This project proposes a set of lab and field experiments to further the fundamental understanding ofbiogeochemical processes governing the behavior and transport of inorganic and organic Arsenic (As)species as well as contribute to the design and management of remediation activities of sites contaminatedwith As. We have chosen the Vineland Chemical site in southern New Jersey as our primary field sitebecause it offers a number of research opportunities. One primary focus will be on experiments that couldhelp optimize pump and treat operations. These studies would include plume capture efficiency assessmentsthrough measurements of tracers of groundwater flow velocities and directions. They would also involvelaboratory and field experiments to investigate whether manipulations of aquifer chemistry could enhanceremediation of groundwater As, primarily through accelerating As mobilization from aquifer solids, therebyenabling pump and treat operations to decrease subsurface As inventories more rapidly. We will alsocollaborate with Project 7 on investigating the feasibility of using permeable reactive barriers of zero valentiron as an additional remediation strategy to the current pump and treat system.Other field experiments will investigate fundamental transport and fate issues of As in two offsite areashighly contaminated with As, specifically the Blackwater Branch and Union Lake. We will further investigateAs cycling in bottom sediments of both the stream (which runs adjacent to the Superfund site) and of UnionLake. Our prior work has shown that the sediments of these two surface water bodies have dramaticallydifferent As chemistries, with fine-grained sediments of the stream having As controlled largely by sulfurchemistry while As in the lake sediments appears to be primarily controlled by iron chemistry. Additionalsediment-porewater research will be done in the Blackwater Branch to investigate whether As behaviorchanges as a function of streamflow/groundwater discharge rates and to investigate As porewater-sedimentinteractions in sandy sediments which represent >80% of the stream bottom. The role of storm events intransporting As in the Blackwater Branch will also be investigated. Finally, research in Union Lake willinvestigate the magnitude of As release from sediments during episodes of anoxia in bottom waters.
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