0.00 | 1.53 ± 0.01 | 0.07 ± 0.01 | 1.17 ± 0.00 | 29.17 ± 7.96 | 9.06 ± 0.00 | 0.80 ± 0.00 | 8.83 ± 0.12 |
2 | 7.49 ± 0.04 | 6.40 ± 0.00 | 0.11 ± 0.05 | 1.62 ± 0.01 | 0.08 ± 0.00 | 1.11 ± 0.00 | 6.63 ± 0.12 | 11.53 ± 0.01 | 0.70 ± 0.00 | 8.73 ± 0.15 |
3 | 7.37 ± 0.06 | 6.50 ± 0.00 | 0.09 ± 0.01 | 0.97 ± 0.01 | 0.09 ± 0.00 | 1.11 ± 0.00 | 7.23 ± 0.06 | 9.65 ± 0.01 | 0.57 ± 0.06 | 8.80 ± 0.10 |
4 | 7.48 ± 0.05 | 6.30 ± 0.00 | 0.09 ± 0.00 | 1.52 ± 0.01 | 0.08 ± 0.00 | 1.11 ± 0.00 | 7.33 ± 0.12 | 9.77 ± 0.01 | 0.57 ± 0.06 | 8.73 ± 0.06 |
5 | 7.44 ± 0.01 | 6.37 ± 0.06 | 0.09 ± 0.00 | 0.98 ± 0.01 | 0.07 ± 0.00 | 1.11 ± 0.00 | 7.30 ± 0.00 | 10.23 ± 0.01 | 0.67 ± 0.06 | 8.70 ± 0.10 |
Control | 6.50 ± 0.00 | 5.10 ± 0.00 | 0.10 ± 0.00 | 1.14 ± 0.00 | 0.06 ± 0.00 | 0.01 ± 0.00 | 5.20 ± 0.00 | 9.70 ± 0.05 | 0.50 ± 0.00 | 5.50 ± 0.00 |
EC: Electrical Conductivity; OM: Organic Matter; TN: Total Nitrogen; AP: Available Phosphorus; S: Sulphur; Cl−: Chloride; CEC: Cation Exchange Capacity.
same order as the study sites. Analysis of variation among the study sites across the seasons showed significant differences (p < 0.05). The varying sources of effluent discharge into the dam across the seasons could be a possible reason. Comparing the pH of study and control sites, pH at the control site is alkaline across the seasons.Within pH range of 5.8 - 6.5, acidity is present (apparently from hydroxyl-Al and organic functional groups, ordinarily hydronium, in amounts sufficient to affect acid-sensitive crops [
The electrical conductivity (EC) across the seasons, cool and dry, hot and dry, warm and wet, and warm and dry showed the range: 0.01 (site 3) - 1.31 (site 4), 0.05 (site 2 and 5) - 0.10 (site 1), 0.07 (site 2 and 4) - 0.30 (site 1), and 0.09 (site 3, 4 and 5) - 0.15 μS/cm (site 1) for the seasons respectively, 0.05, 0.10, 0.10 and 0.10 μS/cm were the EC values for the control site across the seasons in the same order. There were significant differences (p < 0.05) in EC among the various sites. Highest values of EC were recorded at site 4 during cool and dry season. Analysis of variation also indicated that mean values of EC did vary between and within seasons, and did show seasonal pattern. Generally, the values reported in this study are lower than 3 - 80 μS/cm reported in Bakori Dam irrigation soils [
Seasonal variation in percentage organic matter (OM) and the variations between sampling sites were observed. The OM varied between 0.52 (site 2) - 0.78 (site 1 and 4), 0.87 (site 3) - 1.60 (site 2), 1.86 (site 4) - 2.10 (site 1), and 0.97 (site 3) - 1.62% (site 2) for cool and dry season, hot and dry season, warm and wet season, and warm and dry season, respectively for study sites. However, 2.35, 1.14, 1.14 and 1.14 were observed for the control site across the seasons. Analysis of variation among the study sites across the seasons showed significant differences (p < 0.05). Higher OM content in control site compare to study site (cool and dry season) could be due decomposition of weed plants over a long period as compare to study area where these are not found. The range of OM in this study is lower than 2.04% to 2.20% reported by [
The total nitrogen (TN) in the soil varied between 0.04 (site 2) - 0.08% (site 4) for cool and dry season, 0.05 (site 1) - 0.08% (site 2, 3 and 4) for hot and dry season, 0.07 (site 1) - 0.09% (site 3, 4 and 5) for warm and wet season, and 0.07 (site 1 and 5) - 0.09% (site 3) during warm and dry season. Across the seasons highest TN was recorded at site 3 (0.09%d) during warm and dry season. For the control site, TN (%) were observed to be 0.18, 0.06, 0.06 and 0.06 for cool and dry season, hot and dry season, warm and wet season, and warm and dry season, respectively. There were no significant differences (p > 0.05) in EC among the various sites. Analysis of variation also indicated that mean values of EC did vary between and within seasons, and did show seasonal pattern. Across the seasons, there is a general increase in TN in all sites, this suggest increase in content of nitrogen in the soils. The range of TN in this study is lower than the range of 0.5 to 21.9% reported in Nigeria [
The concentration of nitrate (
The available phosphorus (AP) across the seasons, cool and dry, hot and dry, warm and wet, and warm and dry showed the range: 7.81 (site 1) - 13.13 mg/L (site 2), 7.00 (site 2) - 7.17 mg/L (site 5), 7.77 (site 1) - 8.33 mg/L (site 4), and 6.63 (site 2) - 29.71 mg/L (site 1) for the seasons respectively, 136.40, 7.10, 5.17 and 5.20 mg/L were the AP values for the control site across the seasons in the same order. There were significant differences (p = 0.021) in AP among the various sites. Highest values of AP were recorded at site 4 during cool and dry season. Analysis of variation also indicated that values of AP vary (p < 0.05) between the seasons. Similar to nitrogen, phosphorus is an essential elements classified as macronutrient because of the relatively large amounts of phosphorus required by plants [
Sulphate (
Chloride (Cl−) fluctuated between 0.25 (site 3 and 5) - 0.46 mg/l (site 1), 0.57 (site 3 and 4) - 0.80 mg/l (site 1), 0.90 (site 2) - 1.46 mg/l (site 3), and 0.57 (site 3 and 4) - 0.80 mg/l (site 1) in during the cool and dry season, hot and dry season, warm and wet season, and warm and dry season, respectively. Analysis of variance showed that there were significant differences (p < 0.05) in the values of chloride recorded among the various sampling sites across the seasons. Again there was no clear seasonal pattern observed. For control site, Cl− values were 2.23, 0.50, 0.40 and 0.50 mg/l for cool and dry, hot and dry, warm and wet, and warm and dry seasons, respectively. According to [
CEC also varied between 5.17 (site 4) - 9.20 Cmolkg−1 (site 2), 7.83 (site 2) - 8.63 Cmolkg−1 (site 5), 8.90 (site 5) - 10.43 Cmolkg−1 (site 2), and 8.70 (site 5) - 8.83 (site 1) for cool and dry, hot and dry, warm and wet, and warm and dry seasons, respectively. Significantly, there were variations (p < 0.05) among sites across seasons with lowest mean value of CEC recorded in the Cool and Dry Season and the highest mean value recorded in the warm and wet season. For control site, CEC values were 10.13, 6.20, 5.17 and 5.50 Cmolkg−1 for cool and dry, hot and dry, warm and wet, and warm and dry seasons, respectively. Similar, to percentage organic matter content, highest CEC were obtained during warm and wet season across all sites. Analysis of variation showed significant differences (p < 0.05) in the value of CEC recorded among the sites across the seasons. Comparing the study and control sites, high values were obtained in study sites with exception in cool and dry season. The CEC of soils is related to the nature and quality of clay and organic matter. Hence, high % organic carbon from these sites could be responsible for the CEC. According to [
Multivariate correlation analysis between various soil physicochemical parameters across the seasons is presented in Tables 5-8. Some of the parameters were found to bear statistically significant correlation with each
Parameter | pH | ECE | OM | TN | AP | Cl− | CEC | |||
---|---|---|---|---|---|---|---|---|---|---|
pH | 1.000 | |||||||||
0.684** | 1.000 | |||||||||
ECE | −0.791** | −0.277 | 1.000 | |||||||
OM | 0.652** | 0.978** | −0.281 | 1.000 | ||||||
TN | 0.504* | 0.937** | −0.100 | 0.973** | 1.000 | |||||
0.144 | 0.011 | −0.008 | 0.105 | 0.108 | 1.000 | |||||
AP | 0.662** | 0.983** | −0.310 | 0.983** | 0.945** | −0.020 | 1.000 | |||
0.200 | 0.335 | −0.321 | 0.341 | 0.376 | −0.500* | 0.417 | 1.000 | |||
Cl− | 0.689** | 0.986** | −0.302 | 0.988** | 0.959** | 0.051 | 0.991** | 0.394 | 1.000 | |
CEC | 0.551* | 0.564* | −0.675** | 0.550* | 0.444 | −0.446 | 0.648** | 0.735** | 0.581* | 1.000 |
**Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).
Parameter | pH | ECE | OM | TN | AP | Cl− | CEC | |||
---|---|---|---|---|---|---|---|---|---|---|
Ph | 1 | |||||||||
0.298 | 1 | |||||||||
ECE | −0.077 | −0.683** | 1 | |||||||
OM | −0.016 | −0.094 | −0.380 | 1 | ||||||
TN | 0.004 | 0.553* | −0.657** | 0.484* | 1 | |||||
0.697** | −0.190 | 0.595** | −0.294 | −0.561* | 1 | |||||
AP | −0.184 | −0.089 | −0.033 | −0.287 | −0.190 | −0.177 | 1 | |||
−0.128 | 0.278 | −0.440 | 0.698** | 0.323 | −0.275 | −0.309 | 1 | |||
Cl− | 0.697** | 0.235 | 0.000 | −0.019 | −0.345 | 0.715** | −0.189 | 0.239 | 1 | |
