Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake,Lake Taihu,China

The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT_1.92 > DGT_0.78 > DGT_0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.     

Cu(II), Fe(III) and Mn(II) combinations as environmental stress factors have distinguishing effects on Enterococcus hirae

Pollution by various heavy metals as environmental stress factors might affect bacteria. It was established that iron (Fe(III)), manganese (Mn(II)) and copper (Cu(II)) ion combinations caused effects on Enterococcus hirae that differed from the sum of the effects when the metals were added separately. It was shown that the Cu^2 +–Fe^3 + combination decreased the growth and ATPase activity of membrane vesicles of wild-type E. hirae ATCC9790 and atpD mutant (with defective F_oF₁-ATPase) MS116. Addition of Mn^2 +–Fe^3 + combinations within the same concentration range had no effects on growth compared to control (without heavy metals). ATPase activity was increased in the presence of Mn^2 +–Fe^3 +, while together with 0.2 mmol/L N,N′-dicyclohexylcarbodiimide (DCCD), ATPase activity was decreased compared to control (when only 0.2 mmol/L DCCD was present). These results indicate that heavy metals ion combinations probably affect the F_OF₁-ATPase, leading to conformational changes. Moreover the action may be direct or be mediated by environment redox potential. The effects observed when Fe^3 + was added separately disappeared in both cases, which might be a result of competing processes between Fe^3 + and other heavy metals. These findings are novel and improve the understanding of heavy metals ions effects on bacteria, and could be applied for regulation of stress response patterns in the environment.     

Composition and source apportionment of dust fall around a natural lake

The aim of this study was to determine the source apportionment of dust fall around Lake Chini, Malaysia. Samples were collected monthly between December 2012 and March2013 at seven sampling stations located around Lake Chini. The samples were filtered to separate the dissolved and undissolved solids. The ionic compositions(NO-3, SO2-4, Cl-and NH+4) were determined using ion chromatography(IC) while major elements(K, Na, Ca and Mg) and trace metals(Zn, Fe, Al, Ni, Mn, Cr, Pb and Cd) were determined using inductively coupled plasma mass spectrometry(ICP-MS). The results showed that the average concentration of total solids around Lake Chini was 93.49 ± 16.16 mg/(m2·day). SO2-4, Na and Zn dominated the dissolved portion of the dust fall. The enrichment factors(EF) revealed that the source of the trace metals and major elements in the rain water was anthropogenic, except for Fe. Hierarchical agglomerative cluster analysis(HACA) classified the seven monitoring stations and 16 variables into five groups and three groups respectively. A coupled receptor model, principal component analysis multiple linear regression(PCA-MLR), revealed that the sources of dust fall in Lake Chini were dominated by agricultural and biomass burning(42%),followed by the earth's crust(28%), sea spray(16%) and a mixture of soil dust and vehicle emissions(14%).     

Cu(Ⅱ), Fe(Ⅲ) and Mn(Ⅱ) combinations as environmental stress factors have distinguishing effects on Enterococcus hirae

Pollution by various heavy metals as environmental stress factors might affect bacteria. It was established that iron(Fe(Ⅲ)), manganese(Mn(Ⅱ)) and copper(Cu(Ⅱ)) ion combinations caused effects on Enterococcus hirae that differed from the sum of the effects when the metals were added separately. It was shown that the Cu2+–Fe3+combination decreased the growth and ATPase activity of membrane vesicles of wild-type E. hirae ATCC9790 and atp D mutant(with defective FoF1-ATPase) MS116. Addition of Mn2+–Fe3+combinations within the same concentration range had no effects on growth compared to control(without heavy metals). ATPase activity was increased in the presence of Mn2+–Fe3+, while together with0.2 mmol/L N,N′-dicyclohexylcarbodiimide(DCCD), ATPase activity was decreased compared to control(when only 0.2 mmol/L DCCD was present). These results indicate that heavy metals ion combinations probably affect the FOF1-ATPase, leading to conformational changes. Moreover the action may be direct or be mediated by environment redox potential.The effects observed when Fe3+was added separately disappeared in both cases, which might be a result of competing processes between Fe3+and other heavy metals. These findings are novel and improve the understanding of heavy metals ions effects on bacteria,and could be applied for regulation of stress response patterns in the environment.     

水稻秸秆经漆酶预处理后产沼气研究

利用秸秆产沼气是秸秆无害化处理解决环境污染问题的可行手段.本研究针对秸秆特殊结构而导致产沼气少、启动慢、利用率低等问题,采用自培养漆酶预处理水稻秸秆,提高了秸秆产气率及利用率.通过研究发现,当漆酶添加量为40 mL、发酵温度为35℃、预处理7d的条件下,秸秆的产气量最高;同时发现,金属离子的添加对沼气产量有很大影响,其中Cu2添加后产气量提高最多.另外,研究发现预处理天数为24 d的秸秆木质素纤维素降解率最高.     

