Assessment of a sequential extraction procedure for fractionation of soil arsenic in contaminated soils

A sequential fractionation scheme, based on a soil phosphorous fractionation, was developed to assess the chemical nature, and thus the potential bioavailability and mobility of As, at the sites. Soil As was separated into five fractions with (i) anion exchange resin, (ii) NaHCO₃, (iii) NaOH, (iv) HCl, (v) residual. Most sites contained relatively low concentrations of As in the two most labile fractions. The bulk of the contaminant As at the sites seemed to be associated with soil amorphous Fe and Al minerals and the dominant clay minerals which help in As sorption are montmorillonite and mica. Resin-extractable As in particular might provide a good index of potential As bioavailability and mobility.     

Modeling of arsenic immobilization by zero valent iron

Ground waters in geothermal regions contain arsenic concentrations that exceed the recommended drinking water standards. In addition, when these regions have agricultural activities, the waters also contain high levels of nitrates and phosphates. These contaminants can be removed from the water with the use of filters containing zero valent iron (ZVI). The objective of this study was to model the removal of arsenate (As(V)) and arsenite (As(III)) by ZVI and to model the effect of competing ions (phosphate and nitrate) on arsenate removal. Arsenic immobilization by ZVI columns was simulated by the HM-1D chemical transport and speciation model and an one-dimensional analytical solution model. Laboratory column studies were conducted in order to obtain representative experimental data for simulation with both models. Arsenic speciation and the presence of competing ions greatly affect arsenic removal by ZVI. Most arsenic is precipitated/co-precipitated on ZVI and on the corrosion products formed on ZVI. The simulations suggested that As(V) process parameters are higher than the As(III) parameters and that they are affected by the presence of nitrates and phosphates in the system. Such models can be used to design treatment units by incorporating the impact of nitrates and phosphates in the removal of arsenic by ZVI as well as the impact of temperature on the process.     

铅.镉.砷.汞污染的治理研究进展

重金属污染问题是工业化和城市化活动导致的最有危害性环境问题之一,环境中重金属能通过食物链污染食品、危害人体健康。治理重金属污染已成为热点研究话题。分别对重金属铅、镉、砷、汞污染的治理现状进行了综述。     

As胁迫对不同品种小麦种子萌发及幼苗生长特性的影响

以商麦5226、商麦1619和3-3等3个小麦品种为材料,测定不同As浓度（0 mg/L、25 mg/L和50 mg/L）胁迫下小麦种子萌发和幼苗生长指标。结果表明：随着As浓度增加,小麦种子萌发期主胚根长、芽长、芽鲜重、发芽势、发芽率和幼苗期叶片叶绿素含量呈下降趋势;苗期可溶性糖含量和POD活性呈先增后减的变化趋势;萌发期根鲜重呈先减后增的变化趋势;MDA含量随着As浓度增加而增加。As对小麦种子根生长的抑制作用大于芽。     

广东鼎湖山土壤中砷氧化菌的分离与鉴定

通过外加砷源驯化肇庆市鼎湖山自然保护区土壤中细菌,采用富集、稀释平板、硝酸盐漫过、16S rDNA、生理生化等方法,从中分离、鉴定出具有氧化砷功能的产碱杆菌和土壤杆菌2种菌株。     

改进的水砷浓度比色测量技术

[目的]研究改进的饮水砷浓度比色测量技术。[方法]选用处理过的细棉线作为显色载体,设计独立分装并集于一体的试剂包对现有饮水砷快速测定法的试验装置进行改进,并粗测了5种金属离子（Ca2＋、Mg2＋、Fe3＋、Al3＋、Mn2＋）对快速法的影响,明确该技术在高砷饮水地区的适用条件。[结果]改进后的显色载体,使显色分布较均匀,有利于测试结果的观察;设计便捷式试剂包对试剂运输和用户操作使用更加方便;比色测定表明,水中Ca2＋、Mg2＋、Al3＋、Mn2＋的存在,基本上不会影响快速测定法的使用;Fe3＋浓度〈20 mg/L时对测定没有影响,当其浓度高于20 mg/L时必须对水样进行先稀释,再测定。[结论]改进的测试技术灵敏可靠、操作简单、携带方便、造价低廉,值得在砷中毒地区的砷清查和监测工作中推广使用。     

