Biological responses in edible crab, <Emphasis Type="Italic">Callinectes amnicola</Emphasis> that could serve as markers of heavy metals pollution

Responses of lagoon crab, Callinectes amnicola were explored as useful biological markers of heavy metal pollution. The toxicity level of the metals based on the 96-h LC50 values showed that copper with LC50 value of 0.018 mM was found to be two times more toxic than Lead (0.041 mM) against the lagoon crab, C. amnicola. The exposure of the lagoon crab to sublethal concentrations (1/100th and 1/10th of 96-h LC50 values) of Cu and Pb compound, respectively, resulted in the bioaccumulation of the test metals to varying degrees in the selected organs that were dependent on the type of metal and concentration of metal compound in the test media. The degree of metal (Cu and Pb) accumulation was generally in the following order: gills > muscle > heptopancrease. Exposure of the crabs to sublethal concentrations of the metals also caused pathological changes such as the disruption of the gill filaments and degeneration of glandular cells with multifocal areas of calcification in the hepatopancreas. A reduction in the weight of the exposed animals over a 14-day period of observation was also recorded. The significance of these results and the usefulness of the biological endpoints in monitoring programmes aimed at establishing the total environmental level of heavy metals in aquatic ecosystems were discussed.     

Estimation of “environmentally sensitive” dispersal ratios for chemical dispersants used in crude oil spill control

The toxicities of two dispersants (Biosolve and OSD 9460), Forcados light crude oil and their mixtures based on ratios 6:1, 9:1, and 12:1 (v/v) were evaluated against the juvenile stage of African catfish, Clarias gariepinus, in laboratory bioassays. On the basis of the derived toxicity indices, Biosolve (96-h LC₅₀ = 0.211 μl/l) was found to be about 27,284 times more toxic than crude oil (96-h LC₅₀ = 5.757 ml/l) and 6,450 times more toxic than OSD 9460 (96-h LC₅₀ = 1.361 ml/l). OSD 9460 was also found to be four times more toxic than crude oil when acting alone against C. gariepinus. Toxicity evaluations of the mixtures of crude oil/dispersants mixtures varied, depending largely upon the proportion of addition of the mixture components. The interactions between mixture of crude oil and Biosolve at the test ratios of 6:1, 9:1, and 12:1 were found to conform with the model of synergism (SR = 7,655, 14,876, and 8,792, respectively), and the mixtures were therefore more toxic than the crude oil acting singly. Similarly, the interactions between mixture of crude oil and OSD 9460 at the test ratios of 6:1 and 9:1 also conformed to the model of synergism (SR = 2.2 and 1.84, respectively). Interactions between the dispersant OSD 9460 and the crude oil at test ratio 12:1, however, conformed to the model of antagonism (SR = 0.84), indicating that the mixture was less toxic than crude oil acting alone. The results of the emulsification potential of OSD 9460 and Biosolve [measured in terms of optical transmittance (%)] prepared at the dispersal ratios 6:1, 9:1, and 12:1 revealed that the dispersal ratio of 6:1 achieved the highest emulsification of the crude oil with optical transmittance value of 4% and 6%, respectively. Estimation of an “environmentally sensitive” dispersal ratio for OSD 9460 and Biosolve revealed the optimum dispersal ratio for OSD 9460 range between ratios 7.5:1 and 9:1, while for Biosolve such an optimum dispersal ratio was indeterminate within the range of test dispersal ratios. The implications of these results in setting manufacturer’s and regulatory dispersal ratios for chemical dispersants used for oil spill control were discussed.     

Use of toxicity identification evaluation techniques to identify dredged material disposal options: A proposed approach

It is common to use the results of various solid-phase and aqueous-fraction toxicity tests as part of the decision-making process for selecting disposal options for dredged sediments. The mere presence of toxicity, however, does not provide a logical basis for selecting economical, environmentally protective disposal techniques. To achieve this, it is necessary to be able to identify specific compounds responsible for sediment toxicity. Toxicity identification evaluation (TIE) procedures, originally developed for complex effluents, represent a useful approach for identifying acutely toxic compounds in dredged materials. Herein we present a conceptual overview for TIE use in part of the decision-making framework for selecting dredged material disposal options; included are discussions concerning appropriate test fractions and species for TIE analyses, and specific TIE manipulations useful for ascertaining whether toxicity is due to any of a number of common sediment contaminants including ammonia, hydrogen sulfide, metals, or nonpolar organics.     

