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Lead exposure in American black ducks after implementation of non-toxic shot

Lead poisoning from the ingestion of spent shotgun pellets has been recognized as an important disease of North American waterfowl since Bellrose's (1959) research >40 years ago. Nation-wide regulations banning the use of lead shot for waterfowl hunting were established in 1991. We compared the prevalence of lead exposure in American black ducks ( Anas rubripes ) wintering on 2 areas in Tennessee before (1986-88) and after the ban (1997-99) to assess the effect of the ban on lead shot on this species. Prevalence of elevated blood lead in black ducks declined by 44% from before (11.7% prevalence) to after (6.5% prevalence) the implementation of non-toxic shot. The reduction in lead exposure was pronounced in adult black ducks (from 14.3% to 5.3%). However, prevalence in lead exposure remained similar in juvenile black ducks (from 8.2% to 8.3%). Additional evidence from lead ingestion and lead poisoning mortality events also indicates that lead exposure has declined in waterfowl in the Mississippi flyway. We believe that lead ingestion will continue to decline, despite the persistence of lead shot in some wetlands. The impact of reduced lead exposure on waterfowl populations needs to be assessed.

Tennessee↗

USGS Toxic Substances Hydrology Program, 2010

The U.S. Geological Survey (USGS) Toxic Substances Hydrology Program adapts research priorities to address the most important contamination issues facing the Nation and to identify new threats to environmental health. The Program investigates two major types of contamination problems: * Subsurface Point-Source Contamination, and * Watershed and Regional Contamination. Research objectives include developing remediation methods that use natural processes, characterizing and remediating contaminant plumes in fractured-rock aquifers, identifying new environmental contaminants, characterizing new and understudied pesticides in common pesticide-use settings, explaining mercury methylation and bioaccumulation, and developing approaches for remediating watersheds affected by active and historic mining.

Fact Sheet↗

Occurrence of organic compounds and trace elements in the upper Passaic and Elizabeth Rivers and their tributaries in New Jersey, July 2003 to February 2004: Phase II of the New Jersey toxics reduction workplan for New York-New Jersey Harbor

