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Chemical Contamination (chemical + contamination)
Selected AbstractsVariation in Pesticide Tolerance of Tadpoles among and within Species of Ranidae and Patterns of Amphibian DeclineCONSERVATION BIOLOGY, Issue 5 2000Christine M. Bridges Because variability exists among organisms in their sensitivity to environmental stressors, it is important to determine the degree of this variation when undertaking conservation efforts. We conducted both lethal (time-to-death) and sublethal (activity change) assays to determine the degree of variation in the sensitivity of tadpoles to a pesticide, carbaryl, at three hierarchical levels: among ranid species, among several populations of a single ranid species ( Rana sphenocephala), and within populations of R. sphenocephala. We observed significant variation in time to death among the nine ranid species and among the 10 R. sphenocephala populations we tested. Four out of eight R. sphenocephala populations exhibited significantly different times to death among families. The magnitude of the activity change in response to exposure to sublethal carbaryl levels was significantly different among species and within R. sphenocephala populations. Chemical contamination, at lethal or sublethal levels, can alter natural regulatory processes such as juvenile recruitment in amphibian populations and should be considered a contributing cause of declines in amphibian populations. Resumen: Existe una variación significativa entre y dentro de especies de anfibios con respecto a los reportes de disminuciones poblacionales; las especies en disminución son frecuentemente encontradas en ambientes que son fisiográficamente similares a ambientes donde las mismas especies están prosperando. Debido a que la variabilidad existe entre organismos en lo referente a su sensibilidad a estresores ambientales, es importante determinar el grado de esta variación cuando se lleven a cabo esfuerzos de conservación. Nosotros llevamos a cabo ensayos tanto letales (tiempo de muerte) como subletales (cambios de actividad) para determinar el grado de variación en la sensibilidad de renacuajos a un pesticida, carbaryl, en tres niveles jerárquicos: entre especies de ránidos, entre diversas poblaciones de una sola especie de ránido ( Rana sphenocephala) y dentro de poblaciones de R. sphenocephala. Observamos diferencias significativas en tiempo de muerte entre las nueve especies de ránidos y entre las 10 poblaciones de R. sphenocephala evaluadas. Cuatro de ocho poblaciones de R. sphenocephala exhibieron tiempos de muerte significativamente diferentes entre familias. La magnitud del cambio de actividad al ser expuestas a niveles subletales de carbaryl fue significativamente diferente entre especies y dentro de poblaciones de R. sphenocephala. La contaminación química, a niveles letales y subletales, puede alterar los procesos reguladores naturales (por ejemplo el reclutamiento de juveniles) en poblaciones de anfibios y debería ser considerado como una causa que contribuye a la disminución de poblaciones de anfibios. [source] Ecotoxicologic impacts of agricultural drain water in the Salinas River, California, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2003Brian S. Anderson Abstract The Salinas River is the largest of the three rivers that drain into the Monterey Bay National Marine Sanctuary in central California (USA). Large areas of this watershed are cultivated year-round in row crops, and previous laboratory studies have demonstrated that acute toxicity of agricultural drain water to Ceriodaphnia dubia is caused by the organophosphate (OP) pesticides chlorpyrifos and diazinon. We investigated chemical contamination and toxicity in waters and sediments in the river downstream of an agricultural drain water input. Ecological impacts of drain water were investigated by using bioassessments of macroinvertebrate community structure. Toxicity identification evaluations were used to characterize chemicals responsible for toxicity. Salinas River water downstream of the agricultural drain was acutely toxic to the cladoceran Ceriodaphnia dubia, and toxicity to C. dubia was highly correlated with combined toxic units (TUs) of chlorpyrifos and diazinon. Laboratory tests were used to demonstrate that sediments in this system were acutely toxic to the amphipod Hyalella azteca, a resident invertebrate. Toxicity identification evaluations (TIEs) conducted on sediment pore water suggested that toxicity to amphipods was due in part to OP pesticides; concentrations of chlorpyrifos in pore water sometimes exceeded the 10-d mean lethal concentration (LC50) for H. azteca. Potentiation of toxicity with addition of the metabolic inhibitor piperonyl butoxide suggested that sediment toxicity also was due to other non,metabolically activated compounds. Macroinvertebrate community structure was highly impacted downstream of the agricultural drain input, and a number of macroinvertebrate community metrics were negatively correlated with combined TUs of chlorpyrifos and diazinon, as well as turbidity associated with the drain water. Some macroinvertebrate metrics were also correlated with bank vegetation cover. This study suggests that pesticide pollution is the likely cause of ecological damage in the Salinas River, and this factor may interact with other stressors associated with agricultural drain water to impact the macroinvertebrate community in the system. [source] Sediment chemical contamination and toxicity associated with a coastal golf course complex,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2001Michael A. Lewis Abstract The increasing density of golf courses represents a potential source of sediment contamination to nearby coastal areas, the chemical and biological magnitude of which is almost unknown. The objective of this study was to determine the concentrations of contaminants and toxicities of sediments impacted by a coastal golf course complex. Sediment contaminant concentrations were determined at least twice during