Source attributions of heavy metals in rice plant along highway in Eastern China

Air and soil pollution from traffic has been considered as a critical issue to crop production and food safety, however, few efforts have been paid on distinguish the source origin of traffic-related contaminants in rice plant along highway. Therefore, we investigated metals (Pb, Cd, Cr, Zn and Cu) concentrations and stable Pb isotope ratios in rice plants exposed and unexposed to highway traffic pollution in Eastern China in 2008. Significant differences in metals concentrations between the exposed and unexposed plants existed in leaf for Pb, Cd and Zn, in stem only for Zn, and in grain for Pb and Cd. About 46% of Pb and 41% of Cd in the grain were attributed to the foliar uptake from atmosphere, and there were no obvious contribution of atmosphere to the accumulations of Cr, Zn and Cu in grain. Except for Zn, all of the heavy metals in stem were attributed to the root uptake from soil, although significant accumulations of Pb and Cd from atmosphere existed in leaf. This indicated that different processes existed in the subsequent translocation of foliar-absorbed heavy metals between rice organs. The distinct separation of stable Pb isotope ratios among rice grain, leaf, stem, soil and vehicle exhaust further provided evidences on the different pathways of heavy metal accumulation in rice plant. These results suggested that further more attentions should be paid to the atmospheric deposition of heavy metals from traffic emission when plan crop layout for food safety along highway.     

扬州市不同行政区域空气重金属污染评价

采用活藓监测法,选择广泛分布的小羽藓为材料,对扬州市区、高邮市、仪征市、宝应县4个区域空气中Pb、Zn、Cd、Cr、Ni、Zn、Hg 7种重金属元素污染情况进行监测.利用污染因子分析法、内梅罗综合指数分析法及重金属污染潜在生态风险评价法对不同区域空气重金属危害等级进行评价.结果表明:Zn、Pb、Cd元素主要污染地区为扬州市区,Cu元素主要污染地区为仪征市,Ni、Hg元素主要污染地区为宝应县,Cr元素主要污染地区为高邮市.4个区域空气重金属均处于重度污染水平,存在强生态风险.就整体而言,7种重金属元素中Cd、Zn、Hg为主要污染元素,污染情况最为严重,而Cu、Ni污染程度相对较轻.区域间空气重金属污染特征差别显著,制造业与港口航运发达的南部仪征市、江都区等地比以农业为主的北部宝应县污染重,污染程度由高到低为扬州市区仪征市高邮市宝应县.     

鄂州市蔬菜地土壤重金属污染评价

为了解鄂州市蔬菜地重金属的污染状况,对鄂州市蔬菜地土壤进行采样,并对其重金属铜、铅、镉、铬、汞、砷含量进行测定。利用单项污染指数法和内梅罗综合污染指数法对其进行分析和评价,其中土壤重金属元素单因子污染指数(Pi)由大到小的顺序为:铜(Cu)>汞(Hg)>铬(Cr)>砷(As)>铅(Pb)>镉(Cd)。其中铜、汞、铬、砷属于中度污染,铅、镉处于警戒线中。内梅罗综合污染指数法表明鄂州蔬菜地土壤整体受到了轻度的重金属污染.     

重金属对硫酸盐还原菌影响

含重金属硫酸盐废水是我国工业水污染的突出问题,利用硫酸盐还原菌的生物去除重金属的方法具有投资少、成本低、能耗少、去除率高,没有二次污染等优点而成为研究的热点。文章以混合培混养物作为接种污泥,考察不同浓度的重金属离子(Cu2+、Cd2+、Ni2+、Hg2+)对硫酸盐还原菌(Sulfate reducing bacteria,SRB)的抑制作用。研究表明:10 mg/L的Cu2+、Cd2+和20 mg/L的Hg2+对SRB还原硫酸盐的影响较小,硫酸盐最大去除率可分别达到94.1%、94.6%、91.3%,与空白(93.9%)相近;20 mg/L的Cu2+对SRB的抑制最为强烈,硫酸盐最大还原率仅为48.2%,剩余金属离子(Cd2+、Ni2+、Hg2+)都分别随着浓度的增大而对SRB的抑制作用增强;相同浓度的重金属离子对SRB的抑制顺序为Ni2+>Cu2+>Cd2+>Hg2+,抑制浓度分别为10、20、30、60 mg/L。最后阐述了各个反应器中硫酸盐还原率最大时,(WCOD/WSO42-)与硫酸盐还原率的关系。     

Heavy metal availability and impact on activity of soil microorganisms along a Cu/Zn contamination gradient

All the regulations that define a maximum concentration of metals in the receiving soil are based on total soil metal concentration. However, the potential toxicity of a heavy metal in the soil depends on its speciation and availability. We studied the effects of heavy metal speciation and availability on soil microorganism activities along a Cu/Zn contamination gradient. Microbial biomass and enzyme activity of soil contaminated with both Cu and Zn were investigated. The results showed that microbial biomass was negatively affected by the elevated metal levels. The microbial biomass-C （Cmic）/organic C （Corg） ratio was closely correlated to heavy metal stress. There were negative correlations between soil microbial biomass, phosphatase activity and NH4NO3 extractable heavy metals. The soil microorganism activity could be predicted using empirical models with the availability of Cu and Zn. We observed that 72% of the variation in phosphatase activity could be explained by the NH4NO3-extractable and total heavy metal concentration. By considering different monitoring approaches and different viewpoints, this set of methods applied in this study seemed sensitive to site differences and contributed to a better understanding of the effects of heavy metals on the size and activity of microorganisms in soils. The data presented demonstrate the relationship between heavy metals availability and heavy metal toxicity to soil microorganism along a contamination gradient.     

