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81.
82.
83.
Monsoon rain causes large scale sediment-water movement and reworking of sediments of the Ganga Plain which is one of the
largest fluvial systems on Earth. Geomorphology and drainage type combined with sedimentation processes play a substantial
role on dispersion and transport patterns of metals bound to sediments and soils. The study area of Kanpur-Unnao industrial
region in the Ganga Plain has been divided into five independent geochemical domains on the basis of sediment-geomorphic,
hydrological and geochemical characters. The monsoon hydrography and physico-chemical parameters (pH, conductivity) of the
river and urban drain waters play a prominent role in regulating the concentrations and behaviour of the metals in the aquatic
system of the Ganga Plain. Values of pH and specific electrical conductivity of the river water of the study area decrease
whereas those of the urban drain water increase in post-monsoon period. The monsoon rain reduces the contents of Co, C-org,
Cr, Fe and Ni and enhances the contents of Cd, Sn and Zn in sediments of post-monsoon period. In soils, it reduces the contents
of Al, Co, Fe, Mn and Ni and enhances the contents of Cd, Sn and Zn in the post-monsoon period. These changes in concentrations
vary from metal to metal and from one geochemical domain to the other. An increase in the concentrations of few metals in
the soils from pre- to post-monsoon periods indicates that these metals were mobilized from the overflooding of metal rich
waste-water onto the fields during high water stage and also by reworking of the soils through sheet floods during the monsoon
time. Despite the changes in concentrations, metal dispersion patterns in each domain remain similar both in pre- and post-monsoon
periods which indicate that the geochemical and sediment-geomorphic processes operating for the metal dispersion and mobilization
in sediments are persistent even after large scale sediment-water movement and reworking of the sediments during the monsoon
period.
Received: 4 May 1998 · Accepted: 20 October 1998 相似文献
84.
Persistent organic pollutants carried by synthetic polymers in the ocean environment 总被引:4,自引:0,他引:4
Thermoplastic resin pellets are melted and formed into an enormous number of inexpensive consumer goods, many of which are discarded after a relatively short period of use, dropped haphazardly onto watersheds and then make their way to the ocean where some get ingested by marine life. In 2003 and 2004 pre-production thermoplastic resin pellets and post-consumer plastic fragments were collected and analyzed for contamination for persistent organic pollutants (POPs). Samples were taken from the North Pacific Gyre, and selected sites in California, Hawaii, and from Guadalupe Island, Mexico. The total concentration of PCBs ranged from 27 to 980 ng/g; DDTs from 22 to 7100 ng/g and PAHs from 39 to 1200 ng/g, and aliphatic hydrocarbons from 1.1 to 8600 microg/g. Analytical methods were developed to extract, concentrate and identify POPs that may have accumulated on plastic fragments and plastic pellets. The results of this study confirm that plastic debris is a trap for POPs. 相似文献
85.
天津武清能见度特征分析 总被引:5,自引:0,他引:5
利用2006年8~9月的野外观测资料,分析了天津武清区晴天能见度的变化特征,并分析了能见度与细粒子(PM2.5)、大气污染物和大气相对湿度(RH)的相关性。结果表明:观测期内大气平均能见度为6.3km,低于4km的时间段占50%;日变化表现为日出前(北京时间5时)能见度最低,约为2.6km,下午15时最高,约为11.1km;不同大气相对湿度下能见度与大气中细颗粒物浓度相关性不同;污染气体浓度与能见度呈反相关关系,φ(SO2)、φ(NO2)、φ(NO)、φ(NH3)和φ(CO)越高,能见度越低。 相似文献
86.
Assessment of the anthropogenic influx of metallic pollutants in Yarmouk River, Jordan 总被引:2,自引:0,他引:2
Chemical data for 15 elements at depths at 10-cm intervals in 6 cores at two locations along the Yarmouk River as well as
the heavy-metal enrichment factors (EFs) and anthropogenic factors (AFs) show that Cd and Ni for all the cores, and Mn, Zn,
Cr, Co and Pb for core 3 at location A are anthropogenically enriched. The contents of these elements decrease clearly with
depth in the sediment column. The sequence of element enrichment depends on whether the EF and the AF are used to calculate
the elements which show no systematic decrease in enrichment with depth in all cores, especially for location A, probably
due mainly to a higher sedimentation rate. The results of the present study show that the sediments of the Yarmouk River are
uncontaminated with Fe, Cr, and Mn, whereas they are uncontaminated to moderately contaminated with Ni, Co, and Zn, moderately
contaminated with Pb, and strongly to extremely contaminated with respect to Cd. Also, the study shows that the EF and AF
values are higher than 1, which indicates that all the metals measured in the sediments of the Yarmouk River were enriched
by various anthropogenic sources in the catchment area of this river. Heavy metal enrichment reflects the combined effects
of agricultural activities, a treatment plant, a landfill site at El-Akader, and small industries in the region.
