Copper Concentration In Water Research Articles

Copper Contamination of Different Prawn Farms at Shatkhira District

Copper (Cu) contamination of six prawn farms under three upazilas of Satkhira district were evaluated. Total 54 water, sediment and prawn samples were collected from six farms, 18 samples from each category were examined to observe the Cu contamination of water, sediment and prawn. Cu was determined by Atomic Absorption Spectrophotometer at the central laboratory of Bangladesh Agricultural University and toxicity laboratory of Bangladesh Fisheries Research Institute, Mymensingh. The levels of Cu in water sample, sediment sample and samples of prawn species were collected from different surface and ground sources. The concentration of Cu in sediment samples were ranged from 45.3895 to 127.8771 ?g-1 and the average mean concentration was 76.92101 ?g-1. The concentration of Cu in prawn was ranged from 16.1069 to 97.3841 ?g-1 and the average mean concentration was 51.2342 ?g-1. The copper concentration in water ranged from 0.0309 to 0.0702 ppm. Cu concentrations in those samples were higher in sediment than prawn, but very lower concentration was found in water sample. The Cu in sediment samples were present higher amount than allowable limit. So prawn was mostly affected by contaminated water and sediment.DOI: http://dx.doi.org/10.3329/jesnr.v4i2.10157 J. Environ. Sci. & Natural Resources, 4(2): 105-109, 2011

Rapid increase in copper concentrations in a new marina, San Diego Bay

Concentrations of copper in water rose rapidly following the introduction of boats to a new marina in San Diego Bay. Two months after the marina reached half its capacity, a majority of water samples exceeded chronic and acute criteria for dissolved copper, and copper concentrations in several samples exceeded the highest concentrations observed in another marina that has been listed as an impaired water body. A box model suggested that a small fraction of the leached copper was sequestered in sediment. Copper concentrations in water entering the marina from the bay was more than half the chronic concentration limit, so only 50% of marina boat capacity could be accommodated without exceeding the chronic criterion more than 50% of the time. Copper concentrations in water may increase rapidly following boat introduction in small marinas, but could return to pre-introduction levels by controlling boat numbers or reducing use of copper-based paints.

Impacts of ambient salinity and copper on brown algae: 1. Interactive effects on photosynthesis, growth, and copper accumulation

The effect of copper enrichment and salinity on growth, photosynthesis and copper accumulation of two temperate brown seaweeds, Ascophyllum nodosum and Fucus vesiculosus, was investigated in laboratory experiments. A significant negative impact of reduced salinity on photosynthetic activity and growth was observed for both species. After 15 days at a salinity of 5, photosynthesis of A. nodosum was entirely inhibited and growth ceased at a salinity of 15. Increased copper concentration negatively affected photosynthetic activity of A. nodosum and F. vesiculosus resulting in chlorosis and reduced seaweed growth; 5 mg L −1 copper caused an inhibition of the photosynthesis and the degradation of seaweed tips. Under reduced salinity, copper toxicity was enhanced and caused an earlier impact on the physiology of seaweed tips. After exposure to copper and different salinities for 15 days, copper contents of seaweeds were closely related to copper concentration in the water; seaweed copper contents reached their maximum after 1 day of exposure; contents only increased again when additional, free copper was added to the water. At high water copper concentrations or low salinity, or a combination of both, copper content of A. nodosum decreased. By contrast, copper content of F. vesiculosus increased, suggesting that different binding sites or uptake mechanisms exist in the two species. The results suggest that when using brown seaweeds in biomonitoring in situ, any change in the environment will directly and significantly affect algal physiology and thus their metal binding capacity; the assessment of the physiological status of the algae in combination with the analysis of thallus metal content will enhance the reliability of the biomonitoring process.

Screening of antifouling biocides around a pleasure boat marina in the Baltic Sea after legal restrictions.

Copper, zinc, and Irgarol 1051 concentrations were determined around a pleasure boat marina in the Stockholm Archipelago. Copper concentrations in water were twice as high (6.62 μg L⁻¹) in 2004 as 1992-1993, zinc concentrations six times higher (20.0 μg L⁻¹). Concentrations in bladder wrack (Fucus vesiculosus) had also risen. Irgarol concentrations in water were similar (~0.17 μg L⁻¹) in 1996 and 2004, while concentrations in bladder wrack halved from 1993 to 2004. The peak concentrations of copper and Irgarol in water have shifted indicating that the main source in the 1990 s were local boats, but in 2004 visiting boats.

