北部湾北部滨海湿地沉积物中砷与镉和汞元素的分布与累积

基于表层和柱状沉积物样品的理化分析和²¹⁰Pb、¹³⁷Cs测年,揭示了北部湾北部滨海湿地(0~6 m水深范围)沉积物中砷(As)、镉(Cd)和汞(Hg)元素的空间分布特征、近百年来的累积趋势及控制因素。结果表明研究区表层沉积物类型主要为砂,并且大风江口以东沉积物的粒度比以西的要粗;表层沉积物中As、Cd、Hg和有机质的含量分别是(8.11±5.80)、(0.08±0.11)、(0.034±0.028)μg/g和(0.73±0.74)%,铁山港顶部、南流江口东部、钦州湾和大风江口中部表层沉积物中3种元素含量相对较高;沉积物的粒度是控制元素空间分布的最主要因素,从钦江口、南周江(南流江)口和山口红树林保护区获得柱状样所处区域的平均沉积速率在20世纪20年代至今分别为0.93、1.75和1.35 cm/a;3个柱状样中As、Cd和Hg的含量在20世纪80年代中期至2000s中期呈现出明显增加的趋势,特别是钦江口和南周江(南流江)口区。河口区及上游沿岸人类活动对这些元素的输入是其近20年来含量增加的主要原因。     

Groundwater contamination with arsenic in Sherajdikhan,Bangladesh: geochemical and hydrological implications

An integrated study has been carried out to elucidate the distribution and occurrence of arsenic in selected groundwater samples in the area of Sherajdikhan, Bangladesh. Arsenic and other parameters (T, pH, EC, Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, NO₃ ⁻, SO₄ ²⁻, HCO₃ ⁻, PO₄ ³⁻, Fe, Mn and DOC) have been measured in groundwater samples collected from shallow/deep tube wells at different depths. Hydrogeochemical data suggest that the groundwaters are generally Ca–Mg–HCO₃ and Mg–Ca–HCO₃ types with bicarbonate (HCO₃ ⁻) as the dominant anion, though the other type of water has also been observed. Dissolved arsenic in groundwater ranged from 0.006 to 0.461 mg/l, with 69% groundwater samples exceeded the Bangladesh limit for safe drinking water (0.05 mg/l). Correlation and principal component analysis have been performed to find out possible relationships among the examined parameters in groundwater. Low concentrations of NO₃ ⁻ and SO₄ ²⁻, and high concentrations of DOC, HCO₃ ⁻ and PO₄ ³⁻ indicate the reducing condition of subsurface aquifer where sediments are deposited with abundant organic matter. Distinct relationship of As with Fe and Mn, and strong correlation with DOC suggests that the biodegradation of organic matter along with reductive dissolution of Fe–Mn oxyhydroxides has being considered the dominant process to release As in the aquifers studied herein.     

土壤砷污染特点与植物修复探讨

土壤砷污染一直是国内外关注的热点,植物修复技术是20世纪80年代提出的利用植物治理土壤污染的一种"绿色技术".土壤中砷主要以无机态的形式存在,并主要为Al、Fe、Ca等所吸附而产生共沉淀,水溶态的砷含量一般小于总砷的5%.砷污染区的植物砷含量一般高于非污染区,具有耐贫瘠、耐干旱且地带性不是很强的特点.到目前为止,世界范围内已发现3种超富集砷的植物.根据野外调查与分析,利用超富集植物治理土壤轻度砷污染是可行的.     

吉林省西部地方性氟、砷中毒现状及治理

吉林省西部是地方病高发地区,尤其是地方性氟、砷中毒的情况比较严重,尽管防氟改水工作已经进行40多年,但目前仍有相当多村屯的村民饮用高氟水,严重威胁人民的身体健康并影响当地的经济发展。针对现状作者分析了产生的原因并提出具体治理建议。     

Influence of diurnal cycles on metal concentrations and loads in streams draining abandoned mine lands: an example from High Ore Creek,Montana

Diurnal water samples were collected simultaneously at four locations along High Ore Creek (Montana, USA), a small stream with near-neutral pH that contains elevated concentrations of Zn, Mn, Cd, and As from abandoned mines near its headwaters. During the same time period, two sets of synoptic samples were collected by workers moving in opposite directions along the stream. Large diurnal fluctuations in Zn concentration were found at three of the 24-h monitoring stations, but not at the outlet to a settling pond. Because the concentrations of Zn were dropping at most locations in the creek during the day (in response to the daily cycle of day-time attenuation and night-time release), the synoptic sampler who moved upstream obtained a data set that led to the conclusion that Zn load increased with distance downstream. The sampler who moved in a downstream direction obtained the opposite results. Thus, failure to take short-term diurnal cycling into account can lead to incorrect conclusions regarding spatial or temporal trends in water quality within a watershed.     