Assessing potential bioavailability of metals in sediments: A proposed approach

Due to anthropogenic inputs, elevated concentrations of metals frequently occur in aquatic sediments. In order to make defensible estimates of the potential risk of metals in sediments and/or develop sediment quality criteria for metals, it is essential to identify that fraction of the total metal in the sediments that is bioavailable. Studies with a variety of benthic invertebrates indicate that interstitial (pore) water concentrations of metals correspond very well with the bioavailability of metals in test sediments. Many factors may influence pore water concentrations of metals; however, in anaerobic sediments a key phase controlling partitioning of several cationic metals (cadmium, nickel, lead, zinc, copper) into pore water is acid volatile sulfide (AVS). In this paper, we present an overview of the technical basis for predicting bioavailability of cationic metals to benthic organisms based on pore water metal concentrations and metal-AVS relationships. Included are discussions of the advantages and limitations of metal bioavailability predictions based on these parameters, relative both to site-specific assessments and the development of sediment quality criteria.     

Dissolution kinetics of heavy metals in Dutch carbonate- and sulfide-rich freshwater sediments

In two sulfide-rich freshwater sediments from the Biesbosch and Kromme Rijn River in the Netherlands differing in carbonate content and acid volatile sulfide (AVS) content, metal and sulfide dissolution kinetics were studied at different acid concentrations by varying both the procedure of acid addition and the extraction time. The establishment of equilibrium was monitored by measuring the pH in time, which reached a near constant value. The equilibrium pH was reached quickly when large amounts of acid were added and slowly when small amounts of acid were added. This observation was confirmed by the yield of extracted metals after either a 45-min or 24-h extraction over a pH range from 0 to 5. The pH factor seemed to be of more influence than time for the dissolution of metals. The amount of extracted metals was highly dependent on the metal itself due to its physico-chemical behavior. Although the sediments studied varied in carbonate content, acid volatile sulfide (AVS), and total metal content, the extracted fraction of metals compared with their total content in the sediment was similar for most metals. Finally, the AVS content as well as the ratio of simultaneously extracted metals (SEM; sum of Cd, Cu, Ni, Pb, and Zn) to AVS decreased with increasing pH. Because the SEM to AVS ratio may be used to set environmental quality criteria for the sediment compartment, this observation is of significance.     

Leaching characteristics of copper flotation waste before and after vitrification

Copper flotation waste from copper production using a pyrometallurgical process contains toxic metals such as Cu, Zn, Co and Pb. Because of the presence of trace amounts of these highly toxic metals, copper flotation waste contributes to environmental pollution. In this study, the leaching characteristics of copper flotation waste from the Black Sea Copper Works in Samsun, Turkey have been investigated before and after vitrification. Samples obtained from the factory were subjected to toxicity tests such as the extraction procedure toxicity test (EP Tox), the toxicity characteristic leaching procedure (TCLP) and the "method A" extraction procedure of the American Society of Testing and Materials. The leaching tests showed that the content of some elements in the waste before vitrification exceed the regulatory limits and cannot be disposed of in the present form. Therefore, a stabilization or inertization treatment is necessary prior to disposal. Vitrification was found to stabilize heavy metals in the copper flotation waste successfully and leaching of these metals was largely reduced. Therefore, vitrification can be an acceptable method for disposal of copper flotation waste.     