Effect of copper ions on spatial density of NO synthase-positive cells in intestine of the mussel Crenomytilus grayanus (mollusca: bivalvia: mytilidae). A histochemical study

By the histochemical method of detection of NADPH-diaphorase (NADPH-d) (EC 1.6.99.1) the state of nitroxidergic enteric nervous system of the mussel Crenomytilus grayanus was studied under conditions of an increased copper concentration in water. Under the action of copper ions the density of distribution of NADPH-d-positive cells has been established to be changed as compared with control throughout 28 days. A sharp rise of proportion of the labeled cells and their enzyme activity was noted after one day of the experiment. The labeled bipolar cells were of dark blue color and were located within the epithelium. There were revealed numerous nerve fibers penetrating the intestinal epithelium throughout its entire length as well as bipolar nerve cells in epithelium of the minor typhlosole and of crystalline style sac; in control molluscs the NADPH-d-positive cells in these parts were absent. After 7 days the difference between control and experimental decreased and remained at this level after 14 days, while after 21 days of exposition the proportion of labeled cells in the experimental mussels was lower than in control, but increased again after 28 days. It is suggested that nitric oxide is an important protective factor of the intestinal epithelium of the mussel C. grayanus and participates in adaptation of this mollusc to action of the elevated concentration of copper ions in water.

Industrial Copper Intoxication of Iranian Fat-Tailed Sheep in Kerman Province, Iran

An outbreak of industrial chronic copper poisoning in Iranian fat-tailed sheep in a region of southeast Iran is described. At least 10,000 out of 75,000 sheep (13.3%) originating from 50 flocks died over a period of 3 years in the Khatoon Abad region in Kerman province, Iran. The diagnosis was based on epidemiological, clinical, hematological, serum biochemical, urinalysis, necropsy and histopathological evaluations. Then findings were confirmed by toxicological analysis of liver and kidney samples. The details of epidemiological, clinical, laboratory and pathologic findings are described in the manuscript. These findings were indicative of chronic copper poisoning in affected sheep. Toxicological analysis showed an exceeding of the permitted limit (150 mg/kg w.w.) of copper in liver samples by 7.97 times (1196.9 ± 20.6 mg/kg) (wet weight-w.w.). In kidney samples the excess was by 9.14 times (137.2 ± 8.96 mg/kg) (w.w.). The copper concentrations in water and pasture plant samples around the factory were very high, suggesting that water and pasture plants were the sources of intoxication. In conclusion, the environmental pollution by a copper smelter factory in the region was the source of intoxication. Chronic copper intoxication through inhalation and ingestion may result in severe economic losses and a public health hazard. Thus it is necessary to determine copper concentrations in the organs (liver, kidney, muscle, and lung) of sheep in the influence area of chemical units.

Sediment copper bioavailability to freshwater snails in south Florida: risk implications for the Everglade snail kite (Rostrhamus sociabilis plumbeus)

Many properties being acquired as part of the Comprehensive Everglades Restoration Plan (CERP) are heavily contaminated with copper. Estimated copper bioaccumulation in the Florida apple snail (Pomacea paludosa) has led to the prediction of risk to the Everglade snail kite (Rostrhamus sociabilis plumbeus) at some CERP projects. Field study results presented in this paper examine the relationship between copper levels in sediments, snails, and other biota. Copper concentrations in all biota (snails, aquatic vascular plants, and periphyton) were strongly correlated with those in sediments. No correlation with water copper concentrations was evident. Mean copper concentrations in snails ranged from 23.9 mg/kg at the reference site to 732 mg/kg at a high copper site. Calculated biota-sediment accumulation factors (BSAFs) ranged from 36.7 to 7.0 over the range of copper levels in sediments. BSAFs were highest at low copper levels in sediments and declined sharply as copper levels in sediment increased. Risk for the snail kite is discussed in light of the results of this study.

