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Sulfate-reducing bacteria (SRB) have received particular attention in the bioremediation of sediments contaminated with heavy metals. In this study, indigenous SRB were used to stabilize Cd in sediments spiked with different Cd concentrations (≤ 600 mg kg?1).
Materials and methodsThe study investigated the Cd leaching efficiency from sediments after 166 days (d) of biotreatment and assessed the bacterial community and bacteria relationship in sediments during SRB biostabilization.
Results and discussionThe study found that the Cd leaching efficiency of sediments was reduced by 18.1–40.3% (29.4 ± 8.7%) after 166 days of biotreatment. During the biostabilization, the bacterial community in sediments significantly changed, particularly after 61 days of biotreatment. At the family level, the identified dominant bacteria (mean abundance > 3%) included Bacillaceae, norank Nitrospira, Anaerolineaceae, Nitrospinaceae, Streptococcaceae, and Hydrogenophilaceae. The study also speculated the complex relationships between these bacteria. The relative abundance of Desulfobacteraceae and Desulfobulbaceae in sediments was enhanced after biotreatment. Bacillaceae and Streptococcaceae may play a negative role in Cd biostabilization and inhibited SRB biological activity. However, Anaerolineaceae and Hydrogenophilaceae may have commensalism and mutualism relationships, respectively, with typical SRB. The presence of Nitrospinacea and norank Nitrospira may reduce the inhibitive effect of denitrifying bacteria on SRB, thereby exhibiting a positive effect on biologic sulfate reduction and Cd biostabilization.
ConclusionsIndigenous SRB treatment increased Cd stability in sediments and changed bacterial community. During SRB biostabilization, complex relationships between bacteria in sediments were speculated, including competition, syntrophism, and antagonism. These results provide insights for better regulating and controlling SRB biostabilization.
相似文献Soil nutrients, elemental stoichiometry, and their associated environmental control play important roles in nutrient cycling. The objectives of this study were (1) to investigate soil nutrients and elemental stoichiometry, especially potassium and its associative elemental stoichiometry with other nutrients under different land uses in terrestrial ecosystems; (2) to discuss the impacts of climate factors, soil texture, and soil physicochemical properties; and (3) to identify the key factors on soil nutrient levels and elemental stoichiometry.
Materials and methodsSoil data, including pH, bulk density (BD), cation exchange capacity (CEC), volumetric water content (VMC), clay, silt and sand contents, total carbon (TC), nitrogen (TN), phosphorous (TP) and potassium (TK), available nitrogen (AN), phosphorus (AP), potassium (AK), and soil organic matter (SOM) under different land-use types, were collected, and their elemental stoichiometry ratios were calculated. Climate data including temperature, precipitation, relative humidity, wind speed, and evapotranspiration were collected. The least significant difference test and one-way analysis of variance were applied to investigate the variability of soil nutrients and elemental stoichiometry among land-use types; the ordinary least squares method and the general linear model were used to illustrate the correlations between soil nutrients, elemental stoichiometry, and soil properties or climate factors and to identify the key influencing factors.
Results and discussionWoodlands had the highest SOM, TN, AN, and AK contents, followed by grasslands, croplands, and shrublands, while the TP and TK contents only varied slightly among land-use types. SOM, TN, AN, N/P, and N/K were strongly negatively correlated to soil pH (p <?0.05) and were strongly positively correlated to soil CEC (p <?0.05). For soil texture, only C/N was moderately negatively correlated to silt content but moderately positively correlated to sand content (p <?0.05). For climate factors, SOM, TN, AN, N/P, and N/K were significantly negatively correlated to evapotranspiration and temperature (p <?0.05), and the correlations were usually moderate. Soil pH explained most of the total variation in soil nutrients, and climate factors explained 5.64–28.16% of soil nutrients and elemental stoichiometry (except for AP (0.0%) and TK (68.35%)).
ConclusionsThe results suggest that climate factors and soil properties both affect soil nutrients and elemental stoichiometry, and soil properties generally contribute more than climate factors to soil nutrient levels. The findings will help to improve our knowledge of nutrient flux responses to climate change while also assisting in developing management measures related to soil nutrients under conditions of climate change.
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