Mercury pollution in the atmosphere-soil-biology ecosystem along the trunk road in Guilin

Abstract

Based on the mercury distribution in soil, atmosphere and plant in seven sections beside the trunk road, some advances are obtained: (1) Mercury content of fuel oil of petrol station in Guilin is 3.66-9.74 ng/g, higher than that reported by other countries (0.7-3.2 ng/g). The higher the number of petrol, the lower the content. Number 90 petrol widely used is the highest (9.74 ng/g). (2) Mercury content in soil is commonly 0.30-0.80 ixg/g near the road, (0.30--2.60 ~tg/g) besides the street, both are higher than the average of Guilin background value (0.204 ~tg/g). Mercury content in vegetable near the road is generally 0.025-0.055 ~tg/g, higher than that far away from the road (0.022-0.038 ~g/g). The content in cinnamon leaves on both sides of the street is 0.064).16 ~tg/g, also higher than that far away from the street (0.051-0.067 ~tg/g). Guilin Highway atmospheric mercury content is usually 7-12 ng/m 3, higher than the mean background value (4.4--6.6 ng/m3). Atmospheric mercury content near rural roads is below the level on urban roads. The atmospheric mercury content increases apparently in traffic-intensive stations and intersections. (3) The average concentration of mercury in vegetables is mostly 0.025-0.055 ~tg/g. Mercury content in various tissues of vegetable follows the order of leaves (mostly 0.044).09 ~tg/g)>roots (mostly 0.02-0.05 ~tg/g)>stems (mostly 0.01-0.04 ~tg/g). (4) The distribution of mercury in soil, plants and atmosphere near the road is of certain similarity, with a single peak, nearly symmetrical. As far away from road, the content reduces gradually, which shows the release of exhaust gas mercury is the main source of atmospheric mercury pollution. (5) The correlation analysis on different types of samples shows the correlation coefficients are 0.404 (atmosphere, vegetable leaves), 0.297 (soil, vegetable leaves), 0.06 (soil, cinnamon leaves) and 0.909 (traffic flow, leaves, respectively). It is suggested atmospheric mercury is the main contributor to mercury in leaves. (6) The atmospheric mercury content before rain is higher than that after rain. The flow status of air has apparent impact on mercury enrichment. (7) The mercury content of postman's hair is 2.968 ~tg/g, it is 2.74 times that of ordinary crowds hair (1.083 ~tg/g). This indicated mercury pollution from exhaust gas can affect ecological environment, and the effect should not be ignored.