CEC | 0.774** | 0.738** | −0.553* | −0.153 | 0.316 | 0.200 | 0.000 | −0.114 | 0.442 | 1 |
**Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).
Parameter | pH | ECE | OM | TN | AP | Cl− | CEC | |||
---|---|---|---|---|---|---|---|---|---|---|
pH | 1 | |||||||||
CaCl2 | 0.801** | 1 | ||||||||
ECE | 0.090 | −0.016 | 1 | |||||||
OM | 0.923** | 0.794** | 0.314 | 1 | ||||||
TN | 0.709** | 0.732** | −0.422 | 0.650** | 1 | |||||
0.254 | 0.141 | 0.984** | 0.472* | −0.275 | 1 | |||||
AP | 0.899** | 0.900** | −0.002 | 0.916** | 0.833** | 0.172 | 1 | |||
0.650** | 0.570* | 0.104 | 0.519* | 0.160 | 0.211 | 0.537* | 1 | |||
Cl− | 0.771** | 0.677** | −0.031 | 0.696** | 0.693** | 0.091 | 0.718** | 0.268 | 1 | |
CEC | 0.943** | 0.906** | 0.062 | 0.919** | 0.726** | 0.235 | 0.970** | 0.697** | 0.736** | 1 |
**Correlation is significant at the 0.01 level (2-tailed). *Correlation is significant at the 0.05 level (2-tailed).
Parameter | pH | ECE | OM | TN | AP | Cl− | CEC | |||
---|---|---|---|---|---|---|---|---|---|---|
Ph | 1 | |||||||||
pHCaCl2 | 0.960** | 1 | ||||||||
ECE | 0.061 | 0.027 | 1 | |||||||
OM | 0.316 | 0.172 | 0.481* | 1 | ||||||
TN | 0.682** | 0.704** | −0.245 | 0.247 | 1 | |||||
0.972** | 0.981** | 0.124 | 0.277 | 0.647** | 1 | |||||
AP | 0.261 | 0.116 | 0.395 | 0.204 | −0.051 | 0.187 | 1 | |||
0.241 | 0.203 | −0.170 | 0.249 | 0.398 | 0.132 | −0.296 | 1 | |||
Cl− | 0.558* | 0.519* | 0.612** | 0.455 | 0.000 | 0.601** | 0.405 | 0.063 | 1 | |
CEC | 0.970** | 0.981** | 0.082 | 0.261 | 0.678** | 0.997** | 0.183 | 0.145 | 0.571* | 1 |
other indicating close association of the parameters. In the cool and dry season (
The total metals concentration of namely Cd, Cr, Cu, Fe, Ni, Pb and Znin soils samples from the sites studied are presented in Tables 9-12. In each case the presented value is a mean observed in three determinations. Analysis of variance (ANOVA) revealed significant differences (p < 0.05) in the contents of all the heavy metals across seasons with exception of Cr and Zn. The concentrations across the seasons varied to a greater extent among the samples: 2.82 (site 4 and 5) - 2.86 (site 1), 1.00 (site 5) - 1.21 (site 1), 3.32 (site 4) - 3.38 (site 1) and 3.32 (site 1) - 4.31 mgkg−1 (site 5) for Cd, 52.87 (site 2) - 107.83 (site 5), 29.58 (site 5) - 32.57 (site 1), 24.44 (site 5) - 25.73 (site 1) and 27.94 (site 3) - 29.61 mgkg−1 (site 1) for Cr, 48.01 (site 4) - 48.65 (site 5), 2.22 (site 4) - 2.42 (site 2), 5.69 (site 5) - 5.81 (site 1) and 6.88 (site 2) - 7.40 mgkg−1 (site 5) for Cu, 699.74 (site 5) - 701.72 (site 1), 3156.82 (site 4) - 3162.18 (site 1), 3821.57 (site 3) - 7540.01 (site 4) and 3076.76 (site 4) - 3160.51 mgkg−1 (site 2) for Fe, 7.51 (site 4) - 7.65 (site 1), 23.82 (site 5) - 26.27 (site 1), 29.19 (site 4) - 29.56 (site 1)
Site | Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn |
---|---|---|---|---|---|---|---|---|
1 | 2.86 ± 0.06 | 53.68 ± 0.47 | 48.15 ± 0.13 | 701.72 ± 0.49 | 7.65 ± 0.01 | 137.52 ± 0.53 | 164.45 ± 0.21 | 272.95 ± 0.72 |
2 | 2.79 ± 0.04 | 52.87 ± 1.00 | 48.64 ± 0.75 | 699.94 ± 1.78 | 7.59 ± 0.08 | 137.60 ± 1.23 | 162.89 ± 0.92 | 271.82 ± 0.63 |
3 | 2.77 ± 0.10 | 53.17 ± 0.60 | 49.14 ± 1.18 | 700.61 ± 1.83 | 7.58 ± 0.09 | 137.45 ± 1.04 | 163.03 ± 1.62 | 273.32 ± 0.73 |
4 | 2.82 ± 0.08 | 53.33 ± 0.82 | 48.01 ± 0.61 | 700.94 ± 2.46 | 7.51 ± 0.06 | 136.39 ± 1.38 | 163.48 ± 1.35 | 272.30 ± 1.47 |
5 | 2.82 ± 0.05 | 107.83 ± 3.87 | 48.65 ± 1.02 | 699.74 ± 2.03 | 7.59 ± 0.10 | 136.83 ± 0.92 | 163.32 ± 0.90 | 271.30 ± 1.63 |
Control | 3.63 ± 0.21 | 47.48 ± 0.49 | 44.04 ± 1.62 | 650.2 ± 11.22 | 6.87 ± 0.23 | 123.95 ± 2.27 | 152.59 ± 3.49 | 258.68 ± 4.33 |
Site | Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn |
---|---|---|---|---|---|---|---|---|
1 | 1.21 ± 0.02 | 32.57 ± 0.30 | 2.51 ± 0.01 | 3162.18 ± 0.19 | 26.27 ± 0.15 | 15.45 ± 0.08 | 12.85 ± 0.07 | 227.52 ± 0.04 |
2 | 1.17 ± 0.01 | 31.20 ± 0.15 | 2.42 ± 0.07 | 3160.42 ± 0.23 | 24.59 ± 0.63 | 15.04 ± 0.09 | 12.18 ± 0.07 | 226.46 ± 1.11 |
3 | 1.09 ± 0.02 | 31.66 ± 0.16 | 2.24 ± 0.04 | 3158.85 ± 0.30 | 24.53 ± 0.66 | 14.61 ± 0.28 | 12.48 ± 0.13 | 225.41 ± 1.24 |
4 | 1.05 ± 0.04 | 30.42 ± 0.04 | 2.22 ± 0.10 | 3156.82 ± 0.12 | 24.70 ± 0.74 | 17.29 ± 5.20 | 12.34 ± 0.03 | 225.50 ± 1.06 |
5 | 1.00 ± 0.01 | 29.58 ± 0.02 | 2.29 ± 0.06 | 3158.68 ± 0.21 | 23.82 ± 0.10 | 14.94 ± 0.05 | 12.16 ± 0.09 | 225.15 ± 0.64 |
Control | 1.69 ± 0.14 | 13.82 ± 0.04 | 1.66 ± 0.14 | 2008.72 ± 0.76 | 11.37 ± 0.10 | 10.19 ± 0.27 | 0.18 ± 0.01 | 30.27 ± 0.30 |
Site | Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn |
---|---|---|---|---|---|---|---|---|
1 | 3.38 ± 0.01 | 25.73 ± 0.10 | 5.81 ± 0.01 | 4100.17 ± 1.46 | 29.56 ± 0.10 | 17.54 ± 0.02 | 12.76 ± 0.05 | 344.47 ± 0.64 |
2 | 3.37 ± 0.01 | 25.61 ± 0.09 | 5.74 ± 0.02 | 4099.76 ± 1.11 | 29.55 ± 0.16 | 17.48 ± 0.09 | 12.70 ± 0.04 | 343.62 ± 1.42 |
3 | 3.37 ± 0.01 | 25.56 ± 0.11 | 5.72 ± 0.02 | 3821.57 ± 11.80 | 29.41 ± 0.22 | 17.49 ± 0.06 | 12.67 ± 0.04 | 343.35 ± 0.65 |
4 | 3.32 ± 0.03 | 25.53 ± 0.09 | 5.75 ± 0.04 | 7540.01 ± 62.82 | 29.19 ± 0.47 | 17.47 ± 0.06 | 12.53 ± 0.13 | 343.10 ± 1.20 |
5 | 3.33 ± 0.02 | 25.44 ± 0.12 | 5.69 ± 0.06 | 4094.58 ± 5.90 | 29.37 ± 0.18 | 17.05 ± 0.36 | 12.58 ± 0.08 | 342.69 ± 0.17 |
Control | 2.18 ± 0.14 | 13.82 ± 0.04 | 1.37 ± 0.14 | 3186.02 ± 0.82 | 14.74 ± 0.09 | 9.71 ± 0.22 | 2.41 ± 0.14 | 34.26 ± 0.46 |
and 28.24 (site 3) ? 29.03 mgkg−1 (site 1) for Mn, and 136.39 (site 4) - 137.60 (site 2), 14.61 (site 3) - 17.29 (site 4), 17.05 (site 5) - 17.54 (site 1) and 16.96 (site 3 and 4) - 43.21 mgkg−1 (site 1)for Ni, 162.89 (site 2) - 164.45 (site 1), 12.16 (site 5) - 12.85 (site 1), 12.53 (site 4) - 12.76 (site 1) and 12.94 (site 3) - 13.74 mgkg−1 (site 1) for Pb, and 271.30 (site 5) - 273.32 (site 3), 225.15 (site 5) - 227.52 (site 1), 342.69 (site 5) - 344.47 (site 1) and 319.82 (site 4) - 321.41 mgkg−1 (site 1) for Zn in cool and dry, hot and dry, warm and wet, and warm and dry seasons, respectively.
Irrespective of sampling site, the distribution of total metals in the soil samples generally followed the order: Fe > Zn > Cr > Mn > Pb > Ni > Cu > Cd. Highest levels of Cd, Cr and Cu were found at site 5, while highest concentrations of Fe, Mn, Pb and Zn, and Ni were found at site 1 and 2, respectively. Also in all the sites, highest concentration of Cr, Cu, Ni and Pb was recorded in cool and dry season, Fe, Mn and Zn was recorded in warm and wet season, and Cd was recorded in warm and dry season.
