Trends in low flows of German rivers since 1950: Comparability of different low‐flow indicators and their spatial patterns

Climate change, land‐use shifts, reservoir storage, and water withdrawals impact low flows in rivers, creating challenges for ecological integrity and human uses. A systematic investigation of river discharges was carried out for 79 stream gauges in Germany. Available time series between 1950 and 2013 were analysed for trends in annual minimum low flows, discharge deficits, and low‐flow durations. The application of different low‐flow indicators led to similar spatial patterns, although each metric is used for different purposes in water management applications. Statistical tests identified significant discharge trends at more than half of the stations investigated. Low‐flow trends since 1950 tended to be catchment specific, suggesting that climate change has not been the dominant driver. Most of the gauges investigated showed statistically significant increases in low flows. This can be mainly attributed to reservoir management. For rivers showing snow‐ and icemelt‐dominated flow regimes, such trends are probably overlain by climate‐driven changes (increasing amounts of rainfall, earlier snowmelt in spring). In contrast, stations showing statistically significant decreases in low flows were correlated with areas of decreasing mining activity. Hydrologic impacts of climate change are widespread and significant, but the results here suggest that human river management remains the dominant hydrologic driver on many rivers.     

城市人为热及其影响城市热环境的研究综述

建筑群布局与空间几何形态、下垫面物理属性以及人为热排放是影响城市热岛的3大人为因素.近年来,针对城市热岛与影响因素的研究层出不穷.对城市人为热及其影响室外热环境的研究进行梳理是对影响城市热岛的人为因素进行研究的完善和补充.本文从城市人为排热量统计、人为热对城市室外气温的影响2方面展开,对国内外相关研究进展进行综述,对研究对象、人为排热量计算方法和人为排热量对城市热环境影响研究方法3个方面进行总结,并提炼了一些重要结论.本文为该领域接下来相关研究工作的重点提供了线索,即关注人为热排放与城市规划重要指标的关系,探索人为热对城市热环境的影响机理和内在规律,从而提出更全面、更有效改善城市气候的措施.     

城市局地-建筑耦合气候评价模型的开发应用

利用数值计算方法研究建筑内部气候与城市局地气候之间的能量及物质传递关系,寻找热舒适与节能和环保之间的平衡点具有重要的意义.介绍了改进后生成的城市局地-建筑耦合气候评价模型的主要内容和计算方法,以上海地区为例,计算了一个理想化的高层办公楼区的局地气候参数,空调系统排热及室内外新标准有效温度TS*E等.结果表明,空调时间段内室外平均TS*E值受空调设定温度的强烈影响.当空调设定温度从28℃降至22℃时,空调排热平均值增加了193 W/m2,这个增值造成室外平均TS*E提高了约0.23℃.     

人为源VOC清单及重点工业贡献和治理分析

VOC的大量污染不仅不利于社会可持续发展,更为人们的生活和身体带来了严重的伤害,VOC治理问题迫在眉睫。基于此,本文以人为源VOC污染为研究对象,分析其污染特性,及人为源VOC清单排放特征,从整体排放、省份排放及地区排放特征对我国工业VOC排放的特征进行分析,结合当前所使用的人为源VOC治理的技术进行阐述。     

南方岩溶区地下河主要离子浓度变化趋势分析

对我国南方岩溶区典型地下河——官村地下河的降雨量、流量和钾、钠、钙、镁、氯、重碳酸根、硫酸根以及硝酸根离子的浓度进行了两年多的监测和分析。结果显示:地下河的水化学类型为Ca-HCO3型;硝酸根和硫酸根的浓度在雨季大于旱季;钠离子、钙离子、镁离子、重碳酸根离子在雨季浓度降低;钾离子和氯离子浓度的变化没有规律,这些离子浓度的变化受到稀释作用、淋滤作用或岩溶作用和人类活动的控制。与20世纪80年代的离子浓度相比,只有硝酸根和硫酸根的浓度有明显的升高。地下河的水质虽然未超标,但探讨地下河主要离子浓度变化趋势及原因对保护岩溶含水层是非常必要的。     

中国人为主导的铝循环分析(英文)

采用铝产品生命周期的铝流程图进行中国人为主导的铝循环分析。人为主导的铝循环主要包括4个阶段:氧化铝及电解铝的生产、铝制品的加工和制造、铝制品的使用和报废铝制品的回收。采用加权平均法确定我国铝制品的平均使用寿命。基于中国2003-2007年的铝循环分析,发现了铝工业发生的一些变化。氧化铝生产阶段的原料自给率从95.42%下降到55.50%,原铝生产阶段的原料自给率从52.45%上升到79.25%,但整个铝工业的原料自给率基本维持在50%左右。在2007年铝工业中,国内自产废铝和进口废铝的使用比例分别占总原料的5.38%和9.40%。在此阶段,净进口各类含铝资源和铝产品生命周期中铝的损失量都是上升的,同时,社会蓄积量中铝的存量及铝的循环量都是增加的。提出了改善铝循环的对策、建议以及中国铝工业的进出口政策和降低铝产品生命周期铝损失量的措施。     