Modelling copper uptake by Saccostrea glomerata with diffusive gradients in a thin film measurements

Environmental context. Organisms, like commercially available rock oysters, can be used to measure the uptake of contaminants (e.g. trace metals) and thereby provide a relative measure of water quality between sites or of water quality changes over time. However, these measurements cannot be directly compared with water quality guidelines, which require water concentrations and not tissue concentrations, to provide an absolute indication of water quality. The present study found that the amount of copper accumulated in oyster tissue was proportional to water copper concentrations measured by passive sampler devices, thereby allowing oyster copper accumulation to be interpreted in terms of biologically-available copper water concentrations and to be compared with the water quality guidelines. Abstract. Copper bioaccumulation in transplanted oysters, Saccostrea glomerata, was compared with measurements of water concentrations. Tissue copper measurements were positively correlated with acid-soluble copper concentrations (n = 6, r = 0.874, P = 0.023) and with DGT (diffusive gradients in a thin film)-accumulated copper mass at two sites (n = 9, r = 0.967, P < 0.001; n = 9, r = 0.888, P = 0.001) where continual bioaccumulation occurred. The more significant correlations are likely due to the time-integrated nature of DGT measurements, despite the biomonitor measuring different copper species. This empirical relationship allowed S. glomerata-available copper concentrations (0.70–1.6 μg L–1) to be modelled across 14 sites and produced a highly significant correlation (r = 0.787, P = 0.001) with DGT-labile copper measurements (0.10–0.49 μg L–1). This approach allowed biomonitor measurements to be compared with water quality guidelines and would further expand the use of biomonitors for aquatic monitoring if widely replicated.

Adverse effects of chronic copper exposure in larval northern leopard frogs (Rana pipiens)

Northern leopard frogs (Rana pipiens) were exposed to environmentally relevant concentrations of copper in water (control and 5, 25, and 100 microg/L, as CuSO4) in a static renewal system for 154 d from posthatch stage to metamorphosis. After 10 d of copper exposure (from Gosner stages 19-25), survival of tadpoles was not significantly different between treatments (averages range from 96.7 to 99.3%), but a significantly higher incidence of deformities (p < 0.05) was observed in the 100-microg/L treatment. Tadpole growth rate was decreased in the 25- and 100-microg/L treatments relative to controls. Tadpole survival, swimming performance, percent metamorphosis, time to metamorphosis, and survival during and time required for tail resorption were also negatively affected in the 100-microg/L treatment. Copper concentrations in tadpole tissues ranged from 46.5 to 769.5 mg/ kg dry mass and were positively related to copper concentrations in the water. In conclusion, copper was shown to affect development, growth, survival, and behavior in larval northern leopard frogs at ecologically relevant concentrations. The existing U.S. Environmental Protection Agency freshwater-quality chronic criterion for copper appears to be protective for larval Rana pipiens.

Practical aspects of the uncertainty and traceability of spectrochemical measurement results by electrothermal atomic absorption spectrometry

The determination of trace elements concentration in water by electrothermal atomic absorption spectrometry (ETAAS) is a common and well established technique in many chemical testing laboratories. However, the evaluation of measurement uncertainty results is not systematically implemented. The paper presents an easy step-by-step example leading to the evaluation of the combined standard uncertainty of copper determination in water using ETAAS. The major contributors to the overall measurement uncertainty are identified due to amount of copper in water sample that mainly depends on the absorbance measurements, due to certified reference material and due to auto-sampler volume measurements. The practical aspects how the traceability of copper concentration in water can be established and demonstrated are also pointed out.

Estimates of microbial quality and concentration of copper in distributed drinking water are highly dependent on sampling strategy

The numbers of bacteria generally increase in distributed water. Often household pipelines or water fittings (e.g., taps) represent the most critical location for microbial growth in water distribution systems. According to the European Union drinking water directive, there should not be abnormal changes in the colony counts in water. We used a pilot distribution system to study the effects of water stagnation on drinking water microbial quality, concentration of copper and formation of biofilms with two commonly used pipeline materials in households; copper and plastic (polyethylene). Water stagnation for more than 4h significantly increased both the copper concentration and the number of bacteria in water. Heterotrophic plate counts were six times higher in PE pipes and ten times higher in copper pipes after 16h of stagnation than after only 40min stagnation. The increase in the heterotrophic plate counts was linear with time in both copper and plastic pipelines. In the distribution system, bacteria originated mainly from biofilms, because in laboratory tests with water, there was only minor growth of bacteria after 16h stagnation. Our study indicates that water stagnation in the distribution system clearly affects microbial numbers and the concentration of copper in water, and should be considered when planning the sampling strategy for drinking water quality control in distribution systems.