Correlation analysis as shown in Tables 13-16 indicates significant positive correlation (p < 0.05) between Pb and Cd (cool and dry season), Cd: Cr and Zn, Cu: Zn and Fe, and Mn: Pb and Zn (hot and dry season), Cu: Cr, Cd: Mn and Pb (warm and wet season) and Mn and Fe (warm and dry season). Positive correlation of metals indicate common source of metals. As shown in the results, after the rainy season (Warm and Dry Season), there was a decrease in levels of metals across at all the sites with exception of Fe, Mn and Zn. The differences observed after rains for Fe, Mn and Zn could represent a more recent accumulation of these metals after the rainy season.
From the result as presented for the metals (Tables 9-12), it is observed that the concentrations of Cd and Zn in the soil during warm and wet, and warm and dry seasons across the sites is above 1 - 3 and 50 - 300 mg/kg recommended for these metals in soil by European Standards . The values in this study is higher than 0.27 - 1.47 and 32.30 - 98.50 mg/kg reported in soils [
Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn | |
---|---|---|---|---|---|---|---|---|
1 | 3.32 ± 0.11 | 28.35 ± 1.48 | 6.93 ± 0.40 | 3202.89 ± 5.49 | 29.03 ± 0.88 | 43.21 ± 1.28 | 13.09 ± 0.38 | 321.41 ± 2.08 |
2 | 3.54 ± 0.67 | 29.61 ± 1.30 | 6.88 ± 0.23 | 3160.51 ± 16.69 | 28.94 ± 1.15 | 17.35 ± 1.12 | 13.09 ± 0.38 | 319.96 ± 3.06 |
3 | 3.65 ± 0.38 | 27.94 ± 1.53 | 7.34 ± 0.39 | 2543.87 ± 74.42 | 28.24 ± 1.25 | 16.96 ± 0.96 | 12.94 ± 0.47 | 319.87 ± 2.98 |
4 | 4.03 ± 0.60 | 28.35 ± 2.19 | 7.20 ± 0.48 | 3076.76 ± 10.37 | 28.68 ± 1.07 | 16.96 ± 0.96 | 12.98 ± 0.70 | 319.82 ± 3.34 |
5 | 4.31 ± 0.65 | 28.58 ± 0.84 | 7.40 ± 0.60 | 3117.73 ± 5.29 | 29.14 ± 1.47 | 17.64 ± 0.80 | 13.74 ± 0.90 | 320.73 ± 2.32 |
Control | na | na | na | na | na | na | na | na |
na: not available.
Parameter | Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn |
---|---|---|---|---|---|---|---|---|
Cd | 1.000 | |||||||
Cr | 0.141 | 1.000 | ||||||
Cu | −0.802 | 0.157 | 1.000 | |||||
Fe | 0.584 | −0.586 | −0.537 | 1.000 | ||||
Mn | 0.390 | 0.072 | 0.137 | 0.249 | 1.000 | |||
Ni | −0.186 | −0.350 | 0.473 | 0.082 | 0.765 | 1.000 | ||
Pb | 0.919* | −0.093 | −0.660 | 0.821 | 0.502 | 0.009 | 1.000 | |
Zn | −0.081 | −0.703 | 0.139 | 0.733 | 0.183 | 0.376 | 0.310 | 1.000 |
*Correlation is significant at the 0.05 level (2-tailed).
Parameter | Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn |
---|---|---|---|---|---|---|---|---|
Cd | 1.000 | |||||||
Cr | 0.887* | 1.000 | ||||||
Cu | 0.850 | 0.629 | 1.000 | |||||
Fe | 0.843 | 0.728 | 0.950* | 1.0000 | ||||
Mn | 0.817 | 0.858 | 0.714 | 0.686 | 1.000 | |||
Ni | −0.169 | −0.202 | −0.271 | −0.506 | 0.165 | 1.000 | ||
Pb | 0.621 | 0.842 | 0.499 | 0.576 | 0.912* | 0.029 | 1.000 | |
Zn | 0.936* | 0.797 | 0.935* | 0.876 | 0.901* | −0.043 | 0.696 | 1.000 |
*Correlation is significant at the 0.05 level (2-tailed).
Parameter | Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn |
---|---|---|---|---|---|---|---|---|
Cd | 1.000 | |||||||
Cr | 0.789 | 1.000 | ||||||
Cu | 0.492 | 0.920* | 1.000 | |||||
Fe | −0.713 | −0.218 | 0.121 | 1.000 | ||||
Mn | 0.890* | 0.671 | 0.380 | −0.812 | 1.000 | |||
Ni | 0.570 | 0.783 | 0.733 | 0.157 | 0.251 | 1.000 | ||
Pb | 0.974** | 0.842 | 0.585 | −0.706 | 0.940* | 0.502 | 1.000 | |
Zn | 0.802 | 0.995** | 0.912* | −0.2760 | 0.703 | 0.726 | 0.866 | 1.000 |
*Correlation is significant at the 0.05 level (2-tailed). **Correlation is significant at the 0.01 level (2-tailed).
Parameter | Cd | Cr | Cu | Fe | Mn | Ni | Pb | Zn |
---|---|---|---|---|---|---|---|---|
Cd | 1 | |||||||
Cr | −0.117 | 1 | ||||||
Cu | 0.765 | −0.609 | 1 | |||||
Fe | 0.023 | 0.581 | −0.554 | 1 | ||||
Mn | 0.147 | 0.530 | −0.342 | 0.913* | 1 | |||
Ni | −0.626 | −0.180 | −0.521 | 0.391 | 0.369 | 1 | ||
Pb | 0.657 | 0.155 | 0.417 | 0.364 | 0.673 | −0.111 | 1 | |
Zn | −0.238 | −0.124 | −0.230 | 0.498 | 0.652 | 0.858 | 0.412 | 1 |
*Correlation is significant at the 0.05 level (2-tailed).
The distribution of heavy metals Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the six fractions (water soluble (FI) exchangeable (FII), carbonate bound (FIII), Fe-Mn oxide (FIV), organic bound (FV) and residual (FVI)) for all the samples are summarized in Tables 17-24. The results obtained showed that the amounts of heavy metals extracted from each fraction varied widely among the sites across seasons (p < 0.05).
As observed in
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 0.46 ± 0.03 (15.95) | 0.28 ± 0.01 (9.90) | 0.44 ± 0.00 (15.37) | 0.42 ± 0.01 (14.55) | 0.35 ± 0.01 (12.11) | 0.92 ± 0.00 (32.13) |
Hot and dry | 0.00 ± 0.01 (0.28) | 0.04 ± 0.00 (3.07) | 0.07 ± 0.00 (6.16) | 0.42 ± 0.01 (35.10) | 0.24 ± 0.01 (20.18) | 0.42 ± 0.00 (35.21) | |
Warm and wet | 0.03 ± 0.00 (0.94) | 0.42 ± 0.00 (12.48) | 0.74 ± 0.00 (21.84) | 0.84 ± 0.00 (24.90) | 0.42 ± 0.00 (12.52) | 0.92 ± 0.00 (27.33) | |
Warm and dry | 0.06 ± 0.00 (1.79) | 0.65 ± 0.01 (19.41) | 0.85 ± 0.01 (25.48) | 0.66 ± 0.02 (19.96) | 0.51 ± 0.03 (15.29) | 0.60 ± 0.04 (18.07) | |
2 | Cool and dry | 0.43 ± 0.01 (15.55) | 0.28 ± 0.01 (10.05) | 0.43 ± 0.01 (15.31) | 0.41 ± 0.01 (14.59) | 0.33 ± 0.01 (11.72) | 0.91 ± 0.01 (32.78) |
Hot and dry | 0.00 ± 0.00 (0.09) | 0.03 ± 0.00 (2.26) | 0.07 ± 0.00 (6.28) | 0.41 ± 0.01 (35.41) | 0.23 ± 0.00 (19.70) | 0.42 ± 0.00 (36.26) | |
Warm and wet | 0.03 ± 0.00 (1.00) | 0.42 ± 0.00 (12.31) | 0.74 ± 0.00 (21.86) | 0.84 ± 0.00 (24.93) | 0.42 ± 0.00 (12.50) | 0.92 ± 0.00 (27.40) | |
Warm and dry | 0.07 ± 0.02 (1.92) | 0.69 ± 0.05 (19.43) | 0.90 ± 0.12 (25.31) | 0.72 ± 0.03 (20.45) | 0.36 ± 0.26 (10.11) | 0.81 ± 0.19 (22.77) | |
3 | Cool and dry | 0.46 ± 0.02 (16.49) | 0.28 ± 0.01 (10.23) | 0.40 ± 0.03 (14.44) | 0.40 ± 0.02 (14.56) | 0.32 ± 0.02 (11.43) | 0.91 ± 0.01 (32.85) |
Hot and dry | 0.00 ± 0.00 (0.03) | 0.02 ± 0.00 (1.98) | 0.07 ± 0.00 (6.38) | 0.36 ± 0.01 (32.84) | 0.22 ± 0.01 (19.95) | 0.42 ± 0.00 (38.82) | |
Warm and wet | 0.03 ± 0.00 (0.92) | 0.42 ± 0.00 (12.34) | 0.73 ± 0.00 (21.82) | 0.84 ± 0.00 (24.92) | 0.42 ± 0.00 (12.57) | 0.92 ± 0.00 (27.43) | |
Warm and dry | 0.10 ± 0.05 (2.71) | 0.74 ± 0.01 (20.26) | 0.89 ± 0.03 (24.27) | 0.61 ± 0.06 (16.61) | 0.55 ± 0.04 (14.96) | 0.77 ± 0.20 (21.20) | |
4 | Cool and dry | 0.47 ± 0.01 (16.69) | 0.28 ± 0.01 (10.06) | 0.41 ± 0.02 (14.67) | 0.40 ± 0.03 (14.20) | 0.33 ± 0.01 (11.83) | 0.92 ± 0.01 (32.54) |
Hot and dry | 0.00 ± 0.00 (0.03) | 0.02 ± 0.00 (2.18) | 0.06 ± 0.01 (5.67) | 0.36 ± 0.01 (33.90) | 0.19 ± 0.02 (18.37) | 0.42 ± 0.00 (39.85) | |
Warm and wet | 0.03 ± 0.00 (0.93) | 0.42 ± 0.00 (12.68) | 0.70 ± 0.01 (20.95) | 0.84 ± 0.00 (25.25) | 0.41 ± 0.01 (12.39) | 0.92 ± 0.00 (27.80) | |
Warm and dry | 0.11 ± 0.06 (2.72) | 0.75 ± 0.02 (18.52) | 0.80 ± 0.04 (19.94) | 0.68 ± 0.02 (16.81) | 0.94 ± 0.22 (23.33) | 0.75 ± 0.24 (18.69) | |
5 | Cool and dry | 0.44 ± 0.01 (15.48) | 0.28 ± 0.00 (9.93) | 0.43 ± 0.01 (15.25) | 0.41 ± 0.01 (14.66) | 0.34 ± 0.02 (12.17) | 0.92 ± 0.01 (32.51) |
Hot and dry | 0.00 ± 0.00 (0.10) | 0.02 ± 0.00 (1.52) | 0.06 ± 0.00 (5.58) | 0.34 ± 0.01 (33.52) | 0.17 ± 0.01 (17.26) | 0.42 ± 0.00 (42.02) | |
Warm and wet | 0.03 ± 0.00 (0.90) | 0.42 ± 0.00 (12.47) | 0.72 ± 0.00 (21.65) | 0.84 ± 0.00 (25.08) | 0.41 ± 0.01 (12.34) | 0.92 ± 0.00 (27.56) | |
warm and dry | 0.10 ± 0.07 (2.26) | 0.65 ± 0.08 (15.12) | 0.99 ± 0.12 (22.87) | 0.94 ± 0.17 (21.81) | 0.98 ± 0.12 (22.69) | 0.66 ± 0.08 (15.25) | |
Control | Cool and dry | 0.20 ± 0.00 (5.50) | 0.90 ± 0.02 (24.77) | 0.74 ± 0.08 (20.46) | 0.43 ± 0.02 (11.74) | 0.45 ± 0.08 (12.48) | 0.91 ± 0.01 (25.05) |
Hot and dry | 0.02 ± 0.00 (1.26) | 0.01 ± 0.01 (0.79) | 0.74 ± 0.08 (44.07) | 0.46 ± 0.05 (27.27) | 0.03 ± 0.01 (1.58) | 0.42 ± 0.00 (25.02) | |
Warm and wet | 0.02 ± 0.00 (0.98) | 0.01 ± 0.01 (0.61) | 0.74 ± 0.08 (34.04) | 0.46 ± 0.05 (21.07) | 0.03 ± 0.01 (1.22) | 0.92 ± 0.00 (42.09) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction; na: not available.
