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1.
基于浙江省台风灾害保险数据的农村住房易损性评价   总被引:2,自引:1,他引:1  
利用浙江省农业政策性保险试点项目中的农村住房保险及理赔数据,定量分析了浙江省2007年圣帕、韦帕及罗莎3场台风灾害期间农村住房投保金额、赔付金额、保额损失率的分县汇总数据,以及与这3场台风的极大风速、过程降水量等致灾因子强度的定量关系.研究发现,浙江省农村住房的台风灾害保险金额损失率,其对数与过程降雨量有着很好的线性相关关系.依据这一关系,建立了浙江省农村住房台风易损性方程并给出相关参数.  相似文献   
2.
以救荒野豌豆为材料,研究其对邻体根的响应机制以及根之间的识别方式.结果表明:邻体根存在时,叶、茎、冠、根生物量,根冠比和花数量均没有变化,而繁殖生物量明显增加,表明根的生长与繁殖不存在权衡,也表明救荒野豌豆能够检测到邻体根的存在并做出响应;根之间的识别方式既有直接接触,也有间接的化感作用.  相似文献   
3.
Perfluorinated compounds (PFCs) have been detected in many environmental matrices, biota, and nonoccupationally exposed populations in China recently. However, little is known about the distribution and levels of various PFCs in the general population living in areas where there is PFC exposure. In the present study, the levels and prevalence of ten target PFCs were determined in 227 serum samples from a population of nonoccupationally exposed individuals in Shenzhen, China. Results indicated that human exposure to PFCs was prevalent in Shenzhen. Perfluorooctanoate (PFOA) was the dominant PFC contaminant in the serum samples, with a median concentration of 6.72 ng/mL, followed by perfluorooctane sulfonate (PFOS) with a median concentration of 2.07 ng/mL. Other PFCs were detected at much lower concentrations, with median concentrations ranging from 0.02 to 0.87 ng/mL. Statistically, no significant (P>0.05) gender differences were observed for any of the PFCs. Significant (P<0.01) positive correlations were found between age and serum concentrations of the target PFCs, except for perfluorobutane sulfonate (R = 0.16, P = 0.01), perfluorohexanoic acid (R = 0.08, P = 0.22), and perfluoroheptanoic acid (R = 0.11, P = 0.10). Based on the one-compartment pharmacokinetic model, the total daily intakes of PFOA and PFOS for the general population in Shenzhen were calculated as 0.63 and 0.20 ng/kg body weight/day, respectively.  相似文献   
4.
不同热解温度生物炭改良铅和镉污染土壤的研究   总被引:5,自引:0,他引:5  
 为了探究热解温度对生物炭修复重金属污染土壤的影响,将300℃、500℃和700℃下制备的生物炭加入铅(Pb)和镉(Cd)污染土壤进行培养,检测重金属形态的变化。结果表明,加入生物炭培养60d后,Pb和Cd污染土壤pH值较对照上升0.35—0.86单位值,土壤中重金属的酸可提取态含量下降,残渣态含量上升,对目标重金属生物有效性降低的改良效果700℃>500℃>300℃;在生物炭添加量相同的情况下,复合污染土壤中Pb的残渣态含量比对应单一污染高50.60%—72.79%,而复合污染土壤中Cd的酸可提取态含量较对应单一污染高7.53%—12.99%;热解温度影响生物炭的表面特征和吸附重金属机制,进而影响生物炭改良土壤中目标重金属形态分布。  相似文献   
5.
杉木萌芽更新适于短轮伐作业,在实践中对其利弊尚存在争议,本文根据在苏南丘陵地区的长期试验,对萌芽林与实生林的生长、树干圆满度,树干基部弯曲根系分布与重量和更新费用作了分析比较,得出萌芽林无论在生长和干形上均不比实生林逊色,而投资却仅占实生林1/3,具有投资少,更新可靠,经济效益好的特点,文内还比较了伐桩萌条存留株数对高生长的影响,在去萌定株时以保留两株萌条者高生长最佳。  相似文献   
6.