Effects of Metal Mining and Milling on Boundary Waters of Yellowstone National Park, USA

/ Aquatic resources in Soda Butte Creek within Yellowstone National Park, USA, continue to be threatened by heavy metals from historical mining and milling activities that occurred upstream of the park's boundary. This includes the residue of gold, silver, and copper ore mining and processing in the early 1900s near Cooke City, Montana, just downstream of the creek's headwaters. Toxicity tests, using surrogate test species, and analyses of metals in water, sediments, and macroinvertebrate tissue were conducted from 1993 to 1995. Chronic toxicity to test species was greater in the spring than the fall and metal concentrations were elevated in the spring with copper exceeding water quality criteria in 1995. Tests with amphipods using pore water and whole sediment from the creek and copper concentrations in the tissue of macroinvertebrates and fish also suggest that copper is the metal of concern in the watershed. In order to understand current conditions in Soda Butte Creek, heavy metals, especially copper, must be considered important factors in the aquatic and riparian ecosystems within and along the creek extending into Yellowstone National Park.KEY WORDS: Mining; Metals; Toxicity; Biomonitoring; Copper; Yellowstone National Park     

MODELING METALS TRANSPORT AND SEDIMENT/WATER INTERACTIONS IN A MINING IMPACTED MOUNTAIN STREAM1

ABSTRACT: The U.S. Environmental Protection Agency (USEPA) Water Quality Analysis Simulation Program (WASP5) was used to model the transport and sediment/water interactions of metals under low flow, steady state conditions in Tenmile Creek, a mountain stream supplying drinking water to the City of Helena, Montana, impacted by numerous abandoned hard rock mines. The model was calibrated for base flow using data collected by USEPA and validated using data from the U.S. Geological Survey (USGS) for higher flows. It was used to assess metals loadings and losses, exceedances of Montana State water quality standards, metals interactions in stream water and bed sediment, uncertainty in fate and transport processes and model parameters, and effectiveness of remedial alternatives that include leaving contaminated sediment in the stream. Results indicated that during base flow, adits and point sources contribute significant metals loadings to the stream, but that shallow ground water and bed sediment also contribute metals in some key locations. Losses from the water column occur in some areas, primarily due to adsorption and precipitation onto bed sediments. Some uncertainty exists in the metal partition coefficients associated with sediment, significance of precipitation reactions, and in the specific locations of unidentified sources and losses of metals. Standards exceedances are widespread throughout the stream, but the model showed that remediation of point sources and mine waste near water courses can help improve water quality. Model results also indicate, however, that alteration of the water supply scheme and increasing base flow will probably be required to meet all water quality standards.     

Heavy metal content and distribution in surface sediments of the Seyhan River, Turkey

Chemical fractionation of seven heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) was studied using a modified three-step sequential procedure to assess their impacts in the sediments of the Seyhan River, Turkey. Samples were collected from six representative stations in two campaigns in October 2009 and June 2010, which correspond to the wet and dry seasons, respectively. The total metal concentrations in the sediments demonstrated different distribution patterns at the various stations. Cadmium was the only metal that was below detection at all stations during both sampling periods. Metal fractionation showed that, except for Mn and Pb, the majority of metals were found in the residual fraction regardless of sampling time, indicating that these metals were strongly bound to the sediments. The potential mobility of the metals (non-residual fractions) is reflected in the following ranking: Pb > Mn > Zn > Cu > Ni > Cr in October 2009 and Mn > Pb > Zn > Cu > Ni > Cr in June 2010. The second highest proportion of metals was bound to organic matter/sulfides, originating primarily from anthropogenic activities. Non-residual metal fractions for all stations were highest in June 2010, which may be linked to higher organic matter concentrations in the sediment samples with 1.40% and 15.1% in October 2009 and June 2010, respectively. Potential sediment toxicity was evaluated using the Risk Assessment Code (RAC). Based on RAC classification, Cd and Cr pose no risk, Cu and Ni pose low risk, Pb and Zn were classified as medium risk metals, while the environmental risk from Mn was high. In addition, based on the sediment quality guidelines (SQG), the Seyhan River can be classified as a river with no, to moderate, toxicological risks, based on total metal concentrations.     