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 0.73 ± 0.01 (1.36) | 1.45 ± 0.01 (2.70) | 1.78 ± 0.01 (3.32) | 0.73 ± 0.01 (1.37) | 2.52 ± 0.01 (4.69) | 46.46 ± 0.42 (86.56) |
Hot and dry | 2.26 ± 0.25 (6.95) | 3.60 ± 0.03 (11.04) | 3.59 ± 0.00 (11.01) | 3.73 ± 0.01 (11.44) | 5.67 ± 0.00 (17.42) | 13.72 ± 0.02 (42.13) | |
Warm and wet | 0.45 ± 0.01 (1.75) | 1.77 ± 0.01 (6.88) | 2.56 ± 0.01 (9.95) | 1.84 ± 0.00 (7.16) | 5.35 ± 0.01 (20.79) | 13.76 ± 0.06 (53.47) | |
Warm and dry | 1.49 ± 0.04 (5.26) | 1.78 ± 0.09 (6.27) | 2.32 ± 0.30 (8.18) | 1.78 ± 0.06 (6.29) | 5.50 ± 0.45 (19.39) | 15.48 ± 0.55 (54.61) | |
2 | Cool and dry | 0.70 ± 0.01 (1.32) | 1.45 ± 0.01 (2.74) | 1.74 ± 0.02 (3.28) | 0.70 ± 0.01 (1.32) | 2.49 ± 0.02 (4.70) | 45.80 ± 0.93 (86.62) |
Hot and dry | 1.79 ± 0.07 (5.75) | 2.74 ± 0.00 (8.79) | 3.61 ± 0.06 (11.57) | 3.66 ± 0.02 (11.72) | 5.67 ± 0.00 (18.18) | 13.72 ± 0.01 (43.99) | |
Warm and wet | 0.43 ± 0.01 (1.68) | 1.71 ± 0.04 (6.66) | 2.53 ± 0.01 (9.89) | 1.84 ± 0.00 (7.18) | 5.32 ± 0.01 (20.78) | 13.78 ± 0.03 (53.80) | |
Warm and dry | 1.45 ± 0.09 (4.90) | 1.86 ± 0.09 (6.27) | 2.53 ± 0.04 (8.56) | 1.76 ± 0.03 (5.96) | 5.56 ± 0.50 (18.77) | 16.45 ± 0.55 (55.55) | |
3 | Cool and dry | 0.75 ± 0.02 (1.41) | 1.41 ± 0.03 (2.65) | 1.74 ± 0.07 (3.28) | 0.68 ± 0.03 (1.27) | 2.43 ± 0.08 (4.58) | 46.16 ± 0.38 (86.81) |
Hot and dry | 1.62 ± 0.07 (5.11) | 3.53 ± 0.01 (11.15) | 3.64 ± 0.00 (11.51) | 3.61 ± 0.05 (11.40) | 5.58 ± 0.00 (17.61) | 13.68 ± 0.02 (43.22) | |
Warm and wet | 0.43 ± 0.02 (1.70) | 1.72 ± 0.01 (6.72) | 2.52 ± 0.01 (9.86) | 1.84 ± 0.00 (7.18) | 5.33 ± 0.03 (20.85) | 13.73 ± 0.06 (53.70) | |
Warm and dry | 1.57 ± 0.06 (5.63) | 1.80 ± 0.04 (6.44) | 2.27 ± 0.35 (8.14) | 1.80 ± 0.05 (6.45) | 5.49 ± 0.47 (19.63) | 15.01 ± 0.57 (53.71) |
4 | Cool and dry | 0.74 ± 0.02 (1.38) | 1.47 ± 0.06 (2.76) | 1.68 ± 0.15 (3.15) | 0.71 ± 0.02 (1.33) | 2.38 ± 0.14 (4.46) | 46.35 ± 0.44 (86.91) |
---|---|---|---|---|---|---|---|
Hot and dry | 1.43 ± 0.01 (4.70) | 2.75 ± 0.01 (9.06) | 3.46 ± 0.01 (11.38) | 3.53 ± 0.01 (11.62) | 5.56 ± 0.00 (18.29) | 13.68 ± 0.01 (44.96) | |
Warm and wet | 0.44 ± 0.01 (1.74) | 1.69 ± 0.02 (6.63) | 2.52 ± 0.01 (9.87) | 1.83 ± 0.00 (7.18) | 5.32 ± 0.02 (20.82) | 13.72 ± 0.04 (53.75) | |
Warm and dry | 1.71 ± 0.32 (6.04) | 1.80 ± 0.05 (6.36) | 2.49 ± 0.07 (8.79) | 1.75 ± 0.05 (6.17) | 5.80 ± 0.05 (20.44) | 14.80 ± 1.65 (52.19) | |
5 | Cool and dry | 0.69 ± 0.02 (0.64) | 1.42 ± 0.03 (1.32) | 55.87 ± 3.65 (51.81) | 0.74 ± 0.06 (0.69) | 2.39 ± 0.12 (2.21) | 46.72 ± 0.01 (43.33) |
Hot and dry | 1.33 ± 0.01 (4.49) | 1.87 ± 0.00 (6.34) | 3.46 ± 0.00 (11.71) | 3.63 ± 0.01 (12.26) | 5.57 ± 0.01 (18.84) | 13.71 ± 0.01 (46.37) | |
Warm and wet | 0.39 ± 0.03 (1.52) | 1.72 ± 0.04 (6.76) | 2.47 ± 0.01 (9.71) | 1.84 ± 0.00 (7.22) | 5.33 ± 0.01 (20.95) | 13.70 ± 0.03 (53.85) | |
Warm and dry | 1.53 ± 0.11 (5.35) | 1.76 ± 0.10 (6.16) | 2.58 ± 0.06 (9.01) | 1.81 ± 0.04 (6.33) | 5.71 ± 0.04 (19.96) | 15.20 ± 0.50 (53.18) | |
Control | Cool and dry | 0.02 ± 0.01 (0.04) | 0.03 ± 0.01 (0.06) | 0.01 ± 0.01 (0.03) | 0.32 ± 0.07 (0.67) | 0.09 ± 0.10 (0.20) | 47.00 ± 0.01 (99.00) |
Hot and dry | 0.02 ± 0.01 (0.14) | 0.03 ± 0.01 (0.19) | 0.01 ± 0.01 (0.10) | 0.02 ± 0.01 (0.17) | 0.03 ± 0.01 (0.24) | 13.71 ± 0.01 (99.16) | |
Warm and wet | 0.02 ± 0.01 (0.14) | 0.03 ± 0.01 (0.19) | 0.01 ± 0.01 (0.10) | 0.02 ± 0.01 (0.17) | 0.03 ± 0.01 (0.24) | 13.71 ± 0.01 (99.16) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction.
