You are here:
A TOXICITY ASSESSMENT APPROACH TO EVALUATING IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS
Citation:
Lazorchak, J M., M E. Smith, AND H H. Tabak. A TOXICITY ASSESSMENT APPROACH TO EVALUATING IN-SITU BIOREMEDIATION OF PAH CONTAMINATED SEDIMENTS. Presented at 6th International Symposium: In-Situ and On-Site Bioremediation, San Diego, CA, June 4-7, 2001.
Impact/Purpose:
The current goals of this task's research are to (1) develop miniaturized sediment exposure methods using selected marine and freshwater fish and amphipods that can be used for screening contaminants in sediments from surface waters and remediation studies and (2) to modify present sediment toxicity methods to include molecular methods for the detection of sublethal changes associated with exposure to contaminants.
Description:
Freshwater and marine sediment toxicity tests were used to measure baseline toxicity of sediment samples collected from New Jersey/New York Harbor (NJ/NY) (non-PAH- contaminated) sediment (ERC). Four freshwater toxicity tests were used: 1) amphipod (Hyalella azteca) mortality and growth tests (a standard 10-day USEPA method and two 7-day exposure methods (one using the standard amount of sediment, 100 ml; one using a reduced sediment volume, 17 ml)-the reduced volume freshwater amphipod test was developed and used in this study since existing volume requirements of the USEPA standard method exceeded the amounts available from enhanced or natural attenuation treatment); 2) a 7-day aquatic worm (lumbriculus variegatus) mortality and budding test; 3) a 7/8-day fathead minnow (Pimephales promelas) embryo-larval survival and teratogenic test (FHM-EL); and 4) a 4-day vascular aquatic plant (Lemna minor) frond number/growth/chlorophyll a test (Duckweed). Two marine tests were also used: 1) amphipod (Ampelisca abdita) 10-day mortality test and a sheepshead minnow (Cyprinodon variegatus) embryo-larval sediment test (SHM-EL). ERC sediments were found to be highly toxic to all freshwater and marine organisms tested while the NJ/NY non-PAH contaminated sample showed no significant toxicity to the marine amphipod, but was slightly toxic to the freshwater worm and to freshwater and marine fish. For all tests run with freshwater organisms and the one marine amphipod no survival was found in any of the tests except for one of the freshwater amphipod tests (55%). The ERC sediment significantly reduced frond production (-58.3%) and chlorophyll a levels (-35.4%) in the freshwater duckweed test. To determine the cause of toxicity in the sediments, five sediment manipulations were performed: 1) a sediment purge procedure, where 2-4 volumes of lab water were replaced over the sediment in a 24-h period; 2) a sediment dilution procedure where grade 40 silica sand was mixed with PAH-contaminated sedments on a weight:weight basis; 3) a sediment aeration procedure where sediment samples were aerated by adding 80 ml of sediment (140 gms) to a 250 ml glass graduated cylinder and 120 ml of overlying water followed by aeration for 24-48h; 4) an Ambersorb Treatment Procedure, where PAH-contaminated sediment samples were treated with two types of organic removal resins - Ambersorb 563 and 572; and 5) an Amberlite Treatment Procedure where IRC-718, an inorganic removal resin was mixed with PAH-contaminated sediments. Results showed that freshwater amphipod survival was improved with the sediment aeration procedure and with 8% AS 563 and 572 treatments. Toxicity can also be reduced with the sediment dilution technique (100-fold). These manipulations revealed that hydrogen sulfide, organic compounds and inorganic compounds (metals) were factors in ERC sediment toxicity.