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851.
为提高衡阳市降水型地质灾害预报预警的针对性和时效性,本文利用1994—2007年衡阳市地质灾害个例资料和相应的降水资料,分析了地质灾害与降水的关系;划分了地质灾害易发区,并针对不同易发区确定了降水型地质灾害预报预警指标;对预报预警方法进行检验,并提出了改善建议。结果显示:衡阳市降水型地质灾害与前期降水强度、当日降水量等有着密切关系;建立的预报预警方法对衡阳市暴雨突发性地质灾害预报具有较好的地域针对性和准确性,将预报时效延长至24小时,对地质灾害的防御有着重要的现实意义。 相似文献
852.
853.
甘南高寒退化草地生态位特征及生产力研究 总被引:9,自引:1,他引:8
采取样方法,对玛曲县高寒中度退化草地的植物种群群落进行了研究分析,结果表明:以莎草植物(嵩草)为绝对优势种,杂类草(金莲花)为主要伴生种。非优势种垂穗披碱草、甘青青兰生态位宽度较大,分别为0.913和0.911,而绝对优势种嵩草和主要伴生种金莲花的生态位宽度较低,分别为0.906和0.641。生态位相似性比例大于0.50%的种对约占种群总对数的42.29%。生态位重叠值大于0.040的种对,约占种群总对数的20.55%。生态位宽度较大的两个种群,种对相似性比例一般较高,具有较大的生态位重叠(如种对乳白香青和毛茛0.082),而生态位窄的物种相互间生态位重叠比例较小(如种对二裂委陵菜和金莲花0.033)。高生态位宽度与低生态位宽度的种群也可能有较高的重叠值(如种对车前和毛茛0.065),反之则低。杂类草鲜草产量、地上生物量比例最高,依次为100.00 g/(m2.a)、43.37%。 相似文献
854.
Effects of sediment dredging on water quality and zooplankton community
structure in a shallow of eutrophic lake 总被引:4,自引:0,他引:4
Shiyang Zhang Qiaohong Zhou Dong Xu Jidong Lin Shuiping Cheng Zhenbin Wu 《环境科学学报(英文版)》2010,22(2):218-224
Effects of suction dredging on water quality and zooplankton community structure in a shallow of eutrophic lake,were evaluated.The results showed that a decreasing trend for levels of phosphorus,organic matter,total suspended solids,Chlorophyll a and Secchi transparency in the water column was found,while levels of water depth,electrical conductivity,total dissolved solids and NO 3--N concentration increased markedly post-dredging.The effects of dredging on dissolved oxygen,pH value and temperature were alm... 相似文献
855.
2010年7月29日至8月2日,环境保护部在内蒙古满洲里市举办了2010年全国环境保护新闻发言人培训班,周生贤部长出席开班仪式并作了重要讲话。根据录音整理后的全文摘录如下。 相似文献
856.
Soil samples were collected from three plots under di erent land utilization patterns including degradation, farming, and restoration.
The abundances of methanotrophs were quantified using real-time polymerase chain reaction (PCR) based on the pmoA and 16S
rRNA genes, and the community fingerprint was analyzed using denaturing gradient gel electrophoresis (DGGE) aiming at pmoA
gene. Significantly lower 16S rRNA and pmoA genes copies were found in the degradation treatment than in farming and restoration.
Higher abundances of Type I than those of Type II methanotrophs were detected in all treatments. The treatment of farming was
clearly separated from degradation and restoration according to the DGGE profile by cluster analysis. The lowest diversity indices
were observed in the F (farming plot), suggesting that the community structure was strongly a ected by farming activities. There were
significantly positive correlations between the copy numbers of pmoA also Type II-related 16S rRNA genes and soil available K content.
Strong negative and positive correlations were found between Type I and soil pH, and available P content, respectively. We concluded
that the vegetation cover or not, soil characteristics including pH and nutrients of P and K as a result of anthropogenic disturbance may
be key factors a ecting methanotrophic communities in upland soil. 相似文献
857.
Single and joint toxic e ects of polycyclic musks including 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-
benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronapthalene (AHTN) and cadmium (Cd) on seed
germination and seedling growth of wheat (Triticum aestivum) were investigated. The results showed that the toxicity sequence of
HHCB toxic to wheat seed germination and seedling growth was similar to that of AHTN, that is, germination rate > shoot elongation
> root elongation, while the toxicity of Cd was in the sequence of root elongation > shoot elongation > germination rate, according
to the LC50 and EC50 values. It is suggested that polycyclic musks and Cd had di erent toxicological mechanisms. Root and shoot
elongation of wheat might be good bioindicators for the contamination of polycyclic musks and Cd in soil. The mixture of polycyclic
musks and Cd had synergistic e ects on T. aestivum according to the equi-toxic mixture approach when root elongation was selected as
the toxicological endpoint. Thus, the joint toxicity of HHCB and Cd was significantly higher than the single toxicity of HHCB or Cd,
which was also confirmed by the EC50 mix value of the mixture (EC50 mix = 0.530 TUmix). The EC50 mix value of the mixture of AHTN
and Cd was 0.614 TUmix, which indicated that the mixture toxicity was strengthened when AHTN coexisted with Cd. 相似文献
858.
Degradation and detoxification of microcystin-LR in drinking water by
sequential use of UV and ozone
Microcystins (MCs) produced by cyanobacteria are strong hepatotoxins and classified as possible carcinogens.MCs pose a considerable threat to human health through tainted drinking and surface waters.Herein filtrated water from a waterworks in Harbin,China,was spiked with microcystin-LR (MC-LR) extracted from a toxic scum of microcystis aeruginosa,and the spiked sample waters were treated using UV irradiation with consequent ozonation process (UV/O3),compared with ozonation at a dose range commonly applied in water treatment plants,UV irradiation at 254 nm and UV irradiation combined with ozonation (UV+O3),respectively.The remaining of toxins were analyzed using high-performance liquid chromatography and also determined using a protein phosphatase type 2A inhibition assay,which was utilized to evaluate the reduction in toxicity.Results indicated that in comparison to other three processes (O3,UV,and UV+O3),UV/O 3 process could effectively decrease both the concentration and toxicity of MC-LR at 100 μg/L level after 5 min UV irradiation with consequent 5 min ozonation at 0.2 mg/L (below 1 μg/L),while 0.5 mg/L ozone dose was required for the level below 0.1 μg/L.The addition of an UV treatment step to the existing treatment train may induce significant transformation of micropollutants and breaks down the natural organic matters into moieties unfavorable for ozone decomposition,stabilizing the ozone residual.These findings suggested that sequential use of UV and ozone may be a suitable method for the removal of these potentially hazardous microcystins from drinking water. 相似文献
859.
本文分析了环境监测实验室污染物的种类及危害,指出环境监测站要高度重视实验室环境污染问题,并针对不同污染提出相应防治措施。同时提出了推行绿色化学、清洁实验的概念,具有很好的参考价值。 相似文献
860.