青海湖沙柳河流域不同时期地表水与地下水的相互作用

氢氧稳定同位素技术是研究地表水和地下水相互作用的有效手段。依据青海湖沙柳河流域2018年消融期、多雨期和冰冻期所收集的降水、河水和地下水样品中对氢氧同位素组成（δD、δ¹⁸O）的测定结果,识别和量化不同时期高山草原带和高山草甸带地表水和地下水间的补给关系和比例,其目的旨在明确高寒内陆河流域地表水和地下水δD和δ¹⁸O受降水影响的时空差异。结果表明：青海湖沙柳河流域地表水和地下水δD和δ¹⁸O值受降水响应存在时空差异性,δD和δ¹⁸O值在消融期受降水影响最强,冰冻期最弱;在高山草甸带δD和δ¹⁸O值受降水的影响强于高山草原带。消融期的高山草甸带、高山草原带和冰冻期的高山草原带地表水补给地下水的比例分别为80.65%、93.36%和89.44%;多雨期的高山草甸带、高山草原带和冰冻期的高山草甸带地下水补给地表水的比例分别为44.50%、74.85%和88.58%。研究结果可为该流域水资源优化配置和管理提供科学依据。     

采煤影响下峰峰煤炭矿区岩溶地下水水动力环境的演变

采煤影响后的岩溶地下水,强径流区的水动力特征虽未根本改变,但仍发生了明显的变化。采煤后,岩溶水的水流速率明显变慢,水力梯度加大,含水层间水力联系加强,因溶解矿物的差异也造成了水化学场的异同。因处于煤矿开发利用的不同阶段,不同径流区岩溶水水动力特征也存有明显的差异。     

Engineered in situ bioremediation of a petroleum hydrocarbon-contaminated aquifer: assessment of mineralization based on alkalinity, inorganic carbon and stable carbon isotope balances

A concept is proposed to assess in situ petroleum hydrocarbon mineralization by combining data on oxidant consumption, production of reduced species, CH₄, alkalinity and dissolved inorganic carbon (DIC) with measurements of stable isotope ratios. The concept was applied to a diesel fuel contaminated aquifer in Menziken, Switzerland, which was treated by engineered in situ bioremediation. In the contaminated aquifer, added oxidants (O₂ and NO₃⁻) were consumed, elevated concentrations of Fe(II), Mn(II), CH₄, alkalinity and DIC were detected and the DIC was generally depleted in ¹³C compared to the background. The DIC production was larger than expected based on the consumption of dissolved oxidants and the production of reduced species. Stable carbon isotope balances revealed that the DIC production in the aquifer originated mainly from microbial petroleum hydrocarbon mineralization, and that geochemical reactions such as carbonate dissolution produced little DIC. This suggests that petroleum hydrocarbon mineralization can be underestimated if it is determined based on concentrations of dissolved oxidants and reduced species.     

新疆北部沙漠边缘植被恢复可能性初探

古尔班通古特沙漠边缘植被破坏严重,沙丘活化明显,是新疆干旱植被恢复的重点地区之一,一般缺乏地表水补充,其沙丘的水分状况便成为植被生存和恢复过程的关键条件,为探究古尔班通古特沙漠边缘植被恢复的可能性,在植物生长期内对流动沙丘和固定沙丘不同部位的水分状况进行了连续监测,结果表明:沙丘大多数层次含水量月变化与月降水量分布相一致;流动沙丘含水量从上部到下部依次升高;流动沙丘中部和下部稳定湿沙层处在距沙丘表面60 cm以下,且厚度超过100 cm,固定沙丘稳定湿沙层只存在于沙丘中部距沙丘表面60～150 cm内,其厚度不超过100 cm,在一般年份,该地区利用本地种进行植被恢复是可行的.     

Allocation and source attribution of lead and cadmium in maize (Zea mays L.) impacted by smelting emissions

Plants grown in contaminated areas may accumulate trace metals to a toxic level via their roots and/or leaves. In the present study, we investigated the distribution and sources of Pb and Cd in maize plants (Zea mays L.) grown in a typical zinc smelting impacted area of southwestern China. Results showed that the smelting activities caused significantly elevated concentrations of Pb and Cd in the surrounding soils and maize plants. Pb isotope data revealed that the foliar uptake of atmospheric Pb was the dominant pathway for Pb to the leaf and grain tissues of maize, while Pb in the stalk and root tissues was mainly derived from root uptake. The ratio of Pb to Cd concentrations in the plants indicated that Cd had a different behavior from Pb, with most Cd in the maize plants coming from the soil via root uptake.     

Plants' use of different nitrogen forms in response to crude oil contamination

In this study, we investigated Phragmites australis’ use of different forms of nitrogen (N) and associated soil N transformations in response to petroleum contamination. ¹⁵N tracer studies indicated that the total amount of inorganic and organic N assimilated by P. australis was low in petroleum-contaminated soil, while the rates of inorganic and organic N uptake on a per-unit-biomass basis were higher in petroleum-contaminated soil than those in un-contaminated soil. The percentage of organic N in total plant-assimilated N increased with petroleum concentration. In addition, high gross N immobilization and nitrification rates relative to gross N mineralization rate might reduce inorganic-N availability to the plants. Therefore, the enhanced rate of N uptake and increased importance of organic N in plant N assimilation might be of great significance to plants growing in petroleum-contaminated soils. Our results suggest that plants might regulate N capture under petroleum contamination.     