Risk-Based Analysis of Environmental Monitoring Data: Application to Heavy Metals in North Carolina Surface Waters

The state of North Carolina's Department of Environment and Natural Resources (NCDENR) conducts routine water quality monitoring throughout the state to assess the health of aquatic systems. The current study reports the results of a retrospective (1990–2000) ecological risk assessment of six heavy metals (arsenic, cadmium, copper, lead, mercury, and zinc) in 17 North Carolina basins that was conducted to estimate the risk of heavy metal toxicity to freshwater organisms and assess the sufficiency of NCDENR's monitoring data to identify water-quality-related ecological threats. Acute and chronic ecotoxicological thresholds (ETs) were calculated for each metal based upon the 10th percentile of species sensitivity distributions and were normalized for water hardness. Statewide probabilities (expressed as percentages) of a random sample exceeding acute or chronic ETs among the six metals ranged from 0.01% to 12.19% and 0.76% to 21.21%, respectively, with copper having the highest and arsenic and mercury the lowest risk. Basin-specific probabilities varied significantly depending upon water hardness and presumably watershed development. Although the majority of specific sites where data were collected were at low risk for metal toxicity, some specific sites had a high probability of toxic events associated with one or more metals. Analytical detection limits for metals were frequently higher than estimated chronic ET, limiting the ability to assess the risk of chronic toxicity in soft-water basins. Results suggest risk-based criteria may be useful for assessing and validating the sufficiency of monitoring programs and prioritizing management goals.     

Assessing the application of an additive model to estimate toxicity of a complex effluent

A number of industries monitor levels of chemicals in their effluent, but few have undertaken prolonged biological monitoring of this wastewater. The focus of the present study was to determine whether past chemical data for effluent from a lead smelter could be used to estimate its past toxicity. Since the interactive effects of metals in effluents are often assumed to be additive, it was hypothesized that an additive model, 100/[sigma(metal concentration in effluent/EC50 for individual metal)], could be used to generate an EC50 from chemical data (where EC50 is the concentration of test material that affects 50% of the test organisms). To test the approach, a larval development toxicity test with the marine polychaete, Galeolaria caespitosa, was used to test 26 separate samples of effluent from a lead smelter, generating empirical EC50 values. EC50 values for each individual metal in the effluent were also generated using the larval development toxicity test. The concentrations of trace metals in each effluent sample were determined and, using the additive model, EC50 values were calculated. For the majority of effluent samples tested, the additive model underestimated toxicity, suggesting the presence of additional unidentified contaminants in the effluent samples. Additionally, a nonlinear rather than linear regression curve was found to best describe the relationship between the model and empirically derived EC50 values. This relationship was then used to estimate past trends in toxicity of the smelter effluent. Forty-eight percent of the variability in measured toxicity was explained by the model, with the model underestimating toxicity in the majority of samples.     

Building contraventions and incidence of flood in the Lagos Metropolis,Nigeria

Frequent floods have led to loss of lives and destruction of property in both coastal and landlocked cities across the globe, particularly where floodplains have been developed without recourse to space standards. This paper investigated the contributions of contravention of building codes to flooding in flood-prone areas in the Lagos metropolis. Global Positioning Systems (GPSs) were used to determine the location and elevation above sea level of 1,025 buildings situated in 211 streets that were prone to flooding. The distance of buildings from drainage channels/the lagoon was determined in ArcGIS 10.2 environment. Findings revealed that building code contravention contributed significantly to flooding (r = 0.926). About 63.5% and 63.3% of sampled buildings contravened building-plot ratio and statutory setbacks from drainage channels/the lagoon, respectively. Proactive urban planning, strict enforcement of building codes and development control regulations are required to reduce flooding and its consequences in cities of developing nations where flooding has become an annual occurrence.     

Phytoextraction of toxic metals: a review of biological mechanisms

Remediation of sites contaminated with toxic metals is particularly challenging. Unlike organic compounds, metals cannot be degraded, and the cleanup usually requires their removal. However, this energy-intensive approach can be prohibitively expensive. In addition, the metal removing process often employs stringent physicochemical agents which can dramatically inhibit soil fertility with subsequent negative impacts on the ecosystem. Phytoremediation has been proposed as a cost-effective, environmental-friendly alternative technology. A great deal of research indicates that plants have the genetic potential to remove many toxic metals from the soil. Despite this potential, phytoremediation is yet to become a commercially available technology. Progress in the field is hindered by a lack of understanding of complex interactions in the rhizosphere and plant-based mechanisms which allow metal translocation and accumulation in plants. In this paper, four research areas relevant to metal phytoextraction from contaminated soil are reviewed. The review concludes with an assessment of the current status of technology deployment and suggestions for future phytoremediation research.     