Environmental statistical process control using an augmented neural network classification approach

Shifts in the values of monitored environmental parameters can help to indicate changes in an underlying system. For example, increased concentrations of copper in water discharged from a manufacturing facility might indicate a problem in the wastewater treatment process. The ability to identify such shifts can lead to early detection of problems and appropriate remedial action, thus reducing the risk of long-term consequences. Statistical process control (SPC) techniques have traditionally been used to identify when process parameters have shifted away from their nominal values. In situations where there are correlations among the observed outputs of the process, however, as in many environmental processes, the underlying assumptions of SPC are violated and alternative approaches such as neural networks become necessary. A neural network approach that incorporates a geometric data preprocessing algorithm and identifies the need for increased sampling of observations was applied to facilitate early detection of shifts in autocorrelated environmental process parameters. Utilization of the preprocessing algorithm and the increased sampling technique enabled the neural network to accurately identify the process state of control. The algorithm was able to identify shifts in the highly correlated process parameters with accuracies ranging from 96.4% to 99.8%.

ANTIOXIDANT RESPONSES IN SCYTOSIPHON LOMENTARIA (PHAEOPHYCEAE) INHABITING COPPER‐ENRICHED COASTAL ENVIRONMENTS1

Scytosiphon lomentaria (Lingb.) Link. (Phaeophyceae) is one of the two dominant seaweeds in a coastal area of northern Chile affected by copper mine wastes, where the concentration of copper in water and algal tissues remains higher than in nonimpacted sites. Copper‐loaded plants develop oxidative stress, as demonstrated by the increased levels of reactive oxygen species and lipoperoxides. This stress was associated with 1) an enhanced activity of the antioxidant enzymes catalase, glutathione peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, and dehydroascorbate reductase and 2) an inhibition of the glutathione reductase activity. Furthermore, stressed plants showed a decrease in glutathione and phenolic compounds levels and an increase in total ascorbate. Reciprocal transplants revealed that plants rapidly adjusted their antioxidant system in response to the conditions of the receiving site. In individuals transplanted from the copper‐enriched environment to the control site, normal levels of lipoperoxides and antioxidant compounds were restored in 48 h and antioxidant enzymes recovered their basal activities in 96 h. Individuals transplanted from the control site to the copper‐enriched area adjusted their antioxidant compounds and antioxidant enzymes within 48 h and 96 h, respectively, and reached the functional status of the local plants. We conclude that S. lomentaria inhabiting the copper‐enriched area buffered oxidative stress by a simultaneous involvement of antioxidant enzymes and water‐soluble antioxidant compounds. These antioxidant responses were rapid and reversible, suggesting that copper resistance in S. lomentaria is a constitutive trait and that copper enrichment of the area did not result in a locally adapted copper‐tolerant ecotype.

Hardness corrections for copper are inappropriate for protecting sensitive freshwater biota

Toxicity testing using a freshwater alga ( Chlorella sp.), a bacterium ( Erwinnia sp.) and a cladoceran ( Ceriodaphnia cf. dubia) exposed to copper in synthetic and natural freshwaters of varying hardness (44–375 mg CaCO 3/l), with constant alkalinity, pH and dissolved organic carbon concentration, demonstrated negligible hardness effects in the pH range 6.1–7.8. Therefore, the use of a generic hardness-correction algorithm, developed as part of national water quality guidelines for protecting freshwater biota, is not recommended for assessing the toxicity of copper to these, and other, sensitive freshwater species. Use of the algorithm for these sensitive species will be underprotective because the calculated concentrations of copper in water that cause a toxic effect will be higher.

Effect of sublethal concentrations of copper on the growth performance of Oreochromis niloticus