the two-year study period at 14 sampling stations. In addition, a combination of acute and chronic bioassays were conducted exposing four invertebrate test species to whole sediments and associated pore waters. Overall, the Florida, USA, golf course complex had a measurable impact on sediment chemical quality, particularly in near-field areas. Higher concentrations of several trace metals and organochlorine pesticides were detected in many golf course-associated sediments compared with reference areas; however, concentrations decreased seaward and only a few, primarily chlorinated pesticides, exceeded proposed sediment quality guidelines. Chromium, zinc, and mercury were detected more frequently than other trace metals. The DDT and associated metabolites, dieldrin and chlordane, were the more commonly detected organic contaminants. Acute toxicity was uncommon and occurred consistently for sediment collected from one coastal location. In contrast, chronic toxicity occurred at several study sites based on the response of Mysidopsis bahia. It was concluded that the impact of golf course runoff on sediment quality may be subtle and sensitive biological assessment methods, such as chronic toxicity tests, will be needed to detect adverse effects. [source] Interaction of an insecticide with larval density in pond-breeding salamanders (Ambystoma)FRESHWATER BIOLOGY, Issue 4 2005BRIAN S. METTS Summary 1. Amphibian populations residing in or near agricultural areas are often susceptible to pesticide contamination. Recent evidence suggests that the effects of pesticides on amphibians often exceed those estimated in laboratory toxicity tests because other environmental factors (e.g. predators, resource abundance) can influence pesticide toxicity. 2. To examine the effects of an insecticide (carbaryl) on two species of Ambystoma salamanders experiencing the natural stress of competition, we manipulated chemical concentration (control, 3.5 and 7.0 mg L,1) and larval density (low and high). We determined the effect of treatments on snout-vent length (SVL), growth rate, lipid reserves, time to metamorphosis, per cent survival and per cent metamorphosis. 3. Carbaryl negatively affected all response variables of Ambystoma maculatum significantly, and significantly reduced survival and metamorphosis of A. opacum. Increased density significantly influenced SVL, lipid reserves, growth rate and metamorphosis of A. maculatum. 4. The effects of carbaryl and increased density on per cent metamorphosis were nearly additive, but were generally less than additive on other variables. 5. The negative effects of chemical contamination on salamanders were likely because of pesticide-induced reductions of food resources, as zooplankton abundance decreased by as much as 97% following carbaryl application. 6. Our study demonstrates the importance of the interactive effects that chemical contamination and natural environmental factors have on salamanders. [source] Polycyclic aromatic hydrocarbon residues in the sediments of a dune lake as a result of power boatingLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 1 2001Thorsten D. Mosisch Abstract The potential chemical effects of motorized recreational activities (power boating, water skiing, jet skiing) on Brown Lake, an Australian perched, acid dune lake, were investigated. The objective of this study was to identify and quantify polycyclic aromatic hydrocarbon compounds (PAHs) that may have accumulated in the water and/or the organic bottom sediments of the test lake as a result of the operation of powered recreational watercraft, and to evaluate any risk to aquatic biota. To achieve this, a detailed sampling and analysis programme of the lake water and sediments was implemented. Basic water quality, ionic and nutrient data gave no indication of any deterioration in the water quality of the lake, which was attributable to human usage in general or motorized recreational activities in particular. However, analysis of samples taken from the organic bottom sediments of the lake revealed the presence of 10 PAH, including benzo(a)pyrene, chrysene, fluoranthene, phenanthrene and pyrene, which are known to be indicative of fossil fuel combustion processes. Three PAH compounds were found at all survey sites: benzo(a)pyrene (in 46% of samples), fluoranthene (in 53% of samples) and pyrene (in 44% of samples). Results of the analyses were compared with values from published guidelines for residues in freshwaters and sediments, as well as with previous studies dealing with the effects of fossil fuel combustion products on lakes. The highest PAH concentrations in sediments were recorded for benzo(a)pyrene, with three values (830, 955 and 1070 ,g kg,1 dryweight) exceeding the upper threshold recommended in the draft Canadian freshwater sediment quality guidelines. Benzo(a)pyrene also exceeded the lower Canadian sediment threshold in 51 (40%) samples. These results indicate a significant level of chemical contamination of Brown Lake as a consequence of four decades of motorized recreational activities and present a significant risk to aquatic biota, particularly benthic and littoral invertebrates associated with the contaminated sediments. [source] PHOSPHATES IN ARCHAEOLOGICAL FINDS: IMPLICATIONS FOR ENVIRONMENTAL CONDITIONS OF BURIAL,ARCHAEOMETRY, Issue 4 2004L. MARITAN The occurrence of coarse-grained vivianite and mitridatite aggregates in a potsherd, a grand ring and a timber imprint from the Second Iron Age site of Adria (Rovigo, northeastern Italy) suggest contrasting environmental conditions of burial. In particular, bone fragments were replaced by vivianite at relatively low pH and Eh, due to the presence of deteriorating organic matter, together with slag and iron flakes. Subsequent interactions with Ca-rich groundwater characterized by higher pH and Eh determined the growth of mitridatite after vivianite. Although phosphates crystallized after burial, the examined samples were not involved in pervasive chemical contamination. [source] | ||||||||||