Formation of methyl mercury in an aquatic macrophyte

In the nature, inorganic forms of mercury (Hg) may be transformed to the organic, very toxic, methyl-Hg. Occasionally methyl-Hg has been detected in plants, also so in the aquatic macrophyte water spinach (Ipomoea aquatica), which is a popular vegetable in tropical regions. The objectives of this study were to investigate if methyl-Hg is formed and/or degraded in water spinach. Water spinach plants were exposed to inorganic Hg via spiked soil or spiked nutrient solution. Tests were performed in a climate chamber and in experimental units, one for each individual plant, that were equipped with separated shoot and root compartments. Plant tissues were analysed for total- and methyl-Hg. The results showed that methyl-Hg was accumulated in water spinach, especially in young metabolically active parts, when exposed to external inorganic Hg, even at sterilized conditions. Results also showed that methyl-Hg was formed in water spinach in the absence of external Hg, i.e., during recovery in a not Hg-spiked medium following after HgCl₂-exposure. There was however, no sign of demethylation. Summarizing, most of the Hg that is taken up by the plants is bound in the roots, but of the comparatively small amounts of Hg that reach the young growing shoots, a part will be methylated. Since the young shoots of this plant make a delicious and very appreciated vegetable, Hg in I. aquatica may contribute to human health problems.     

Freshwater systems and ecosystem services: Challenges and chances for cross-fertilization of disciplines

Freshwater ecosystems are among the most threatened in the world, while providing numerous essential ecosystem services (ES) to humans. Despite their importance, research on freshwater ecosystem services is limited. Here, we examine how freshwater studies could help to advance ES research and vice versa. We summarize major knowledge gaps and suggest solutions focusing on science and policy in Europe. We found several features that are unique to freshwater ecosystems, but often disregarded in ES assessments. Insufficient transfer of knowledge towards stakeholders is also problematic. Knowledge transfer and implementation seems to be less effective towards South-east Europe. Focusing on the strengths of freshwater research regarding connectivity, across borders, involving multiple actors can help to improve ES research towards a more dynamic, landscape-level approach, which we believe can boost the implementation of the ES concept in freshwater policies. Bridging these gaps can contribute to achieve the ambitious targets of the EU’s Green Deal.     

海洋贝类类立克次体的感染

类立克次体的感染可以引起海洋贝类病害的发生,并且有时会导致贝类的大规模死亡,成为在世界范围内影响海洋贝类养殖业发展的重要制约因素.本文首先从海洋贝类类立克次体的分类地位、宿主种类及地理分布、海洋贝类类立克次体及其包涵体的生物学特征、致病性、传播途径、检测与防治方法等方面进行了系统的阐述.文章提出对海洋贝类类立克次体进行研究的必要性,分析了研究的重点及难点,展望了此研究领域的发展趋势.     

高效除草尿素(药肥)对稻区非目标生物影响研究

研究了高效除草尿素（药肥）对稻区水生生物的影响。结果表明,药肥对蟾 Ｂｕｆｏｂｕｆｏｇａｒｇａｒｉｚａｎｓ蝌蚪、棘胸蛙Ｒａｎａｓｐｉｎｏｓａ蝌蚪、食蚊鱼Ｇａｍｂｕｓｉａａｆｆｉｎｉｓ、虹鳟Ｓａｌｍｏｇａｉｒｄｎｅｒｉ、湖螺Ｂａｌｌａｍｙａｓｐ和蚤状蚤Ｄａｐｈｎｉａｐｕｌｅｘ的９６ｈＬＣ５０分别分别为５４３６、１５７９、４０７３、５６８、４１３９和９７８１ｍｇ／Ｌ。按照用量和目前国内外普遍采用的评价     

