施用土壤调理剂对酸性土壤中芝麻菜吸收砷的影响

选择亿鼎土壤调理剂、硅钙钾镁肥、木本泥炭3种土壤调理剂,采用酸性土壤进行盆栽试验,探究光照培养箱内不同土壤调理剂施用量(1.3 g · kg^-1和13 g · kg^-1)对土壤砷的钝化效果及芝麻菜砷吸收的影响。结果表明:施用13 g · kg^-1亿鼎土壤调理剂、硅钙钾镁肥可显著提高土壤pH,而施用13 g · kg^-1木本泥炭显著提高了土壤有机碳含量。施加1.3 g · kg^-1木本泥炭时,土壤中有效态砷含量显著降低了5.17%。与不添加任何土壤调理剂的对照相比,3种土壤调理剂均能促进芝麻菜生长,施用1.3 g · kg^-1亿鼎土壤调理剂时芝麻菜地上部鲜质量最大,相比对照显著增加了51.3%,且施用土壤调理剂均能显著降低芝麻菜地上部的砷含量。     

Isolation and characterisation of symbiotically effective Rhizobium resistant to arsenic and heavy metals after the toxic spill at the Aznalcóllar pyrite mine

After the toxic spill occurred at Aznalcóllar pyrite mine (Southern Spain), a wide area of croplands near the Doñana Wild Park was contaminated with 4.5 million m³ of slurries composed of acidic waters loaded with toxic metals and metalloids such as As, Sb, Zn, Pb, Cu, Co, Tl, Bi, Cd, Ag, Hg and Se. Today, 6 years after the spill, the concentration of toxic elements in these soils is still very high, in spite of the efforts to clean the zone. However, some plant species have colonised this contaminated area. Legumes possessing N₂-fixing nodules on their roots represented a significant proportion of these plants. Our objective was to use the Rhizobium-legume symbiosis as a new tool for bioremediate the affected area. We have isolated about 100 Rhizobium strains, 41 of them being resistant to high concentrations of As (300 mg l⁻¹), Cu (100 mg l⁻¹) and Pb (500 mg l⁻¹). Their phenotypes and bioaccumulation potentials have been characterised by their growth rates in media supplemented with As and heavy metals. The presence of the resistance genes in some strains has been confirmed by PCR and Southern blot hybridisation. Several Rhizobium were symbiotically effective in the contaminated soils. On the other hand, the first steps in nodule establishment seemed to be more affected by heavy metals than N₂-fixation.     

磷影响下根际无机砷的形态分布及其对水稻生长的影响

两种有代表性的紫色土的水稻盆裁试验结果表明，磷的加入可减轻受砷污染的红紫泥中砷对水稻的毒害；但磷的加入会加剧受砷污染的红棕紫泥中砷对水稻的毒害。根际无机砷的形态分布研究表明：试验土壤上，根际砷各形态都比非根际高，砷在根际呈富集状态；在根际环境的作用下，红紫泥中，磷的加入加剧了砷由有效态砷（Al-As、Fe-As）向相对无效态砷（O－As）转化，砷对水稻的毒性减弱；红棕紫泥中，磷的加入加剧了砷由相对无效态砷Fe-As和Al-As向有效态砷Ca-As和A-As（表示水溶态砷及松结态砷）的转化，砷对水稻的毒性增强。     

土壤中砷污染研究进展

本文综述了土壤中As污染的主要污染源,土壤中主要含As化合物的形态及转化,土壤对As的吸附缓冲行为,土壤As对植物和微生物的生态毒理及微生物在As不同形态转化中的作用等方面的研究成果;并分析了尚需加强研究的方面。     

Weathering of sulphide minerals and trace element speciation in tailings of various ages in the Guanajuato mining district, Mexico