Summary The study evaluated the effect of different sublethal concentrations of copper in water (0, 0.15, 0.3 and 0.5 p.p.m.) on the behavioural response, growth performance, and whole body and liver composition of Oreochromis niloticus. Hyperactivity and reduced exploratory behaviour were observed when fishes were subjected to different levels of copper in water as compared with the control. Fish refused to accept the feed immediately after exposure and only began taking it up after about 4–5 h as compared with the control. Weight gain, specific growth rate and condition factor (k) decreased significantly (P < 0.05) as compared with the control; this decrease was linearly correlated with the increase of copper concentration in water. Exposure of the fish to different copper concentrations in water significantly (P < 0.05) reduced their feed consumption as compared with the control. Values for the feed conversion ratio increased (P < 0.05) whereas the protein efficiency ratio and net protein retention values decreased (P < 0.05) with the copper level increase in water. The hepatosomatic index increased with the copper concentration increase in water. Body moisture and ash contents were the highest (P < 0.05) whereas the fat and gross energy contents were the lowest (P < 0.05) in fish reared in water containing 0.5 p.p.m. of copper as compared with others. No significant (P < 0.05) differences were observed in the whole body crude protein content of fish exposed to different concentrations of copper as compared with the control. Liver moisture and ash contents increased (P < 0.05) whereas the crude protein, fat, nitrogen free extract and gross energy contents decreased (P < 0.05) when the fish were exposed to different concentrations of copper as compared with the control. The liver glycogen level decreased whereas the copper level in the whole body and liver increased significantly (P < 0.05) with the copper concentration increase in water.

Low Dietary Copper Increases Fecal Free Radical Production, Fecal Water Alkaline Phosphatase Activity and Cytotoxicity in Healthy Men

One possible dietary factor that may increase susceptibility to colon cancer is inadequate copper intake. The objective of this study was to investigate the effects of low and adequate copper intakes on copper nutriture and putative risk factors for colon cancer susceptibility in healthy men. Seventeen healthy free-living nonsmoking men aged 21-52 y completed a 13-wk controlled feeding study in a randomized crossover design. The basal diet contained 0.59 mg Cu/13.65 MJ. After a 1-wk equilibration period in which the men consumed the basal diet supplemented with 1.0 mg Cu/d, they were randomly assigned to receive either the basal diet or the basal diet supplemented with 2 mg Cu/d for 6 wk. After the first dietary period, the men immediately began to consume the other level of Cu for the last 6 wk. They collected their feces during the equilibration period and during the last 2 wk of the two dietary periods for free radical and fecal water analysis. Low dietary copper significantly (P < 0.01) increased fecal free radical production and fecal water alkaline phosphatase activity. Low dietary copper significantly (P < 0.0001) decreased fecal water copper concentrations but did not affect fecal water volume, pH, iron or zinc concentrations. In contrast to the fecal analysis, hematological indicators of copper status were not significantly affected by the dietary treatments. These results suggest that low dietary copper adversely affects fecal free radical production and fecal water alkaline phosphatase activity, which are putative risk factors for colon cancer.

The influence of mineral solubility and soil solution concentration on the toxicity of copper to Eisenia fetida Savigny : The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

The OECD 14 d earthworm acute toxicity test was used to determine the toxicity of copper added as copper nitrate (Cu(NO3)2), copper sulphate (CuSO4) and malachite (Cu2(OH)2(CO3)) to Eisenia fetida Savigny. Cu(NO3)2, and CuSO4 were applied in both an aqueous (aq) and solid (s) form, Cu2(OH)2(CO3) was added as a solid. Soil solution was extracted by centrifugation, and analysed for copper. Two extractants [0.01 M CaCl2 and 0.005 M diethylenetriminpentaacetic acid (DTPA)] were used as a proxy of the bioavailable copper fraction in the soil. For bulk soil copper content the calculated copper toxicity decreased in the order nitrate > sulphide > carbonate, the same order as decreasing solubility of the metal compounds. For Cu(NO3)2 and CuSO4, the LC50s obtained were not significantly different when the compound was added in solution or solid form. There was a significant correlation between the soil solution copper concentration and the percentage earthworm mortality for all 3 copper compounds (P ≤ 0.05) indicating that the soil pore water copper concentration is important for determining copper availability and toxicity to E. fetida. In soil avoidance tests the earthworms avoided the soils treated with Cu(NO3)2 (aq and s) and CuSO4 (aq and s), at all concentrations used (110–8750 μg Cu g–1, and 600–8750 μg Cu g–1 respectively). In soils treated with Cu2(OH2)CO3, avoidance behaviour was exhibited at all concentrations ≥3500 μg Cu g–1. There was no significant correlation between the copper extracted by either CaCl2 or DTPA and percentage mortality. These two extractants are therefore not useful indicators of copper availability and toxicity to E. fetida.

