Microbial diversity of soil bacteria in agricultural field contaminated with heavy metals

In this study we evaluated the bacterial diversity in a soil sample from a site next to a chemical industrial factory previously contaminated with heavy metals. Analysis of 16S rDNA sequences amplified from DNA directly extracted from the soil revealed 17 different bacterial types （genera and/or species）. They included Polyangium spp., Sphingomonas spp., Variovorax spp., Hafina spp., Clostridia, Acidobacteria, the enterics and some uncultured strains. Microbes able to tolerate high concentrations of cadmium （500μmol/L and above） were also isolated from the soil. These isolates included strains of Acinetobacter （strain CD06）, Enterobacter sp. （strains CD01, CD03, CD04 and CD08） （similar strains also identified in culture-independent approach） and a strain of Stenotrophomonas sp. The results indicated that the species identified from direct analysis of 16S rDNA of the soil can be quite different from those strains obtained from enrichment cultures and the microbial activities for heavy metal resistance might be more appropriately addressed by the actual isolates.     

交通环境与城市行道树重金属铅和镉的关系

以南方常见的18种受到机动车污染的城市行道树及其对照树作为研究材料，用原子吸收分光光度法分析了其叶片和树皮的重金属含量以研究交通环境与城市行道树叶片的树皮含铅量及含镉量之间的关系。研究表明，不同的城市行道树吸收交通环境中重金属的量不同。城市行道树采样部位离杨车道水平距离越近，其树皮和叶片的含铅量和含镉量越高。     

重金属镉胁迫对尼罗罗非鱼抗氧化酶系统的影响

为评估重金属镉（Cd2+）对鱼类抗氧化酶活性的影响,本文采用静水生物测试的方法,将尼罗罗非鱼暴露于不同浓度水平（0、0.5、1.5、3.0和6.0mg/L）的Cd2+溶液中,21d后测定尼罗罗非鱼肌肉、肝脏、肾脏、脾脏和鳃5种组织中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）的活性和谷胱甘肽（GSH）的含量。结果表明:重金属镉对尼罗罗非鱼抗氧化酶活性产生影响。尼罗罗非鱼肝脏组织的SOD、CAT活性和GSH含量显著高于其他4种组织,具有组织特异性。肝脏组织的SOD、CAT活性和GSH含量随着镉浓度的升高呈下降趋势,高浓度组（3.0mg/L）和极高浓度组（6.0mg/L）尼罗罗非鱼肝脏组织的SOD活性显著低于对照组（P<0.05）。肝脏组织中SOD、CAT活性和暴露水体中镉的浓度水平呈现明显的剂量-效应关系。与对照组相比,暴露组尼罗罗非鱼肾脏组织中SOD、CAT活性及GSH含量均处于诱导状态;对于鳃组织而言,SOD、CAT活性呈现低浓度（0.5mg/L）时被诱导,高浓度时被抑制。不同暴露组尼罗罗非鱼肌肉和脾脏组织中SOD、CAT活性与对照组没有显著性差异（P>0.05）。     

土壤作物生态系统中的铅镉污染影响研究

土壤的铅镉污染是一个非常严重的环境问题。利用植物生长实验确认在土壤中添加有机肥后可以抑制和减缓Pb、Cd向作物器官中的迁移。     

不同土壤改良剂及其组合对降低大白菜镉和铅含量的作用

为寻求有效抑制污染土壤上大白菜对重金属镉(Cd)和铅(Pb)的吸收、保持大白菜卫生品质的技术方法,利用土壤盆栽试验,对施用不同土壤改良剂及其组合降低大白菜地上部Cd和Pb含量的效应进行了比较研究.结果表明,施用改良剂对大白菜的生长具有促进作用,施用改良剂可升高土壤的pH值和降低土壤中的有效态Cd含量,施用改良剂可显著降低大白菜中Cd和Pb的含量.加入5.0 mg.kg-1 Cd,2种大白菜地上部的Cd含量在所有的改良剂处理下均超过了0.5 mg.kg-1.在投加Pb 1500 mg.kg-1后,2种大白菜在加入石灰+鸡粪+过磷酸钙后,其地上部Pb含量均小于2.0 mg.kg-1,可以满足大白菜在Pb(1500 mg.kg-1)污染土壤上的安全生产.     

