R. James Maguire

Acute toxicity, uptake, depuration and tissue distribution of tri-n-butyltin in rainbow trout, Salmo gairdneri

Abstract The tri- n -butyltin cation (Bu 3 Sn + ), the active ingredient in organotin-containing antifouling paints, was highly toxic to rainbow trout ( Salmo gairdneri , mean weight, 1.5 g); the 96-h LC 50 was 1.41 μg Sn/l. Lake trout ( Salvelinus namaycush , mean weight, 5.9 g) were more tolerant, with a 96-h LC 50 of 5.21 μg Sn/l. Rainbow trout concentrated significant levels of Bu 3 Sn + during a 64-d exposure at 0.21 μg Sn/l, with bioconcentration factors of 406 and 570 (based on Bu 3 Sn + and total Sn, respectively). Rainbow trout depurated Sn slowly on transfer to Bu 3 Sn + -free water. During the 32 d period following transfer, the whole-body concentration of Bu 3 Sn + fell by 25% while the total Sn concentration was reduced by 17%. The total Sn concentrations in tissues of rainbow trout at the end of a 15-d exposure to 0.42 μg Sn/l indicated that Bu 3 Sn + partitions into trout on the basis of a three-compartment model. Peritoneal fat (mean concentration, 9.18 mg Sn/kg) constituted one compartment, kidney, liver and gall bladder/bile (mean concentration range, 3.07 to 3.72 mg Sn/kg) a second, and all other tissues (mean concentration range, 0.49 to 1.53 mg Sn/kg) a third. After 15 d of depuration the system had simplified; only two compartments (liver plus gall bladder/bile and all other tissues) were apparent. Varying proportions of Bu 3 Sn + and its metabolites di- n -butyltin, n -butyltin and inorganic tin were present in all tissues sampled. The percent of metabolites in liver (74) and gall bladder/bile (89) were, however, significantly higher than the levels in all other tissues, which ranged from 10 to 43. This suggests hepatic dealkylation and biliary-fecal excretion.

Determination of nonylphenol polyethoxylates and their carboxylic acid metabolites in sewage treatment plant sludge by supercritical carbon dioxide extraction

A supercritical fluid extraction (SFE) method was developed for the extraction of nonylphenol polyethoxylate (NPnEO) non-ionic surfactants from dried sewage treatment plant sludge. Extraction was carried out at 80°C and 5100 p.s.i. with carbon dioxide using water as a modifier. The ethoxylates were analyzed by gradient high-performance liquid chromatography (HPLC) with an APS Hypersil column and a fluorescence detector (230 nm excitation and 300 nm emission). This SFE method was more time-efficient and it produced higher recovery than the traditional Soxhlet extraction and steam distillation techniques used for NPnEO in sewage sludge. The same procedure was also applicable to the coextraction of nonylphenoxyacetic (NP1EC) and nonylphenoxyethoxyacetic (NP2EC) acids, which were metabolites of the ethoxylates under aerobic conditions. Following an off-line methylation, analysis of the acids was achieved by GC-MS in selected ion monitoring mode. In a brief survey of sludge samples collected from nine sewage treatment plants across Canada, very high levels of nonylphenol mono- (NP1EO, 28–304 μg/g) and di-ethoxylates (NP2EO, 4–118 μg/g) were found. In contrast, the total polyethoxylate concentration (from 3 to 17 ethoxy units) was generally less than 50% of the sum of NP1EO and NP2EO in the same sample. NP1EC and NP2EC were found in only three of the seven samples tested, with concentrations ranging from 4 to 38 μg/g.

An Ecological Risk Assessment of Nonylphenol and Its Ethoxylates in the Aquatic Environment

Nonylphenol ethoxylates (NPEs) are a group of surfactants that are widely used for industrial, commercial, institutional and household purposes in Canada. Ethoxylation of nonylphenol (NP) occurs upon reaction with ethylene oxide, producing NPEs, although NP is also used in the production of the antioxidant tris(nonylphenol)phosphite. NP and NPEs are not produced naturally, and the primary route of environmental exposure to NP and NPEs is via textile mill, pulp and paper mill and municipal wastewater treatment plant effluents. NPEs occur as complex mixtures and are described by the average ethoxylate chain length, which ranges from 1 to 100. The environmental fate of NPEs is strongly dependent on the effluent and, the degree and type of treatment to which the effluent is subjected. An ecological risk assessment was performed to determine if exposure to NP and NPEs results in effects on the Canadian environment, based on current use patterns. The Canadian ecological risk assessment found that adverse effects on aquatic organisms are likely, although assumptions were made with respect to appropriate dilution factors.

