贵州汞矿矿区不同位置土壤中总汞和甲基汞污染特征的研究

为了深入理解汞矿矿区土壤中总汞和甲基汞的污染特征,应用AAS、GC-CVAFS方法,分别对贵州万山、务川和滥木厂汞矿矿区不同位置土壤以及对照区土壤中的总汞(THg)和甲基汞(MeHg)进行了测定.结果表明,万山汞矿区土壤THg和MeHg含量范围分别为1.1～790 mg·kg^-1和0.19～15μg·kg^-1,务川汞矿区土壤THg和MeHg含量范围分别为0.33～317mg·kg^-1和0.41～20μg·kg^-1,滥木厂汞矿区土壤THg和MeHg含量范围分别为0.41～610 mg·kg^-1和0.70～8.8μg·kg^-1.对照区土壤汞含量明显低于矿区土壤,其THg和MeHg含量范围分别为0.14～1.2 mg·kg^-1和0.09～0.23μg·kg^-1;对照区土壤THg含量接近或稍高于全球背景土壤THg含量0.01～0.5 mg·kg^-1.研究表明,汞矿区稻田土壤具有较强的汞甲基化能力,其MeHg含量明显高于菜地和旱田土壤;万山汞矿区土壤汞污染程度明显高于滥木厂和务川汞矿区土壤汞污染.     

植物的非传统稳定同位素前处理及测定技术研究进展

一直以来植物都是多领域的研究重点,随着非传统稳定同位素的不断发展,植物非传统稳定同位素研究日益增加。但因植物样品中有机物含量高,同位素分馏复杂,样品前处理及测定中存在诸多难题。本文对植物样品非传统稳定同位素工作中常用的前处理方法和测定技术进行了总结。综述了直接萃取法、湿法消解和高温灰化法的原理、操作和优缺点;以K、Ca、Mg、Fe、B等典型非传统稳定同位素为例介绍了非传统稳定同位素常用测定技术,旨在为植物样品的非传统稳定同位素测定进行梳理,最后对其应用方向和测试方法的发展方向进行了展望。     

铜锌同位素方法在环境地球化学研究中的应用

近年来,随着多接收电感耦合等离子体质谱(MC-ICP-MS)逐渐应用,过渡族金属(Cu,Zn和Fe等)同位素测试方法逐渐成熟,测定精度可达0.04‰,使得铜锌铁等同位素地球化学研究成为近年来国际地学研究领域的热点。本文对铜锌同位素的测试方法、分馏机理及其在环境地球化学研究领域的应用进行了较系统综述。     

拉萨河夏季氢氧同位素空间分布特征及分析

稳定同位素示踪技术是河流水文过程研究的重要方式,可以用来判定河流补给的来源、研究河流与其它水体相互作用、示踪水文循环过程等.本文采用TC/EA-IRMS分析法对拉萨河水体的氢氧同位素进行测定,分析了 δD和δ18O的含量及空间分布特征,并分析了拉萨河的同位素效应,包括与大气降水氢氧同位素的关系、氢氧同位素的沿程变化特征...     

Trace Element Concentrations and Bioindicator Responses in Tree Swallows from Northwestern Minnesota

Extremely high concentrations of cadmium (3.5 μg/g dry wgt.) and elevated concentrations of chromium (>10 μg/g dry wgt.) and mercury (1.6 μg/g dry wgt.) were reported in waterbird tissues at Agassiz National Wildlife Refuge in northwestern Minnesota in 1994. Tree swallows (Tachycineta bicolor) were studied during 1998–2001 at three drainages into the Refuge, two pools on the Refuge, and at a nearby reference location to document whether high levels of contaminants were still present, and if so to quantify the source and severity of the contamination. Trace elements were measured in tree swallow eggs, livers, and diet. Reproductive success and bioindicator responses were monitored. In 2000, water was drawn down on Agassiz Pool, one of the main pools on the Refuge. This presented an opportunity to evaluate the response of trace element concentrations in the diet and tissues of tree swallows after reflooding. High concentrations of trace elements were not detected in swallow tissues, nor were there differences among locations. Less than 20% of swallow samples had detectable concentrations of cadmium or chromium. Mercury concentrations were low and averaged <0.25 μg/g dry wgt. in swallow tissues. Trace elements, including mercury, did not increase in tree swallows following the 2000 drawdown at Agassiz Pool. Hatching success and survival of nestlings to 12 days-of-age for tree swallows on the Refuge were similar to the national average and consistent with background trace element concentrations. Bioindicator measurements were within the normal ranges as well.     

Cancer and Non-Cancer Health Risk from Eating Cassava Grown in Some Mining Communities in Ghana

Food crops such as cassava, cocoyam and other tuber crops grown in mining communities uptake toxic or hazardous chemicals such as arsenic, and cadmium, from the soil. Cassava is a stable food for Ghanaians. This study evaluated human health risk from eating cassava grown in some mining communities in Ghana such as Bogoso, Prestea, Tarkwa and Tamso, which are important mining towns in the Western Region of Ghana. The study evaluated cancer and non-cancer health effects from eating cassava grown in the study areas in accordance with US Environmental Protection Agency’s Risk Assessment guidelines. The results of the study revealed the following: cancer health risk for Tamso, 0.098 (RME – Reasonable Maximum Exposure) and 0.082 (CTE – Central Tendency Exposure). This means that approximately 10 and 8 out of 100 resident adults are likely to suffer from cancer related cases by RME and CTE parameters respectively. For Prestea, we have 0.010 and 0.12, which also means that approximately 1 out of 100 and 10 resident adults out of 100 are also likely to suffer from cancer related diseases by RME and CTE parameters. The results of the study obtained were found to be above the acceptable cancer risk range of 1× 10⁻⁶ to 1× 10⁻⁴, i.e., 1 case of cancer out of 1 million or 100,000 people respectively.     

