نتایج جستجو برای: degree of contamination
تعداد نتایج: 21171351 فیلتر نتایج به سال:
concentrations of elements (as, co, cu, ni, mo, pb, v, cd, cr and zn) are studied in the surface sediments of bakhtegan lake, northwest of nyriz city, iran, to assess metal contamination. the average abundance order of trace elements content in bakhtegan lake sediments is cr>ni> v> zn> cu> co> as> pb> mo>cd. the comparison of trace elements concentration in bakhtegan lake sediments with toxicol...
The toxicity of heavy metals in sediments of the Nayband Bay and Asaluyeh region and potential ecological risk to sediment organisms assessed. Three stations with different degrees of vulnerability of South Pars Oil and Gas Activities (1: Control - 2: medium affected and 3: severely affected) were selected in the study area. Sediment sampling at each station in both cold and hot seasons (2010) ...
Toxicity of trace metals in the environment, bioaccumulation in aquatic environments and in food chains are of great importance.This study concentrates on the distribution patterns of some heavy metals (Pb, Ni, Zn and Fe) in surface sediments of Shoor River estuary to obtain an overall classification for the origins of the metals in the studied area. In order to determine the degree of Contamin...
Background and Objective: Urban and industrial development has increased concentration of heavy metals in the environment. The goal of this study was to assess the impact of Kerman steel complex on their surrounding soil by heavy metals. Materials and Methods: This study was a snapshot and its type was descriptive-analytical research. Heavy metals contents from 60 soil samples (top soil, 0-1...
within the components of communicative competence, a special emphasis is put on the “rules of politeness,” specifically the politeness strategies (brown and levinson, 1978) that speakers deploy when performing the request speech act. this is because the degree of imposition that making a request places upon one’s interlocutor(s) has been seen to be influenced by several factors among which, as ...
background: heavy metal pollution in the sediment of the yellow river draws wide attention in the recent years. the yellow river wetland nature reserve of zhengzhou is one of the major wetlands of the river and located at the beginning of the lower reach. in this article, we aimed to investigate the degree and the sources of the metal pollution in the reserve. methods: metals as cu, pb, cr, cd ...
In this study, concentrations of heavy metals in soils around a Zn-smelter in Qeshm island, Iran, are investigated. Calculated geoaccumulation index (Igeo), contamination factor (Cf), and contamination degree (Cdeg) values indicate surface soil contamination by toxic metals (As, Cd, Pb, and Zn). The results also indicate that most contaminated areas are located in the vicinity of the smelter an...
background: the pollution of the aquatic environment with heavy metals has become a worldwide problem during recent years, due to their potential toxic effects and ability to bio-accumulate in aquatic ecosystems. heavy metals are sensitive indicators for monitoring changes in the aquatic environment. methods: in this study, total concentrations of cr, pb, cu, zn, and fe were measured in water a...
this study investigated the effects of planning on second-language written production with regard to task type. the participants were 75 iranian learners of english as a foreign language attending a private foreign language institution. they were asked to complete two different types of writing tasks (expository writing task and argumentative writing task) in different planned conditions (indiv...
in this study, concentrations of heavy metals in soils around a zn-smelter in qeshm island, iran, are investigated. calculated geoaccumulation index (igeo), contamination factor (cf), and contamination degree (cdeg) values indicate surface soil contamination by toxic metals (as, cd, pb, and zn). the results also indicate that most contaminated areas are located in the vicinity of the smelter an...
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