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 0.72 ± 0.01 (1.50) | 2.90 ± 0.02 (6.02) | 1.44 ± 0.02 (2.99) | 1.23 ± 0.06 (2.56) | 1.67 ± 0.01 (3.48) | 40.19 ± 0.01 (83.46) |
Hot and dry | 0.28 ± 0.01 (11.320 | 0.06v0.00 (2.52) | 0.32 ± 0.00 (12.92) | 0.96 ± 0.01 (38.38) | 0.38 ± 0.00 (14.94) | 0.50 ± 0.00 (19.92) | |
Warm and wet | 0.27 ± 0.00 (4.61) | 0.37 ± 0.00 (6.39) | 3.83 ± 0.01 (65.93) | 0.74 ± 0.00 (12.78) | 0.38 ± 0.00 (6.45) | 0.22 ± 0.00 (3.85) | |
Warm and dry | 0.86 ± 0.05 (12.42) | 0.57 ± 0.05 (8.23) | 1.69 ± 0.11 (24.35) | 1.47 ± 0.05 (21.27) | 1.60 ± 0.04 (23.10) | 0.74 ± 0.09 (10.64) | |
2 | Cool and dry | 0.72 ± 0.02 (1.48) | 2.92 ± 0.06 (6.01) | 1.36 ± 0.06 (2.80) | 1.14 ± 0.06 (2.34) | 1.62 ± 0.06 (3.34) | 40.87 ± 0.50 (84.04) |
Hot and dry | 0.26 ± 0.05 (10.82) | 0.07 ± 0.00 (2.94) | 0.32 ± 0.00 (13.27) | 0.95 ± 0.01 (39.05) | 0.37 ± 0.00 (15.21) | 0.45 ± 0.01 (18.70) | |
Warm and wet | 0.27 ± 0.00 (4.67) | 0.37 ± 0.00 (6.42) | 3.78 ± 0.01 (65.82) | 0.74 ± 0.00 (12.87) | 0.37 ± 0.00 (6.42) | 0.22 ± 0.00 (3.80) | |
Warm and dry | 0.86 ± 0.06 (12.54) | 0.62 ± 0.03 (9.04) | 1.64 ± 0.07 (23.78) | 1.48 ± 0.03 (21.51) | 1.61 ± 0.03 (23.45) | 0.67 ± 0.01 (9.69) | |
3 | Cool and dry | 0.74 ± 0.02 (1.50) | 2.89 ± 0.01 (5.88) | 1.48 ± 0.17 (3.01) | 1.10 ± 0.12 (2.24) | 1.60 ± 0.03 (3.26) | 41.33 ± 0.83 (84.11) |
Hot and dry | 0.16 ± 0.01 (7.06) | 0.06 ± 0.00 (2.47) | 0.31 ± 0.00 (14.02) | 0.86 ± 0.01 (38.48) | 0.37 ± 0.00 (16.58) | 0.48 ± 0.03 (21.39) | |
Warm and wet | 0.27 ± 0.00 (4.66) | 0.37 ± 0.00 (6.44) | 3.76 ± 0.01 (65.72) | 0.74 ± 0.00 (12.87) | 0.37 ± 0.00 (6.51) | 0.22 ± 0.00 (3.80) | |
Warm and dry | 1.08 ± 0.03 (14.69) | 0.72 ± 0.03 (9.82) | 1.68 ± 0.06 (22.80) | 1.45 ± 0.02 (19.76) | 1.60 ± 0.04 (21.80) | 0.82 ± 0.21 (11.13) | |
4 | Cool and dry | 0.70 ± 0.02 (1.46) | 2.83 ± 0.05 (5.89) | 1.38 ± 0.05 (2.87) | 1.13 ± 0.15 (2.36) | 1.61 ± 0.05 (3.36) | 40.36 ± 0.30 (84.06) |
Hot and dry | 0.26 ± 0.05 (11.48) | 0.05 ± 0.00 (2.10) | 0.31 ± 0.00 (14.03) | 0.77 ± 0.01 (34.62) | 0.37 ± 0.00 (16.64) | 0.47 ± 0.03 (21.13) | |
Warm and wet | 0.26 ± 0.00 (4.57) | 0.37 ± 0.00 (6.38) | 3.80 ± 0.02 (66.03) | 0.74 ± 0.00 (12.80) | 0.37 ± 0.00 (6.44) | 0.22 ± 0.01 (3.78) | |
Warm and dry | 0.99 ± 0.07 (13.81) | 0.63 ± 0.04 (8.80) | 1.66 ± 0.08 (23.05) | 1.41 ± 0.05 (19.53) | 1.81 ± 0.20 (25.09) | 0.70 ± 0.04 (9.72) | |
5 | Cool and dry | 0.70 ± 0.02 (1.45) | 2.80 ± 0.07 (5.76) | 1.42 ± 0.12 (2.91) | 1.10 ± 0.11 (2.26) | 1.67 ± 0.03 (3.43) | 40.96 ± 0.67 (84.20) |
Hot and dry | 0.22 ± 0.01 (9.53) | 0.04 ± 0.00 (1.92) | 0.32 ± 0.01 (13.87) | 0.84 ± 0.00 (36.75) | 0.37 ± 0.00 (16.14) | 0.50 ± 0.03 (21.79) | |
Warm and wet | 0.24 ± 0.04 (4.20) | 0.37 ± 0.00 (6.47) | 3.76 ± 0.02 (66.09) | 0.74 ± 0.00 (12.91) | 0.37 ± 0.00 (6.50) | 0.22 ± 0.00 (3.83) | |
Warm and dry | 1.02 ± 0.08 (13.81) | 0.58 ± 0.05 (7.90) | 1.62 ± 0.09 (21.90) | 1.52 ± 0.04 (20.55) | 1.84 ± 0.18 (24.83) | 0.81 ± 0.17 (11.01) | |
Control | Cool and dry | 0.02 ± 0.01 (0.05) | 0.95 ± 0.06 (2.16) | 0.70 ± 0.03 (1.58) | 0.79 ± 0.35 (1.80) | 0.91 ± 0.60 (2.07) | 40.68 ± 0.58 (92.35) |
Hot and dry | 0.02 ± 0.01 (1.21) | 0.01 ± 0.01 (0.84) | 0.06 ± 0.01 (3.42) | 0.51 ± 0.05 (30.97) | 0.54 ± 0.06 (32.38) | 0.52 ± 0.01 (31.17) | |
Warm and wet | 0.02 ± 0.01 (1.47) | 0.01 ± 0.01 (1.03) | 0.06 ± 0.01 (4.15) | 0.51 ± 0.05 (37.61) | 0.54 ± 0.06 (39.32) | 0.22 ± 0.01 (16.43) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction.
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 5.54 ± 0.10 (0.79) | 25.13 ± 0.23 (3.58) | 16.85 ± 0.01 (2.40) | 14.05 ± 0.01 (2.00) | 8.42 ± 0.02 (1.20) | 631.73 ± 0.12 (90.03) |
Hot and dry | 13.93 ± 0.01 (.044) | 6.17 ± 0.01 (0.20) | 92.98 ± 0.01 (2.94) | 23.40 ± 0.10 (0.74) | 1030.24 ± 0.01 (32.58) | 1995.47 ± 0.06 (63.10 | |
Warm and wet | 10.42 ± 0.02 (0.25) | 9.42 ± 0.01 (0.23) | 45.80 ± 0.03 (1.12) | 24.36 ± 0.04 (0.59) | 836.01 ± 1.21 (20.39) | 3173.17 ± 0.15 (77.42) | |
Warm and dry | 12.19 ± 0.35 (0.38) | 9.34 ± 0.31 (0.29) | 46.89 ± 1.48 (1.46) | 23.26 ± 0.43 (0.73) | 978.28 ± 1.53 (30.54) | 2132.94 ± 1.38 (66.59) | |
2 | Cool and dry | 5.55 ± 0.03 (0.79) | 25.06 ± 0.33 (3.58) | 16.47 ± 0.43 (2.35) | 13.96 ± 0.07 (1.99) | 8.35 ± 0.34 (1.19) | 630.55 ± 0.59 (90.09) |
Hot and dry | 12.81 ± 0.06 (0.41) | 6.04 ± 0.00 (0.19) | 92.91 ± 0.06 (2.94) | 23.19 ± 0.02 (0.73) | 1030.20 ± 0.03 (32.60) | 1995.27 ± 0.06 (63.13) | |
Warm and wet | 10.14 ± 0.34 (0.25) | 9.40 ± 0.02 (0.23) | 45.70 ± 0.06 (1.11) | 24.41 ± 0.04 (0.60) | 836.70 ± 0.56 (20.41) | 3173.40 ± 0.10 (77.40) | |
Warm and dry | 12.11 ± 0.38 (0.38) | 9.74 ± 0.10 (0.31) | 45.81 ± 1.67 (1.45) | 22.93 ± 0.52 (0.73) | 940.74 ± 5.83 (29.77) | 2129.18 ± 9.03 (67.37) | |
3 | Cool and dry | 5.63 ± 0.02 (0.80) | 25.18 ± 0.17 (3.59) | 16.01 ± 1.08 (2.29) | 14.05 ± 0.06 (2.00) | 8.36 ± 0.07 (1.19) | 631.37 ± 0.43 (90.12) |
Hot and dry | 11.95 ± 0.01 (0.38) | 5.75 ± 0.01 (0.18) | 92.80 ± 0.05 (2.94) | 23.16 ± 0.01 (0.73) | 1030.17 ± 0.01 (32.61) | 1995.03 ± 0.22 (63.16) | |
Warm and wet | 10.40 ± 0.04 (0.27) | 9.37 ± 0.02 (0.25) | 44.84 ± 0.06 (1.17) | 24.29 ± 0.30 (0.64) | 560.37 ± 478.01 (14.66) | 3172.30 ± 3.38 (83.01) | |
Warm and dry | 11.77 ± 0.05 (0.46) | 9.37 ± 0.43 (0.37) | 47.25 ± 0.50 (1.86) | 23.61 ± 0.11 (0.93) | 921.13 ± 1.33 (36.21) | 1530.73 ± 32.29 (60.17) | |
4 | Cool and dry | 5.64 ± 0.02 (0.80) | 25.11 ± 0.58 (3.58) | 16.28 ± 0.41 (2.32) | 13.96 ± 0.07 (1.99) | 8.43 ± 0.03 (1.20) | 631.53 ± 1.36 (90.10) |
Hot and dry | 10.60 ± 0.02 (0.34) | 5.65 ± 0.01 (0.18) | 92.77 ± 0.01 (2.94) | 22.86 ± 0.01 (0.72) | 1030.22 ± 0.01 (32.63) | 1994.68 ± 0.08 (63.19) | |
Warm and wet | 3452.05 ± 61.68 (45.78) | 9.34 ± 0.01 (0.12) | 44.83 ± 0.06 (0.59) | 24.00 ± 0.29 (0.32) | 836.63 ± 0.58 (11.10) | 3173.17 ± 0.59 (42.08) | |
Warm and dry | 12.18 ± 0.31 (0.40) | 8.96 ± 0.43 (0.29) | 47.52 ± 0.78 (1.54) | 22.70 ± 0.85 (0.74) | 884.79 ± 8.90 (28.76) | 2100.62 ± 8.00 (68.27) | |
5 | Cool and dry | 4.90 ± 0.59 (0.70) | 25.11 ± 0.21 (3.59) | 16.42 ± 0.59 (2.35) | 13.98 ± 0.08 (2.00) | 8.48 ± 0.06 (1.21) | 630.86 ± 0.50 (90.16) |
Hot and dry | 12.58 ± 0.06 (0.40) | 5.34 ± 0.00 (0.17) | 92.76 ± 0.01 (2.94) | 22.77 ± 0.02 (0.72) | 1029.76 ± 0.01 (32.60) | 1995.47 ± 0.12 (63.17) | |
Warm and wet | 10.36 ± 0.05 (0.25) | 9.32 ± 0.01 (0.23) | 44.36 ± 0.33 (1.08) | 24.01 ± 0.34 (0.59) | 834.96 ± 1.46 (20.39) | 3171.57 ± 3.72 (77.46) | |
Warm and dry | 12.13 ± 0.31 (0.39) | 9.35 ± 0.07 (0.30) | 46.63 ± 0.79 (1.50) | 23.89 ± 0.29 (0.77) | 976.64 ± 10.05 (31.33) | 2049.09 ± 7.79 (65.72) | |
Control | Cool and dry | 4.21 ± 0.21 (0.65) | 2.51 ± 0.21 (0.39) | 2.36 ± 0.18 (0.36) | 6.28 ± 6.68 (0.97) | 4.54 ± 3.35 (0.70) | 630.33 ± 0.58 (96.94) |
Hot and dry | 4.32 ± 0.11 (0.22) | 2.22 ± 0.01 (0.11) | 2.36 ± 0.18 (0.12) | 2.41 ± 0.11 (0.12) | 2.53 ± 0.13 (0.13) | 1994.87 ± 0.23 (99.31) | |
Warm and wet | 4.32 ± 0.11 (0.14) | 2.22 ± 0.01 (0.07) | 2.36 ± 0.18 (0.07) | 2.41 ± 0.11 (0.08) | 2.53 ± 0.13 (0.08) | 3172.17 ± 0.29 (9.57) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction.
