Radium removal from mine waters in underground treatment installations

The underground mining of hard coal is widespread in the Upper Silesian Coal Basin (southern Poland). In deep mines, inflows of highly mineralised waters containing radium isotopes are numerous. These waters cause severe damage to the natural environment due to the salinity, but additionally radioactive pollution occurs. The region is densely populated, therefore mitigation methods are very important. The method of radium removal has been applied in full technical scale in two coal mines with very good results - in one of the mines radium-bearing waters are treated at the rate of approximately 0.1m(3)s(-1), while in another mine salty waters are purified at the rate of 0.1m(3)s(-1). The purification takes place in special underground galleries without any contact of the mining crew with the radioactive deposits produced during the process. As a result, release of radium is significantly lower, more than 200MBq of (226)Ra and (228)Ra remains underground each day.     

Life in extreme environments: survival strategy of the endolithic desert lichen Verrucaria rubrocincta

Verrucaria rubrocincta Breuss is an endolithic lichen that inhabits caliche plates exposed on the surface of the Sonoran Desert. Caliche surface temperatures are regularly in excess of 60 degrees C during the summer and approach 0 degrees C in the winter. Incident light intensities are high, with photosynthetically active radiation levels typically to 2,600 micromol/m(2) s(-1) during the summer. A cross-section of rock inhabited by V. rubrocincta shows an anatomical zonation comprising an upper micrite layer, a photobiont layer containing clusters of algal cells, and a pseudomedulla embedded in the caliche. Hyphae of the pseudomedulla become less numerous with depth below the rock surface. Stable carbon and oxygen isotopic data for the caliche and micrite fall into two sloping, well-separated arrays on a delta(13)C-delta(18)O plot. The delta(13)C(PDB) of the micrite ranges from 2.1 to 8.1 and delta(18)O(SMOW) from 25.4 to 28.9, whereas delta(13)C(PDB) of the caliche ranges from -4.7 to 0.7 and delta(18)O(SMOW) from 23.7 to 29.2. The isotopic data of the micrite can be explained by preferential fixing of (12)C into the alga, leaving local (13)C enrichment and evaporative enrichment of (18)O in the water. The (14)C dates of the micrite range from recent to 884 years b.p., indicating that "dead" carbon from the caliche is not a significant source for the lichen-precipitated micrite. The endolithic growth is an adaptation to the environmental extremes of exposed rock surfaces in the hot desert. The micrite layer is highly reflective and reduces light intensity to the algae below and acts as an efficient sunscreen that blocks harmful UV radiation. The micrite also acts as a cap to the lichen and helps trap moisture. The lichen survives by the combined effects of biodeterioration and biomineralization. Biodeterioration of the caliche concomitant with biomineralization of a protective surface coating of micrite results in the distinctive anatomy of V. rubrocincta.     

稳定同位素技术在河岸带功能研究中的应用

简要概述稳定同位素技术在生态学的应用领域,通过对河岸带反硝化作用限制因素、效率以及机理的回顾,体现稳定同位素技术应用的优势。重点阐述该技术在研究河岸带功能实现机理、分析河岸带生态系统物质来源和时空迁移转化规律以及研究河岸带与外界环境物质联系,生态系统食物网络组成及营养级关系中的应用,指出其能够科学反映物质空间变化和时间累积效应的特点。稳定同位素技术与传统地球化学技术的结合对国内河岸带功能研究以及生态河岸带建设具有重大的实际应用价值。     

泉州市大气降尘中金属元素污染特征及来源解析

测定了泉州市不同功能区大气降尘中23种金属元素的含量,采用多种方法对其富集程度、污染水平及生态风险进行评价,并用多元统计分析法结合Pb、Sr同位素示踪对污染来源进行解析.结果表明:泉州市大气降尘中不同金属含量空间分布差异较大;富集因子和地累积指数表明,Cd、Hg、Zn、Ca、Pb、Cu、Ni、Sr的富集程度及污染水平相对较高;生态风险指数显示,所有功能区的多元素综合潜在生态风险程度极高,由高到低顺序为工业区交通繁忙区商业区居住区风景区农业区;Cd和Hg的潜在生态危害程度极高,二者对综合潜在生态风险指数的贡献达95.56%.多元统计分析结果表明,V、Fe、Ba、Bi、Ni、Sr、Pb、Cs、Sc、Zn、Cd主要来源于工业污染和交通排放,Th、U、Rb、Y、Ti主要来源于土壤尘,Li、Mn、Cu、Hg、Cr、Co、Ca主要来源于燃煤.铅同位素三元混合模型计算得到降尘中铅来源主要为土壤母质(29.41%~64.00%)、燃煤尘(22.53%~60.48%)和汽车尾气(3.13%~13.47%);87Sr/86Sr和1/Sr分布图显示降尘中锶来源主要为燃煤尘和汽车尾气.     

