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971.
Bu Duo Yunchen Zhang Lingdong Kong Hongbo Fu Yunjie Hu Jianmin Chen Lin Li A. Qiong 《环境科学学报(英文版)》2015
To understand the composition and major sources of aerosol particles in Lhasa City on the Tibetan Plateau (TP), individual particles were collected from 2 February to 8 March, 2013 in Tibet University. The mean concentrations of both PM2.5 and PM10 during the sampling were 25.7 ± 21.7 and 57.2 ± 46.7 μg/m3, respectively, much lower than those of other cities in East and South Asia, but higher than those in the remote region in TP like Nam Co, indicating minor urban pollution. Combining the observations with the meteorological parameters and back trajectory analysis, it was concluded that local sources controlled the pollution during the sampling. Transmission electron microscopy (TEM) combined with energydispersive X-ray spectra (EDS) was used to study 408 particles sampled on four days. Based on the EDS analysis, a total of 8 different particle categories were classified for all 408 particles, including Si-rich, Ca-rich, soot, K-rich, Fe-rich, Pb-rich, Al-rich and other particles. The dominant elements were Si, Al and Ca, which were mainly attributed to mineral dust in the earth's crust such as feldspar and clay. Fe-, Pb-, K-, Al-rich particles and soot mainly originated from anthropogenic sources like firework combustion and biomass burning during the sampling. During the sampling, the pollution mainly came from mineral dust, while the celebration ceremony and religious ritual produced a large quantity of anthropogenic metal-bearing particles on 9 and 25 February 2013. Cement particles also had a minor influence. The data obtained in this study can be useful for developing pollution control strategies. 相似文献
972.
土壤重金属污染评价是土壤环境质量评价研究的重要组成部分。基于模糊数学理论建立的属性识别理论模型在其他环境要素评价中已有所应用,现将其应用到土壤重金属污染评价中。该法能较好地把握土壤环境质量各级标准界限的模糊性,并继承了模糊数学方法本身在评价领域应用的优点,实际操作较为简便。为较客观地反映评价因子对土壤环境质量的影响,模型中引入重金属生物有效性的概念与传统权重系数确定法相结合构造各指标权重。该模型评价结果基本上与其他评价方法的结果相一致,并能较为客观地反映出土壤环境的污染状况。 相似文献
973.
针对目前宁夏电网变电站语音通信接入方式中存在的瓶颈问题,分析了传统脉冲编码调制(pulse code modulation,PCM)技术对电力通信网发展的影响,结合宁夏电网变电站语音通信业务接入需求及 PCM 设备配置情况,提出基于数字交叉连接设备 (digital cross connectequipment,DXC)语音复接设备的优化业务接入方案。应用结果表明:该方案有效解决了机房空间资源需求大、组网方式单一、业务扩展能力差、不便于维护等问题,具有投资少、收效明显、工程量小、便于实施等特点。 相似文献
974.
研究了氯氰菊酯对蛋白核小球藻(Chlorella pyrenoidosa)生长、细胞内含物(可溶性蛋白、可溶性糖)及抗氧化酶类(超氧化物歧化酶,SOD)、膜脂氧化产物(丙二醛,MDA)的影响.结果表明,在氯氰菊酯暴露下,藻细胞的生长受到不同程度的抑制,且抑制程度随氯氰菊酯浓度的增大而增大,氯氰菊酯对蛋白核小球藻生长的72h半效应浓度(EC50)为4.89mg·L-1.藻细胞所有生理生化指标对氯氰菊酯响应迅速,在暴露初期较为敏感,24h后趋于平稳.其中,可溶性糖和可溶性蛋白含量上升,中等浓度组(3.2,5.6mg·L-1)上升趋势最为显著.SOD活性则呈现出低浓度(1.0,1.8mg·L-1)促进、高浓度(>3.2mg·L-1)抑制效应.氯氰菊酯可使藻体内丙二醛(MDA)含量升高,氯氰菊酯浓度越高,藻体内MDA含量越高.研究结果表明,对藻细胞SOD活性的抑制及膜脂过氧化可能是氯氰菊酯对蛋白核小球藻产生毒害作用的重要原因. 相似文献
975.
976.
以浙江某制革、纺织印染工业园区污水处理厂为研究对象,分析了该污水处理厂进水、出水和污泥中Cr、Zn、Cu、Ni、Pb、Cd、Fe、Mn等重金属含量、来源及污染分布特性,探讨了重金属对该污水处理运行的影响。结果表明:该污水处理厂进水中Cr和Fe的含量最高,分别达16.40和15.80mg/L;重金属在污泥中发生富集,其中Cr和Fe的浓度高达12550和13671mg/kg。重金属在污泥中富集,不仅制约了污泥处置及资源化利用,而且影响了污泥的固液分离性能和常规污染物的去除效果。 相似文献
977.
