Effects of heavy metal pollution on the soil microbial activity
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The effects of heavy metals on soil microbial processes were investigated over a period of six weeks. Analytical grade (Sigma) sulphate salts of copper, zinc and nickel were added individually and in combinations to soil samples and incubated in different plastic pots. Samples were taken from the pots forthnightly and the rates of microbial carbon and nitrogen mineralization, microbial biomass carbon and respiration were measured. The results showed the effect of metals on the measured parameters were significant (P<0.05.). By the 6th week postreatment, the rates of carbon accumulated were high in the copper (6.03 %) and copper:Zinc (5.80 %) treatments but low in the nickel and zinc (4.93 % and 5.02 % respectively). The rates of Nitrogen mineralization were 0.41 and 0.44 % in samples treated with copper and copper:zinc compared to 0.22 %–0.24 % obtained at the beginning of the experiments. Soil microbial biomass carbon declined from average value of 183.7–185.6 μg/g before treatment to as low as 100.8 and 124.6 μg/g in samples treated with copper:zinc and copper respectively.The rate of respiration of the soil microbial populations was equally inhibited by the metals. From an average rate of 2.51–2.56 μg of C/g respiration of the soil microbes declined to 0.98, 1.08 and 1.61 μg of C/g in the copper:zinc, copper and zinc treated soils by the end of the experiment. The results suggest additive or synergistic effects of the metals.
KeywordsMineralization microbial biomass carbon additive synergistic heavy metals
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- Baath, E.; Diaz Ravina, M.; Frostegard, A.; Campell, C. D., (1998). Effect of metal rich sludge amendments on the soil microbial community. Appl. Environ. Microbiol., 64(1), 238–245.Google Scholar
- Bremner, J. M., (1965). Total Nitrogen. In: C.A. Black (Ed.) Methods of Soil analysis. Part 2 Agron. Monogr. 9 A American Society for Agronomy, Madison, WI., 1149–1178.Google Scholar
- Chen, X.; Wright, J. V.; Conca, J. L.; Peurrung, L. M., (1997). Evaluation of heavy metal remediation using mineral apatite. Water, Air Soil Pollut., 98(1–2), 57–78.Google Scholar
- Clarke, K. R., (1999). Nonmetric multivariate analysis in community level ecotoxicology. Environ. Toxicol. Chem., 18(2), 118–127.Google Scholar
- Diaz Ravina, M.; Baath, E.; Frostegard., A., (1994). Multiple heavy metal tolerance of soil bacterial communities and its measurement by the thymidine incorporation technique. Appl._Environ. Microbiol., 60(7), 2238–2247.Google Scholar
- Diaz Ravina, M.; Baath, E., (1996). Development of metal tolerance in soil bacterial communities exposed to experimentally increased metal levels. Appl. Environ. Microbiol., 62(8), 2970–2977.Google Scholar
- Gazso, L. G., (2001). The key microbial processes in the removal of toxic metals and radionuclides from the environment. (a review) Cent. Eur. J of Occup. Environ. Med., 7(3), 178–185.Google Scholar
- Pennanem, T.; Frostegard, A.; Fritze, H.; Baath, E., (1996). Phospholipid fattyacid composition and heavy metal tolerance of soil microbial communities along two heavy metal-polluted gradients in coniferous forests. Appl. Environ. Microbiol., 62(2), 420–428.Google Scholar
- Petersen, S. O.; Klug, M. J., (1994). Effects of sieving, storage and incubation temperature on the phospholipids fattyacid profile of a soil microbial community. Appl. Environ. Microbiol., 60(7), 2421–2430.Google Scholar
- Sani, R. K.; Peyton, B. M.; Jadhyala, M., (2003) Toxicity of lead in aqueous medium to Desulfovibrio desulfuricans G20. Environ. Toxicol., 22(2), 252–260.Google Scholar