Samples of surface water and suspended sediment were collected from the Passaic and Elizabeth Rivers and their tributaries in New Jersey from July 2003 to February 2004 to determine the concentrations of selected chlorinated organic and inorganic constituents. This sampling and analysis was conducted as Phase II of the New York-New Jersey Harbor Estuary Workplan—Contaminant Assessment and Reduction Program (CARP), which is overseen by the New Jersey Department of Environmental Protection. Phase II of the New Jersey Workplan was conducted to define upstream tributary and point sources of contaminants in those rivers sampled during Phase I work, with special emphasis on the Passaic and Elizabeth Rivers. Samples were collected from three groups of tributaries: (1) the Second, Third, and Saddle Rivers; (2) the Pompton and upper Passaic Rivers; and (3) the West Branch and main stem of the Elizabeth River. The Second, Third, and Saddle Rivers were sampled near their confluence with the tidal Passaic River, but at locations not affected by tidal flooding. The Pompton and upper Passaic Rivers were sampled immediately upstream from their confluence at Two Bridges, N.J. The West Branch and the main stem of the Elizabeth River were sampled just upstream from their confluence at Hillside, N.J. All tributaries were sampled during low-flow discharge conditions using the protocols and analytical methods for organic constituents used in low-flow sampling in Phase I. Grab samples of streamflow also were collected at each site and were analyzed for trace elements (mercury, methylmercury, cadmium, and lead) and for suspended sediment, particulate organic carbon, and dissolved organic carbon. The measured concentrations and available historical suspended-sediment and stream-discharge data (where available) were used to estimate average annual loads of suspended sediment and organic compounds in these rivers. Total suspended-sediment loads for 1975–2000 were estimated using rating curves developed from historical U.S. Geological Survey (USGS) suspended-sediment and discharge data, where available. Average annual loads of suspended sediment, in millions of kilograms per year (Mkg/yr), were estimated to be 0.190 for the Second River, 0.23 for the Third River, 1.00 for the Saddle River, 1.76 for the Pompton River, and 7.40 for the upper Passaic River. On the basis of the available discharge records, the upper Passaic River was estimated to provide approximately 60 percent of the water and 80 percent of the total suspended-sediment load at the Passaic River head-of-tide, whereas the Pompton River provided roughly 20 percent of the total suspended-sediment load estimated at the head-of-tide. The combined suspended-sediment loads of the upper Passaic and Pompton Rivers (9.2 Mkg/yr), however, represent only 40 percent of the average annual suspended-sediment load estimated for the head-of-tide (23 Mkg/yr) at Little Falls, N.J. The difference between the combined suspended-sediment loads of the tributaries and the estimated load at Little Falls represents either sediment trapped upriver from the dam at Little Falls, additional inputs of suspended sediment downstream from the tributary confluence, or uncertainty in the suspended-sediment and discharge data that were used. The concentrations of total suspended sediment-bound polychlorinated biphenyls (PCBs) in the tributaries to the Passaic River were 194 ng/g (nanograms per gram) in the Second River, 575 ng/g in the Third River, 2,320 ng/g in the Saddle River, 200 ng/g in the Pompton River, and 87 ng/g in the upper Passic River. The dissolved PCB concentrations in the tributaries were 563 pg/L (picograms per liter) in the Second River, 2,510 pg/L in the Third River, 2,270 pg/L in the Saddle River, 887 pg/L in the Pompton River, and 1,000 pg/L in the upper Passaic River. Combined with the sediment loads and discharge, these concentrations resulted in annual loads of suspended sediment-bound PCBs, in grams per year (g/yr), of 37 in the Second River; 132 in the Third River; 2,320 in the Saddle River; 352 in the Pompton River; and 644 in the upper Passaic River. Annual loads of dissolved PCBs, in grams per year, are 9.2 in the Second River; 47 in the Third River; 212 in the Saddle River; 349 in the Pompton River; and 549 in the upper Passaic River. Concentrations of total suspended sediment-bound polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-difurans (PCDD/PCDFs) were 6,000 pg/g (picograms per gram) in the Second River; 11,300 pg/g in the Third River; 37,700 pg/g in the Saddle River; 7,140 pg/g in the Pompton River; and 9,640 pg/g in the upper Passaic River. Total toxic equivalence quotients (TEQs), which included PCDD/PCDFs and coplanar PCBs, ranged from 2.7 pg/g in the Second River to 132 pg/g (as 2,3,7,8-TCDD) in the Saddle River. Average annual loads of PCDD/PCDFs were from 1.1 g/yr in the Second River to 71 g/yr in the upper Passaic River. The load of TEQs (as 2,3,7,8-TCDD) from PCDD/PCDFs and coplanar PCBs in the tributaries were 0.5 mg/yr (milligrams per year) in the Second River, 5.8 mg/yr in the Third River, 130 mg/yr in the Saddle River, 46 mg/yr in the Pompton River, and 100 mg/yr in the upper Passaic River. These loads represent an addition to the TEQ load estimated to cross the head-of-tide of 0.1 percent by the Second River, 0.7 percent by the Third River, and 15 percent by the Saddle River. Loads of sediment-bound trace elements mercury, methylmercury, lead, and cadmium were calculated using concentrations obtained from grab samples, which were assumed to represent average annual concentrations in these rivers. Loads of sediment-bound mercury were estimated to be 1,200 g/yr in the Second River; 130 g/yr in the Third River; 4,200 g/yr in the Saddle River; 3,400 g/yr in the Pompton River; and 6,500 g/yr in the upper Passaic River. Loads of sediment-bound lead were estimated to be 56 kg/yr (kilograms per year) in the Second River; 89 kg/yr in the Third River; 1,140 kg/yr in the Saddle River; 310 kg/yr in the Pompton River; and 1,040 kg/yr in the upper Passaic River. Loads of sediment-bound cadmium were estimated to be 1 kg/yr in the Second River; 0.59 kg/yr in the Third River; 60 kg/yr in the Saddle River; 16 kg/yr in the Pompton River; and 11 kg/yr in the upper Passaic River. These loads indicate the importance of the sediment-bound contributions of organic compounds and trace elements to the upper Passaic and Saddle Rivers. Concentrations of suspended sediment-bound PCBs in the main stem and the West Branch of the Elizabeth River were 806 ng/g and 3,100 ng/g, respectively, representing loads of 40 g/yr and 1,150 g/yr, respectively. These loads were estimated using assumed discharge conditions. Concentrations of suspended sediment-bound PCDD/PCDFs were 7,270 pg/g and 9,980 pg/g in the main stem and West Branch, respectively, representing average annual loads of 0.36 g/yr and 3.7 g/yr, respectively. Total TEQ loads (sum of PCDD/PCDFs and PCBs) were 2.1 mg/yr (as 2,3,7,8-TCDD) in the main stem and 34 mg/yr in the West Branch, respectively. These load estimates, however, were directly related to the assumed annual discharge for the two branches. Long-term measurement of stream discharge and suspended-sediment concentrations would be needed to verify these loads. On the basis of the concentrations measured in this work, it appears that the West Branch is the principal source of PCBs, PCDD/PCDFs, total TEQs, and metals to the main stem of the Elizabeth River. Additional sources of these constituents may exist between the confluence and the head-of-tide.