长江水δ~(18)O和δD时空变化特征及其影响因素分析

稳定同位素示踪技术已成为研究河流的水文过程及其变化的重要手段,尤其在河网交错密集和水力关系复杂的长江流域。通过分析枯水期和丰水期长江水及大气降水中δ~(18)O和δD组成的变化,揭示其时空变化特征及其影响因素。结果发现长江流域大气降水δ~(18)O组成表征出明显的空间分布差异特征,长江河源区降水δ~(18)O值最低,随着海拔高度降低降水中δ~(18)O值自长江上游向下游地区逐渐减小,这与流域的水汽来源及海拔高度密切有关;枯水期长江水δ~(18)O和δD值明显要高于丰水期,原因在于丰水期河水受到较弱的蒸发富集作用和大量降水补给影响;无论在丰水期还是枯水期长江水自上游到下游其同位素值呈逐渐增大的趋势,这主要受不同河段支流和湖泊等水体补给的影响。三峡大坝的蓄水和放水过程对河水同位素组成产生一定的影响,丰水期对相应河段河水同位素组成的影响不大,但在枯水期则影响较为明显,这将对充分认识长江流域大气降水-河水-湖水间水力联系与探讨其水资源合理利用提供科学依据。     

长江靖江段近岸小型渔业生物碳氮稳定同位素特征分析

长江靖江段是众多洄游性渔业生物的重要栖息地,为进一步的研究和渔业资源评估提供基础生物学资料、掌握该水域食物网结构特征,应用碳、氮稳定同位素技术测定了2016年8月在长江靖江段近岸采集的蟹类、小型鱼类、虾类等渔业生物样品的δ~(13)C值和δ~(15)N值,并由此构建了所采集的各类渔业生物的连续营养谱。结果表明:长江靖江段近岸各类生物中浮游动物的δ~(13)C值最低,为-30.34‰;其次是底栖碎屑的-30.24‰;贝类、水生植物类、鱼类和虾类居中,它们的δ~(13)C值均值分别为-29.75‰±0.75‰、-28.98‰±0.88‰、-26.74‰±2.37‰、-26.1‰±0.16‰;蟹类最高,为-25.86‰±0.74‰。水生植物类的δ~(15)N均值最低,为5.16‰±0.85‰;底栖碎屑其次,为5.58‰;贝类、鱼类、浮游动物和蟹类的δ~(15)N值均居中,δ~(15)N均值分别为8.13‰±0.31‰、11.56‰±1.59‰、12.02‰和12.51‰±1.43‰;虾类的δ~(15)N均值最高,为13.05‰±0.45‰;营养级由低到高依次为:水生植物类、底栖碎屑、贝类、浮游动物、小型鱼类、蟹类和虾类。近岸水域的小型鱼类、蟹类和虾类拥有着比较接近的食物源,生态位重叠较为明显。     

稳定态纳米零价铁-厌氧菌联合处理法降解2,4,6-三氯苯酚

利用SEM、XRD、FTIR等手段对稳定态纳米零价铁（NH₂-SiO₂@NZVI）进行表征,并考察NH₂-SiO₂@NZVI-厌氧菌体系对2,4,6-三氯苯酚（2,4,6-TCP）的降解效果。实验结果表明：NH₂-SiO₂@NZVI具有较强的抗氧化能力及较好的分散性;当2,4,6-TCP质量浓度 50 mg/L、NH₂-SiO₂@NZVI加入量1 g/L、初始 pH 7.00、反应120 h时,2,4,6-TCP的去除率为34.76%,一级降解速率常数为0.022 1,均远大于普通纳米零价铁颗粒;在NH₂-SiO₂@NZVI-厌氧菌体系中,2,4,6-TCP的去除率可达82.70%,NH₂-SiO₂@NZVI与厌氧微生物之间表现出明显的协同效应,能有效缓解2,4,6-TCP对厌氧微生物的抑制作用,稳定体系pH,提高微生物的降解活性和产甲烷活性。     

西南水汽通道上昆明站降水中的稳定同位素

位于西南水汽通道上的昆明站降水中的稳定同位素比率具有显著的季节变化。旱季(11~4月)降水中平均δ18O明显高于雨季(5~10月)。显著的降水量效应说明昆明站降水的水汽主要来源于低纬度海洋。与全球大气水线相比,昆明站大气水线的斜率和常数项均较小。这与雨滴在未饱和大气中降落时重同位素的蒸发富集作用有关。统计分析显示,近地面温度露点差ΔTd与降水中稳定同位素比率存在显著的正相关关系。在旱季,受大陆性气团的影响,空气干燥,降水量小,大气中ΔTd大,因此蒸发强,重同位素的富集作用强,从而降水中稳定同位素比率高;在雨季,受来自海洋水汽的影响,空气湿润,降水量大,大气中ΔTd小,因此蒸发弱,重同位素的富集作用轻,从而降水中稳定同位素比率低。据此推测,降水量效应可能是不同水汽来源对降水中稳定同位素影响的产物。