原子吸收光度法测定树叶中的重金属

用浓硝酸与高氯酸消解树叶,Ｃｕ、Ｚｎ、Ｍｎ含量较高,可直接用火焰原子吸收法测定,含量较低的Ｐｄ、Ｃｄ,Ｃｒ则用石墨炉法测定。Ｐｂ及Ｃｄ含量甚微,受基体及共存元素干扰严重用标准加入法可消除干扰,结果令人满意。     

中国居民饮用水镉暴露非致癌风险的年龄分层权重

饮水是人体镉(Cd)暴露的重要途径,为了定量表征中国居民饮用水镉暴露风险,通过文献调研收集我国3类主要饮用水类型的镉浓度数据.利用回归模型获得不同年龄段人群饮水暴露参数分布模式.基于概率方法评价不同水体和不同人群由于饮用水镉暴露造成的非致癌风险.结果发现,3种类型水体镉浓度存在显著差异.自来水、未处理的地下水和地表水源...     

污泥焚烧中Cd形态转化的热力学平衡模拟

采用热力学平衡分析方法,结合典型污泥成分和焚烧条件预测了污泥焚烧过程中重金属Cd的转化和迁移规律。模拟计算中考虑了主量矿物质与Cl、S对Cd的形态转化的影响。研究结果表明,污泥焚烧过程中,在低温的条件下Cd主要以固体碳酸盐形式存在,随着温度升高,碳酸盐分解为固态CdO,随后有气态Cd(OH)2、Cd和CdO生成,并且在较高温度主要以气态Cd存在。焚烧体系中,矿物质SiO2对Cd的形态转化影响大于其他矿物质,SiO2能与Cd结合生成稳定的CdSiO3,从而可有效抑制含Cd气态污染物的排放。焚烧体系中Cl较易与Cd结合形成CdCl2而导致Cd的挥发,Cl含量的增加促进了Cd在焚烧体系中的挥发。在低温阶段,Cd易与S结合形成固态硫酸盐,抑制了金属的挥发;在高温阶段,金属的形态转化基本不受S的影响,但是可以影响气态金属Cd的生成温度。根据污泥在不同焚烧温度、Cl含量、S含量条件下Cd的不同产物形态,可以对Cd的污染进行有效控制。     

胞外聚合物对水中Cd(Ⅱ)的吸附性能研究

以Pseudomonas fluorescens C-2产生的胞外聚合物PF-2作为新型生物吸附剂,以傅里叶变换红外光谱(FTIR)对其进行表征。系统地研究了胞外聚合物PF-2对水中Cd(II)的吸附行为。结果表明,在pH值为6.0,该吸附剂对水中的Cd(II)具有很强的吸附能力。聚合物PF-2对Cd(Ⅱ)的吸附较易进行,吸附等温线能较好地用Langmuir模型来描述,最大单分子层吸附量为33.50 mg/g,吸附动力学很好地符合准二级动力学模型。胞外聚合物PF-2含有的主要官能团为羧基、羟基和氨基等,其中羧基、羟基参与了Cd(Ⅱ)的吸附。结果表明利用胞外聚合物PF-2去除环境水样中的Cd(Ⅱ)是可行的。     