New Jersey, New York↗

Organic compounds and cadmium in the tributaries to the Elizabeth River in New Jersey, October 2008 to November 2008: Phase II of the New Jersey Toxics Reduction Workplan for New York-New Jersey Harbor

Samples of surface water and suspended sediment were collected from the two branches that make up the Elizabeth River in New Jersey - the West Branch and the Main Stem - from October to November 2008 to determine the concentrations of selected chlorinated organic and inorganic constituents. The sampling and analyses were conducted as part of Phase II of the New York-New Jersey Harbor Estuary Plan-Contaminant Assessment and Reduction Program (CARP), which is overseen by the New Jersey Department of Environmental Protection. Phase II of the New Jersey Workplan was conducted by the U.S. Geological Survey to define upstream tributary and point sources of contaminants in those rivers sampled during Phase I work, with special emphasis on the Passaic and Elizabeth Rivers. This portion of the Phase II study was conducted on the two branches of the Elizabeth River, which were previously sampled during July and August of 2003 at low-flow conditions. Samples were collected during 2008 from the West Branch and Main Stem of the Elizabeth River just upstream from their confluence at Hillside, N.J. Both tributaries were sampled once during low-flow discharge conditions and once during high-flow discharge conditions using the protocols and analytical methods that were used in the initial part of Phase II of the Workplan. Grab samples of streamwater also were collected at each site and were analyzed for cadmium, suspended sediment, and particulate organic carbon. The measured concentrations, along with available historical suspended-sediment and stream-discharge data were used to estimate average annual loads of suspended sediment and organic compounds in the two branches of the Elizabeth River. Total suspended-sediment loads for 1975 to 2000 were estimated using rating curves developed from historical U.S. Geological Survey suspended-sediment and discharge data, where available. Concentrations of suspended-sediment-bound polychlorinated biphenyls (PCBs) in the Main Stem and the West Branch of the Elizabeth River during low-flow conditions were 534 ng/g (nanograms per gram) and 1,120 ng/g, respectively, representing loads of 27 g/yr (grams per year) and 416 g/yr, respectively. These loads were estimated using contaminant concentrations during low flow, and the assumed 25-year average discharge, and 25-year average suspended-sediment concentration. Concentrations of suspended-sediment-bound PCBs in the Main Stem and the West Branch of the Elizabeth River during high-flow conditions were 3,530 ng/g and 623 ng/g, respectively, representing loads of 176 g/yr and 231 g/yr, respectively. These loads were estimated using contaminant concentrations during high-flow conditions, the assumed 25-year average discharge, and 25-year average suspended-sediment concentration. Concentrations of suspended-sediment-bound polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-difuran compounds (PCDD/PCDFs) during low-flow conditions were 2,880 pg/g (picograms per gram) and 5,910 pg/g in the Main Stem and West Branch, respectively, representing average annual loads of 0.14 g/yr and 2.2 g/yr, respectively. Concentrations of suspended-sediment-bound PCDD/PCDFs during high-flow conditions were 40,900 pg/g and 12,400 pg/g in the Main Stem and West Branch, respectively, representing average annual loads of 2.05 g/yr and 4.6 g/yr, respectively. Total toxic equivalency (TEQ) loads (sum of PCDD/PCDF and PCB TEQs) were 3.1 mg/yr (milligrams per year) (as 2, 3, 7, 8-TCDD) in the Main Stem and 28 mg/yr in the West Branch during low-flow conditions. Total TEQ loads (sum of PCDD/PCDFs and PCBs) were 27 mg/yr (as 2, 3, 7, 8-TCDD) in the Main Stem and 32 mg/yr in the West Branch during high-flow conditions. All of these load estimates, however, are directly related to the assumed annual discharge for the two branches. Long-term measurement of stream discharge and suspended-sediment concentrations would be needed to verify these loads. On the basis of the loads cal

Scientific Investigations Report↗

Characterization of the biological, physical, and chemical properties of a toxic thin layer in a temperate marine system