双台子河口近2a春季同期典型生物群落变化

2002年和2003年春季同期对双台子河口近岸海域的典型生物群落进行调查。2002年采集到浮游植物39种,平均细胞数为1.4×1010／m3,优势种为棕囊藻;浮游动物31种,平均生物量为2 098 mg／m3,优势种为中华哲水蚤;底栖动物32种,平均栖息密度为122个／m2,平均生物量为9.64 g／m2,优势种不明显,种类分布较均匀。2003年采集到浮游植物35种,平均细胞数为20×104／m3,优势种近河口区为骨条藻,远河口区为夜光藻;浮游动物18种,平均生物量为1 356 mg／m3,优势种为中华哲水蚤;底栖动物22种,平均栖息密度为12 670个／m2,平均生物量为25.66 g／m2,优势种为托氏昌螺和脆壳理蛤。     

典型水生生物中微塑料的累积、清除及食物链传递效应

以环境中双壳类、鱼类及节肢类等水生生物为对象,介绍了其对微塑料的累积与清除,重点分析了微塑料特性、生物特性和食物等因素对微塑料生物累积与清除的影响,并进一步概述了微塑料沿水生食物链的传递效应,阐述了其对复合污染物食物链传递的影响过程。结果发现,微塑料在水生生物中的累积、清除与其自身尺寸、形态和聚合物类型等密切相关,水生生物的结构特异性是干扰微塑料从生物体内排泄的重要因素,有无食物的环境条件是调节双壳类和节肢类生物对微塑料累积与清除的重要路径;微塑料虽然可以通过食物链由低营养级向高营养级传递,但不一定会产生生物放大效应;微塑料的载体效应导致其复合污染物的食物链传递过程发生改变,共存污染物在生物体内的释放和吸收时间是调控微塑料复合污染物食物链传递能力的重要因素。     

有机锡污染调控对策初步分析

评述了有机锡化合物的生产与使用情况。有机锡污染及对生物的毒性效应、有机锡研究现状与趋势,并在此基础上初步提出了我国控制有机锡污染的对策与建议。     

亚热带地区组合氧化塘的研究

本文研究了亚热带地区升流式厌氧塘与水生植物兼性塘、好氧塘串连组合处理生活污水的运行规律,获得了该组合工艺的设计参数;推导出可供设计用的经验方程式;不推荐用好氧塘作为二级处理出水的深度处理。      

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。     

抗抑郁药物舍曲林和氟西汀在实验室构建的三层水生食物链中的生物积累和营养动力学研究

目前关于药物在水生生物中富集的报道越来越多,但人们对它们在水生食物网中的营养转移却知之甚少。选择了2种在水环境中经常被监测到的选择性5-羟色胺再摄取抑制剂(SSRIs),本文在实验室可控条件下,通过构建水生链的SSRIs暴露试验,研究了舍曲林和氟西汀的生物积累和营养动力学。在2个3层食物链中(Acer platanoides,是 Asellus aquaticus的食物,而相应地 Asellus aquaticus是Notonecta glauca 或 Pungitius pungitius的食物),随着营养级的递增,这2种可离子化的、弱碱药物均显示出较低的生物积累因子(BAFs)(这表明没有生物放大)。A. platanoides、A. aquaticus、N. glauca和P. pungitius体内的舍曲林的平均BAFs分别为2200 L/kg、360 L/kg、26 L/kg和49 L/kg,氟西汀的平均BAFs分别为1300 L/kg、110 L/kg、11 L/kg和41 L/kg。生物积累因子(BAFs)的测量值等于或低于生物富集因子(BCFs)的测量值,这进一步证明了饮食的微弱影响。生物脂含量与BAFs没有正相关性,这表明其他的过程在驱动SSRI生物累积的种间差异。这里将经验参数值带入一个生物累积模型中计算,发现模拟与经验BAFs(预测r²=-0.63)之间相关性较差。综上所述,这些可离子化的药物明显缺乏生物放大作用,环境问题不应只关注较高的营养水平,而应关注在任何营养水平上有高BCFs的物种。
精选自Bostr?m, M. L., Ugge, G., J?nsson, J. ?. and Berglund, O. (2017), Bioaccumulation and trophodynamics of the antidepressants sertraline and fluoxetine in laboratory-constructed, 3-level aquatic food chains. Environmental Toxicology and Chemistry, 36: 1029–1037. doi: 10.1002/etc.3637
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3637/full