镉污水灌溉下芦蒿生长及镉富集特性研究

通过生物盆栽试验,研究了不同浓度Cd污水灌溉对芦蒿生长及Cd富集特性的影响.结果表明,芦蒿具有很强的Cd抗性.在Cd污水浇灌下,供试土壤中累积的Cd处理量分别为0.3 mg/kg、1.0 mg/kg、5.0 mg/kg、10.0 mg/kg、15.0 mg/kg、20.0 mg/kg、25.0 mg/kg、30.0 mg/kg、35.0和40.0 mg/kg(分别记为C1、C2、C3、C4、C5、C6、C7、C8、C9和C10),各处理芦蒿的干物重和根系活力均高于对照;叶绿素a和叶绿素b的质量比大体呈现低Cd(0.3～20.0 mg/kg)处理下增加,高Cd(>20.0 mg/kg)处理下减少的规律;C1(0.3 mg/kg)和C2(1.0 mg/kg)两个处理的类胡萝卜素质量比比对照高,Cd处理水平超过1.0 mg/kg后类胡萝卜素质量比都比对照低,且随着Cd处理量的增加呈现逐渐降低趋势;芦蒿根、茎、叶均有较强的Cd富集性,不同器官Cd质量比从大到小为根、茎、叶,土壤Cd处理量在0.3～40.0 mg/kg内时,根茎叶中Cd累积量随着土壤Cd处理量的提高而增加,且二者呈极显著(p<0.01)正相关关系.在低Cd处理水平下芦蒿地上部分的富集系数大于1,芦蒿如此高的富集系数作为蔬菜来种植是不安全的,控制芦蒿的质量安全是一项具有重大现实意义的工作.     

Cd-Pb复合污染在土壤-水稻系统中生态效应的研究

采用盆栽试验研究了重金属复合污染物在土壤 -水稻系统中迁移、积累规律及生态效应。结果表明 :Cd、Pb复合污染使水稻株高比对照的下降了 5～ 7cm ,水稻减产 2 0 % ,2元素交互作用特别是 5元素复合作用影响了水稻的正常生长发育 ;不同处理中重金属在水稻籽实的分配比例依次为 5元素 >2元素 >单元素 ;Cd -Pb 2元素交互作用时 ,Pb元素的存在促进了水稻对Cd元素的吸收 ,而Cd元素却抑制了水稻对Pb元素的吸收 ;Cd比Pb元素易向地上部迁移 ,Pb元素大部分积累于水稻根部     

Identification of Pollution Source of Cadmium in Soil. Application of Material Flow Analysis and A Case Study in Taiwan (11 pp)

Background Since the 1970s, at least 200 hectares (ha) of farmland has been polluted by the heavy metal cadmium (Cd).Consequently, the Cd pollution has led to contaminate the rice production and caused acute social panic. According to the recent investigation results performed by the Taiwan Environmental Protection Administration (TEPA), it is indicated that most of the Cd pollution incidents in Taiwan resulted from the wastewater discharge of stearate Cd factories. To prevent the Cd pollution incidents from spreading, the TEPA has either forced these factories to close down or assisted them in improving their production processes since the 1980s. Unfortunately, accidental incidents of Cd pollution still emerge in an endless stream, despite the strict governmental controls placed on these questionable factories. Whether this pollution has resulted from undetected or hidden pollution sources stemming from two decades ago or comes from some new source, will be an outstanding issue. Therefore, this study attempts to identify the pollution sources of Cd in soil in Taiwan as well as to find the solution to the above-mentioned, outstanding issue by way of a methodology termed Material Flow Analysis (MFA). Method logy. The MFA has proved to be a useful tool on providing quantitative information of the flow of substances through an economic to an environmental system. Based upon the supply-and-demand theory of MFA, researchers have successfully conducted an overview of the use of materials in many industries, the construction industry being one of these. Therefore, this study tries to establish a set of analytical processes by way of MFA for identifying the pollution source of Cd in soil in Taiwan. In addition, the spirit of Life Cycle Analysis (LCA) technique was also employed to identify the materials, and products should be ignored as a crucial pollution source in this study. Results and Discussion According to the MFA methodology applied in this study and on the basis of related studies performed by Taiwanese governmental authorities, we arrive at the following analysis results: (1) the total amount of Cd from the economic perspective of material and product flow was approximately 441.2 tons; (2) the wastewater directly discharged into irrigation water can be concluded to be the major pollution route of Cd in farmland soil in Taiwan; (3) material plastic stabilizer (cadmium oxide, CdO), Zn-Pd compounds and Cu compounds should be the crucial pollution sources to contaminate environment through the route of wastewater in Cd flow analysis; (4) the crucial pollution sources to contaminate environment through the route of wastewater in Cd flow analysis were five factories, Coin, Jili, Taiwan Dye, Guangzheng and Mingguan, and they were all categorized as stearate Cd industries; (5) the typical source of the Cd pollution in soil in Changhua County through the pollution route of wastewater should be the metal surfacing process industries. Conclusions This study proved that MFA can be a good tool for identifying Cd flow as well as for recognizing the crux of the problem concerning incidents of Cd pollution. This study led to the conclusion that the causal relationship between farmland pollution caused by Cd and stearate Cd factories in Taiwan seemed quite close by way of MFA methodology. In addition, this study also found that the wastewater discharged from a single metal surfacing process factory will not cause remarkable farmland pollution. However, the wastewater simultaneously discharged from a group of pollution factories can result in a significant pollution incident. Recommendations and Outlook This case study is only a small contribution to the understanding of the toxic material flow related to Cd in the environment. This study recommends that Taiwanese governmental authorities should not deal with problems on an ad hoc basis, but should instead deal with Cd pollution problems overall employing control measures. Finally, the more accurate information or data we can collect, the more reliable results we can identify. Therefore, the quality and quantity of related data used in this MFA model should be closely scrutinized in order to ensure the most correct and comprehensive investigation on the toxic material flow.     