The distribution of plankton in the ocean is patchy across a wide range of spatial and temporal scales. One type of oceanographic feature that exemplifies this patchiness is a ‘thin layer’. Thin layers are subsurface aggregations of plankton that range in vertical thickness from centimeters to a few meters, which may extend horizontally for kilometers and persist for days. We undertook a field campaign to characterize the biological, physical, and chemical properties of thin layers in Monterey Bay, California (USA), an area where these features can be persistent. The particle aggregates (marine snow) sampled in the study had several quantifiable properties indicating how the layer was formed and how its structure was maintained. Particles were more elongated above the layer, and then changed orientation angle and increased in size within the layer, suggesting passive accumulation of particles along a physical gradient. The shift in particle aggregate orientation angle near the pycnocline suggests that shear may also have played a role in generating the thin layer. Pseudo-nitzschia spp. were the most abundant phytoplankton within the thin layer. Further, both dissolved and particulate domoic acid were highest within the thin layer. We suggest that phosphate stress is responsible for the formation of Pseudo-nitzschia spp. aggregates. This stress together with increased nitrogen in the layer may lead to increased bloom toxicity in the subsurface blooms of Pseudo-nitzschia spp. Several zooplankton groups were observed to aggregate above and below the layer. With the knowledge that harmful algal bloom events can occur in subsurface thin layers, modified sampling methods to monitor for these hidden incubators could greatly improve the efficacy of early-warning systems designed to detect harmful algal blooms in coastal waters.

Marine Ecology Progress Series (MEPS)↗

Amino acid variation at the mitochondrial binding site of Antimycin A is proposed to reflect sensitivity and toxicity differences among fish species

To better understand differential sensitivities among fish species to the piscicidal compound Antimycin-A (ANT-A), we hypothesized that variations in amino acids at the ANT-A binding site may reflect toxicity differences. Protein sequences for six motifs comprising the ANT-A binding site were obtained and compared for invasive carp species ( N = 515) and seven non-target species ( N = 277); a consensus was delineated from each species. The carp species, Common Carp ( Cyprinus carpio ), Silver Carp ( Hypophthalmichthys molitrix ), Bighead Carp ( Hypophthalmichthys nobilis ), Grass Carp ( Ctenopharyngodon idella ), and Black Carp ( Mylopharyngodon piceus ) , showed the same amino acids at the site; thus, it was termed the carp consensus motif sequence (CCM). Channel Catfish ( Ictalurus punctatus ) showed the most amino acid polymorphisms, with three motifs 96–100% different from CCM. Within a species, Bluegill ( Lepomis macrochirus ) and Fathead Minnow ( Pimephales promelas ) variation per motif was most dissimilar (46.7% and 21.6%, respectively). Organismal mortality data from the literature indicated Yellow Perch ( Perca flavescens ) , Walleye ( Sander vitreus ) , and American Gizzard Shad ( Dorosoma cepedianum ) to be most sensitive to the piscicide, Catfish least sensitive, and all others intermediate. The protein sequence variations of the binding site appeared to be in accord with organismal sensitivity categories when they differed from the CCM; the motifs in Gizzard Shad and Walleye were the same as in CCM. The physical/chemical nature of ANT-A is important to consider in organismal response comparisons. This cellular approach of studying ANT-A binding at its target enzyme is a non-destructive way to predict piscicidal efficacy of ANT-A against fishes of interest, informs management decisions in control efforts for invasives, and can be used to forecast effects on sympatric species.

Fishes↗

Toxicity of potassium chloride to veliger and byssal stage dreissenid mussels related to water quality

Natural resource managers are seeking appropriate chemical eradication and control protocols for infestations of zebra mussels, Dreissena polymorpha (Pallas, 1769), and quagga mussels. D. rostiformis bugensis (Andrusov, 1897) that have limited effect on non-target species. Applications of low concentrations of potassium salt (as potash) have shown promise for use where the infestation and treatment can be contained or isolated. To further our understanding of such applications and obtain data that could support a pesticide registration, we conducted studies of the acute and chronic toxicity of potassium chloride to dreissenid mussels in four different water sources from infested and non-infested locations (ground water from northern Idaho, surface water from the Snake River, Idaho, USA, surface water from Lake Ontario, Ontario, Canada, and surface water from the Colorado River, Arizona, USA). We found short term exposure of veligers (< 24 h) to concentrations of 960 mg/L KCl produced rapid mortality in water from three locations, but veligers tested in Colorado River water were resistant. We used probit models to compare the mortality responses, predicted median lethal times and 95% confidence intervals. In separate experiments, we explored the sensitivity of byssal stage mussels in chronic exposures (>29 d) at concentrations of 100 and 200 mg/L KCl. Rapid mortality occurred within 10 d of exposure to concentrations of 200 mg/L KCl, regardless of water source. Kaplan-Meier estimates of mean survival of byssal mussels in 100 mg/L KCl prepared in surface water from Idaho and Lake Ontario were 4.9 or 6.9 d, respectively; however, mean survival of mussels tested in the Colorado River water was > 23 d. The sodium content of the Colorado River water was nearly three times that measured in waters from the other locations, and we hypothesized sodium concentrations may affect mussel survival. To test our hypothesis, we supplemented Snake River and Lake Ontario water with NaCl to equivalent conductivity as the Colorado River, and found mussel survival increased to levels observed in tests of veliger and byssal mussels in Colorado River water. We recommend KCl disinfection and eradication protocols must be developed to carefully consider the water quality characteristics of treatment locations.

