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于2008年7-9月对贵阳市中心城区采集的21个大气降水进行了总汞、甲基汞及阴、阳离子浓度的测定,分析了大气降水中总汞与阴阳离子间的相互关系.结果表明:大气降水中总汞的平均含量为18 ng·L-1,变化范围为0.4~57.4 ng·L-1;甲基汞的平均含量为0.07 ng·L-1,变化范围为0.02~0.2 ng·L-1.大气降水中的阴离子以SO2-4和NO-3为主,其浓度平均值分别为151和145 mol·L-1;阳离子主要以Ca2+为主,平均浓度达到了123 mol·L-1,变化范围为3.7~560 mol·L-1,其次是NH4+和Mg2+,其浓度平均值分别为52.2和20.4 mol·L-1.通过分析降水中总汞和阴阳离子之间的相互关系,发现总汞和阴离子SO2-4具有显著的相关性,与F-有一定的相关性,而与NO-3不具有相关性.由此初步判定,大气降水中的总汞主要来源于燃煤等人为释放源. 相似文献
153.
目的:探究Hg2 对水稻幼苗生长的影响。方法:通过水培实验,研究分析了水稻幼苗在不同浓度Hg2 (0~2.0mmol/L)胁迫下株高、鲜重、叶绿素含量和过氧化物酶(POD)活性的变化。结果:表明0.05mmol/L的Hg2 短时间内对水稻幼苗生长有一定的促进作用,高于0.05mmol/L的处理,随着Hg2 浓度的增加,植株生长明显受到限制。当Hg2 浓度≤0.1mmol/L时,POD活性先上升后下降,而Hg2 浓度≥0.5mmol/L时则持续降低。结论:Hg2 对水稻幼苗生长抑制程度与处理浓度和处理时间成正相关。 相似文献
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用含低浓度Hg2 的水饲养泥鳅(Misgurnus anguillicaudatus),研究Hg2 污染对视网膜中S100免疫反应阳性结构数量及分布的影响。用免疫组织化学ABC法标记S100免疫阳性(S100-IR)细胞,显微镜下观察S100免疫反应阳性细胞并计数。结果显示,处理组S100首先在神经节细胞层(GCL)、神经纤维层(NFL)表达,然后逐渐在其他各层表达。与对照组相比,处理组S100免疫反应阳性细胞数显著增多,且该变化与环境中无机汞处理时间成正相关;阳性细胞胞体明显膨胀,突起稠密粗大,S100阳性反应强。研究提示,Hg2 的神经毒害作用导致泥鳅视网膜中S100-IR细胞数的增多。推测Hg2 污染可能对视网膜有伤害性影响,而神经胶质细胞在视网膜修复过程中起了重要作用。 相似文献
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Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes 下载免费PDF全文
Irena F. Creed Ann‐Kristin Bergström Charles G. Trick Nancy B. Grimm Dag O. Hessen Jan Karlsson Karen A. Kidd Emma Kritzberg Diane M. McKnight Erika C. Freeman Oscar E. Senar Agneta Andersson Jenny Ask Martin Berggren Mehdi Cherif Reiner Giesler Erin R. Hotchkiss Pirkko Kortelainen Monica M. Palta Tobias Vrede Gesa A. Weyhenmeyer 《Global Change Biology》2018,24(8):3692-3714
Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial–aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)—the messenger between terrestrial and lake ecosystems—with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change‐driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice‐out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans. 相似文献
158.
This study was carried out on the transported bed soil dredged from the outlet of Lake Burullus to the Mediterranean Sea and deposited nearby, forming by this way new land that underwent a primary plant succession. The multi-methodological approach comprised floristic inventories, vegetation sampling and soil composition analyses of the study site in order to detect the crucial parameters controlling the plant resettlement on recently deposited soil as related to time, local micro-topography and substrate characteristics. Floristic composition was assessed for the first 10 years of primary succession (2001–2010) on 18 stands of the area, distributed on basement, slope stands and plateau of the landfill, respectively. Vegetation surveys were the basis of multivariate analyses of the vegetation and soil data using TWINSPAN, DCA and CCA. Relationships between the edaphic gradients, floristic composition and species diversity were assessed. 相似文献
159.
Tao Ke Filipe Marques Gonçalves Cinara Ludvig Gonçalves Alessandra Antunes dos Santos João B.T. Rocha Marcelo Farina Anatoly Skalny Aristidis Tsatsakis Aaron B. Bowman Michael Aschner 《生物化学与生物物理学报:疾病的分子基础》2019,1865(8):2068-2081
Mercury (Hg) exposure remains a major public health concern due to its widespread distribution in the environment. Organic mercurials, such as MeHg, have been extensively investigated especially because of their congenital effects. In this context, studies on the molecular mechanism of MeHg-induced neurotoxicity are pivotal to the understanding of its toxic effects and the development of preventive measures. Post-translational modifications (PTMs) of proteins, such as phosphorylation, ubiquitination, and acetylation are essential for the proper function of proteins and play important roles in the regulation of cellular homeostasis. The rapid and transient nature of many PTMs allows efficient signal transduction in response to stress. This review summarizes the current knowledge of PTMs in MeHg-induced neurotoxicity, including the most commonly PTMs, as well as PTMs induced by oxidative stress and PTMs of antioxidant proteins. Though PTMs represent an important molecular mechanism for maintaining cellular homeostasis and are involved in the neurotoxic effects of MeHg, we are far from understanding the complete picture on their role, and further research is warranted to increase our knowledge of PTMs in MeHg-induced neurotoxicity. 相似文献
160.
文章研究了华中地区池塘养殖大口黑鲈(Micropterus salmoides)卵巢的发育规律, 分析了水温与光照条件变化对卵巢发育的影响, 探究了大口黑鲈反季节繁殖的方法, 旨在充分利用本地区的气候条件, 化劣势为优势, 从根本上解决本地大口黑鲈产业所面临的问题。实验采用形态学、组织学等方法比较分析了大口黑鲈卵巢发育特征, 采用人工控温和人工促熟的方法探究了温度和性激素对大口黑鲈性腺启动发育的影响。研究发现, 华中地区大口黑鲈雌鱼性腺指数(GSI)周年变化在0.63%—7.95%, 10月中旬至12月初水温由20.6℃降至11.0℃期间, 卵巢开始发育至Ⅲ期, 并以Ⅲ期越冬, 至4月中旬繁殖产卵, 5月底结束, 繁殖前约80%的雌鱼绝对繁殖力在4.5万—6.5万粒, 但受水温升高的影响, 卵巢中15%成熟卵母细胞未能产出而逐步退化, 产卵结束时仍有一半以上卵未产出(GSI为4.6%); 雌鱼GSI与肠系膜脂肪系数(MFI)、肝体比(HSI)在10月份至次年4月份呈显著负相关(P<0.05), 表明在此期间, 机体储存的营养物质部分转移至性腺, 优先保证性腺发育。在大口黑鲈反季节繁殖实验中, 采用井水[水温(20±1)℃]降温和控温处理的方法能够促进大口黑鲈性腺的启动发育, 经过3个月处理, 控温组雌鱼卵巢发育至Ⅳ期末, GSI达到4.06%, 而对照组雌鱼卵巢处于Ⅲ期, GSI为2.52%, 两组差异显著(P<0.05), 两组雄鱼精巢均发育至Ⅳ期末, 控温组GSI达0.89%, 对照组为0.73%, 这表明可以通过温度处理来调控大口黑鲈性腺的发育。最后针对反季节繁殖中亲本的培育方法和处理时间等进行了总结, 以期为后续培育反季节大口黑鲈提供依据。 相似文献