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91.
Wang Shengli Yan Linlin Guan Xiaohui Jia Yanping Song Lianfa Zhang Haifeng 《Environmental Chemistry Letters》2019,17(4):1831-1837
Environmental Chemistry Letters - Hydroxyl radicals are commonly produced either by metal activation or by using external energy. However, the application of these methods is limited by low working... 相似文献
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管东生 《生态与农村环境学报》1996,(1)
研究了刈割频率对香港草地于物质生产的影响。结果表明,刈割使干物质生产量下降,刈割频率越高生产量下降越大。禾本科植物受刈割影响比木本和非禾本科草本植物大,且停止刚割一年后生物量仍低于对照点。认为常年刈割是华南草地生产力下降的重要原因之一。 相似文献
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本文以桑树和家蚕为试验生物,采用静态模拟熏气和自然污染调查相结合的方法,对大气苯酚污染蚕桑引起家蚕生长发育障碍进行了观察、分析,认为大气苯酚以间歇性较高浓度侵入蚕室时,会直接致蚕中毒;大气中苯酚以持续较低浓度作用时桑叶内会累积苯酚,间接对象蚕有毒害。家蚕受害后,轻则表现力食欲不振,群体发育不齐,体色灰暗、体重减轻、主要经济性状下降,重则死亡。,F_(0.01)=2.80说明因熏气处理次数引起盛食蚕体重变化的差异极显著,也即较高浓度的苯酚气会直接危害家蚕生长、发育。综上所述,在有关工厂附近大气内苯酚浓度虽然不是很高,也没有被正式列入监测范围,因此也没有监测指标。但此浓度下桑叶内会累积苯酚,家蚕食叶则会间接遭受其危害;如急性排放的苯酚气侵入蚕室,则会对家蚕直接致害,造成经济性状下降,甚至死亡。苯酚是有机毒物,食品上禁用早有规定,如何防止大气苯酚在生态系统中积累、迁移,保障陆地生物包括人类免受其毒害,是值得引起重视的环境问题。 相似文献
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Summary In polygynous mammals, it may be adaptive for mothers to invest more in sons and/or to adjust the sex ratio of offspring in relation to body condition. Calving patterns were examined over an 8-year period (1982–1989) for a population of Bison bison in which barren females are not selectively culled. From these data, we tested predictions of the sex ratio adjustment hypothesis as well as two assumptions: (1) that offspring weight at the end of the period of parental investment (PI) is correlated with later condition, and (2) that maternal and offspring condition during the period of PI are correlated. In contrast to predictions, there was little evidence that mothers in better condition bear more sons. Short- and long-term measures of maternal condition (previous reproductive status, age, dominance status, pre-pubertal body weight, age at first reproduction, birth date, and the duration of the mother's own suckling period) were little related to offspring sex ratio, although the last calves of old females were nearly always female. Similarly, there was little evidence for sex-biased PI. Weights at about 7 months of age were greater for males than females; males also had somewhat later birth dates, suggesting either longer gestation or later conception. However, maternal reproductive costs, as measured by subsequent fecundity, weight loss, and interbirth intervals, did not vary with calf sex. Both assumptions of the model received some support. However, while maternal condition was correlated with offspring condition, there may be sex differences in investment patterns. Mothers appear better able to influence the condition of daughters than of sons. This sex difference may negate any benefit from male-biased investment. 相似文献
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我国近海是经济增长和发展最重要和最集中的区域。然而,随着沿海工业的发展,大量未经处理的陆源污染物随间排海,沿岸水域形成“黑潮”、“赤潮”致使我国近海海域污染加剧,生态平衡失调,严重影响了海域资源环境的可持续发展。 相似文献
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辽河口营养要素的化学特性及其入海通量估算 总被引:14,自引:6,他引:14
本文根据1992年5月和8月辽河口水域营养要素的两次实测结果,讨论了溶解态无机氮(NO3^--N、NO2^--N、NH4^+-N)、活性磷酸盐(PO4^3--P)和活性硅酸盐(SiO3^2-Si)在辽河口水域的含量,分布特征,化学特性及其入海通量。结果表明:辽河口水域溶解态无机氮含量范围为12.13 ̄222.70μmol/L,活性磷酸盐含量范围为0.71 ̄2.81μmol/L,活性硅酸盐含量范围为 相似文献
98.
The global re-cycling of persistent organic pollutants is strongly retarded by soils 总被引:12,自引:0,他引:12
Ockende WA Breivik K Meijer SN Steinnes E Sweetman AJ Jones KC 《Environmental pollution (Barking, Essex : 1987)》2003,121(1):75-80
'Persistent organic pollutants' (POPs) are semi-volatile, mobile in the environment and bioaccumulate. Their toxicity and propensity for long-range atmospheric transport (LRAT) has led to international bans/restrictions on their use/release. LRAT of POPs may occur by a 'single hop' or repeated temperature-driven air-surface exchange. It has been hypothesised that this will result in global fractionation and distillation-with condensation and accumulation in polar regions. Polychlorinated biphenyls (PCBs)--industrial chemicals banned/restricted in the 1970s--provide a classic illustration of POP behaviour. A latitudinally-segmented global PCB inventory has been produced, which shows that approximately 86% of the 1.3 x 10(6) tonnes produced was used in the temperate industrial zone of the northern hemisphere. A global survey of background surface soils gives evidence for 'fractionation' of PCBs. More significantly, however, very little of the total inventory has 'made the journey' via primary emission and/or air-surface exchange and LRAT out of the heavily populated source regions, in the 70 years since PCBs were first produced. Soils generally occlude PCBs, especially soils with dynamic turnover of C/bioturbation/burial mechanisms. This limits the fraction of PCBs available for repeated air-soil exchange. The forested soils of the northern hemisphere, and other C-rich soils, appear to be playing an important role in 'protecting' the Arctic from the advective supply of POPs. Whilst investigations on POPs in remote environments are important, it is imperative that researchers also seek to better understand their release from sources, persistence in source regions, and the significant loss mechanisms/global sinks of these compounds, if they wish to predict future trends. 相似文献
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