Effects Of Flue Gas Desulfurization Gypsum On Acidified Forest Soil

Acidification of forest soil is a severe environmental issue now and in the future inChina, and utilization of flue gas desulfurization gypsum (FGDG) is also a problem atpresent. It is important for solving the both issues to try FGDG for remediation of acidsoil. In this study, effects of FGDG application on remediation of a typical acidifiedforest soil was studied through field experiments at Tieshanping, Chongqing insouthwest China for two years.The remediation effects of FGDG application are evaluated by observing pH,major ions and DOC of soil waters in different soil layers in the FGDG-treated plotsdynamically. Results show that FGDG addition obviously elevated Ca2+concentrationand pH of soil waters, and base saturation of soil also increased, indicating that theacidified soil was improved. The decreases of N-NO3-content in soil waters lessen H+produced by nitrification, and reduce the loss of base cation caused by NO3-leaching.DOC content in soil waters of FGDG-treated plots was lower than control plots,implying that carbon pool of forest soil was less affected by FGDG.Simultaneously, To evaluate the effects of FGDG application on mercurymigration and distribution in the forest, the content and species of Hg in FGDG wereanalyzed, Hg concentration of litterfall, throughfall and soil waters were observeddynamically, and Hg content in air below the canopy, soil and vegetation weremeasured. Results show that FGDG addition lowered the Hg concentration in air,litterfall, and ground vegetation, and Hg content in soil waters also decreased, implyingthat FGDG not only inhibit the Hg emission from soil but also reduce the mobility ofHg in soil. Almost all mercury added by FGDG retained in the Oe&Oahorizon of soil,indicating that the organic horizon in this forest has enough capacity to reserve newlydeposited Hg.In addition, this study also analyzed some other heavy metals content in FGDG,observed their concentration in soil waters dynamically, and measured their content insoil of different layers two years after FGDG addition to evaluate the risk of FGDGapplication. Results show that FGDG application did not increase, or even decreased theconcentration of heavy metals in soil waters, so that FGDG will not bring heavy metal contamination in soil water in a short period. However, slight enrichment of Cr, Cu andZn in some upper soil layers were observed, indicating that the potential risk exists,which needs further study.In summury, FGDG can remediate acidified soil effectively with less risk of heavymeal contamination, even beneficial for significantly reducing soil Hg emission.Therefore, it possesses some application prospects.