蜂窝煤灰渣对酸性和石灰性污染土壤中重金属的稳定研究

本研究的目的是探讨不同洗涤蜂窝煤灰渣在不同酸碱性土壤中对重金属的稳定效果.在酸性的淳安土壤(铅、镉、铜、锌污染)和石灰性的济源土壤(铅、镉污染)中以4%用量加入灰渣,培养60 d后测定土壤性质.结果表明,灰渣对淳安土壤pH和EC值的增加效果要大于对济源土壤的影响.原灰渣、硫酸洗灰渣和盐酸洗灰渣加入淳安土壤均可显著降低土壤DTPA提取态铅、镉、铜和锌的含量(p0.05),灰渣对济源土壤DTPA提取态重金属的含量影响较小.对于济源土壤,硫酸洗和盐酸洗灰渣与磷酸盐结合施用后土壤DTPA-Pb含量分别下降20.9%和33.1%.对于淳安土壤,加入3类灰渣后土壤DTPA-Pb含量下降26.8%~41.8%;对于淳安土壤,不论是单独施用还是与磷酸盐结合施用,硫酸洗灰渣对铜、锌稳定效果均强于盐酸洗灰渣.以上结果说明,蜂窝煤灰渣在酸性土壤中对重金属有更强的稳定作用,硫酸洗灰渣和盐酸洗灰渣对土壤重金属的稳定作用存在差异.     

单一重金属污染对水稻叶片光合特性的影响

以杂交稻协优818为材料，研究了Cu^2＋、Hg^2＋、Cd^2＋ 3种重金属离子对水稻叶片光合特性的影响。试验结果表明：（1）Cu^2＋在低浓度时BI起叶片叶绿素含量降低。而Hg^2＋、Cd^2＋在低浓度时。则导致叶绿素含量增加：高浓度时，3种重金属均BI起叶绿素含量降低。同时，低浓度时3种重金属离子均导致叶绿素a／b值升高：高浓度时则均引起叶绿素a／b值下降。（2）Cu^2＋、Hg^2＋、Cd^2＋对水稻叶片叶绿素的吸收光谱均无明显影响，在活体条件下并未发生卟啉环中Mg^2＋的置换。（3）Cu^2＋、Hg^2＋、Cd^2＋均引起叶片希尔反应活力降低，即重金属污染明显影响光合作用。     

金铜矿下游农户家养番鸭体内重金属分布特征及其评价

为研究采矿活动及其污染事故对家禽养殖的影响,分别采集了金铜矿下游两岸不同村庄农户家养番鸭10只,分析了鸭肉、鸭肝和鸭血样品中Cu、Hg和As的含量,并对番鸭体内重金属的健康安全进行了评价.结果表明,在相同组织中,Cu含量较Hg和As高.在不同组织中,鸭肝样品中Cu含量最高,平均值为17.20 mg.kg-1,而Hg和As在3个组织间含量无明显差异.金铜矿下游两岸不同村庄农户番鸭样品体内3个组织中Cu、Hg和As的含量均未显示出明显的空间分布规律,表明污染事故及正常的采矿活动未对下游两岸村庄农户家养番鸭样品构成明显影响.所研究番鸭体内3个组织中的Cu、Hg和As的含量都处于正常值范围,且番鸭健康状况未表现出异常.但参照国家食品卫生标准评价结果显示,鸭肝样品中Cu超标率达到100%,最高超标1.74倍,部分鸭肉、鸭血与鸭肝样品中Hg含量也达到较高水平.     

三峡库区典型支流库湾消落带沉积泥沙特征及重金属评价

为了分析三峡库区支流消落带沉积泥沙的理化特征以及重金属污染的空间变化特征,选择9条典型一级支流,共采集54个消落带沉积泥沙样品,测定了粒径分布、容重、有机质(TOC)、总氮(TN)、总磷(TP)、钾(K)等养分元素含量特征以及运用地累积指数评价铬(Cr)、铜(Cu)、镍(Ni)、铅(Pb)、锌(Zn)等重金属.结果表明消落带沉积泥沙粒径分布在空间上(乌江-磨刀溪)中值粒径呈波动变化;支流消落带下部(160~165 m)沉积泥沙相比上部(165~175 m)偏粗,不同高程带砂粒和黏粒体积分数变化属于中等变异,粉粒属于弱变异.独立样本t检验表明消落带上部和下部之间沉积泥沙特征差异不显著.地累积指数评价表明支流消落带沉积泥沙只有Zn元素在珍溪河、龙洞河和龙河属于无-中的污染程度,Pb元素在磨刀溪属于无-中的污染程度,其他元素在所选支流消落带均为无污染.     

重金属污染土壤螯合诱导植物修复研究进展

土壤重金属污染来源广泛、危害严重,已经成为环境污染治理中的热点、难点问题。重金属污染土壤螯合诱导植物修复技术是在化学修复、植物修复的基础上发展起来的,具有绿色环保、经济高效等优点,在重金属污染土壤修复领域具有很大的发展空间。本文在综合螯合诱导植物修复技术发展概况的基础上,系统介绍了螯合剂种类、螯合剂施入时间、施入方式、浓度与剂量、不同富集植物以及土壤理化性质等对重金属污染土壤修复效果的影响及国内外研究概况,综述了螯合诱导植物修复技术的作用机理及其环境风险研究进展。最后,提出了重金属污染土壤螯合诱导植物修复技术还有待深入研究的有关问题。