生活垃圾焚烧中重金属行为的研究进展

垃圾中的金属以氧化物、氮化物、碳化物及其它形态转移到焚烧产物如烟气、飞灰和底灰中，需严格控制焚烧过程中重金属的排放，故清楚了解金属在焚烧中的行为是很必要的。经研究发现，飞灰中重金属含量远远大于底灰中的含量，因此以垃圾焚烧飞灰中重金属的稳定化处理为目标，分析了目前国内外处理垃圾焚烧飞灰的方法和重金属在各种影响因素下的行为，并进行了比较，为飞灰的无害化和资源化处理提供参考。     

滇池沉积物重金属污染状况评估

本文通过多年滇池底泥的采样监测数据,采用地积累指数法和对数衰减模型评估滇池的底泥质量状况,希望摸清底泥中重金属污染状况,并分析评价其对水生生物的风险,为底泥疏浚、截污护岸的滇池治理工程提供一定的科学依据。研究表明:以地积累指数法评价,(1)滇池监测断面底泥质量呈现轻度污染,镉出现一定程度富集,汞在个别监测断面也出现富集情况;(2)6种重金属污染排序为镉>汞>铅>铜>铬>砷;(3)从监测断面来看,海口西污染程度较重,滇池南底泥质量较好。采用对数衰减模型评价,(1)滇池监测断面沉积物重金属污染存在潜在生物风险,应引起重视;(2)从产生可以观察到毒性效果的可能性大小看,6种重金属潜在危害可能性排序为砷>铅>铜>铬>镉>汞;(3)从监测断面来看,白鱼口和观音山中潜在危害可能性大。从富集污染程度分析,海口西监测断面的底泥污染最重,可考虑在海口西监测断面附近进行一定的底泥疏浚工程。从而达到治标治本的目的。滇池监测断面沉积物重金属污染存在潜在生物风险,应引起重视,但在可控范围。     

ENVIRONMENTAL IMPACT ASSESSMENT OF TAILINGS DISPERSAL FROM A URANIUM MINE USING TOXICITY TESTING PROTOCOLS1

ABSTRACT: Toxicity testing is a means of establishing the environmental risk of a uranium tailings release. It is valuable in designing tailings containment structures because it assists in setting acceptable levels of risk for the design. This paper presents details of toxicity tests of the tailings from Ranger Uranium Mine, Northern Territory, Australia. The results suggest that the non-radiological toxicity of the tailings is low. The environmental risk of a tailings release is more likely to be related to the physical impacts of the tailings, including infilling of billabongs and changes in the sedimentology of riparian ecosystems rather than their biogeochemical impact. Two major results were: (1) water from treatment with washed tailing fines were not toxic to Hydra viridissima, and (2) mixtures of washed tailings fines and natural floodplain sediment (overlying water or elutriates) were not toxic to Hydra viridissima or Moinodaphnia macleayi.     

Evaluation of best management practice products in preventing discharge of metals: a laboratory evaluation

Heavy metal accumulation in soil poses serious environmental and health risks, as metals are carried with eroded soils. In this study, 17 different soil erosion and sediment control products were investigated for their effectiveness in controlling transport of particulate heavy metals (Cu, Zn, Pb, Cd). Among the treatments investigated, wood mulch and tackifiers were found to be the most effective in reducing total suspended solids (TSS) and total heavy metal losses. They reduced TSS to an undetectable level during short-term simulation tests. Paper mulch was the only treatment that had no significant reduction in both total metal loss and TSS. Fiber rolls, silt fences, and gravel bags were effective in reducing sediment loss. Although the netting/blanket treatments were not effective in reducing total metal discharge, they significantly reduced sediment loss compared with the control.     

