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1.
痕量有机氯化合物分析中的样品预处理方法   总被引:7,自引:4,他引:3       下载免费PDF全文
近些年来,痕量有机氯化合物分析中,各种样品预处理技术得到了迅速发展,文章介绍了一些样品预处理方法的原理和最新进展,阐述了索氏提取,超临界流体萃取,微波萃取,固相萃取等几种富集方法的原理,特点,性能及应用,论述了吸附柱层析法,凝胶渗透色谱,高效液相色谱等样品净化技术的特点和应用。  相似文献
2.
采用微宇宙培养法,分析了不同水动力条件(不循环、水循环和泥循环)对微污染景观水体富营养化模拟过程中藻类演替的影响。结果表明,水循环和泥循环使得水体的TP值前期增加后期减少,前期藻类生长主要受TP影响,而后期浊度成了重要的影响因素;水循环引起的TP值减少及蓝藻聚集状态的破坏,导致了藻类的生长明显减缓,但优势种的演化过程却变得复杂;泥循环导致了水体TP值的极大减少及浊度的极大增加,从而明显的抑制了藻类的生长,其优势种的演替过程也变得更简单。  相似文献
3.
污灌农田土壤镉污染状况及分布特征研究   总被引:3,自引:0,他引:3  
对沈阳郊区某河沿岸部分乡镇的污灌农田土壤中重金属全镉含量进行了分析,评价了土壤镉污染状况,并探讨了该河沿岸土壤中镉的沿程分布特征、横向分布特征和垂向分布特征.结果表明,农田土壤重金属镉含量范围为0.15~8.23mg/kg,均值为1.75mg/kg.用土壤环境质量标准二级标准值对土壤中的全镉含量进行评价,平均镉污染指数为5.95,为重度污染;用土壤背景值标准评价,平均镉污染指数为5.95,超过当地背景值水平8.39倍,污灌已造成该地区重金属镉污染,且污染程度十分严重.该河渠从上游到下游,沿岸土壤镉含量呈降低趋势;横向分布上,距离该河渠越远,镉含量有逐渐减少的趋势;垂向分布上,表层土壤镉含量最高.  相似文献
4.
高氟水沸石除氟的效果研究   总被引:2,自引:0,他引:2  
通过静态搅拌实验和恒温震荡实验,研究了接触时间、pH、温度及反复使用次数对沸石除氟效果的影响.结果表明,在适宜的条件下,沸石除氟效果随着使用次数的增多有上升趋势,除氟效果良好,适用于我国高氟水地区.  相似文献
5.
对西安市城区景观水体浮游藻类状况及生物多样性进行了研究。结果表明,7个景观水体中有5个水体的水质未达到Ⅴ类水质标准,主要超标项目为pH值和TN;7个水体的ρ(N)/ρ(P)为16.6-43.6,磷为限制性因子;其中2个水体富营养化严重,DO含量低,水质达不到要求,其优势藻种为蓝藻门,含量占浮游藻类总数的64.3%-93.4%;而水质较好的贫营养水体优势种为黄藻门,含量占到浮游藻类总数的54.3%;通过6种生物多样性指数与景观水体营养状态的拟合,发现MeNaughton's多样性指数适合城区景观水体的富营养化评价。  相似文献
6.
根据2010年3月(冬季)、5月(春季)、8月(夏季)、11月(秋季)对江苏省如东县贝类养殖区4次现场监测资料,着重对养殖区海水和表层沉积物中重金属的分布特征进行了分析,并对养殖区进行了生态环境质量评价及潜在生态风险评价。结果表明:海水中重金属污染程度顺序为Pb>Zn>Hg>Cu>As>Cd;表层沉积物中重金属的污染程度顺序依次为Zn>Pb>As>Cu>Hg>Cd;表层沉积物中重金属的潜在生态危害程度顺序依次为Hg>Cd>As>Pb>Cu>Zn。4次调查结果的多种重金属的潜在生态风险指数(RI)均低于140,表明这些重金属对海洋生态系统的潜在生态风险属于低潜在生态风险水平,养殖环境良好。  相似文献
7.
Human dietary intake and excretion of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs)--collectively referred to as dioxin-like compounds (DLCs)--were investigated. Two groups of seven subjects were studied during 1999 and 2000: one aged 23.9 +/- 4.5 years, the other aged 49.4 +/- 5.2 years. For each subject, two week-long experiments were held. In one, omnivorous diets were administered, whilst in the other, a vegan diet was studied. While exposures via the omnivorous diets exceeded those via the vegan diet on a sigmaWHO-TEQ basis; for some subjects sigmaPCB exposures were comparable in both diets, implying that plant-based foods can make an appreciable contribution to exposure to sigmaPCB. For all subjects, the average dietary exposure during the omnivorous trial to PCDD/Fs and PCBs combined (expressed as WHO-TEQ) was--at 1.09 pg kg(-1) bw d(-1)--lower than recent UK "food-basket" estimates. For the same diet, the average sigmaPCB exposure for all subjects was--at 5.01 microg person(-1) d(-1)--higher than recent UK "food-basket" estimates, but consistent with recent estimates for other industrialised countries. Net absorption/excretion but not faecal excretion rates of DLCs were related to dietary intakes. Furthermore, excretion rates of the most persistent DLCs--i.e. PCB #s 138, 153, and 1,2,3,6,7,8-HxCDD--were statistically significantly greater for the older subjects. Combined, these data imply that excretion rate is dependent on body burden, and that the majority of DLCs in human faeces arise from endogenous excretion.  相似文献
8.
探讨了空气质量监测中现场空白的测定方法,通过对封口的现场空白与实验室对白比对及采样过程现场空白吸收管开口与封口对照试验,认为采样时应对现场空白吸收管作封口处理,才能体现现场空白的真实性。  相似文献
9.
Cyhalofop-butyl is an aryloxyphenoxypropionate postemergence herbicide with good control of barnyard grass in rice paddies. In this study, method for the determination of cyhalofop-butyl and its metabolite was developed with high-performance liquid chromatography tandem mass spectrometry. Dissipation and residue levels of cyhalofop-butyl and its metabolite in rice ecosystems were also investigated. Recoveries and relative standard deviations of cyhalofop-butyl and cyhalofop acid in six matrices at three spiking levels ranged from 76.1 to 107.5 % and 1.1 to 8.2 %, respectively. The limit of quantitation (LOQ) of cyhalofop-butyl and cyhalofop acid was 0.01 mg/kg in paddy water, paddy soil, rice plant, rice straw, rice hulls, and husked rice. For field experiments, the results showed that cyhalofop-butyl degraded to cyhalofop acid quickly, and the half-lives of cyhalofop acid in paddy water, paddy soil, and rice plant were 1.01–1.53, 0.88–0.97, and 2.09–2.42 days, respectively. Ultimate residues of cyhalofop-butyl and its metabolite in the rice samples were not detectable or below 0.01 mg/kg at harvest.  相似文献
10.
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