Pollution level and human health risk assessment of some pesticides and polychlorinated biphenyls in Nantong of Southeast China 总被引:1,自引:0,他引:1
Na Wang Li Yi Lili Shi Deyang Kong Daoji Cai Donghua Wang Zhengjun Shan 《环境科学学报(英文版)》2012,24(10):1854-1860
Food consumption is one of the key exposure routes of humans to contaminants. This article evaluated the residue levels of 51 pesticides and 16 polychlorinated biphenyls (PCBs) in selected fish and food items which were commonly consumed in the Nantong area of Jiangsu Province, Southeast China. The 51 pesticides and 16 PCBs were analyzed by highly sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS). The results showed that organochlorine pesticides such as dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and mirex and other pesticides including chlorpyrifos, pyrethroid pesticides, metolachlor, pyridaben and trifluralin were frequently detected in the samples, which was consistent with the accumulation level and characteristics of these toxic chemicals in human adipose tissue of people living in Nantong. Meanwhile, correlation of the residue level of toxic chemicals with their physical chemical properties and historic use pattern in Nantong area was observed. Combined with dietary survey results at the same sampling locations, human health risk assessment of ingestion through the dietary route was performed. The results suggested that the non-cancer risks of the chemicals investigated can be considered negligible in the Nantong area, however, the cancer risks from lifetime dietary exposure to DDTs and HCB have exceeded the acceptable levels. 相似文献
978.
Photocatalytic degradation of phenanthrene on soil surfaces in the presence of nanometer anatase TiO2 under UV-light 总被引:1,自引:1,他引:0
The effect of nanometer anatase TiO2 was investigated on the photocatalytic degradation of phenanthrene on soil surfaces under a variety of conditions. After being spiked with phenanthrene, soil samples loaded with different amounts of TiO2 (0 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, and 4 wt.%) were exposed to UV-light irradiation for 25 hr. The results indicated that the photocatalytic degradation of phenanthrene followed the pseudo first-order kinetics. TiO2 significantly accelerated the degradation of phenanthrene with the half-life reduced from 45.90 to 31.36 hr for TiO2 loading of 0 wt.% and 4 wt.%, respectively. In addition, the effects of H2O2, light intensity and humic acid on the degradation of phenanthrene were investigated. The degradation of phenanthrene increased with the concentration of H2O2, light intensity and the concentration of humic acids. It has been demonstrated that the photocatalytic method in the presence of nanometer anatase TiO2 was a very promising technology for the treatments of soil polluted with organic substances in the future. 相似文献
979.
Spatial and temporal variability of agricultural pollutants in an agricultural headwater stream within a multipond system, southeastern China 总被引:1,自引:0,他引:1
The spatial and temporal variability of nutrients and suspended solids were investigated for two years in a 1.8 km agricultural headwater stream, located by Chaohu Lake, southeastern China. The stream form was greatly modified by human activities into channelized, pond and estuary shapes. The stream could be divided into 4 channelized reaches(1.3 km), a pond reach(0.15 km) and 3 estuary reaches(0.36 km). It was found that nutrients and TSS concentrations in the stream showed temporal variability, and higher concentrations occurred in months with high precipitation and intensive agricultural activities. And, retention of total nitrogen ( TN ), nitrate ( NO3-N ),ammonium( NH4^ -N) and total suspended solids (TSS) predominantly occurred in the pond reach and estuary reaches with larger width and low current velocity. Pollutants retained in these reaches accounted for more than 50% of those retained in whole stream. The retention mostly happened in the rain-runoff events and it was 7 to 27 times than that in base flow. The results showed that the channelized reach was the most important source for pollutants release under either runoff or base flow, and its release accounted for more than 90% of whole stream release.There was a high spatial variability of nutrients retention in different channelized reaches. The channelized reach directly discharging into the pond did always retain nutrients and TSS under base flow and runoff conditions, whereas the other channelized reaches performed differently in different hydrological conditions. The high spatial and temporal variability of nutrients and TSS in the stream indicated that anthropogenic disturbance of the agricultural headwater stream, such as channelization and excavation, would be expected to decrease the capacity of nutrients retention in the stream. 相似文献
980.
Min Shang Yadong Kong Zhijuan Yang Rong Cheng Xiang Zheng Yi Liu Tongping Chen 《Frontiers of Environmental Science & Engineering》2023,17(3):27