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871.
872.
青岛大气气溶胶中氨基化合物的分布特征 总被引:2,自引:1,他引:1
氨基化合物是大气气溶胶和雨水中常被检出的一类有机氮化合物,由于其可作为生物生长直接的氮源,因此可能对海洋生态系统产生直接作用.利用2008年1~12月在青岛采集的66个总悬浮颗粒物样品,采用邻苯二甲醛/N-乙酰-L-半胱氨酸柱前衍生高效液相色谱法,分析了其中溶解态(DAC)和颗粒态氨基化合物(PAC)的浓度.气溶胶中DAC浓度为2.4~40.9nmol·m-3,在春季最高,夏季次之,秋季、冬季最低.PAC浓度为0.7~76.1nmol·m-3,呈现春季冬季秋季夏季的变化趋势.不同季节氨基化合物的组成不同.依据气团的后向轨迹,气溶胶样品可分为受北方陆源、南方陆源和海洋源影响,DAC和PAC在受南方陆源影响的气溶胶中浓度最高,北方陆源次之,海洋源气溶胶中最低.不同来源的气溶胶中氨基化合物的组成不同,蛋白质类氨基化合物对总氨基化合物的贡献在海洋源气溶胶中最高,在南方源气溶胶中最低. 相似文献
873.
874.
875.
Carbonyl sulfide (COS) and dimethyl sulfide (DMS) fluxes from an urban Cynodon dactylon lawn and adjacent bare soil were
measured during April–July 2005 in Guangzhou, China. Both the lawn and bare soil acted as sinks for COS and sources for DMS.
The mean fluxes of COS and DMS in the lawn (–19.27 and 18.16 pmol/(m2 sec), respectively) were significantly higher than those
in the bare soil (–9.89 and 9.35 pmol/(m2 sec), respectively). Fluxes of COS and DMS in mowed lawn were also higher than those
in bare soils. Both COS and DMS fluxes showed diurnal variation with detectable but much lower values in the nighttime than in the
daytime. COS fluxes were related significantly to temperature and the optimal temperature for COS uptake was 29°C. While positive
linear correlations were found between DMS fluxes and temperature. COS fluxes increased linearly with ambient COS mixing ratios,
and had a compensation point of 336 ppt. 相似文献
876.
The competition between submersed plants has been recognized as an important factor influencing the structure of plant communities
in shallow lakes. The ability of different species to take up and store nutrients from the surrounding ambience varies, and hence plant
community structure might be expected to affect the cycling of nutrients in lake ecosystems. In this study, the uptake of phosphorus
by Hydrilla verticillata and Vallisneria natans was studied and compared in monoculture and competitive mixed-culture plantings.
Results showed that for both studied species the phosphorus concentrations of different tissues and of whole plants was unaffected by
competition. However, the quantity of phosphorus accumulated by whole plants of H. verticillata was significantly higher in mixture
culture than in monoculture, while that of V. natans was lower in the mixed culture. The results indicated that H. verticillata has a
competitive advantage over V. natans, when the two species are grown in competition, and is able to accumulate a greater quantity of
phosphorus. 相似文献
877.
Sedimentary record of polycyclic aromatic hydrocarbons in Lake Erhai,
Southwest China 总被引:1,自引:0,他引:1
Jianyang Guo Zhang Liang Haiqing Liao Zhi Tang Xiaoli Zhao Fengchang Wu 《环境科学学报(英文版)》2011,23(8):1308-1315
The temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was investigated in a sediment core from Lake Erhal in Southwest China using gas-chromatography/mass spectrometry (GC/MS) method.The total organic carbon (TOC) normalized total PAHs concentrations (sum of US Environmental Protection Agency proposed 16 priority PAHs) ranged from 31.9 to 269 μg/g dry weight (dw),and were characterized by a slowly increasing stage in the deeper sediments and a sharp increasing stage in the upper sediments.The PAHs in the sediments were dominated by low molecular weight (LMW) PAHs,suggesting that the primary source of PAHs was low- and moderate temperature combustion processes.However,both the significant increase in high molecular weight (HMW) PAHs in the upper sediments and the vertical profile of diagnostic ratios pointed out a change in the sources of PAHs from low-temperature combustion to high-temperature combustion.The ecotoxicological assessment based on consensus-based sediment quality guidelines implied that potential adverse biological impacts were possible for benzo(ghi)perylenelene and most LMW PAHs.In addition,the total BaP equivalent quotient of seven carcinogenic polycyclic aromatic hydrocarbons (BaA,CHr,BbF,BkF,BaP,DBA and INP) was 106.1 ng/g,according to the toxic equivalency factors.Although there was no great biological impact associated with the HMW PAlls,great attention should be paid to these PAH components based on their rapid increase in the upper sediments. 相似文献
879.
880.
地球优先!(Earth First!,简称EF!)是1979年在美国西南部兴起的一个激进的环境主义团体.这是以戴夫·佛曼(Dave Foreman)、青年国际党成员麦克·洛索尔( Mike Roselle)、怀俄明州荒野协会代表巴特·科勒(Bart Koehler)等为代表的一群环境主义行动分子在去往墨西哥的汽车上成立的组织.
地球优先!组织的成员们自称为EF!er,不同地区的成员谙熟自已地区的生态和它所受到的最紧迫、最严重的威胁.成员们为了阻止环境遭受破环而对破坏者施加“直接的压力”,并结合教育、诉讼和创造性的非暴力抵抗.另外EF!号召成员们:学会利用媒体,把媒体的注意力吸引到环境问题上,并利用一定的方法劝阻人们和公司不要毁了地球;学习相关的法律知识,虽然被逮捕往往能增加媒体的关注,但还是要权衡轻重,自由是一项宝贵的财富,避免监禁有时是上策;清楚地了解将面临的风险,行动分子常在法律行动中被“不懂法”的警方逮捕;为当地建立一个网站,这样任何人都可以与进行保护行动的人取得联系;把人们团结起来,鼓动他们去行动,宣传为了保护地球而需要去做的事情. 相似文献