基于PSR模型的潜江市后湖管理区生态系统健康评价

为评价城市小流域健康状况,以潜江市后湖管理区为例,于2019年10月对18个样点进行生态环境调查,采用压力—状态—响应模型构建包含压力、状态、响应指标3个层次的健康评价体系,利用熵权法计算评价指标权重,应用综合健康指数法评估后湖管理区健康状况。结果表明,全流域18个采样点中,6个处于健康状态,7个处于亚健康状态,5个处于不健康状态,后湖管理区健康状态处于中等水平;影响城市小流域生态系统健康的主要因素为人口密度和水资源利用率,未来的小流域生态修复工程应注重城市化进程与生态环境保护协调发展,正确处理人类行为与环境变化的相互关系。     

Anthropogenic and natural radionuclides in caribou and muskoxen in the western Alaskan Arctic and marine fish in the Aleutian Islands in the first half of 2000s

A number of caribou and muskoxen samples from the western Alaskan Arctic and fish samples from the Aleutian Islands were collected between 1998 and 2006 and analyzed for anthropogenic (⁹⁰Sr and ¹³⁷Cs) and natural radionculides (⁴⁰ K, ²¹⁰Pb and ²²⁶Ra), as part of the radiological assessment for the regional subsistence hunting communities in the first half of 2000s. We examined the relationship between the activities of these nuclides with the size of the fish. In caribou samples, concentration of ⁹⁰Sr in muscle was below the detection limit of 0.14 Bq kg^− 1 and ¹³⁷Cs concentration in bones was below the detection limit of 0.15 Bq kg^− 1.¹³⁷Cs activity varied over an order of magnitude in caribou muscle samples with an average value of 2.5 Bq/kg wet wt. Average ¹³⁷Cs activity in muskoxen muscle was found to be 9.7 Bq/kg wet wt. However, there were a little variation (less than 60%) in ²¹⁰Pb, ⁴⁰ K, and ²²⁶Ra in both muscle and bone of both caribou and muskoxen. The activities of total ²¹⁰Pb in caribou and muskox bones were found to be 1-2 orders of magnitude higher than that of parent-supported ²¹⁰Pb indicating the potential for dating of bones of terrestrial mammals (time elapsed since the death of the animal) based on the excess ²¹⁰Pb method exists. In fish muscle samples, ¹³⁷Cs activity varied from below detection limit to 154 mBq/kg wet wt. and its content increased with the size of the fish due to its transfer through the food chain. Among the seven fish species investigated, ²¹⁰Pb activities varied almost an order of magnitude; however, ⁴⁰K and ²²⁶Ra activities varied less than a factor of two. Total annual effective dose due to ⁹⁰Sr and ¹³⁷Cs from the ingestion of those terrestrial and marine meats was estimated to be negligible (ca. 9 μSV/a) compared to the natural radionuclides present thus posing negligible radiological threat to humans.     

Longitudinal changes in macroinvertebrate assemblages in the Meuse River: anthropogenic effects versus natural change

A collaborative study among three nations (France, Belgium, Netherlands) along the Meuse River developed a consistent approach for collecting and interpreting macroinvertebrate data. Specific mesohabitats were sampled in 16 locations along an 800‐km stretch of this lowland regulated river. The objective was to assess the ‘river health’ using macroinvertebrate communities as indicators of biological and ecological variation in space. The main changes in assemblages were investigated using multimetric and multivariate approaches. The authors examined relationships between faunal variations and both physico‐chemical gradients and man‐made disturbances. We related species traits to faunal changes and habitat characteristics. Both a gradual shift from a macroinvertebrate assemblage dominated by insects to a community dominated by crustaceans and molluscs and a drastic decrease in biotic index values were observed along the longitudinal gradient. Taxa were distributed according to oxygen, nitrate and ammonium concentrations, pH, conductivity and summer hydraulic conditions. But major faunal differences among sites could not be explained simply by physico‐chemical variables. The trait analysis underlined the role of temporary habitats in structuring the summer macroinvertebrate community of sites of the uppermost French sector, which supported the most diverse community in terms of trait combination. Downstream the macroinvertebrate community exhibited a more simple and less stable functional organization. We concluded that the Meuse River exhibited both a high biodiversity and a ‘reasonably good’ water quality in the upper reaches. Two transition zones highlighted the influence of a high degree of human impact on stream integrity. Regulation for navigation, ship traffic and heavily polluted effluent discharges influenced instream conditions via multiple processes determining a decline of both habitat stability and diversity. However, the rare occurrence of habitat‐sensitive species in the lower reaches indicated that a partial recovery of communities may be predicted if restoration and protection of disturbed (especially riparian) habitats are fulfilled. Copyright © 2002 John Wiley & Sons, Ltd.     

The chemistry of stratospheric ozone: its response to natural and anthropogenic influences

The current rapid changes in the composition of the atmosphere reflect both the metabolism of the biosphere and the broad range of influencing human activities. However, the only known sources of CFCs are industrial. In predicting future changes in ozone depletion and global warming it is necessary to understand the role of the biosphere in regulating emissions as well as future industrial emissions. This paper discusses theoretical predictions and trends in global ozone concentrations from 1969–1986. Antarctic and Arctic ozone trends and the global implications of the Antarctic ozone hole are described in detail. It is concluded that even if the control measures of the Montreal Protocol are implemented by all nations, the atmospheric abundance of chlorine will at least double during the next few decades. Future global ozone depletion could be larger than originally predicted because the PSC-induced chemical reactions that cause ozone depletion were not included in the stratospheric ozone assessment models on which the Montreal Protocol was based. To return the Antarctic ozone layer to its natural state will require very strong measures, including a complere phase out of all fully halogenated CFCs, halons, carbon tetrachloride and methyl chloroform, as well as careful use of HCFC substitutes.