Lead: Peter R. Jaffé, Department of Civil and Environmental Engineering, PrincetonUniversity

Status: Start date: February 1, 2008; End date: January 31, 2010

Problem:

The fate and transport of many trace metals in soils is closely linked to biogeochemical reactions. Plant driven processes in particular will affect the newly developed Secaucus High School high marsh wetlands. New insights will allow for proper management of existing marshes, and/or design of treatment wetlands to maximize trace metal immobilization.

Objective:

To gain a thorough understanding of sulfate reducing conditions coupled to trace metal immobilization in sediments at the two high marsh sites at the Secaucus wetland.

Strategy:

A series of key dissolved species we will be monitored over a two-year period. Simultaneously nests of piezometers will be installed in order to determine the water level, and to determine infiltration or discharge fluxes.

Eight dialysis samplers will be built and installed, four at each of the two high marsh areas. Two will be placed in the direct vicinity of plants and two in areas where plants are not growing. The objective is to determine which of the measured variables (chemical species) is directly affected by the activity of the plants. The dialysis samplers will be monitored on a monthly basis.

Dissolved chemical species to be monitored will include: NO2-, NO3-, Mn2+, Fe2+, SO42-, HS-, Cl-, TOC (and possibly individual root exudates) and dissolved trace metals such as Cr, Cd, Zn, or other metals based on the ongoing sampling by MERI at the Secaucus site.

Additional dialysis samplers will be deployed at an established marsh near the Secaucus site.

Sediment cores will be extracted on a much more limited basis and analyzed for Fe(III), organic content, acid volatile sulfides (AVS), and trace metals (sorbed and associated with the AVS).

A small greenhouse experiment will contrast the effect of sage and spartina on wetland biogeochemistry.

Activities:

Construction, deployment and sampling using dialysis samplers

Installation of piezometers (by MERI)

Sample analysis (location to be determined)

Deliverable:

Results in new insights on the redox profile in the newly constructed high marsh at the Secaucus High School. In particular:

Development of the profile

Changes seasonally

Affects on trace-metal sequestration

Affects of different sediment strata on these processes.

The results will be presented in a detailed final report and are expected to yield at least one full length manuscript as well as conference presentations.