Butyltin Species and Inorganic Tin in Water and Sediment of the Detroit and St. Clair Rivers

Water and sediment samples from 29 locations in the Detroit and St. Clair rivers were analyzed for the highly toxic tri-n-butyltin (Bu3Sn+) species and for the less toxic di-n-butyltin (Bu2Sn2+) and n-butyltin (BuSn3+) species and inorganic tin. In general, locations sampled in the St. Clair River were less contaminated with butyltin species than those in the Detroit River. Inorganic tin and BuSn3+ were detected in over 90% of all subsurface water samples, while Bu2Sn2+ and Bu3Sn+ were detected in 45 and 28% of the same samples, respectively. The highest concentration ofBu3Sn+ in subsurface water, 5.9 × 10−10 mol Sn/L, was at the mouth of the Ecorse River, a tributary of the Detroit River. The three butyltin species and inorganic tin were also detected in 23–46% of all sediment samples. The highest concentrations of Bu3Sn+ in sediment were found close to the mouths of the River Rouge, another tributary of the Detroit River, and the Ecorse River, and were 6.2 × I0–7 and 1.7 × I0–7 mol Sn/kg dry weight, respectively, for the top 2 cm of sediment.

Potential underestimation of chlorinated hydrocarbon concentrations in fresh water

Abstract Significant concentrations of PCBs and other chlorinated hydrocarbons have been found in dichloromethane extracts of filtered Niagara River, Canada, water at pH 12 after the water had been thoroughly extracted at pH 1. In samples from 43 dates in 1985-86, the contribution of the basic extract to the total concentration derived from acidic, basic and suspended solids extracts ranged from 0% for 31 of these chemicals to 100% for PCBs 15, 114 and 201, aldrin and p,p′-DDT. When the sums of concentrations of each chemical found in Niagara River water in the acidic, basic and suspended solids extracts over the 43 sampling dates were themselves summed, the basic fraction contributed 40% to the total concentrations of all chemicals, and 48% if only PCBs were considered. Experiments with water from another source showed that some PCBs were recovered in dichloromethane extracts of basic filtered water which had previously been thoroughly extracted under either acidic or neutral conditions. These results indicate that concentrations of chlorinated hydrocarbons in Niagara River water determined by extraction solely at neutral pH, the usual technique, may be underestimated. This finding, which may have general applicability to fresh waters, may be the result of a strong association between a fraction of the dissolved lipophilic chemicals and dissolved organic matter in fresh water, an association that is resistant to organic solvent extraction at acidic or neutral pH, but which is at least partially disrupted by extraction at high pH.

Accumulation of tributyltin in Hyalella azteca as an indicator of chronic toxicity: Survival, growth, and reproduction

The chronic toxicity of tributyltin (TBT) was examined by exposing two successive generations of the freshwater amphipod, Hyalella azteca, to sediments spiked with TBT. Survival was the most sensitive measure of effect, with lethal concentration resulting in 50% mortality (LC50) values on a water and body concentration basis ranging from 76 to 145 ng Sn/L and 2,790 to 4,300 ng Sn/g, respectively. Individual growth of amphipods was not negatively affected by TBT, and although reproduction might be more sensitive than survival, the data were too variable to use on a routine basis. There were no detectable TBT-induced differences in the response between first- and second-generation animals. The relationship between toxicity and bioaccumulation of TBT in H. azteca was determined and can be used as a tool to predict the toxicity of TBT in environmental samples. Body concentrations exceeding 2,000 ng Sn/g in H. azteca exposed to field-collected samples would indicate that chronic toxicity due to TBT is likely occurring in amphipod populations at those sites.

Photodegradation of quinoline in water

Abstract The photodegradation kinetics of quinoline have been studied at 313 nm and in sunlight in organic-free water, lake water, and water containing several different solutes. The half-life of sunlight photodegradation is slightly shorter in lake water than in organic-free water (4–8%, depending upon the season). In near-surface lake water at 40° N latitude in summer, quinoline was predicted to degrade readily in sunlight, with a half-life of about 14 calendar days. The calculated half-life in winter was about 123 calendar days. The photodegradation of quinoline was accelerated significantly by NaNO 3 and dissolved organic matter, two effective producers of hydroxyl radicals in aquatic environments. The rate was also faster at pH 4.5 than at pH 7.0. Two photoproducts were identified in low yield, 2-hydroxyquinoline and 8-hydroxyquinoline; prolonged irradiation appeared to destroy the aromatic nucleus.