南宁市河流型水源地重金属污染调查与健康风险评价

通过对南宁市河流型水源地水体中Pb、Cd、Hg、As浓度调查与健康风险评价研究,结果表明:这4种元素在水体中的质量浓度较低,均达到《地表水环境质量标准》(GB 3838-2002)Ⅱ类标准;经饮水途径引起的健康风险从大到小依次为AsCdPbHg,说明As是南宁市饮用水源中的主要风险因子;4种元素通过饮水途径引起的平均个人年健康致癌风险值为1.48×10-6a-1~13.75×10-6a-1,非致癌风险值为7.05×10-10a-1,均低于美国环保局和国际辐射防护委员会的推荐值。     

矿区炼金废渣的固化/稳定化处理

通过对金矿矿区炼金废渣的酸中和能力、净产酸量及浸出毒性实验,测定了废渣的产酸潜力及重金属砷、镉、铅、锌的总量和它们的浸出量。为了合理处置矿区炼金废渣,并为矿区重金属污染土壤的修复提供技术支持,采用石灰、粉煤灰、堆肥化污泥作为添加剂对废渣进行固化/稳定化处理;通过浸出毒性实验对固化/稳定化处理效果进行综合分析,试图寻求一种最佳的稳定剂。结果表明,无论是单独添加石灰、粉煤灰或者堆肥化污泥还是两两组合混合添加,样品浸出液的pH都有升高,As、Cd的浸出浓度都有明显下降,而且两两组合添加比单独添加的固化/稳定化处理效果更好。在两两组合添加中,粉煤灰混合堆肥化污泥的处理效果最好,浸出液的pH值达到7.82,As、Cd的浸出率分别下降72.0%和72.2%。说明粉煤灰混合堆肥化污泥处理炼金废渣效果最佳,同时具有以废治污的资源化生态效能。     

Molecular mechanism for cadmium-induced anthocyanin accumulation in Azolla imbricata

Anthocyanins inducibly synthesized by Cd treatment showed high antioxidant activity and might be involved in internal detoxification mechanisms of Azolla imbricata against Cd toxicity. In order to understand anthocyanin biosynthesis mechanism during Cd stress, the cDNAs encoding chalcone synthase (CHS) and dihydroflavonol reductase (DFR), two key enzymes in the anthocyanin synthesis pathway, were isolated from A. imbricata. Deduced amino acid sequences of the cDNAs showed high homology to the sequences from other plants. Expression of AiDFR, and to a lesser extent AiCHS, was significantly induced in Cd treatment plant in comparison with the control. CHS and DFR enzymatic activities showed similar pattern changes with these genes expression during Cd stress. These results strongly indicate that Cd induced anthocyanin accumulation is probably mediated by up-regulation of structural genes including CHS and DFR, which might further increase the activities of enzymes encoded by these structural genes that control the anthocyanin biosynthetic steps.