18种杂草对重金属的超积累特性研究   总被引:60,自引:1,他引:60  
针对目前植物修复中Cd—Cu—Zn—Pb复合污染的超富集植物缺乏研究,采用小区试验方法,对东北沈阳地区9科18种田间杂草植物进行其积累特性的初步研究。结果表明:狼把草(Bidens tripartite)、龙葵(Solanum nigrum)地上部Cd和Zn的富集系数均大于1,且地上部Cd和Zn的含量大于根部Cd和Zn的含量,具备了重金属超富集植物的基本特征,杂草植物地上部重金属含量与植物地上部生物量的相关分析表明,这些植物对重金属的积累量与植物地上部生物量的大小无关,它们对重金属污染土壤修复具有重要意义。  相似文献   
7.
胶州湾水环境重金属立体分布、污染及风险   总被引:1,自引:0,他引:1  
为探讨胶州湾水环境中重金属的立体空间分布、污染及风险,分别采集深度为0~10m(表层),10~20m(中层)和20~30m(底层)的海水与海底表层(0~10cm)沉积物样本,测定8种重金属(As,Cd,Cr,Hg,Zn,Pb,Cu和Ni)在水体中的质量浓度(mg/L)和沉积物中的质量分数(mg/kg),基于国家海水水质标准和水质质量指数法、海洋沉积物质量标准和Hakanson潜在生态危害指数法评价了海水和沉积物中重金属的立体分布、污染及其潜在生态风险.结果表明:胶州湾海水重金属质量浓度除Cu,Hg,Ni和Pb外,均未超出IV类标准;相对污染指数值由大到小依次为Cu,Pb,Hg,Ni,Cd,Cr,Zn,As,其中Cu,Pb,Hg,Ni和Cd达到严重污染水平,综合污染指数测算表明胶州湾海水重金属污染严重.就胶州湾海水重金属的平面分布而言,其高值区出现在湾东和西南区,其中Hg高值区沿胶州湾大桥分布.就胶州湾海水重金属的垂直方分布而言,0~10m的表层海水和20~30m的底层海水中重金属质量浓度均高于10~20m的中层海水.除Cr外,沉积物中其他重金属质量分数均高于海洋沉积物的I级质量标准,潜在生态风险指数由大到小依次为Hg,As,Ni,Cd,Pb,Cr,Cu,Zn,并呈现出东高西低、沿污染源分布的特点.  相似文献   
8.
Evidence has accumulated that there is a trade-off between benefits and costs associated with rapid growth. A trade-off between growth rates and critical swimming speed (Ucrit) had been also reported to be common in teleost fish. We hypothesize that growth acceleration in the F3 generation of "all-fish" growth hormone gene (GH) transgenic common carp (Cyprinus carpio L.) would reduce the swimming abilities. Growth and swimming performance between transgenic fish and non-transgenic controls were compared. The results showed that transgenic fish had a mean body weight 1.4―1.9-fold heavier,and a mean specific growth rate (SGR) value 6%―10% higher than the controls. Transgenic fish,however,had a mean absolute Ucrit (cm/s) value 22% or mean relative Ucrit (BL/s) value 24% lower than the controls. It suggested that fast-growing "all-fish" GH-transgenic carp were inferior swimmers. It is also supported that there was a trade-off between growth rates and swimming performance,i.e. faster-growing individuals had lower critical swimming speed.  相似文献   
9.
0Introduction Beingaregionrelativelybehindintermsofruraleconomicdevelopment,theTibetanAutonomousRegionin2003achievedanaveragenetincomepercapitaof1690yuan(RMB)for thefarmersandherdsmen,rankingthe4thnationwide.Comparedwiththatof2001,thisis aconsiderablerise,howeverthereisstillabiggapfromotherprovincesandregionsthatare economicallydeveloped[1].HowtoraiseTibetfarmersandherdsmen’sincome,improve livingqualityoftheminoritynationalityareasandpromoteregionaldevelopmenthavebecome thepriorityoftheCen…  相似文献   
10.
亚硝酸盐、硫化物与氨对河蟹幼体的急性毒性实验   总被引:9,自引:0,他引:9  
本文研究了亚硝酸盐、硫化物与氨对河触幼体的24h,48h,96h的半致死浓度LC50值和安全浓度。  相似文献   
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