Influence Of Biochar On Heavy Metals And Microbial Community During Composting Of River Sediment With Agricultural Wastes

Water sediment(sediment)is an important component of natural water ecosystems such as rivers and lakes,and the heavy metal pollutants enter the water through various channels.After adsorption,complexation,precipitation and so on.Most of the heavy metals are rapidly aqueous phase to solid phase,combined into suspended solids and sediment,and continue to accumulate,so the sediment is often the final destination of pollutants in water.And if the sediment environment changes,these sediment heavy metal pollutants have the possibility of re-release,resulting in secondary pollution,so the formation of potential hazards to aquatic ecosystems.In addition,the water body sediment is the habitat of benthic habitat and food sources,the sediment in the pollutants can be directly or indirectly on the habitat caused by toxic effects.Because heavy metals are nonreducible,these heavy metals may be enriched with the food chain in the organism and become persistent contaminants and may migrate in the ecosystem through various means and eventually enter the human body,resulting in serious harm.In recent years,the problem of heavy metal pollution in the sediment has been paid more and more attention.Studies were performed to evaluate influence of biochar addition on physico-chemical parameters and heavy metals during composting of sediment with agricultural wastes.The associated dynamics of bacterial community was characterized by polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE),and the relationships between bacterial community compositions and those parameters were simultaneously evaluated by redundancy analysis(RDA).The works indicated the total metal concentration was increased during composting process.Meanwhile,the extraction efficiency of DTPA extractable heavy metals decreased in both piles,and pile which biochar addition reduced more.The DGGE profiles revealed that the bacterial community structure dramatically changed during the composting process and DGGE profile had more bands in the piles with biochar addition than that in the control.Moreover,the bacterial community composition was significantly correlated with C/N ratio,water soluble carbon(WSC),and OM(P<0.05)in pile with biochar addition;while significantly correlated with temperature,water soluble carbon(WSC),and C/N in pile which was free of biochar.Significant amounts of the variation(66.7%and 55.5%for bacterial species data in pile with and without biochar addition,respectively)were explained by those parameters,suggesting that those parameters were the most likely ones to influence,or be influenced by the bacterial species in samples.This study provides valuable information for improving composting for disposal of river sediment with heavy metals contamination.