Grantee Research Project Results
Final Report: Concentrations and Enantiomeric Fractions of Chlordane in Sediments from Long Island Sound
EPA Grant Number: R832215Title: Concentrations and Enantiomeric Fractions of Chlordane in Sediments from Long Island Sound
Investigators: Zhang, Pengfei , Melcer, Michael E , Jans, Urs
Institution: City College of the City University of New York , U.S. Merchant Marine Academy
EPA Project Officer: Hahn, Intaek
Project Period: February 1, 2005 through January 31, 2008
Project Amount: $299,728
RFA: Greater Research Opportunities: Persistent, Bioaccumulative Chemicals (2004) RFA Text | Recipients Lists
Research Category: Land and Waste Management , Safer Chemicals , Hazardous Waste/Remediation
Objective:
Long Island Sound (LIS) is one of the largest estuarine systems on the Atlantic coast of the United States, providing vital transportation and rich fishing, including shell-fishing grounds for commercial interests. The Sound, however, has been contaminated with various pollutants, including organochlorine pesticides such as chlordane (a persistent, bioaccumulative pesticide widely used in the United States from 1945 to 1988). Limited long-term monitoring data from the National Oceanic and Atmospheric Administration (NOAA) showed a decline in chlordane concentration in LIS surficial sediments between 1986 and 1996. The objectives of the research were therefore to: (1) determine the rates of chlordane concentration decline in the surficial sediments from LIS; (2) elucidate the mechanisms that caused the chlordane concentration decline in LIS sediments; and (3) examine the chiral signature of chlordane residues in the LIS sediments to assess the significance of microbial degradation on chlordane removal.
Summary/Accomplishments (Outputs/Outcomes):
Our study revealed that chlordane concentrations did not decrease significantly in the past decade when compared to the data collected in 1996. This is in contrast to the clear decline trend observed at earlier times (1986-1996) but nevertheless is consistent with the observation of near-constant chlordane levels in blue mussel tissues in the past decade. Chlordane concentrations in many of the sites exceeded levels above which harmful effects on sediment-dwelling organisms are expected to frequently occur.
Chlordane concentrations in two of the four sediment cores showed a peak below the sediment surface. The lack of a chlordane concentration maximum below the sediment surface in the other two cores, coupled with the lack of a well-defined 137Cs peak, indicated significant sediment mixing. Simulations of 137Cs and 210Pb profiles in sediment cores with a simple sediment mixing model confirmed the occurrence of both sedimentation and significant sediment mixing. Simulations of the chlordane profiles also indicated continued chlordane input to LIS long after the early 1980s, when chlordane was phased out in the United States.
Both trans-chlordane and cis-chlordane were racemic or nearly racemic in most archived and recently collected sediments, indicating that the enantiomeric compositions of the sources of chlordane to LIS sediment did not change in the past two decades, and that house foundation soils are likely the major source of chlordanes to LIS. Invariant enantiomeric compositions temporally in surficial sediments and at different depths in sediment cores clearly indicate the lack of enantioselective biodegradation in LIS sediment, in striking contrast to the widely observed enantioselective biodegradation of chlordanes in soils.
Four other organochlorine pesticides (OCPs), dieldrin, p,p’-DDE, p,p’-DDD, and p,p’-DDT were also widely present in LIS surficial sediment two decades after the use of these pesticides in the United States was banned. In addition, the surficial concentrations did not decrease significantly when compared to the concentrations in archived samples collected two decades ago. Sediment in the western part of the Sound was more contaminated (with concentrations in some western sites being still above probable effect levels) than the sediment in the eastern part, probably as a result of the net westward sediment transport in the Sound. The four OCPs were detected at all depths (down to ~50 cm) in the sediment cores, and concentration profiles indicated a depositional sedimentary environment with significant sediment mixing. Such mixing may redistribute OCPs deposited earlier (deeper in sediment bed) to sediment surface and lead to prolonged presence of OCP concentrations in surficial sediment.
Conclusions:
Chlordane and other OCPs are still widely present in LIS sediment, two decades after their use in the United States was banned. Both continued input and significant sediment mixing may have led to persistent OCP concentrations (and persistent organic pollutant concentrations in general) in LIS surficial sediment, posing long-term threats to benthic organisms (e.g., constant chlordane concentrations in blue mussel tissues). The lack of enantioselective microbial degradation of chlordane in LIS sediment makes it even more persistent in the Sound. This research provided mechanistic understandings of the persistence of chlordane and other OCPs in estuarine sediment. Such understandings are vital for developing administrative strategies to protect our nation’s estuarine environment.
Journal Articles:
No journal articles submitted with this report: View all 7 publications for this projectSupplemental Keywords:
chlordane, Long Island Sound, LIS, organochlorine pesticides, surficial sediments, microbial degradation, sediment, ecosystems, environmental monitoring, aquatic ecosystem, ecosystem restoration, aquatic sediments, Ecosystem Protection/Environmental Exposure & Risk, Water, Scientific Discipline, Restoration, Aquatic Ecosystem Restoration, Biochemistry, Ecology and Ecosystems, remediation, contaminated sediment, chemical remediation, microbial breakdown, aquatic ecosystems, degradation rates., Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Restoration, Ecology and Ecosystems, Aquatic Ecosystem Restoration, contaminated sediment, microbial breakdown, restoration strategies, degradation rates, remediation, aquatic ecosystemsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.