闽江感潮河段夏秋季涨落潮河水稳定同位素（N/D/O-18）组成特征解析

流域氮污染的稳定同位素表征和溯源对于保障流域污染防控和用水安全具有重要意义,本文通过对感潮河段夏、秋季涨落潮主要断面硝态氮（NO₃^-）及稳定同位素(δ¹⁵N-NO₃^-、δ¹⁸O-NO₃^-、δD-H₂O和δ¹⁸O-H₂O)组成特征测定及沿线小流域的氮污染入河量测算,探讨了陆域氮排放和水体交换对感潮河段稳定同位素的影响.研究表明：（1）落潮、涨潮期NO₃^-均为“秋季>夏季”,δ¹⁵N-NO₃^-夏、秋两季组成特征基本相近.落潮期δ¹⁸O-NO₃^-为“夏季>秋季”,涨潮期则相反.同季节的NO₃^-及其同位素总体呈“涨潮期>落...     

Seasonal and Flood‐Induced Variations in Groundwater–Surface Water Exchange in a Northern Coldwater Fishery

Groundwater upwelling is important to coldwater fisheries survival. This study used stable isotopes to identify upwelling zones within a watershed, then combined isotope analyses with reach‐scale monitoring to measure surface water–groundwater exchange over time. Research focused on Amity Creek, Minnesota, a basin that exemplifies conditions limiting coldwater species survival along Lake Superior's North Shore where shallow bedrock limits groundwater capacity, lowering baseflows and increasing temperatures. Groundwater‐fed reaches were identified through synoptic isotope sampling, with results highlighting the importance of isolated shallow surficial aquifers (glacially derived sands and gravels) for providing cold baseflow waters. In an alluvial reach, monitoring well results show groundwater was stored in two reservoirs: one that reacts quickly to changes in stream levels, and one that remained isotopically isolated under most flow conditions, but which helps sustain summer baseflows for weeks to months. A 500‐year flood demonstrated the capacity of high‐flow events to alter surface water–groundwater connectivity. The previously isolated reservoir was exchanged or mixed during the flood pulse, while incision lowered the water table for years. The results here provide insight for streams that lack substantial groundwater inputs yet maintain coldwater species at risk in a warming climate and an approach for managers seeking to protect cold baseflow sources.     

喀斯特小流域黄壤硫同位素组成特征——对环境过程和效应的指示

用连续提取方法分析了黄壤中总硫、SO₄^2-、总还原态硫（TRS）和有机硫的硫同位素组成,探讨黄壤中硫的迁移转化过程及其环境效应.有机硫是主要的硫形态,SO₄^2-是主要的无机硫形态.TRS具有最低的δ³⁴S值,同时SO₄^2-和TRS的δ³⁴S值随剖面加深而平行地增大指示黄壤中存在SO₄^2-异化还原过程.黄壤剖面中总硫和有机硫的δ³⁴S值先增大后降低与有机硫矿化及有机硫组分的迁移和底层吸附有关.生物滞留后剩余SO₄^2-的吸附、解吸、淋溶迁移及深层吸附与累积导致剖面中SO₄^2-的δ³⁴S值先增大后明显降低.酸沉降下剖面中SO₄^2-的吸附、解吸和淋溶迁移可引起黄壤酸化.值得关注的是,酸沉降输入的SO₄^2-主要以有机硫和吸附态SO₄^2-滞留在黄壤中,则在硫的年沉降速率大幅降低后,在较长时期内,黄壤中有机硫矿化和吸附态SO₄^2-解吸可能释放大量SO₄^2-进入地表和地下水体,与之相关的土壤理化性质变化和水体化学组成改变等方面的环境效应值得关注.     

