Research Of The Combined Pollution Of Decabromodiphenyl Ether And Lead On Ecological Effect Of Soil Microbes

Electric waste recycling sites (EWRSs) are widespread in China, numerous hazardous materials releases into the soil due to the primitive dismantling, of which decabromodiphenyl ether (BDE209) and lead (Pb) are the typical pollutants. The reports on the ecological effects of their combined pollution were very scarce. The soils used in this research were collected from a beauty spot and EWRSs in Taizhou, Zhejiang province. The research focused on the transformation of pollutants and the toxicological effect on soil microbes under the pollution of BDE209 and Pb by indoor incubation. Major conclusions are as follows:(1) In the soils of the experiment, BDE209 and Pb decreased the soil microbial biomass C (Cmic), but stimulated the soil basal respiration (SBR) and metabolic quotient (qCO2). In the soil of the beauty spot, Cmic decreased in the early stage, and then kept steady over time; the SBR and qCO2 increased in the primary stage, declined over the incubation, and leveled off at the end. In the soil of EWRSs, Cmic, SBR and qCO2 enhanced in the initial stage, and then decreased, eventually leveled off.(2) In the two soils, BDE209 was barely degraded when exposured to the single BDE209 and BDE209 in combination with exogenous Pb or endogenous Pb; the changes of BDE209 levels were not significant (P>0.05) after 60 days’incubation in all the treatments. In the soil of the beauty spot, the EXCH-Pb gradually transformed into the other fractions over time, the FeMnOX and CAR fractions were the dominant fractions after the incubation; the mobility factor (MF) of soil Pb was declined over time; compared to the single Pb exposure, the additions of BDE209 could barely influence the fraction distribution and the mobility change of soil Pb. In the soil of the EWRSs, the fractions of EXCH and CAR gradually tranformed into the other fractions over time; the FeMnOX fraction was the dominant fraction in the process of the incubation; the MF of soil Pb was gradually decreased; compared to the single Pb exposure, the addition of 100 mg kg-1 BDE209 probably facilitate the fraction transformation and the mobility decline of soil endogenous Pb.(3) After the incubation of 60 days, BDE209 and/or Pb could clearly affect the bacterial community structure of the soil in the beauty spot, of which the treatment of BDE209 and Pb could obviously inhibit the bacterial richness and diversity. Proteobacteria, Actinobacteria and Acidobacteria were the dominant phylum detected in our research. Compared to the control, Massilia and Bacillus genera were enriched in the soils of BDE209 and/or Pb, which might be the tolerant bacteria to the two chemicals.