James N. Huckins

Semipermeable membrane devices containing model lipid: A new approach to monitoring the bioavaiiability of lipophilic contaminants and estimating their bioconcentration potential

Abstract Low density “layflat” polyethylene tubing containing thin films of model lipid may simulate the bioconcentration of nonpolar organic contaminants by aquatic organisms. These semipermeable polymeric membrane devices (SPMDs) are shown to hold considerable promise as time-integrated concentrators of nonpolar organics in aquatic environments, and as a method for estimating bioavailability and potential bioconcentration factors for contaminants in organisms. The devices may also help define the relative role of equilibrium partitioning in the bioaccumulation of organic contaminants. The use of purified lipid extracts from aquatic organisms or specific lipids, such as triolein, in SPMDs is made more practical by a complementary analytical development showing the utility of polyethylene film as a membrane for dialyzing nonpolar organic compounds from coextracted lipids. Data are presented on the uptake kinetics and steady state distribution coefficients of aqueous residues of fenvalerate, mirex, 2,2′,5,5′-, and 3,3′,4,4′-tetrachlorobiphenyls when lipids are used in SPMDs. The feasibility of the SPMD approach for in situ monitoring of environmental contaminants is demonstrated by exposing SPMDs to AsanaR (an isomer of fenvalerate) in a littoral enclosure of a small pond.

Application of semipermeable membrane devices (SPMDs) as passive air samplers

The semipermeable membrane device (SPMD), consisting of a neutral lipid (triolein) enclosed in polyethylene layflat tubing, is demonstrated to be a highly efficient passive air sampler. These devices readily sequester lipophilic organic contaminants from the vapor phase. Specifically, the SPMDs are shown to concentrate polychlorinated biphenyl (PCB) residues from a laboratory atmosphere in a linear manner through 28 days. Under the conditions of this study, a three device composite (1.4 g triolein) extracted PCB residues from ≈ 7 m3 of air per day.

Passive water sampling via semipermfable membrane devices (SPMDS) in concert with bivalves in the Sacramento/San Joaquin River Delta

Freshwater clams (Corbicula fluminea) and the Huckins et al. (1) semi-permeable membrane sampling device (SPMD) were simultaneously deployed at three sites on the Sacramento and San Joaquin rivers in 1990. Both clams and the SPMDs were analyzed for sequestered pesticides and polychlorinated biphenyls (PCBs) by gas chromatography with electron capture detection (GC/ECD). Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and non-ortho PCBs were quantified by high resolution mass spectrometry (MS). In general, levels of organochlorine compounds were approximately 1.6 times higher in clams on a wet weight basis than in the SPMDs, and trends in accumulation were similar except where biofouling of the SPMD membranes decreased uptake rates. Comparisons between the normalized, average levels of PCDDs accumulated showed that while octachlorodibenzo-p-dioxin (OCDD) was most prevalent in both clams and SPMDs, much higher levels of 2,3,7,8 TCDD were found in the SPMDs than in the clams; 2,3,7,8 TCDD was 32% of the profile relative to the OCDD level for the SPMDs and <1% of the clam OCDD level. PCB levels showed the clams primarily accumulated hexachlorinated PCBs while the pentachlorinated and tetrachlorinated congeners were higher in the SPMDs. Differences in profiles for homologous series among the PCBs reveal that some congeners, especially those with 2,4,5 substitution, are more likely to bioaccumulate than those with lower chlorination or adjacent unsubstituted sites. GC/MS chromatograms indicate the SPMDs also sequestered several polyaromatic hydrocarbons. GC/ECD chromatograms indicate the presence of several unidentified, early eluting compounds in the SPMDs.

Use of semipermeable membrane devices for in situ monitoring of polycyclic aromatic hydrocarbons in aquatic environments

Abstract A method is given for the recovery, cleanup, and analysis of polycyclic aromatic hydrocarbons (PAHs) that have been sequestered in SPMDs (semipermeable membrane devices). SPMDs are polymeric membranes enclosing lipids, and mimic the bioconcentration process of aquatic animals. SPMDs are used as passive, in situ monitors of contamination by organic pollutants of aquatic environments. The method reported here includes dialytic recovery of the PAHs, cleanup of the dialysates using size exclusion, adsorption, and argentation chromatographic modules in tandem, then analysis by gas chromatography with photoionization or mass spectrometric detection. The method is demonstrated to overcome the presence of a variety of environmental co-contaminants and other potential interferents in the dialysates. A field application is also demonstrated in which SPMDs are used to monitor PAH contamination in an urban creek. Approaches to the use of SPMD data to calculate aqueous concentrations of PAHs are discussed. The use of SPMDs in combination with the complementary, PAH-specific cleanup procedure provides a unique approach to the analysis of PAH residues in the aquatic environment.

