Distribution And Assessment Of Heavy Metals In Soil (Sediment) From Typical Areas

Mercury, lead and some heavy metals are highly toxic to human health and theenvironment. The environmental pollution problems have been caused widespreadconcern. Soils and sediments because of their particular characters have becomeimportant "source" and "sink" for these heavy metal pollutants. In this paper, thesurrounding soil from a Municipal Solid Waste Incineration (MSWI) located in Chinaand the sediment in two rivers were regarded as research objects. The distribution ofheavy metals and risk assessment for environment and human health were discussed inthis study. The main results are summarized as follows:(1) The first part mainly focused on the distributions of heavy metals in theambient soil of a municipal solid waste incinerator located in north China. Thepollution of the heavy metal and their risks to the local environment and human healthwere assessed.Eight heavy metals in soil contents were as the following order: Mn (545.5±39.81mg/kg)> Zn (100.2±39.83mg/kg)> Cr (52.0±8.23mg/kg)> Cu (27.8±8.63mg/kg)> Ni (23.8±3.79mg/kg)> Pb (18.6±9.03mg/kg)> As (7.70±2.64mg/kg)> Hg (0.088±0.06mg/kg). The concentrations of heavy metals in soilwere obviously influenced by the wind, and most of them were relatively higher innorthwest comparing with that in the southeast. The results of contour maps by KrigingInterpolation method were demonstrated a similar conclusion. According to theevaluation results of Geoaccumulation Index, some ambient soil samples were mainlyaffected by the mercury emission from the municipal solid waste incinerator. However,the result of health risk assessment show that mercury and other metals had not posed non-carcinogenic risk to the local adult human, and for three carcinogenic metals Cr,Ni, As. The single exception was for As, which showed the higher cancinogenic riskthan other metals, with the range of6.49×10-6-9.58×10-6, however these values areacceptable.（2）The second part mainly focused on the heavy metal contents in the surfacesediment from the middle reaches area of Yellow River and Yangtze River. Contents ofZn, Pb, Ni, Cu, Cr, Cd, As were measured, the degree of pollution and potential risk ofthe heavy metals in the sediment were evaluated with single factor index method,Nemerow multi-factor index method and the potential ecological risk index.Seven heavy metal contents in surface sediment of two rivers were as the samefollowing order: Zn> Cr> Cu> Ni> Pb> As> Cd. The enrichment factors of Cu andCr are in the range of1.12-12.4and1.09-2.28, respectively. The single factor indexindicated that many samples were high level of pollution for Cu and Cd; Nemerowmulti-factor index indicated that Yi river, Luo river, Yiluo river, the confluence reachesof Yiluo river and Yellow river and Huayuankou were polluted. The values of potentialecological risk assessment indicated that Cd in G207of tributary of Luo River, YiRiver Bridge, and Yiluo River showed high level, Cd in Huanyuankou and Cu in YiluoRiver showed middle level and other samples showed low level.The enrichment factor of Zn, Ni, Cu, Cd were relatively high in the middle area ofYangtze River, in the range of1.05-2.41,1.03-2.78,1.08-4.41,0-3.47, respectively.The single factor index indicated that Cd, Zn, Cu were polluted with middle level inmany samples, except a high level pollution for Cu in Gujiadian. Nemerowmulti-factor index indicated that Gujiadian were middle-grade polluted, others wereslightly polluted or no polluted. The potential ecological risk factor of Cd belonged tomiddle level, other heavy metal were in low level. The potential ecological risk indexof Gujiadian belonged to middle level; other samples were in low level.Meanwhile, based on the different characteristics of heavy metals for the twotypical areas, we put forward some measures and suggestions about heavy metalpollution prevention, respectively.