Spatial Patterns and Rankings of Contaminant Concentrations in Herring Gull Eggs from 15 Sites in the Great Lakes and Connecting Channels, 1998–2002

Mean values of eight contaminants in Herring Gull (Larus argentatus) eggs were calculated for 15 Great Lakes sites for the 5 year period 1998–2002. The sites were ranked according to the concentrations of each of seven compounds relative to fish flesh criteria for the protection of piscivorous wildlife, and a single overall rank of contamination was calculated for each site. Based on this weighted ranking scheme, we found that sum PCBs, dioxin and DDE contributed the most (60.2, 30.5% and 8.5%, respectively) to the overall rankings. The weighted ranking scheme showed that eggs from Channel-Shelter Island (Saginaw Bay, Lake Huron), Strachan Island (St. Lawrence River) and Gull Island (northern Lake Michigan) ranked as the three most contaminated sites, while Agawa Rocks (eastern Lake Superior), Chantry Island (southern Lake Huron) and Port Colborne (eastern Lake Erie) ranked as the three least contaminated sites. Two of the three most contaminated sites are Areas of Concern; none of the three least contaminated sites are Areas of Concern.     

苯胺-邻氨基酚共聚物对水中Hg(Ⅱ)吸附性能的研究

利用化学氧化法合成了苯胺-邻氨基苯酚的共聚物,并通过静态实验研究了材料对水中汞离子的吸附性能。研究结果表明,该共聚物对废水中汞离子有优异的去除效果,其吸附容量可达212.13 mg/g;吸附等温线符合Langmu ir单层吸附模型,动力学过程符合准二级动力学模型;溶液pH值对吸附影响不是很大,pH 5~10范围都有较好的吸附效果;氯离子易与汞离子形成水溶性更强的络合物,对共聚物的吸附有很大的抑制作用。     

Radium and radium-daughter nuclides in carbonates: a brief overview of strategies for determining chronologies

Radium isotopes have been used extensively to trace the movement of groundwater as well as oceanic water masses, but these radionuclides (and their daughters) are also useful chronometers for the determination of the time scales of other Earth and environmental processes. The purpose of this overview is to present the application of Ra and Ra daughters in the dating of carbonates. We show that the choice of dating method (decay of excess radionuclide or ingrowth of daughter) depends strongly on the parent/daughter activity ratios in the water in which the carbonate was precipitated. Thus freshly precipitated carbonates uniformly show excesses of ²²⁶Ra relative to its parent ²³⁰Th, and ²²⁶Ra decay can provide ages of carbonates over Holocene time scales. In contrast, carbonates are precipitated in waters of greatly varying ²¹⁰Pb/²²⁶Ra. Corals, deep-sea hydrothermal vent clams and the shelled cephalopod Nautilus live in waters with significant dissolved ²¹⁰Pb and all show excesses of ²¹⁰Pb in their carbonate. Bivalve molluscs from nearshore and coastal waters, and carbonates deposited from groundwater environments (e.g. travertines) in which ²¹⁰Pb is efficiently scavenged from solution, show deficiencies of ²¹⁰Pb relative to ²²⁶Ra. In contrast, fish otoliths strongly discriminate against ²¹⁰Pb regardless of the environment in which the fish lives. Deficiencies of ²²⁸Th relative to ²²⁸Ra are common in all carbonates. Useful time ranges for the ²¹⁰Pb/²²⁶Ra and ²²⁸Th/²²⁸Ra chronometers are ∼100 y and ∼10 y, respectively.     

Radium geochemistry in Na-Cl type groundwater in Niigata Prefecture, Japan

Radium isotopes in 23 Na-Cl type groundwater sampled mainly from deep wells in Niigata Prefecture, which is the site of the largest oil- and gas-fields in Japan, were measured along with U isotopes, chemical components and hydrogen and oxygen isotope ratios to elucidate the distribution and behavior of Ra in a brackish environment underground. Also analyzed were U and Th isotopes in 38 rock samples collected from outcrops at 17 locations. Ra-226 concentrations (8.86-1637 mBq kg⁻¹) of groundwater samples roughly correlated with total dissolved solid (TDS) concentrations and other alkaline earth contents. Their ²²⁸Ra/²²⁶Ra activity ratios (0.32-5.2) were similar to or higher than the ²³²Th/²³⁸U activity ratios (0.6-1.7) in the rocks. The most likely transport mechanism of Ra isotopes into groundwater was due to their α-recoil from the solid phase, probably from the water-rock interface where Th isotopes had accumulated, and adsorption/desorption reaction based on the increase in ²²⁶Ra contents with TDS.