Soil Contamination and Remediation Effects on the Structure and Activity of Soil Microbial Communities

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Chapter 3. 1. Soil temperature and moisture:
Soil temperature and moisture were significantly (P 0.01) influenced by soil contamination (Table. 3. 1) irrespective of locations, sources of contamination and season. Soils received agricultural contaminants (AC) recorded a general increase in soil temperature over control (uncontaminated soil) followed by soil contaminated with organic wastes (OW) during monsoon season (Fig. 3. 1). The increase in soil temperature even with the availability of sufficient moisture could be due to the fast rate of organic matter decay in the availability of water emanating heat (Chonkar et al., 2000). Soil temperature showed positive relationship with soil properties such as pH and EC and negative relationship with soil moisture and TOC (Table. 3. 7).
Soil moisture like temperature showed an increase in AC and OW soils (Fig. 3. 2) though their relationship was inverse (Table. 3. 7). The moisture retaining capacity is controlled primarily by the number of pores and their size distribution and the specific surface area of the [...] soils (Haynes and Naidu, 1998). Further, total pore space is typically increased by the addition of organic matter owing to increased aggregation (Sanchez et al., 1989). Though the AC and OW soils received organic matter in varied forms, the data on soil moisture and TOC did not yield a significant positive linear relationship. Therefore the high moisture retention capacity of these soils is presumably due to the physical nature (Cosby et al., 1984) rather than contamination.
3. 2. pH and EC:
AC soils generally exhibited an acidic tendency in all the seasons (Table. 3. 2) probably due to the reason that the soils received continuous application of synthetic fertilizers and manure. Significant positive correlation could be drawn out in the present study between soil pH and nutrients particularly P and K (Table. 3. 7) confirming soil nutrients as a factor determining pH in soil. Increase in soil

M.V. Bindu is Technical Officer at the Project Implementation Unit, Kerala Sustainable Urban Development Programme, Local Self Government Department, Thiruvananthapuram, Kerala India. After securing her Master's Degree in Environmental Management from Mahatma Gandhi University, India, she received her PhD (Biotechnology) in 2009 from the University of Kerala, India. Her area of interest is remediation of contaminated environment through microbial manipulations.

V.S. Harikumar is Associate Professor and Head of the Department of Post Graduate Studies & Research in Botany, Sanatana Dharma College (University of Kerala), Alappuzha, Kerala, India.
He received his PhD in 1998 from the University of Kerala in the field of Agricultural Microbiology. His major area of interest is Microbial Biotechnology. He has more than two decades of Post Graduate teaching experience and has a good number of publications in referred journals. He is a member in the editorial board of journals and member of various academic and professional bodies. He also guides students for doctoral programmes in the field of Botany and Biotechnology.