Dissertation > Excellent graduate degree dissertation topics show

Chongqing City of mercury in precipitation and the Settlement of

Author: WangYongMin
Tutor: WangDingYong
School: Southwestern University
Course: Environmental Science
Keywords: Precipitation Total mercury Methylmercury Concentration Settlement Rainfall
CLC: X52
Type: Master's thesis
Year: 2011
Downloads: 89
Quote: 0
Read: Download Dissertation

Abstract

Mercury is a highly toxic heavy metals, because it can conduct long-distance transport in the atmosphere, it is considered a global contaminants. Different forms of mercury into the atmosphere, in which morphological transformation, and ultimately through dry and wet deposition into the water body or terrestrial ecosystems, since the end of its atmospheric cycle. Enter the land and water ecosystems through methylation and mercury bioaccumulation and other effects on human health hazards, and atmospheric deposition are aquatic and terrestrial ecosystems, a major source of mercury. Annual precipitation in the day, rainfall in the low latitudes, atmospheric deposition of mercury wet deposition are the main types of input. Therefore, the study of mercury in precipitation, the understanding of the distribution of mercury wet deposition, global mercury deposition to establish an accurate database, improve the global biogeochemical cycling of mercury mechanisms and models, and to explore how to reduce atmospheric wet deposition of mercury on human health caused by hazards is important. Currently, North America, Japan and other countries have already established a more mature wet deposition fluxes of mercury monitoring points, while China only Beijing, Changchun, Guiyang, and a few areas of mercury wet deposition monitoring. Especially for the determination of methyl mercury wet deposition, currently only Guiyang Wujiang River Basin and other regions during the Changbai Mountains. Chongqing mountainous and hilly terrain, no wind or breeze all year round, the atmosphere high stability, strong radiation inversion, mercury pollution is difficult to spread easily lead to localized high concentrations of mercury in the atmosphere. With the rain washed into aquatic and terrestrial ecosystems, mercury also increased, thus on the aquatic and terrestrial ecosystems biological hazard. In order to understand the main city of Chongqing, the distribution of mercury in precipitation to make up deficiencies in the areas of domestic wet deposition, this paper established the main city of Chongqing South Bank sampling points (NA), Southwest University sampling points (XD), Jinyun sampling points (JY) , the use of automatic acquisition APS-3A/2B rainfall, with the DMA-80, distillation - ethylation-CVAFS method to determine total mercury and methylmercury in rain levels, the results are as follows: (1) during the study period (July 2010 -2011 February), the main city of Chongqing rain total mercury concentration range of 8.14-157.58ng / L, the average VMW (volume-weighted, volume-weighted) concentration was 34.86 ng / L; methylmercury concentrations ranged from 0.04 -3.7 ng / L, the average VMW concentration 0.36 ng / L, higher than the U.S. each monitoring area, but rather with the detection of Wujiang River in Guiyang. (2) the main city of Chongqing has a spatial distribution of mercury in precipitation characteristics. The sampling period (July 2010 - Feb), three sampling points total mercury concentrations in the order of the average VMW NA (38.85 ng / L) gt; XD (37.44 ng / L) gt; JY (29.58ng / L), shows the city center of Chongqing concentration of total mercury in precipitation is relatively higher than the control peri-urban areas than in urban areas, this also shows that wet deposition of anthropogenic activities on Hg had a significant effect; VMW methylmercury concentrations in the order of: XD (0.64 ng / L) gt; NA (0.38 ng / L) gt; JY (0.16 ng / L). (3) the main city of Chongqing mercury in precipitation has obvious temporal variation. Monthly average concentration of total mercury VMW maximum 69.31ng / L in January, minimum 26.26 ng / L in July ng / L; VMW monthly average concentration of methylmercury maximum 0.62 ng / L in October, the minimum 0.21 ng / L in July. (4) the main city of Chongqing methylmercury to total mercury in precipitation percentage of 0.10% -16.46% range, the average percentage was 1.59%. (5) Chongqing JY, NA sampling points total mercury in precipitation and SO42-concentration showed a significant correlation (r = 0.377 *, r = 0.412 **). Indicated that the two sampling points rainfall atmospheric mercury mainly from coal combustion. (6) Chongqing City of total mercury deposition in precipitation amount 18.47μg/m2, methylmercury settlement of 0.19μg/m2, were associated with precipitation showed a very significant correlation. In order to obtain more complete data and settlement mechanism in the future work, we need to grasp the various sampling points detailed meteorological data to estimate precipitation of mercury and methylmercury sources; need to master atmospheric mercury dry deposition model , to estimate the main city of Chongqing mercury dry deposition fluxes; also through laboratory tests to analyze the atmosphere or rain and other weather conditions for various substances demethylation and methylation effects and to explore the atmosphere Methylmercury sources.

Related Dissertations

CLC: > Environmental science, safety science > Environmental pollution and its prevention > Water pollution and its control
© 2012 www.DissertationTopic.Net Mobile