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 0.16 ± 0.00 (2.03) | 0.20 ± 0.00 (2.66) | 0.56 ± 0.00 (7.34) | 0.10 ± 0.00 (1.33) | 0.25 ± 0.00 (93.32) | 6.37 ± 0.01 (83.32) |
Hot and dry | 0.42 ± 0.00 (1.61) | 12.74 ± 0.04 (48.49) | 0.04 ± 0.00 (0.14) | 0.23 ± 0.00 (0.89) | 1.74 ± 0.00 (6.61) | 11.10 ± 0.10 (42.26) | |
Warm and wet | 0.57 ± 0.00 (1.94) | 13.28 ± 0.06 (44.93) | 0.06 ± 0.00 (0.21) | 0.43 ± 0.00 (1.46) | 1.80 ± 0.03 (6.08) | 13.42 ± 0.02 (45.38) | |
Warm and dry | 1.44 ± 0.12 (4.95) | 13.52 ± 0.10 (46.58) | 0.11 ± 0.04 (0.38) | 0.39 ± 0.03 (1.33) | 1.64 ± 0.05 (5.65) | 11.93 ± 0.55 (41.11) | |
2 | Cool and dry | 0.15 ± 0.00 (2.02) | 0.20 ± 0.00 (2.66) | 0.52 ± 0.04 (6.85) | 0.11 ± 0.00 (1.41) | 0.25 ± 0.01 (3.28) | 6.36 ± 0.04 (83.79) |
Hot and dry | 0.44 ± 0.02 (1.77) | 11.75 ± 0.01 (47.79) | 0.04 ± 0.00 (0.15) | 0.22 ± 0.01 (0.91) | 1.73 ± 0.00 (7.05) | 10.41 ± 0.60 (42.33) | |
Warm and wet | 0.56 ± 0.02 (1.90) | 13.32 ± 0.10 (45.07) | 0.06 ± 0.000 (0.21) | 0.40 ± 0.01 (1.35) | 1.79 ± 0.02 (6.05) | 13.42 ± 0.01 (45.42) | |
Warm and dry | 1.34 ± 0.10 (4.64) | 13.05 ± 0.44 (45.11) | 0.12 ± 0.04 (0.40) | 0.39 ± 0.03 (1.35) | 1.72 ± 0.04 (5.94) | 12.32 ± 0.50 (42.56) | |
3 | Cool and dry | 0.16 ± 0..00 (2.05) | 0.20 ± 0.00 (2.68) | 0.51 ± 0.05 (6.78) | 0.10 ± 0.00 (1.31) | 0.25 ± 0.00 (3.28) | 6.36 ± 0.04 (83.91) |
Hot and dry | 0.49 ± 0.05 (2.02) | 11.65 ± 0.01 (47.50) | 0.03 ± 0.00 (0.13) | 0.21 ± 0.00 (0.86) | 1.73 ± 0.00 (7.06) | 10.41 ± 0.60 (42.43) | |
Warm and wet | 0.59 ± 0.03 (2.00) | 13.14 ± 0.14 (44.69) | 0.06 ± 0.00 (0.21) | 0.42 ± 0.01 (1.42) | 1.81 ± 0.01 (6.14) | 13.39 ± 0.03 (45.53) | |
Warm and dry | 1.23 ± 0.15 (4.36) | 12.82 ± 0.46 (45.39) | 0.10 ± 0.00 (0.34) | 0.39 ± 0.02 (1.37) | 1.65 ± 0.10 (5.84) | 12.06 ± 0.51 (42.71) |
4 | Cool and dry | 0.15 ± 0.00 (2.01) | 0.20 ± 0.00 (2.69) | 0.50 ± 0.01 (6.66) | 0.10 ± 0.00 (1.36) | 0.25 ± 0.00 (3.37) | 6.30 ± 0.04 (83..91) |
---|---|---|---|---|---|---|---|
Hot and dry | 0.48 ± 0.04 (1.93) | 11.52 ± 0.04 (46.62) | 0.03 ± 0.00 (0.11) | 0.20 ± 0.00 (0.80) | 1.70 ± 0.03 (6.88) | 10.78 ± 0.64 (43.66) | |
Warm and wet | 0.53 ± 0.04 (1.83) | 13.00 ± 0.37 (44.53) | 0.06 ± 0.00 (0.21) | 0.43 ± 0.00 (1.46) | 1.77 ± 0.02 (6.06) | 13.40 ± 0.03 (45.91 | |
Warm and dry | 1.14 ± 0.08 (3.97) | 13.22 ± 0.43 (46.08) | 0.12 ± 0.02 (0.40) | 0.41 ± 0.03 (1.42) | 1.72 ± 0.04 (6.01) | 12.08 ± 0.48 (42.11) | |
5 | Cool and dry | 0.15 ± 0.00 (1.99) | 0.20 ± 0.00 (2.64) | 0.54 ± 0.04 (7.06) | 0.10 ± 0.01 (1.37) | 0.25 ± 0.00 (3.34) | 6.35 ± 0.05 (83.59) |
Hot and dry | 0.46 ± 0.05 (1.93) | 11.40 ± 0.03 (47.85) | 0.03 ± 0.00 (0.14) | 0.20 ± 0.00 (0.82) | 1.68 ± 0.01 (7.06) | 10.05 ± 0.01 (42.20) | |
Warm and wet | 0.54 ± 0.05 (1.84) | 13.20 ± 0.02 (44.95) | 0.05 ± 0.00 (0.19) | 0.42 ± 0.02 (1.42) | 1.76 ± 0.06 (5.98) | 13.40 ± 0.03 (45.63) | |
Warm and dry | 1.28 ± 0.19 (4.38) | 13.14 ± 0.33 (45.11) | 0.10 ± 0.02 (0.33) | 0.38 ± 0.02 (1.29) | 1.84 ± 0.16 (6.33) | 12.40 ± 0.75 (42.55) | |
Control | Cool and dry | 0.05 ± 0.00 (0.78) | 0.02 ± 0.02 (0.26) | 0.07 ± 0.01 (1.07) | 0.07 ± 0.03 (1.05) | 0.12 ± 0.11 (1.78) | 6.53 ± 0.06 (95.05) |
Hot and dry | 0.05 ± 0.00 (0.48) | 1.18 ± 0.06 (10.41) | 0.00 ± 0.00 (0.03) | 0.06 ± 0.00 (0.50) | 0.06 ± 0.00 (0.50) | 10.02 ± 0.03 (88.08) | |
Warm and wet | 0.05 ± 0.00 (0.37) | 1.18 ± 0.06 (8.03) | 0.00 ± 0.00 (0.02) | 0.06 ± 0.00 (0.39) | 0.06 ± 0.00 (0.38) | 13.39 ± 0.02 (90.81) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction.