Distribution and bioaccumulation of selenium in aquatic microcosms

Closed-system microcosms were used to study factors affecting the fate of selenium (Se) in aquatic systems. Distribution and bioaccumulation of Se varied among sediment types and Se species. A mixture of dissolved (75)Se species (selenate, selenite and selenomethionine) was sorbed more rapidly to fine-textured, highly organic pond sediments than to sandy riverine sediments. Sulfate did not affect the distribution and bioaccumulation of (75)Se over the range 80-180 mg SO(4) liter(-1). When each Se species was labeled separately, selenomethionine was lost from the water column more rapidly than selenate or selenite. Selenium lost from the water column accumulated primarily in sediments, but volatilization was also an important pathway for loss of Se added as selenomethionine. Loss rates of dissolved Se residues were more rapid than rates reported from mesocosm and field studies, suggesting that sediment: water interactions are more important in microcosms than in larger test systems. Daphnids accumulated highest concentrations of Se, followed by periphyton and macrophytes. Selenium added as selenomethionine was bioaccumulated preferentially compared to that added as selenite or selenate. Organoselenium compounds such as selenomethione may thus contribute disproportionately to Se bioaccumulation and toxicity in aquatic organisms.

Determination, fate, and potential significance of PCBs in fish and sediment samples with emphasis on selected AHH-inducing congeners

Abstract Total PCB residues, non- o , o ′-Cl PCBs, and the most AHH-active mono- o , o′ -Cl PCB congener were determined in Great Lakes fish and sediment samples. Toxic 3,3′,4,4′-tetrachlorobiphenyl and 2,3,3′,4,4′-pentachlorobiphenyl were detected in both fish and sediments. There appeared to be some reduction in the percentage content of the selected AHH-active congeners in fish and sediment PCB residues when compared to their percentage content in the Aroclor mixtures suspected as sources of contamination. The TCDD equivalents (AHH induction potency normalized to TCDD, times residue concentration in pg/g) were as high as 666 pg/g in fish; PCB residues in one sediment sample appeared to have undergone reductive dechlorination by anaerobic microorganisms.

Distribution and impact of trifluralin, atrazine, and fonofos residues in microcosms simulating a Northern Pratrie Wetland

Abstract Extensive use of pesticides in the watersheds of Northern Prairie Wetlands of the U.S.A. has prompted considerable concern about the potential for adverse effects on wetland ecosystems and their associated wildlife. Wetland microcosms, consisting of sediments from a representative wetland, biota associated with the sediments, seeded populations of Daphnia magna and Chironomus riparius , and reconstituted water, were separately exposed to 14 C-atrazine (20 μg/L), 14 C-trifluralin (4 μ/L) and 14 C-fonofos (22 & 94 μg/L) in sediment-water mixtures simulating edge-of-field runoff. The concentrations, distributions, and major processes controlling contaminant fate were elucidated for each pesticide in these microcosm exposures. In addition, adverse effects of pesticidal residues were determined but were limited by requirements for fate modeling.

Acute and Chronic Effects of Kepone and Mirex on the Fathead Minnow

Abstract Acute and chronic toxicity studies were conducted with fathead minnows (Pimephales promelas) and the organochlorine insecticides Kepone and mirex. Kepone was highly toxic to fathead minnows under acute conditions; 96-hour LC50s (median lethal concentrations; 95% confidence limits in parentheses) were as low as 340 (289–400) μg/liter and 96-hour EC50s (median effective concentrations; 95% confidence limits in parentheses) were as low as 18 (15–22) μg/liter. The observed effect, upon which the EC50 calculations were based, was an extensive hemorrhage associated with an apparent fracture or dislocation of the vertebral column in the region of the dorsal fin. Mirex was not acutely toxic to fathead minnows, even at concentrations that exceeded its maximum water solubility. Chronic toxicity testing indicated that the maximum acceptable toxicant concentration for fathead minnows exposed to Kepone was between 1.2 and 3.1 μg/liter. Adverse chronic effects of mirex were limited to a possible impairment o...

Aquatic hazard assessment of the organophosphate insecticide fonofos

This study determined the acute and chronic toxicity of the organophosphate insecticide fonofos to standard freshwater aquatic organisms under laboratory conditions. Fonofos was acutely toxic to bluegill (Lepomis macrochirus), Daphnia (D. magna), and midge (Chironomous riparius) at 5.3, 2.7, and 39 μg/L, respectively. Three fonofos formulations (technical, 94.8% A.I.; 20G, field granular 20% A.I.; and 4E, field liquid 4#/gal A.I.) exhibited similar acute toxicities to bluegill. Exposure to fonofos delayed reproduction and decreased the intrinsic rate of increase of Daphnia during 21-d chronic exposure at the lowest tested concentration (0.08 μg/L). The no observable effect concentration (NOEC) for Daphnia survival was 0.42 μg/L; 0% survival occurred at the lowest observable effect concentration (LOEC) of 1.45 μg/L. The NOEC for midge emergence was 3.42 μg/L; only 34% emergence occurred at the LOEC of 8.24 μg/L. Chronic 30-d exposure of juvenile bluegills decreased growth and survival at 5.65 μg/L (LOEC), but no effects occurred at 2.33 μg/L (NOEC). The relative hazard of fonofos to aquatic life is similar to other carbamate and organophosphate corn insecticides.

Dynamics of isopropylphenyl diphenyl phosphate in fathead minnows

The fate of a triaryl phosphate (ring-UL-14C-2-isopropylphenyl diphenyl phosphate) was examined in fathead minnows. Diphenyl phosphate was identified as a major metabolite in whole body fish samples. A significant portion of the radioactive residues appeared to be associated with biogenic compounds, indicating “in vivo” reactions of biochemicals with 14C-metabolites or 14C-ring cleavage of 2-isopropylphenyl diphenyl phosphate and subsquent incorporation into biochemical pathways.