Tributyltin uptake and depuration in Hyalella azteca: Implications for experimental design

The purpose of this study was to address four aspects of the kinetics of tributyltin (TBT) in the freshwater amphipod Hyalella azteca: time to steady state, route of uptake, depuration rates, and effect of gut clearance. The amphipods accumulated TBT rapidly, reaching steady state within 14 d. Body concentrations were similar between caged and sediment-exposed animals, indicating that the primary route of uptake is via dissolved TBT. However, the rate of uptake was significantly higher in sediment-exposed amphipods. During depuration, body concentrations of TBT exhibited a biphasic decline, with a stronger decrease over the first 24 h that is attributed primarily to gut clearance, followed by a more gradual decrease most likely due to excretion from the body. Gut contents contributed significantly to body concentrations of TBT, accounting for 30% of the initial total body burden in sediment-exposed amphipods. Half-lives of TBT in gut-cleared H. azteca were 8 d and 14 d for amphipods exposed to spiked water and spiked sediment, respectively. The results of this study have significant implications in the experimental design and interpretation of studies involving the effects of TBT in H. azteca.

Recent studies of residual tributyltin in coastal British Columbia sediments

Butyltin concentrations in the sediments of two coastal areas of British Columbia, Canada, are reported. Two recent box cores from the deepest basin in the Strait of Georgia were sectioned and analyzed by GC–atomic emission spectrometry. No butyltin compounds were detected above 0.5 μgSn kg−1 (dry weight) in either core. These results are compared to those for a previous (1991) core from the same area. In that study, tributyltin (TBT) concentrations were in the range 1–2 μgSn kg−1 down the core and were higher than those of either of the degradation products, dibutyltin (DBT) and monobutyltin (MBT). Radioisotope dating (210Po–210Pb counting methods) was used to establish the rates of sedimentation of 0.25 and 2.6 cm y−1 at the two sites. Data suggest that a combination of rapid deposition of new, less-contaminated material and degradation of previously deposited butyltin compounds has resulted in the observed absence. Thirty-three surface sediments from the northern BC coastal harbor at Prince Rupert, collected in 1995, were analyzed for butyltin residues by GC–FPD. Concentrations of TBT, DBT and MBT were in the ranges from below the appropriate limit of detection (LOD) to 1262, to 109 and to 37 μgSn kg−1, respectively. TBT/DBT ratios ranged from 0.2 to 62 with most above unity, indicating that there is continuing fresh input of TBT. The sources are almost exclusively large ocean-going vessels that use the harbor for long-term anchorage. These findings are discussed with reference to the global TBT status.

Distribution and Transformation of Fenitrothion Sprayed on a Pond: Modeling Under Uncertainty

Fenitrothion* was used during the period 1969–1977 in New Brunswick, Canada, to control the spruce budworm (Choristoneura fumiferana [Clemens]) in the province’s forests. Millions of hectares were sprayed annually with 150–300 g active ingredient per hectare. The routes and rates of its environmental transformation and disappearance are subjects of much interest (National Research Council of Canada, 1975, 1977). Maguire and Hale (1980) recently reported on the aquatic fate of fenitrothion. Surface water microlayer, subsurface water, suspended solids, and sediment samples were collected from a small pond in a spruce-fir forest in New Brunswick before and after the aerial spraying of a fenitrothion formulation for spruce budworm control; the samples were then analyzed for fenitrothion and its degradation and transformation products. Fenitrothion concentrations in the surface microlayer, subsurface water, suspended solids, and sediment fell below detectable levels two days after the spray; the only identified products were p-nitro-m-cresol in water, which persisted less than two days, and aminofenitrothion (O,O-dimethyl-O-(p-amino-m-tolyl)phosphorothionate) in sediment, which persisted less than four days. Laboratory experiments showed that chemical hydrolysis of fenitrothion and volatilization of fenitrothion from true solution were both slow processes; however, volatilization of fenitrothion from surface slicks was very fast (t 1/2= 18 min at 20°C). Thus, a large fraction of the fenitrothion that reached the pond surface appeared to volatilize rapidly, while the fraction that remained in the water disappeared or degraded within a few days, largely through photolysis and microbial reduction.