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 2.53 ± 0.02 (1.84) | 7.34 ± 0.02 (5.34) | 6.21 ± 0.02 (4.52) | 3.23 ± 0.02 (2.35) | 2.4 ± 0.04 (1.99) | 115.47 ± 0.42 (83.87) |
Hot and dry | 0.66 ± 0.01 (4.27) | 1.91 ± 0.00 (12.38) | 1.65 ± 0.01 (10.66) | 0.76 ± 0.01 (4.90) | 5.33 ± 0.06 (34.51) | 5.15 ± 0.01 (33.29) | |
Warm and wet | 0.54 ± 0.00 (3.06) | 2.01 ± 0.00 (11.48) | 1.76 ± 0.00 (10.05) | 0.94 ± 0.00 (5.33) | 7.64 ± 0.01 (43.57) | 4..65 ± 0.00 (26.51) | |
Warm and dry | 6.52 ± 0.58 (61.38) | 1.31 ± 0.06 (3.02) | 1.82 ± 0.07 (4.20) | 1.47 ± 0.05 (3.41) | 6.71 ± 0.11 (15.54) | 5.38 ± 0.42 (12.45) | |
2 | Cool and dry | 2.52 ± 0.01 (1.83) | 7.35 ± 0.02 (5.34) | 6.06 ± 0.21 (4.40) | 3.25 ± 0.06 (2.36) | 2.71 ± 0.04 (1.97) | 115.70 ± 0.89 (84.09) |
Hot and dry | 0.62 ± 0.04 (4.11) | 1.85 ± 0.00 (12.33) | 1.57 ± 0.02 (10.42) | 0.68 ± 0.01 (4.50) | 5.19 ± 0.01 (34.54) | 5.13 ± 0.01 (34.10) | |
Warm and wet | 0.45 ± 0.00 (3.06) | 2.02 ± 0.01 (11.53) | 1.76 ± 0.00 (10.05) | 0.94 ± 0.00 (5.36) | 7.61 ± 0.04 (43.52) | 4.63 ± 0.04 (26..48) | |
Warm and dry | 0.85 ± 0.03 (4.90) | 1.37 ± 0.07 (7.90) | 1.83 ± 0.08 (10.57) | 1.49 ± 0.03 (8.57) | 6.44 ± 0.48 (37.10) | 5.37 ± 0.43 (30.96) | |
3 | Cool and dry | 2.53 ± 0.01 (1.84) | 7.34 ± 0.02 (5.34) | 6.25 ± 0.33 (4.54) | 3.17 ± 0.17 (2.30) | 2.73 ± 0.03 (1.98) | 115.43 ± 0.49 (83.98) |
Hot and dry | 0.58 ± 0.05 (3.98) | 1.79 ± 0.00 (12.22) | 1.55 ± 0.01 (10.59) | 0.66 ± 0.01 (4.49) | 5.17 ± 0.01 (35.36) | 4.87 ± 0.21 (33.36) | |
Warm and wet | 0.53 ± 0.01 (3.05) | 2.01 ± 0.00 (11.51) | 1.76 ± 0.00 (10.08) | 0.93 ± 0.00 (5.34) | 7.63 ± 0.01 (43.63) | 4.62 ± 0.04 (26.40) | |
Warm and dry | 0.98 ± 0.07 (5.76) | 1.43 ± 0.10 (8.43) | 1.81 ± 0.06 (10.67) | 1.49 ± 0.04 (8.79) | 6.14 ± 0.38 (3623) | 5.11 ± 0.31 (30.12) | |
4 | Cool and dry | 2.54 ± 0.02 (1.86) | 7.11 ± 0.22 (5.21) | 6.03 ± 0.16 (4.42) | 3.18 ± 0.16 (2.33) | 2.72 ± 0.02 (2.00) | 114.81 ± 0.81 (84.18) |
Hot and dry | 3.70 ± 0.15 (21.39) | 1.76 ± 0.00 (10.15) | 1.49 ± 0.04 (8.60) | 0.74 ± 0.01 (4.26) | 4.87 ± 0.01 (28.18) | 4.74 ± 0.01 (27.43) | |
Warm and wet | 0.52 ± 0.02 (2.98) | 2.01 ± 0.00 (11.51) | 1.76 ± 0.00 (10.07) | 0.91 ± 0.02 (5.19) | 7.63 ± 0.02 (43.65) | 4.65 ± 0.01 (26.59) | |
Warm and dry | 0.98 ± 0.07 (5.76) | 1.43 ± 0.10 (8.43) | 1.81 ± 0.06 (10.67) | 1.49 ± 0.04 (8.79) | 6.14 ± 0.38 (36.23) | 5.11 ± 0.31 (30.12) | |
5 | Cool and dry | 2.52 ± 0.05 (1.84) | 7.36 ± 0.05 (5.38) | 6.11 ± 0.22 (4.47) | 3.11 ± 0.11 (2.27) | 2.65 ± 0.16 (1.94) | 115.08 ± 0.33 (84.10) |
Hot and dry | 0.63 ± 0.02 (4.23) | 1.78 ± 0.00 (11.89) | 1.46 ± 0.02 (9.80) | 0.72 ± 0.01 (4.80) | 5.22 ± 0.01 (34.97) | 5.13 ± 0.01 (34.32) | |
Warm and wet | 0.53 ± 0.01 (3.09) | 2.02 ± 0.01 (11.84) | 1.76 ± 0.00 (10.30) | 0.93 ± 0.00 (5.48) | 7.17 ± 0.33 (42.08) | 4.64 ± 0.02 (27.21) | |
Warm and dry | 0.88 ± 0.07 (4.97) | 1.36 ± 0.08 (7.69) | 1.77 ± 0.03 (10.05) | 1.48 ± 0.05 (8.39) | 6.49 ± 0.46 (36.81) | 5.66 ± 0.11 (32.08) | |
Control | Cool and dry | 1.31 ± 0.05 (1.06) | 1.85 ± 0.08 (1.49) | 1.49 ± 0.05 (1.20) | 1.84 ± 1.19 (1.48) | 1.46 ± 0.90 (1.18) | 116.00 ± 0.00 (93.59) |
Hot and dry | 1.31 ± 0.05 (12..85) | 0.34 ± 0.01 (3.29) | 1.44 ± 0.05 (14.16) | 1.17 ± 0.06 (11.51) | 0.82 ± 0.09 (8.08) | 5.11 ± 0.01 (50.10) | |
Warm and wet | 1.31 ± 0.05 (13.49) | 0.34 ± 0.01 (3.46) | 1.42 ± 0.02 (1462) | 1.17 ± 0.06 (12.08) | 0.82 ± 0.09 (8.48) | 4.65 ± 0.00 (47.88) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction.
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 1.72 ± 0.03 (1.04) | 2.71 ± 0.02 (1.65) | 4.24 ± 0.02 (2.58) | 3.46 ± 0.03 (2.10) | 2.52 ± 0.02 (1.53) | 149.80 ± 0.10 (91.09) |
Hot and dry | 1.73 ± 0.06 (13.49) | 2.86 ± 0.00 (22.28) | 0.69 ± 0.00 (5.35) | 2.13 ± 0.01 (16.56) | 1.19 ± 0.00 (32.59) | 1.25 ± 0.00 (9.73) | |
Warm and wet | 0.76 ± 0.00 (5.97) | 1.56 ± 0.00 (12.24) | 0.96 ± 0.00 (7.51) | 3.46 ± 0.01 (27.12) | 4.28 ± 0.00 (33.51) | 1.74 ± 0.03 (13.64) | |
Warm and dry | 1.24 ± 0.08 (9.44) | 1.81 ± 0.04 (13.80) | 0.80 ± 0.05 (6.09) | 3.50 ± 0.07 (26.76) | 4.40 ± 0.12 (33.62) | 1.35 ± 0.02 (10.29) | |
2 | Cool and dry | 1.73 ± 0.01 (1.06) | 2.70 ± 0.02 (1.66) | 4.07 ± 0.16 (2.50) | 3.40 ± 0.15 (2.09) | 2.49 ± 0.05 (1.53) | 148.50 ± 0.53 (91.17) |
Hot and dry | 1.65 ± 0.01 (13.52) | 2.76 ± 0.00 (22.65) | 0.65 ± 0.05 (5.35) | 2.11 ± 0.01 (17.35) | 3.78 ± 0.00 (30.99) | 1.24 ± 0.01 (10.15) | |
Warm and wet | 0.76 ± 0.00 (5.99) | 1.55 ± 0.00 (12.21) | 0.96 ± 0.00 (7..52) | 3.41 ± 0.03 (26.85) | 4.27 ± 0.00 (33.63) | 1.75 ± 0.00 (13.80) | |
Warm and dry | 1.24 ± 0.08 (9.44) | 1.81 ± 0.04 (13.80) | 0.80 ± 0.05 (6.09) | 3.50 ± 0.07 (26.76) | 4.40 ± 0.12 (33.62) | 1.35 ± 0.02 (10.29) | |
3 | Cool and dry | 1.73 ± 0.02 (1.06) | 2.70 ± 0.02 (1.66) | 4.18 ± 0.06 (2.56) | 3.44 ± 0.09 (2.11) | 2.55 ± 0.06 (1.56) | 148.43 ± 1.39 (91.04) |
Hot and dry | 1.73 ± 0.06 (13.89) | 2.64 ± 0.00 (21.17) | 0.59 ± 0.02 (4.70) | 2.08 ± 0.01 (16.70) | 4.20 ± 0.04 (33.68) | 1.23 ± 0.01 (9.86) | |
Warm and wet | 0.77 ± 0.00 (6.04) | 1.49 ± 0.00 (11.74) | 0.95 ± 0.00 (7.53) | 3.45 ± 0.03 (27.21) | 4.27 ± 0.00 (33.68) | 1.75 ± 0.01 (13.80) | |
Warm and dry | 1.13 ± 0.07 (8.77) | 1.85 ± 0.07 (14.27) | 0.83 ± 0.03 (6.39) | 3.49 ± 0.04 (26.95) | 4.26 ± 0.23 (32.90) | 1.39 ± 0.03 (10.72) | |
4 | Cool and dry | 1.73 ± 0.03 (1.06) | 2.52 ± 0.47 (1.54) | 4.10 ± 0.12 (2.51) | 3.40 ± 0.06 (2.08) | 2.52 ± 0.04 (1.54) | 148.20 ± 0.62 (91.27) |
Hot and dry | 1.55 ± 0.01 (13.45) | 2.56 ± 0.01 (20.76) | 0.65 ± 0.00 (5.30) | 2.07 ± 0.01 (16.75) | 4.18 ± 0.00 (33.85) | 1.22 ± 0.01 (9.89) | |
Warm and wet | 0.73 ± 0.04 (5.85) | 1.44 ± 0.01 (11.47) | 0.95 ± 0.00 (7.61) | 3.41 ± 0.04 (27.25) | 4.26 ± 0.01 (34.00) | 1.73 ± 0.04 (13.82) | |
Warm and dry | 1.14 ± 0.16 (8.78) | 1.69 ± 0.08 (13.04) | 0.82 ± 0.09 (6.29) | 3.40 ± 0.07 (26.21) | 4.54 ± 0.19 (34.99) | 1.39 ± 0.10 (10.68) | |
5 | Cool and dry | 1.70 ± 0.01 (1.04) | 2.70 ± 0.01 (1.65) | 3.98 ± 0.18 (2.43) | 3.36 ± 0.22 (2.06) | 2.51 ± 0.02 (1.54) | 149.07 ± 0.46 (91.27) |
Hot and dry | 1.64 ± 0.01 (13.46) | 2.52 ± 0.03 (20.70) | 0.54 ± 0.04 (4.43) | 2.09 ± 0.02 (17.21) | 4.15 ± 0.00 (34.16) | 1.22 ± 0.01 (10.03) | |
Warm and wet | 0.76 ± 0.01 (6.02) | 1.43 ± 0.01 (11.36) | 0.95 ± 0.00 (7.58) | 3.42 ± 0.06 (27.22) | 4.25 ± 0.00 (33.81) | 1.76 ± 0.00 (14.01) | |
Warm and dry | 1.12 ± 0.08 (8.17) | 1.82 ± 0.04 (13.25) | 0.99 ± 0.11 (7.18) | 3.22 ± 0.31 (23.46) | 5.14 ± 0.23 (37.39) | 1.45 ± 0.14 (10.55) | |
Control | Cool and dry | 0.08 ± 0.06 (0.05) | 0.21 ± 0.10 (0.14) | 0.13 ± 0.06 (0.09) | 1.17 ± 1.97 (0.77) | 1.00 ± 1.30 (0.66) | 150.00 ± 0.00 (98.30) |
Hot and dry | 0.00 ± 0.00 (6.43) | 0.00 ± 5.90 (0.00) | 0.08 ± 7.51 (48.00) | 0.01 ± 1.88 (4.00) | 0.08 ± 13.67 (44.00) | 0.01 ± 64.61 (4.00) | |
Warm and wet | 0.12 ± 0.01 (5.12) | 0.11 ± 0.01 (4.71) | 0.13 ± 0.06 (5.40) | 0.04 ± 0.01 (1.66) | 0.25 ± 0.06 (10.38) | 1.75 ± 0.00 (72.73) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction.