The influence of mineral solubility and soil solution concentration on the toxicity of copper to Eisenia fetida SavignyThe 7th international symposium on earthworm ecology · Cardiff · Wales · 2002

Summary The OECD 14 d earthworm acute toxicity test was used to determine the toxicity of copper added as copper nitrate (Cu(NO3)2), copper sulphate (CuSO4) and malachite (Cu2(OH)2(CO3)) to Eisenia fetida Savigny. Cu(NO3)2, and CuSO4 were applied in both an aqueous (aq) and solid (s) form, Cu2(OH)2(CO3) was added as a solid. Soil solution was extracted by centrifugation, and analysed for copper. Two extractants [0.01 M CaCl2 and 0.005 M diethylenetriminpentaacetic acid (DTPA)] were used as a proxy of the bioavailable copper fraction in the soil. For bulk soil copper content the calculated copper toxicity decreased in the order nitrate > sulphide > carbonate, the same order as decreasing solubility of the metal compounds. For Cu(NO3)2 and CuSO4, the LC50s obtained were not significantly different when the compound was added in solution or solid form. There was a significant correlation between the soil solution copper concentration and the percentage earthworm mortality for all 3 copper compounds (P ≤ 0.05) indicating that the soil pore water copper concentration is important for determining copper availability and toxicity to E. fetida. In soil avoidance tests the earthworms avoided the soils treated with Cu(NO3)2 (aq and s) and CuSO4 (aq and s), at all concentrations used (110–8750 μg Cu g–1, and 600–8750 μg Cu g–1 respectively). In soils treated with Cu2(OH2)CO3, avoidance behaviour was exhibited at all concentrations ≥3500 μg Cu g–1. There was no significant correlation between the copper extracted by either CaCl2 or DTPA and percentage mortality. These two extractants are therefore not useful indicators of copper availability and toxicity to E. fetida.

Gill Cellular Changes Induced by Copper Exposure in the South American Tropical Freshwater Fish Prochilodus scrofa

The cellular changes in gill tissue induced by exposure to copper were studied in the tropical freshwater fish Prochilodus scrofa, with emphasis on chloride and pavement cells. Damage to gills included epithelial changes such as lifting, rupture, peeling of lamellar epithelium, lamellar fusion, hyperplasia, and cellular hypertrophy. Cell degeneration by necrosis and apoptosis was intense in fish exposed to 25 and 29 μg Cu L−1. Pavement cells showed microridge reduction on their surface. Chloride cells proliferated in the lamellar epithelia close to the onset of the lamellae. However, no changes in total chloride cell density in contact with the water were observed. The chloride cell apical area of fish exposed to copper increased, but only fish exposed to 25 μg Cu L−1 showed significant increase in the chloride cell fractional area. At this water copper concentration, almost 60% of the chloride cells were apoptotic. Necrotic chloride cells increased with copper in water, reaching 70% in fish exposed to 29 μg Cu L−1 (=LC50 calculated for this species). Pavement and chloride cell proliferation and hypertrophy on lamellar epithelia increased the thickness of the water–blood barrier. Our findings suggest severe impairment of ion regulation and gas transfer of fish exposed to copper.

Laboratory and field evaluation of metallic copper on Aedes albopictus (Diptera: Culicidae) larval development.

Laboratory bioassays and field trials were carried out to study the effect of metallic copper on the development of Aedes albopictus (Skuse). Multiwire electric cable was used as a source of metallic copper. Three different doses were used in laboratory tests (5, 10, and 20 g/liter) and two in field tests (20 and 40 g/liter). In the laboratory, 10 g/liter induced high mortality and a lack of development in Ae. albopictus larvae and doses of 20 g/liter completely inhibited development. Larval mortality was higher in earlier instars than in third through fourth instars and pupae. No effects were reported on egg hatching. Copper ion concentration in water increased up to 574 ppb for 5 g/liter dose, 710 ppb for 10 g/liter dose, and 1,210 ppb for 20 g/liter dose, within week 6. The increasing concentration of copper in water was correlated positively with the decreasing production of adults. Copper ions concentration < 500 ppb did not or only slightly affected larval development and mortality of Ae. albopictus in laboratory tests. Copper concentrations between 500 and 1,000 ppb delayed larval development and caused high mortality. Copper concentrations > 1,000 ppb inhibited larval development completely killing all the larvae. This last result has been achieved by the use of a 20 g/liter dose of metallic copper in water. Copper also affected adult weight. In field trials, 20 g/liter reduced the number of larvae in treated pots by 90%, and 40 g/liter completely prevented oviposition. Moreover, the persistence of the toxic action of metallic copper in the field lasted for several months.