碳氮氧同位素解析典型岩溶流域地下水中硝酸盐来源与归趋

利用多同位素（C、N和O）和水化学方法解析贵州八步地下河流域水体中硝酸盐（NO₃^-）来源与转化过程,利用SIAR模型定量计算NO₃^-不同输入端的贡献比例.结果表明,研究区地下水NO₃^-污染严重,近38%的地下水样品NO₃^-超过饮用水限值.地下水的δ¹⁵N-NO₃值介于2.3‰~30.33‰,均值9.68‰,δ¹⁸O-NO₃值介于2.65‰~13.73‰,均值6.64‰,δ¹⁸O-H₂O值介于-8.83‰~-7.37‰,均值-8.18‰.同位素组成（δ¹⁵N-NO₃、δ¹⁸O-NO₃和δ¹⁸O-H₂O）指示硝化作用主导着流域内氮素循环.硝化作用产生的硝酸加速了碳酸盐岩溶解,导致地下水中δ¹³C_DIC与δ¹⁵N-NO₃存在显著负相关性（P<0.001）,说明δ¹³C_DIC与δ¹⁵N-NO₃相结合是判断岩溶水中NO₃^-转化的有效手段.地下水和地表水中NO₃^-主要来源于土壤氮、粪肥污水和铵态氮肥料,其对地下水中NO₃^-贡献率分别为36.19%、33.71%和30.1%,对地表水贡献率分别为39.15%、36.08%和24.77%.岩溶流域内污水处理应同时去除污水中的NO₃^-和NH₄⁺,农业区应科学施肥,以有效降低地下水中NO₃^-的补给通量.     

Stable chlorine intramolecular kinetic isotope effects from the abiotic dehydrochlorination of DDT

INTENTION, GOAL, SCOPE, BACKGROUND: Identifying different sources and following reaction pathways of chlorinated organic contaminants in the environment can be challenging, especially when only their concentrations are available. Compound-specific stable chlorine measurements of some contaminants have recently been shown to provide additional information and an increased understanding of their biogeochemistry. These studies, however, have been generally limited to volatile molecules. OBJECTIVE: Here, the stable chlorine isotope ratios of the semi-volatile pesticide, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) were investigated. Specifically, the intramolecular stable chlorine isotopic compositions of DDT and the kinetic isotope effect (KIE) for the abiotic dehydrochlorination of DDT to 2,2-bis(p-chlorophenyl)-1,1-dichloroethene (DDE) were determined. METHODS: Selective chemical oxidation of DDT to dichlorobenzophenone (DCBP) and analysis of each compound was used to calculate the stable chlorine isotope ratios of the alkyl and aromatic chlorines in DDT. To determine the KIE for dehydrochlorination, DDT was reacted in a basic solution to yield DDE at 52 degrees C, 60 degrees C, and 72 degrees C for 3, 5, and 5 days, respectively. RESULTS AND DISCUSSION: Significant intramolecular stable chlorine isotopic differences were observed in one sample of DDT where the alkyl and aromatic delta 37Cl values were -5.76 +/- 0.45 and -2.21 +/- 0.24%@1000, respectively. Dehydrochlorination of DDT to DDE in basic solutions at 52, 60, and 70 degrees C resulted in a substantial intramolecular KIE where the alkyl chlorines of DDE shifted by approximately 3%@1000 relative to the alkyl chlorines in DDT. However, no temperature dependence was observed. The KIE, calculated by an iterative program, was 1.009. CONCLUSIONS: Intramolecular differences in the stable chlorine isotope ratios were observed in DDT and this is the first such finding. Dehydrochlorination of DDT yields a measurable and distinct intramolecular stable chlorine KIE. RECOMMENDATION AND OUTLOOK: The results of this study demonstrate the existence of significant intramolecular differences in chlorinated organic compounds. Many other chlorinated semi-volatile and volatile organic contaminants are synthesized from multiple sources of chlorine, and we recommend that similar studies be performed on many such molecules in order to attain a clear understanding of their intramolecular chlorine isotopic differences. The existence of a measurable KIE for the dehydrochlorination of DDT to DDE shows the potential strength of using isotopic measurements to investigate the biogeochemistry of these important compounds. For example, the isotopically depleted aqueous chloride produced by dehydrochlorination of DDT to DDE may be a useful tracer of these reactions in freshwater environments.     

Use of Stable Isotopes to Identify Sources of Mercury in Sediments: A Review and Uncertainty Analysis

Mass-dependent and mass-independent mercury isotope fractionation potentially generates unique source signatures that can be used to apportion contributions to sediment contamination. This article reviews findings from previous investigations that have used mercury isotopes to identify sources. It also discusses a mass balance mercury isotope fractionation model that simulates changes in isotopic source signatures in aquatic systems caused by natural biogeochemical cycling. According to the model, the extent of source signature alteration depends on chemical speciation, with more labile forms exhibiting greater isotopic fractionation. Apportionment is tractable when differences between δ²⁰²Hg of sources are larger than potential changes in isotopic signatures following the release of mercury into the environment.