Site | Season | Water Soluble | Exchangeable | Organic Bound | Carbonate Bound | Fe-MnO | Residual |
---|---|---|---|---|---|---|---|
1 | Cool and dry | 2.62 ± 0.01 (0.96) | 4.14 ± 0.03 (1.52) | 5.03 ± 0.01 (1.84) | 3.47 ± 0.02 (1.27) | 5.22 ± 0.02 (1.91) | 252.47 ± 0.64 (92.50) |
Hot and dry | 3.13 ± 0.00 (1.37) | 7.56 ± 0.00 (3.32) | 101.50 ± 0.03 (44.61) | 12.05 ± 0.01 (5.30) | 78.04 ± 0.00 (34.30) | 25.24 ± 0.01 (11.10) | |
Warm and wet | 2.37 ± 0.00 (0.69) | 6.46 ± 0.01 (1.88) | 136.41 ± 0.02 (39.60) | 15.07 ± 0.00 (4.38) | 155.83 ± 0.58 (45.24) | 28.34 ± 0.04 (8.23) | |
Warm and dry | 2.69 ± 0.05 (00.84) | 5.74 ± 0.12 (1.79) | 125.75 ± 1.01 (39.12) | 13.63 ± 0.06 (4.24) | 147.27 ± 0.35 (45.82) | 26.33 ± 0.50 (8.19) | |
2 | Cool and dry | 2.63 ± 0.01 (0.97) | 4.13 ± 0.01 (1.52) | 5.00 ± 0.12 (1.84) | 3.48 ± 0.03 (1.28) | 5.35 ± 0.16 (1.97) | 251.23 ± 0.31 (92.43) |
Hot and dry | 3.19 ± 0.05 (1.41) | 7.65 ± 0.01 (3.38) | 100.99 ± 0.45 (44.60) | 12.04 ± 0.01 (5.32) | 78.03 ± 0.00 (34.46) | 24.56 ± 0.59 (10.85) | |
Warm and wet | 2.38 ± 0.03 (0.69) | 6.45 ± 0.01 (1.88) | 135.66 ± 0.59 (39.48) | 14.96 ± 0.19 (4.35) | 155.82 ± 0.58 (45.35) | 28.34 ± 0.02 (8.25) | |
Warm and dry | 2.58 ± 0.05 (0.81) | 5.37 ± 0.45 (1.68) | 126.62 ± 0.90 (39.57) | 13.40 ± 0.44 (4.19) | 146.51 ± 0.56 (45.79) | 25.48 ± 0.69 (7.96) | |
3 | Cool and dry | 2.63 ± 0.02 (0.96) | 4.06 ± 0.07 (1.49) | 4.95 ± 0.06 (1.81) | 3.64 ± 0.12 (1.330 | 5.36 ± 0.07 (1.96) | 252.67 ± 0.38 (92.440 |
Hot and dry | 3.15V0.05 (1.40) | 6.77 ± 0.02 (3.00) | 100.95 ± 0.45 (44.790 | 11.94 ± 0.15 (5.30) | 78.03 ± 0.00 (34.62) | 24.57 ± 0.57 (10.90) | |
Warm and wet | 2.36 ± 0.01 (0.69) | 6.44V0.02 (1.87) | 135.36 ± 0.00 (39.42) | 15.07 ± 0.00 (4.39) | 155.83 ± 0.58 (45.38) | 28.31 ± 0.03 (8.24) | |
Warm and dry | 2.46 ± 0.11 (0.77) | 5.18 ± 0.45 (1.62) | 125.72 ± 0.84 (39.30) | 13.46 ± 0.42 (4.21) | 147.17 ± 0.63 (46.01) | 25.89 ± 0.55 (8.09) |
4 | Cool and dry | 2.62 ± 0.03 (0.96) | 4.16 ± 0.29 (1.53) | 4.98 ± 0.02 (1.83) | 3.53 ± 0.06 (1.30) | 5.17 ± 0.16 (1.90) | 251.83 ± 0.90 (92.48) |
---|---|---|---|---|---|---|---|
Hot and dry | 3.07 ± 0.09 (1.36) | 6.62 ± 0.04 (2.94) | 100.81 ± 0.85 (44.71) | 11.73 ± 0.06 (5.20) | 78.03 ± 0.00 (34.60) | 25.23 ± 0.01 (11.19) | |
Warm and wet | 2.36 ± 0.01 (0.69) | 6.43 ± 0.01 (1.87) | 135.42 ± 0.01 (39.47) | 15.07 ± 0.00 (4.39) | 155.48 ± 1.15 (45.32) | 28.35 ± 0.01 (8.26) | |
Warm and dry | 2.32 ± 0.32 (0.73) | 6.33 ± 0.10 (1.98) | 125.43 ± 1.39 (39.22) | 13.54 ± 0.10 (4.23) | 146.70 ± 0.85 (45.87) | 25.50 ± 0.58 (7.97) | |
5 | Cool and dry | 2.55 ± 0.06 (0.94) | 4.16 ± 0.04 (1.53) | 4.96 ± 0.14 (1.83) | 3.48 ± 0.02 (1.28) | 5.14 ± 0.22 (1.90) | 251.00 ± 1.14 (92.52) |
Hot and dry | 3.15 ± 0.05 (1.40) | 6.51 ± 0.05 (2.89) | 100.92 ± 0.50 (44.82) | 11.66V0.01 (5.18) | 77.66 ± 0.00 (34.49) | 25.25 ± 0.02 (11.21) | |
Warm and wet | 2.41 ± 0.07 (0.70) | 6.41 ± 0.01 (1.87) | 135.41 ± 0.00 (39.52) | 14.93 ± 0.07 (4.36) | 155.16 ± 0.00 (45.28) | 28.36 ± 0.02 (8.27) | |
Warm and dry | 2.61 ± 0.06 (0.81) | 5.89 ± 0.05 (1.84) | 126.55 ± 0.12 (39.46) | 13.92 ± 0.36 (4.34) | 146.32 ± 1.24 (45.62) | 25.43 ± 0.50 (7.93) | |
Control | Cool and dry | 1.38 ± 0.03 (0.53) | 1.21 ± 0.12 (0.47) | 1.11 ± 0.08 (0.43) | 1.88 ± 1.37 (0.73) | 2.76 ± 2.15 (1.07) | 250.33 ± 0.58 (96.77) |
Hot and dry | 1.40V0.04 (4.61) | 0.94 ± 0.02 (3.09) | 1.11 ± 0.08 (3.68) | 1.10 ± 0.11 (3.63) | 1.52 ± 0.05 (5.01) | 24.21 ± 0.01 (79.97) | |
Warm and wet | 1.40 ± 0.04 (4.08) | 0.94 ± 0.02 (2.73) | 1.11 ± 0.08 (3.25) | 1.10 ± 0.11 (3.21) | 1.52 ± 0.05 (4.43) | 28.20 ± 0.17 (82.30) | |
Warm and dry | na | na | na | na | na | na |
Value in parenthesis () is the percentage fraction.
est concentration 0.99 mg/kg is associated with the organic bound fraction for Cd in. This situation is however different from [
As shown in
For Cu (
Also, the predominant form of Cu available in the entire fractions is residual, exchangeable and carbonate bound fractions. The high % of Cu in the residual fraction is due to stable nature of the compound and the fact that the metals are bonded firmly within a mineral lattice restricted the bioavailability of this metal [
Fe across the sites was also associated mostly with the residual phase followed by Fe-MnO and organic bound fractions as shown in
The behaviour of Mn was quite different from other metals in that percentage fractions were mainly associated with the exchangeable fraction of the soil samples (site 1) ranging from 0.20 - 13.52 mg/kg (
As shown in
Highest concentration in residual of Pb was obtained in site 1 during the cool and dry season, then in the Fe-MnO fraction (2.49 - 5.14 mg/kg) as shown in
As for Zn, significant amounts of the metal were associated with the residual fraction (
1) The physicochemical parameters of the soils across the sites indicated values reported for less polluted soils.
2) With the exception of Cd, all metals evaluated in this study were lower than recommended standard limits.
3) The results of sequential extraction of heavy metal in soil sample indicated that all metals were mainly associated with the residual, Fe-MnO and organic bound fractions. The residual fraction had the maximum concentration of metals especially in cool and dry season for Cr, Cu, Ni, Pb and Zn, whereas only a small fraction of all the heavy metal was extracted in water soluble, exchangeable and carbonate bound fractions. It indicated that the bioavailability index was low. Hence, mobility of the heavy metals by the surrounding plants grown on the soils was low.
The authors wish to acknowledge the effort of Mr. Ilu of Soil Chemistry Laboratory, Ahmadu Bello University, Zaria in the soil sample analyses.
Musa Sabo Abdullahi,Adamu Uzairu,Oluwole Joshua Okunola,Muhammad Lawal Balarabe, (2016) Seasonal Quality Assessment of Agricultural Soils along the Bank of Tungan Kawo Dam, Kontagora, Nigeria. Journal of Agricultural Chemistry and Environment,05,132-151. doi: 10.4236/jacen.2016.53015