Received: 16 March 2000 · Accepted: 12 August 2000 相似文献
87.
大气污染物排放清单是空气质量模拟和空气污染治理的重要依据.本研究比较分析了两套覆盖江苏省的2017年大气污染物排放清单,即分别由上海市环境科学研究院、江苏省环境科学研究院编制的"长三角清单"和"江苏省清单",并结合区域空气质量模型CMAQ评估不同清单对长三角地区2017年1、4、7、10月的空气质量模拟的影响.清单比较结果表明,除二氧化硫(SO2)以外,江苏省清单估算的各污染物排放量较长三角清单低.通过与观测数据比较,发现两套清单对SO2、氮氧化物(NOx)、臭氧(O3)和细颗粒物(PM2.5)的模型模拟性能均较好.江苏省清单与长三角清单两者的模拟结果空间分布接近,其中江苏省清单模拟的PM2.5和O3在长三角多数地区略低于长三角清单的模拟结果(1月O3除外).江苏省清单与长三角清单均能够用于空气质量模式模拟,可为江苏地区的细颗粒物和光化学烟雾污染的控制策略制定提供参考. 相似文献
88.
Kong Fanyou 《大气科学进展》1994,11(1):1-12
A two-dimensional, non-reactive convective cloud transport model is used to simulate in detail the vertical transport and wet scavenging of soluble pollutant gases by a deep thunderstorm system, Simulations show that for gases with not very high solubility, a deep and intense thunderstorm can still rapidly and efficiently transport them from boundary layer (PBL) up to mid and upper troposphere, resulting in a local significant increase of concentration in the upper layer and a reduction in PBL. Dissolution effects decrease both the incloud gas concentration and the upward net fluxes. The higher the solubility is, the more remarkable the decrease is. However, for very low soluble gases (H < 102 M atm-1), the influences are very slight. In addition, the effects of irreversible dissolution and aqueous reactions in drops on the vertical transport of gaseous pollutants are estimated in extreme. 相似文献
89.
菌根真菌对土壤中有机污染物的修复研究 总被引:12,自引:0,他引:12
菌根真菌是真菌与植物之间特殊的联合共生体,利用菌根真菌修复土壤,尤其是修复有机污染物污染的土壤,正成为一个崭新的研究方向。菌根真菌是土壤真菌的一种,但与土壤中放线菌和细菌等微生物相比,其对土壤中有机污染物具有更大的忍耐能力,并且能利用土壤中大多数持久性有机污染物作为碳源来获取能量。综述了近20年菌根真菌对土壤有机污染物降解研究,讨论了菌根真菌降解土壤有机污染物的可能机制,并探讨了从引入固氮菌、外源细菌两个方面对菌根调控以提高修复效果的可能性,为进一步研究菌根真菌生物降解土壤中持久性有机污染物、利用菌根植物修复有机污染土壤提供信息。 相似文献
90.
The transport of air pollutants from several big cities in the north of China and theneighboring countries is researched by using the isentropic trajectory model. The trajectories arecalculated twice daily for the cities in January, April. July and October for the period of 1992-1994. The statistical method has been used to deal with trajectory dots at intervals of 30 min forthe forward and backward trajectories during 0-24 h and 24-48 h. The probability distributiondiagrams of trajectory show clearly the ensemble properties of isentropic trajectories for each cityand the dominant transport directions of pollutants. They possess notable seasonal variations. Theforward trajectory areas of the Ulaan Baatar in Mongolia can spread over North China. and thoseof the Chita in Russia can influence Northeast China except in summer. In July the forwardtrajectory of Pyongyang and Seoul can extend northward to the boundaries of China. 相似文献