Management of Biological Invasions↗

Peracute sodium toxicity in free-ranging black-bellied whistling duck ducklings

From 23 to 25 July 2002, 98–103 newly hatched black-bellied whistling ducks ( Dendrocygna autumnalis ) were observed alive at an inland saline lake (La Sal Vieja) in Willacy County, Texas (USA). Seventy-one (71%) died after showing signs indicative of sodium toxicity within 5 hr of entering the water; some died within minutes. Six carcasses were sent to the United States Geological Survey, National Wildlife Health Center (Madison, Wisconsin, USA) for analysis, and brain sodium levels of all ducklings were above 2,000 parts per million wet weight. More black-bellied whistling duck ducklings are likely to have been affected, but they were not observed after hatching.

Texas↗

Wildlife toxicity testing

Reports of anthropogenic environmental contaminants affecting free-ranging wildlife first began to accumulate during the Industrial Revolution of the 1850s. early reports included cases of arsenic and lead shot ingestion, and industrial smokestack emission toxicity. One early report described the death of fallow deer ( Dama dama ) due to arsenic emissions from a silver foundry in Germany in 1887, whereas another report described hydrogen sulfide fumes in the vicinity of a Texas oil field that resulted in a large die-off of both wild birds and mammals. 1 Mortality in waterfowl and ring-necked pheasants ( Phaisanus colchicus ) due to the ingestion of spent lead shot was recognized at least as early as 1874 when lead-poisoned birds were reported in Texas and North Carolina.

Book chapter↗

Toxicity of chlorinated insecticides to quail and pheasants

'Residues from insecticidal applications of chlorinated hydrocarbons may remain toxic for extended periods. In experiments designed to furnish information on the effects upon quail and pheasants of prolonged feeding upon diets containing small percentages of these compounds, it was shown that aldrin, dieldrin and endrin are cumulative, and that quail are unable to survive after ingesting 5-10 mg./kg, of aldrin, 30-50 mg./kg, of dieldrin, or 6-15 mg./kg, of endrin. Maximum levels (p.p.m.) in the diets permitting survival for extended periods were: DDT, 200; strobane, above 500; aldrin, 0.5; dieldrin, 1.0; endrin, 1.0. Inclusion of these compounds in the diets of breeding quail and pheasants affected hatchability of eggs and viability of chicks, even though the adult birds appeared unaffected.' Detailed figures are given for all points mentioned.

Atlantic Naturalist↗

Impacts of forest herbicides on wildlife: Toxicity and habitat alteration

This paper begins with a review of both laboratory and field studies on tbe possible direct toxic effects of herbicides on terrestrial vertebrates, primarily birds and mammals. Alteration of the palatability of forage and changes in reproductive success are also discussed. Emphasis is placed on the use of herbicides in forestry; studies dealing with agricultural systems are referenced where appropriate. The indirect effects of herbicides on wildlife-habitat are then conceptualized and quantified using data from a 3-year study on effects of phenoxy and glyphosate herbicides on bird and small mammal communities in western Oregon. Data on density and habitat use are presented and compared with data available from other geographic regions.

Transactions of the North American Wildlife and Na↗

Lead shot toxicity to passerines

This study evaluated the toxicity of a single size 7.5 lead shot to passerines. No mortalities or signs of plumbism were observed in dosed cowbirds (Molothrus ater) fed a commercial diet, but when given a more natural diet, three of 10 dosed birds died within 1 day. For all survivors from which shot were recovered, all but one excreted the shot within 24 h of dosing, whereas, the dead birds retained their shot. Shot erosion was significantly greater (P < 0.05) when weathered shot were ingested compared to new shot, and the greatest erosion was observed in those birds that died (2.2-9.7%). Blood lead concentrations of birds dosed with new shot were not significantly different (P=0.14) from those of birds exposed to weathered shot. Liver lead concentrations of birds that died ranged from 71 to 137 ppm, dry weight. Despite the short amount of time the shot was retained, songbirds may absorb sufficient lead to compromise their survival.

