Temporal Bioavailability of Organochlorine Pesticides and PCBs

Abstract

Because PCBs and organochlorine pesticides continue to be of global concern, studies that address information gaps, such as factors and influences of spatial and temporal effects on contaminant bioavailability, are valuable. The present study focused on the spatial and temporal distribution of bioavailable organochlorine pesticides and PCBs in surface waters of a contaminated harbor. Passive sampling devices were intensively deployed adjacent to various land uses on the Willamette River, OR, including Portland Harbor and McCormick and Baxter Superfund sites, during summer and fall, extreme conditions, 2001-2004. An increase of bioavailable sigmaDDTs (sum of p,p'-DDT, p,p'-DDD, and p,p'-DDE) concentrations was strongly affected bythe local historic production of DDTs and temporal changes in river conditions. The increase of bioavailable p,p'-DDD and high DDD/DDE ratios observed during summer indicates conditions favoring anaerobic reductive processes. In contrast to sigmaDDTs, the bioavailable concentrations and daily loads of dieldrin and PCBs increased during fall, especially during episodic rainstorms. On the basis of the PCB congener profiles, PCB inputs from urban runoff /sewer overflows were considered likely current sources of bioavailable PCB into the Harbor. The exceedence of the U.S. national and Oregon water quality criteria was a function of the temporal variability of each bioavailable contaminant. This illustrates the impacts associated with temporal changes of bioavailable organochlorine distributions in surface waters and the significance of considering realistic temporal, bioavailability, and site-specific conditions in risk assessment and water quality management.

An approach for calculating a confidence interval from a single aquatic sample for monitoring hydrophobic organic contaminants

“…It was designed specifically to respond to issues of reproducibility and variability associated with sampling with PSDs at the Portland Harbor Superfund site. Future study plans for Portland Harbor contemplated site-specific hypotheses that were not evaluated in prior work, which focused on broader spatial and temporal trends [5,6,12]. The study presented here was proposed to help preemptively define study-design and analysis options for future work as well as examine options for incorporating data from earlier studies with limited replication into current and future site assessments (such as evaluating the success of remediation).…”

Improvements in pollutant monitoring: Optimizing silicone for co-deployment with polyethylene passive sampling devices

“…Water cages were purchased from Environmental Sampling Technologies, Inc. (St. Joseph, MO) with all polymers co-deployed within the same cage, and multiple cages deployed at each site in both sampling years. The deployment system consisted of an anchor, steel cable, water cages, and two buoys: one for buoyancy, and another on top for retrieval (Sethajintanin and Anderson, 2006). Each cage was approximately 2.5 meters off the bottom of the river.…”

“…First, laboratory methods were employed to optimize silicone pre-deployment cleaning to reduce background chromatographic interferences, and for infusing silicone with labeled internal standards for uptake rates and water concentration estimates. Second, we compared five silicone polymers in a field application at a Portland Harbor Superfund site with a history of POP (including PAH and pesticide) contamination (Sethajintanin and Anderson, 2006; Sower and Anderson, 2008). Sequestration data and operational logistics were used to select silicone polymers best suited for co-deployment studies with LDPE.…”

Spatial and Temporal Variation of Freely Dissolved Polycyclic Aromatic Hydrocarbons in an Urban River Undergoing Superfund Remediation

“…In 2006 two 3-week sampling events were added in the spring prior to the beginning of the dry season. At each site five SPMDs were loaded into a stainless steel cage and suspended 3 meters above the river bottom with an anchor-cage-float system described elsewhere (19). The five SPMDs from each site were extracted together as one sample to increase detection capabilities.…”