土壤细菌群落多样性对鸡粪中洛克沙胂代谢物的响应

研究施用含饲料添加剂洛克沙胂（ROX）代谢物的鸡粪对土壤细菌群落结构的影响遥结果表明：土壤中相对含量较高的As（Ⅴ）与细菌Shannon-Weiner指数存在较低的负相关关系,低含量DMA与细菌Shannon-Weiner指数存在较低的正相关性关系,低含量As（Ⅲ）与细菌Shannon-Weiner指数无明显的相关性。在相同培养时间段土壤的细菌群落结构相近性较高,且未表现出对土壤砷形态含量差异的响应。在60d培养期内,土壤细菌群落多样性随着土壤中各种砷化物含量的变化而相应变化,主要受含量较高的As（Ⅴ）与毒性较强的As（Ⅴ）的影响,但全程细菌Shannon-Weiner指数的变化并未表现出明显的ROX添加量的浓度差异效应。     

Element concentrations in meals from krill and amphipods, — Possible alternative protein sources in complete diets for farmed fish

In the marine environment, organisms from lower trophic levels seem as a good alternative to the traditional meal and oil sources. In the present study, meals were produced from Antarctic krill (Euphausia superba), Arctic krill (Thysanoessa inermis) and the Arctic amphipod Themisto libellula. Diets were then prepared for Atlantic salmon and Atlantic cod where up to 100% of the fish meal protein was replaced by protein from these organisms. Concentrations of copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) were determined by ICP-MS in the various krill and amphipod meals, complete diets and muscle samples from fish fed these diets. The element concentrations were related to growth and general fish health as well as present EU legislations on feed ingredients and complete diets. The cod showed no difference in growth during the trial, while salmon fed diets where 40% of the fish meal protein was replaced with Arctic krill or amphipod meal shoved improved SGR during the first period of feeding (first 100 days). No adverse effects on growth rate or fish health were observed in any fish species or treatment. Nevertheless, high levels of Cu were found in the meal from Antarctic krill (46 mg kg^− 1 dry matter (dm)) resulting in a dietary level of Cu exceeding the upper limit for complete feedingstuff set by EU. Furthermore, the Cd level found in the meal from amphipod (12 mg kg^− 1 dm) was 6 times higher than EU's upper limit. This indicates limitations for the use of certain zooplanktons as alternative protein sources in feed for farmed fish, unless future processing methods yield lower levels of these unwanted elements.     

以電化學分析法探討堆肥對土壤三價砷活性的影響

台灣西南沿?貐^土壤中砷含量有偏高情形,砷含量過高會經由各種途徑對人體造成毒害。以X-射線繞射儀與傅立葉轉換紅外線吸收光譜儀證明普魯士藍對三價砷的孯恍晕綑C制,再以普魯士藍修飾電極搭配流動注入系統來偵測土壤三價砷,並探討堆肥對三價砷在不同土壤中吸附與脫附的影響。試驗結果得知電化學分析技術可快速、簡便且準確地偵測土壤三價砷,且結果中也指出堆肥處理會增加秀水與後里土壤對三價砷的吸附。此外,三種土壤不論有無施用堆肥,脫附百分率的大小順序爲興大>秀水>後里,其中秀水土壤雖在施用堆肥後吸附力大小明顯增加,但脫附百分率下降的情形較不明顯,顯示黏土礦物種類與含量控制三價砷的脫附行爲。     

石门雄黄矿区As污染研究Ⅰ—As空间分布、化学形态与酸雨溶出特性

为了全面识别湖南石门雄黄矿区环境的As污染现状,为矿区环境修复和生态健康提供依据,系统分析了该矿区矿渣、农田土壤与地表水体中As污染的空间分布、形态组成和酸雨溶出特性。结果表明:石门雄黄矿区矿渣As浓度高达10.3~389.3 g·kg^-1,XRD分析表明As主要以其矿物晶体As₂S₃形态存在,SPLP模拟酸雨浸提矿渣As溶出浓度达到16.5~84.0 mg·L^-1;矿渣上层覆土As浓度高达3.8~27.3 g·kg^-1,超出国家土壤环境质量三级标准95~682倍,覆土的酸雨浸出液中As浓度达到0.1~0.6 mg·L^-1,超出国家Ⅴ类地表水质量阈值1~6倍。由于矿渣渗滤液污染,矿区黄水河As含量峰值达到765 μg·L^-1;矿区农田土壤As含量为43~2268 mg·kg^-1,其中水溶态、表面吸附态、Fe/Al结合态和碳酸盐结合态As分别占总As 的1.0%、1.6%、27.0%和11.5%,高As值集中分布于果树种植区;在模拟酸雨淋溶与施用磷肥条件下,农田土壤As浸出浓度达到0.03~4.6 mg·L^-1。根据以上结果,高浓度含As矿渣是石门雄黄矿区农田土壤和河流发生持久性严重As污染的重要贡献源,可进一步通过食物链造成人体As暴露。