We studied the behavior of the trace elements (TE) As, Cu, Pb and Zn associated with sulphide minerals in tailings of different age at the Guanajuato mining district, Mexico. The objective was to determine the dominant fractions into which the TE move as tailings age and to identify how much time is needed until the dominant metal fractions approach equilibrium. We collected 21 samples from the surface of mine waste deposits of different ages (0, 2 , 4, 16, 70, 75, and 100 years), and measured their aqua regia extractable contents of As, Cu, Pb and Zn. We also applied a sequential extraction procedure to quantify water soluble TE as well as TE associated with carbonates, iron oxides, sulphides and the residual fraction. The mineralogy was analysed by X-ray diffraction, and selected samples were studied on polished specimens through a stereoscopic microscope. The TE in samples extracted with aqua regia ranged between 10 and 168 mg kg^− 1 for As, 12 to 194 mg kg^− 1 for Cu, 31 to 308 mg kg^− 1 for Pb, and 122 to 1129 mg kg^− 1 for Zn, and varied in a wide range within each age group of tailings. Water soluble Cu, Pb and Zn contents were below detection limits in almost all samples, which was attributed to the alkaline pH (7.17 to 8.61) in the tailings. Water extractable As was detected only in tailings older than 16 years, and concentrations ranged between 0.06 and 7.58 mg kg^− 1. The proportion of TE associated with sulphides decreased in the tailings as they age, while the proportion of TE associated with iron oxides increased with time of exposure to the atmosphere, approximating equilibrium after 60 years for As, Cu and Zn, and after 40 years for Pb. Observations of polished specimens suggests that oxidation proceeds until coatings of secondary minerals cover and protect sulphide mineral grains from further weathering. First order rate equations were adjusted to the proportions of TE associated with either sulphides or iron oxides. Assuming that the TE in sulphide fractions correspond to arsenopyrite (FeAsS), chalcopyrite (CuFeS₂), galena (PbS) and sphalerite (ZnS), the relative oxidation rate of sulphides followed the order: PbS > ZnS > FeAsS ≈ CuFeS₂, while the relative affinity of the elements with iron oxides followed the sequence Cu ≈ Zn > As > Pb.     

Soil and sediment geochemistry of the iron quadrangle,Brazil the case of arsenic

Soils and sediments around gold ore deposit and mining sites in the Iron Quadrangle present positive As anomalies (median concentrations > 100 mg kg^-1) and wide ranges (< 20 to > 2000 mg kg^-1) even in densely populated areas. These anomalies can be related to geological structures, to hydrothermal ore deposits and to their continuous exploitation over the past three centuries. The paper presents new data on both As geochemistry and soil and sediment geochemistry in general, and discusses consequences of the encountered anomalies, their reasons and potential effects and how they compare with current screening and threshold values. While surface soil As-values are reproducible at a given site, sediment anomalies show a strong seasonal variation that can be explained by tropical hydrological variances. Suggestions are presented on how to minimize the As-load in densely populated areas that might otherwise pose a potential health risk.     

氢化物发生原子荧光法测定土壤中的砷

采用HNO3-H2SO4-HC lO4混合酸消解土壤样品,氢化物原子荧光法测定其中的砷。结果表明：检出限为0.01μg/L,标准回收率为91.2%-104.0%,测试数据的相对标准偏差（3.1%。用该法测定土壤中的砷,精密度和准确度高,可满足实际测试工作的要求。     

土壤中砷的吸附行为及其形态分布研究

本文研究了土壤中砷的吸附行为,影响砷吸附的主要因素,以及砷的吸附行为对土壤中的形态分布,有效性,迁移性和缓冲性的影响,为降低土壤中砷的有效性和减轻砷对植物毒性提供依据。     

黄土高原砒砂岩区河岸带沙棘林营造与管护技术的研究

黄土高原砒砂岩区立地条件恶劣,河岸带是该地区具有特殊生态功能的组成部分,在河岸带种植沙棘Hippophae rhamnoides对于改善当地生态环境具有理论和现实的意义。总结几年来在该地营造与管护沙棘林的研究成果与实践经验,能够更好地为实施植被措施改善恶劣地区的生态环境奠定理论和实践基础。具体总结为:因地制宜,科学布设;选择良种壮苗,确保成活率;选择合理季节,抢墒保墒种植;保持苗木活力,搞好假植和保护;认真整地种植,确保造林质量;搞好抚育管理,保证可持续发展。同时对存在的生物多样性、林分抚育管理、病虫害防治问题进行了探讨。     

红葡萄酒中砷含量的流动注射氢化物原子吸收法检测

采用微波消解预处理红葡萄酒,对流动注射氢化物原子吸收法(FI-HAAS)测定砷的载气浓度、流速和载气酸度,预还原剂用量及氧化时间,硼氢化钾用量等参数进行优化,建立流动注射氢化物原子吸收检测红葡萄酒中砷含量的方法.结果表明,FI-HAAS检测红葡萄酒中砷的方法为:氩气为载气,盐酸为氢化物反应的酸介质,载气流速120 mL/min,载流酸度1％,检测使用液为酸度8％的盐酸,硼氢化钾质量浓度为10 mg／mL,氢氧化钠质量分数为0.6％,碘化钾-抗坏血酸作为预还原剂,预还原剂质量分数为1％,用量0.5mL,氧化时间10 min.