Untersuchungen zum Schadstoffpotential von Wasserwerksschlämmen

Investigation on the Pollution Potential of Waterworks Sludges Several contaminated sludges from water treatment plants with known or estimated concentrations of trace elements were investigated for their leaching characteristics and long-term stability using standard and advanced test procedures. Potentially hazardous elements in the sludge are zinc, nickel, and arsenic with concentrations of up to 1.2 g/kg dry matter (mass). Preliminary sorption tests with synthetic sludge components like iron hydroxide, manganese oxide, silicate clay minerals, and chitine powder as a model organic component showed that Cu is associated with the organic phase wheras arsenic is predominantly bound to the iron oxide minerals. The recently suggested pH_stat test procedure was used to assess the leaching characteristics of metals at typical pH values. This procedure was compared with the DEV-S4 test, the current standard test in Germany, consisting of a simple lixiviation of the solids with water, without pH control. The pH_stat test yields results which are much better to interprete than those obtained by the DEV-S4 procedure. The iron and manganese sludges are well buffered against changes in pH and redox potential so that low pH values and/or reducing conditions can hardly occur. Thus, in deposited material a sudden leaching of heavy metals is unlikely and due to the presence of iron and manganese oxides the pentavalent arsenic is protected against conversion into the highly mobile trivalent form at neutral to low pH. Co-deposition with reducing organic matter and alkaline stabilisation material or waste (like fly ash) could influence the binding properties and should be strictly avoided.     

Socio-economic constraints of groundwater in Capital La Rioja, Argentina

Historically, the arid conditions of La Rioja, Argentina have been the main controlling factor in its development. The shortage of surface water, which is fully used, makes groundwater a potential source for development. The government encouraged investment in early 1979, resulting in a 20-fold increase of groundwater extraction by 1998 (0.076–1.450 m³/s, respectively) to cover related needs of agriculture, industry and population growth. This extraction created unjustified uncertainties derived from negative results obtained in hydrological balances. However, a 0.5 m lowering of the water-table surface was experienced. A knowledge of groundwater functioning was required to establish a reliable frame of reference for development and, at the same time, to find possible scenarios of feasible economic activities in harmony with accessible water resources and aptitude of the environment. The flow regime was found to be composed of three main systems: a regional, an intermediate and several local. The intermediate system provides water for the extraction boreholes, and discharges naturally in Salina La Antigua. From the chemical perspective the intermediate system has three groundwater groups. Group I has an outstanding fluoride concentration (1.98–3.10 mg/l) defined to the north of the City of la Rioja and the highest temperature (26.8–33.0°C), the lowest lithium content (0.029–0.059 mg/l) and moderate arsenic (≤0.038 mg/l). Group II has the moderate arsenic content (≤0.38 mg/l) detected to the south of the City of La Rioja and high lithium (0.024–0.085 mg/l), Group III has the lowest TDS (456–931 mg/l) and arsenic (0.007–0.012 mg/l) and the highest lithium (0.067–0.141 mg/l). to A regional flow is represented by Group IV with one order of magnitude higher strontium (4.870 mg/l), lead (0.021 mg/l) and uranium (0.362 mg/l) content than the other groups. Results provide evidence to eliminate several well-established hydro-myths such as “the boreholes are getting dry” and “boreholes are getting saline water”. The aquifer (granular Tertiary and Quaternary material) thickness (≈750m) was defined with the aid of the geological framework, geothermometers and Modflow modelling. The aquifer extent extends far beyond the limits of the study area. Several economic activities were found to be feasible with available groundwater resources and without bordening the environment (fish farming, bottled-water marketing, SPA activities and farming of endangered species).