Comparison of Pb and Cd adsorption to the surface coatings and surficial sediments collected in Xianghai Wetland

Surface coatings and surficial sediments were obtained in four natural waters in Xianghai Wetland in China to study the role of surface coatings and surficial sediments in controlling the transporting and cycling of heavy metals in aquatic environments. Pb and Cd adsorption to the surface coatings and surficial sediments were measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0.0.5 mol/L, 25℃ and pH 6.0 for surface coatings: and 0.00.5 mol/L CaCl2 solution, 25℃ and pH 6.0 for surficial sediments). The Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings and surficial sediments, and the component analyses of surface coatings and surficial sediments were also carried out.Correlation analyses between the maximum adsorption of Pb and Cd (Гmax) and the components in the surface coatings and surficial sediments suggested that there was a statistically significant trend for Pb and Cd adsorption(Гmax) to the surface coatings to increase with increasing in contents of Fe and Mn oxides in the surface coatings and surficial sediments. And the metal adsorption abilities of surface coatings were much stronger than those of surficial sediments, highlighting that in the same water, i.e. at the same pH and initial metal concentrations, the metals(such as lead and cadmium) in supernatant were feasible to be adsorbed by surface coatings than surficial sediments. The more importance of surface coatings than surficial sediments for adsorbing and cycling of heavy metals in aquatic environments was evidenced.     

区域农田土壤镉风险的机理式定量预测模型研究——以江苏省为例

大面积区域土壤风险的精准定量评价和预测一直是研究的热点和难点,以往经验式为主的模型在普适性上存在较大局限.基于土壤理化性质和热力学化学平衡的机理式多表面形态模型(Multi-surface Speciation Model,MSM)已在实验室和小区域尺度成功预测土壤Cd的溶出,但能否应用于更大区域的环境风险评价还未可知.基于此,本研究收集了3354个江苏省表层土壤Cd样品和155个含有理化性质的表层土壤剖面,利用图斑赋值方法得到3354个具有完整理化性质和全量Cd含量的土壤样品数据,在此基础上利用MSM预测各样品的有效态Cd含量,并根据江苏省典型区域MSM-Cd阈值开发了基于MSM的江苏省土壤Cd污染生态风险评价预警模型和敏感性模型,并绘制了江苏省土壤Cd污染风险现状图和土壤Cd敏感地图.结果表明,MSM-Cd比总Cd可更准确预测高污染地区和非污染区域,同时发现增加土壤pH是降低Cd生态风险的最有效途径,而pH是影响土壤Cd敏感度的最重要原因.研究表明,基于MSM的土壤Cd风险预测模型可实现区域土壤风险的精准定量化评估与预测,为土地质量管理和风险管理提供决策依据的实用技术支持.     

磁性固体螯合材料修复农田镉污染土壤研究

为了完善农田耕地土壤Cd污染"磁性固体螯合材料-农机磁选移除"技术,获取相关技术参数,文章采用室内盆栽模拟方法,研究了投料后磁性固体螯合材料在土壤耕层垂直分布以及基于移除效果的最佳材料投加量。结果表明:磁性固体螯合材料施入水田土壤后,经搅拌后,在耕层是均匀分布;固体螯合材料投加量为0.40%时,土壤总Cd、DTPA-Cd和HCl-Cd移除率达到最大,增加投加量土壤Cd移除率趋于稳定。因此,设计的回收机械应考虑在整个耕层回收材料,0.4%的最佳螯合材料投加量以及该投加量是否有利于磁选回收,还需要农机在大田实验验证。     

镉柱法测定海水中硝酸盐氮方法探讨

镉柱法测定海水中硝酸盐氮方法探讨烟台市环境监测中心站翟美华《海洋监测规范》中，硝酸盐氮的测定方法为镉柱法。该法是将待测水样中的硝酸盐氮通过镉柱定量地还原为亚硝酸盐氮，然后按重氮－偶氮光度法测定亚硝酸盐氮的总量，扣除原有的亚硝酸盐氮，即得硝酸盐氮的含量...     

污灌区镉污染土壤钝化修复及其生态效应研究

采用盆栽试验,研究了海泡石对Cd污染污灌区土壤的钝化修复效应及其对土壤环境质量的影响.结果表明,施用海泡石显著地降低了土壤有效态Cd含量(P<0.05),可交换态Cd比例下降了0.8%~3.8%,而残渣态Cd比例增加了0.5%~9.8%.投加海泡石明显地促进菠菜生长,与对照相比,地上部和根部干重分别增加了0.94~2.11倍和1.63~5.21倍.添加海泡石后,土壤过氧化氢酶、脲酶和蔗糖酶的活性分别增加了5.1%~15.4%、14.2%~28.8%和23.5%~34.0%,细菌和真菌的数量分别增加了15.5%~91.7%和45.6%~96.5%.菠菜体内Cd含量、富集系数和转移系数随土壤中海泡石添加量的增加而降低,与对照相比,地上部和根部Cd含量分别降低了19.9%~45.6%和51.2%~70.2%,且在海泡石投加浓度达到5%时,菠菜可食部Cd含量达到国家食品卫生标准的要求.