Environmental Pollution↗

Toxicity of polybrominated diphenyl ethers (de-71) in chicken (Gallus gallus), mallard (Anas platyrhynchos), and American kestrel (Falco sparverius) embryos and hatchlings

Embryonic survival, pipping and hatching success, and sublethal biochemical, endocrine, and histological endpoints were examined in hatchling chickens (Gallus gallus), mallards (Anas platyrhynchos), and American kestrels (Falco sparverius) following air cell administration of a pentabrominated diphenyl ether (penta-BDE; DE-71) mixture (0.01-20 mu g/g egg) or polychlorinated biphenyl (PCB) congener 126 (3,3', 4,4', 5-pentachlorobiphenyl; 0.002 mu g/g egg). The penta-BDE decreased pipping and hatching success at concentrations of 10 and 20 mu g/g egg in kestrels but had no effect on survival endpoints in chickens or mallards. Sublethal effects in hatchling chickens included ethoxyresorufin-O-dealkylase (EROD) induction and histological changes in the bursa, but these responses were not observed in other species. Polychlorinated biphenyl congener 126 (positive control) reduced survival endpoints in chicken and kestrel embryos and caused sublethal effects (EROD induction, reduced bursal mass and follicle size) in chickens. Mallards were clearly less sensitive than the other species to administered penta-BDE and PCB 126. In a second experiment, the absorption of penta-BDE (11.1 mu g/g egg, air cell administered during early development) into the contents of chicken and kestrel eggs was determined at various intervals (24 h postinjection, midincubation, and pipping). By pipping, 29% of the penta-BDE administered dose was present in the egg contents in chickens, and 18% of the administered dose was present in kestrel egg contents. Based on uptake in kestrels, the lowest-observed-effect level on pipping and hatching success may be as low as 1.8 mu g total penta-BDE/g egg, which approaches concentrations detected in eggs of free-ranging birds. Because some penta-BDE congeners are still increasing in the environment, the toxic effects observed in the present study are cause for concern in wildlife.

Environmental Toxicology and Chemistry↗

Chronic toxicity of some new insecticides to bobwhite quail

Presents and discusses results of toxicity studies on northern bobwhite (Colinus virginianus). Compounds tested were chlordane, toxaphene, DDT, benzene hexachioride, methoxychior, TDE (Rhothane}, and parathion.

Special Scientific Report - Wildlife↗

Chronic toxicity of diphenhydramine hydrochloride and erythromycin thiocyanate to Daphnia, Daphnia magna, in a continuous exposure test system

Diphenhydramine hydrochloride (DH; Benadryl TM, an over-the-counter antihistamine) and erythromycin thiocyanate (ET; a commonly used macrolide antibiotic) are pharmaceutical compounds whose chronic toxicity to Daphnia magna had not been characterized. Continuous exposure to DH concentrations about 5 times greater than the maximum reported environmental concentration of 0.023 lg/L for 21 days or to ET concentrations about 40 times the maximum reported environmental concentration of 6 (mu or u)g/L for 21 days did not significantly impact D. magna survival and production. In this study the no observable effect concentration for DH was 0.12 (mu or u)g/L and for ET was 248 (mu or u)g/L.

Bulletin of Environmental Contamination and Toxico↗

Effect of treatment in a constructed wetland on toxicity of textile wastewater

Constructed wetlands for treating wastewater have proliferated in recent years and their characteristics have been studied extensively. In most cases, constructed wetlands have been used primarily for removal of nutrients and heavy metals. Extensive literature is available concerning construction and use of wetlands for treatment of wastewater. Even so, quantitative descriptions of wetland function and processes are highly empirical and difficult to extrapolate. The processes involved in removal of pollutants by wetlands are poorly understood, especially for waste streams as complex as textile effluents. The few studies conducted on treatment of textile wastewater in constructed wetlands were cited in earlier publications. Results of a two-year study of a full-scale wetland treating textile effluent are presented here. The paper describes the effects of the wetland on aquatic toxicity of the wastewater and draws conclusions about the utility and limitations of constructed wetlands for treatment of textile effluents.

AATCC Review↗