城市污泥发酵物土地利用重金属迁移变化研究

文章针对污泥发酵物开展替代草坪基质的规模化应用,对其重金属迁移风险进行了分析,通过对重金属在纵向和横向水平上的迁移量变化进行比较的结果表明,与常规对照相比,随污泥发酵物施用量(45~75 t/hm2)提高,重金属(As、Cd、Ni、Pb、Cu、Zn)在地下纵向和地表横向水平上的迁移量无显著性增加.结果表明污泥发酵物应用于草坪基质,在短期(两年)内,由地下渗流和地表径流引起的重金属迁移量甚微,施用区域内地下水和周边土壤的环境安全性较高.     

Leaching-induced migration and compositional form change of Cu,Zn, and Cd from sludge to loess

Land utilization of sewage sludge has become one of the major issues in environmental mitigation in China. This is particularly important in the Loess Plateau of Northwest China. Sludge enriched with organic matter and nutrients might effectively help to resolve the problems of silty loess soils as evidenced by porosity defect, structural alterations and absence of fertility. After sludge flows into the loess, irrigation water contains heavy metals that leach and migrate into sludge and consequently related human health risks may occur that raise concerns; and this situation needs to be rectified. The characteristics of the vertical migration and composition form change of Cu, Zn, and Cd from composted sludge to loess, and corresponding influencing factors, were investigated by performing a soil column simulation test under the leaching treatment of a one-year irrigation water capacity. Results demonstrated that: (1) composted sludge significantly improved loess fertility, and irrigation leaching transported only a small quantity of organic matter in sludge in the plough layer; (2) although some of the Cu, Zn, and Cd in composted sludge migrated to and concentrated in the middle and upper layers of the soil column during leaching, these metals were mostly retained in the plough layer; and (3) after the leaching treatment of the one-year irrigation water capacity, the compositions of Cu, Zn, and Cd (particularly Cu and Zn) in both plough layer and loess began to stabilize with low concentrations in the exudate. These findings confirmed the applicability of composted sludge in loess regions. This study provided a new insight into the sludge reuse in alkaline soils in arid and semi-arid region.     

宿州市护城河沉积物重金属污染程度及来源分析

在对宿州市护城河沉积物12个采样点重金属含量测试的基础上,运用沉积物富集系数法和内梅罗指数法对该水域沉积物中V、Cr、Ni、Cu、Zn、As及Pb 7种重金属污染程度进行分析,并运用聚类分析法和因子分析法对重金属来源进行识别.结果表明:Cu和Zn处于较强污染状态,Ni、As和Pb处于中等污染状态,Cr处于轻微至中等污染状态,V处于无污染状态;护城河沉积物12个采样点7种重金属的综合污染程度由大到小依次为H7、H10、H3、H9、H1、H11、H6、H5、H12、H8、H2和H4,其中位于工业区附近的H7点污染程度最高,而位于居民区和护城河汇流处附近的H4点最低;聚类分析将7种重金属分为Ⅰ类(Cu、Zn、As和Pb)、Ⅱ类(Cr和Ni)和Ⅲ类(V),每类元素自身具有相似的地球化学过程;旋转成分矩阵后的因子分析从重金属元素变量中提取出3个主成分(PC1、PC2和PC3),与聚类分析结果相对应,可解释总变量的90.97％.PCI(Cu、Zn、As和Pb)表示交通运输和煤炭工业污染,PC2(Cr和Ni)表示机械制造业,PC3(V)表示自然作用.     

共存阴阳离子对针铁矿表面磷固存机制的影响研究

磷素(P)兼具重要养分元素的利和潜在面源污染的弊,其在土壤环境中的固存行为及其迁移转化过程受到广泛关注.该研究选取黄、红壤中典型矿物(针铁矿、赤铁矿及高岭石)为模式矿物,在排除pH干扰的条件下,开展了共存阴(As(V))阳(Cd(II))离子对矿物表面P(V)固存机制的影响研究.结果表明:P(V)在不同矿物表面的吸附效...     

规模化农田土壤重金属污染修复的中试试验研究——以某镇土壤污染治理为例

农用地重金属污染长期以来一直是生态环境的热点和难点问题。2017年,对某镇农田土壤重金属污染开展详查,单项污染指数评价结果表明,镉超标率为67.60%(Pi>1),基于内梅罗污染指数法的评价结果显示,57.30%的点位受到不同程度的污染(PN≥1.0);2018年,分别选取钝化修复和植物修复进行中试试验,经钝化修复后土壤有效镉和总镉含量分别平均降低32.73%和5.64%。经超富集植物籽粒笕种植一季修复后,土壤总镉含量降低15%以上。本次中试试验修复效果良好,能为下一阶段的土壤镉污染修复方案的制定和优化提供科学的依据,为全国农用地重金属污染修复提供了有价值的借鉴意义。