Application of sediment quality guidelines in the assessment and management of contaminated surficial sediments in Port Jackson (Sydney Harbour), Australia

Sediments in the Port Jackson estuary are polluted by a wide range of toxicants and concentrations are among the highest reported for any major harbor in the world. Sediment quality guidelines (SQGs), developed by the National Oceanographic and Atmospheric Administration (NOAA) in the United States are used to estimate possible adverse biological effects of sedimentary contaminants in Port Jackson to benthic animals. The NOAA guidelines indicate that Pb, Zn, DDD, and DDE are the most likely contaminants to cause adverse biological effects in Port Jackson. On an individual chemical basis, the detrimental effects due to these toxicants may occur over extensive areas of the harbor, i.e., about 40%, 30%, 15% and 50%, respectively. The NOAA SQGs can also be used to estimate the probability of sediment toxicity for contaminant mixtures by determining the number of contaminants exceeding an upper guideline value (effects range medium, or ERM), which predicts probable adverse biological effects. The exceedence approach is used in the current study to estimate the probability of sediment toxicity and to prioritize the harbour in terms of possible adverse effects on sediment-dwelling animals. Approximately 1% of the harbor is mantled with sediment containing more than ten contaminants exceeding their respective ERM concentrations and, based on NOAA data, these sediments have an 80% probability of being toxic. Sediment with six to ten contaminants exceeding their respective ERM guidelines extend over approximately 4% of the harbor and have a 57% probability of toxicity. These areas are located in the landward reaches of embayments in the upper and central harbor in proximity to the most industrialised and urbanized part of the catchment. Sediment in a further 17% of the harbor has between one and five exceedences and has a 32% probability of being toxic. The application of SQGs developed by NOAA has not been tested outside North America, and the validity of using them in Port Jackson has yet to be demonstrated. The screening approach adopted here is to use SQGs to identify contaminants of concern and to determine areas of environmental risk. The practical application and management implications of the results of this investigation are discussed.     

Application of Sediment Quality Guidelines in the Assessment and Management of Contaminated Surficial Sediments in Port Jackson (Sydney Harbour), Australia

Sediments in the Port Jackson estuary are polluted by a wide range of toxicants and concentrations are among the highest reported for any major harbor in the world. Sediment quality guidelines (SQGs), developed by the National Oceanographic and Atmospheric Administration (NOAA) in the United States are used to estimate possible adverse biological effects of sedimentary contaminants in Port Jackson to benthic animals. The NOAA guidelines indicate that Pb, Zn, DDD, and DDE are the most likely contaminants to cause adverse biological effects in Port Jackson. On an individual chemical basis, the detrimental effects due to these toxicants may occur over extensive areas of the harbor, i.e., about 40%, 30%, 15% and 50%, respectively. The NOAA SQGs can also be used to estimate the probability of sediment toxicity for contaminant mixtures by determining the number of contaminants exceeding an upper guideline value (effects range medium, or ERM), which predicts probable adverse biological effects. The exceedence approach is used in the current study to estimate the probability of sediment toxicity and to prioritize the harbour in terms of possible adverse effects on sediment-dwelling animals. Approximately 1% of the harbor is mantled with sediment containing more than ten contaminants exceeding their respective ERM concentrations and, based on NOAA data, these sediments have an 80% probability of being toxic. Sediment with six to ten contaminants exceeding their respective ERM guidelines extend over approximately 4% of the harbor and have a 57% probability of toxicity. These areas are located in the landward reaches of embayments in the upper and central harbor in proximity to the most industrialised and urbanized part of the catchment. Sediment in a further 17% of the harbor has between one and five exceedences and has a 32% probability of being toxic. The application of SQGs developed by NOAA has not been tested outside North America, and the validity of using them in Port Jackson has yet to be demonstrated. The screening approach adopted here is to use SQGs to identify contaminants of concern and to determine areas of environmental risk. The practical application and management implications of the results of this investigation are discussed.     

Leaching characteristics of solid wastes from thermal power plants of western Turkey and comparison of toxicity methodologies

Use of lignite in power generation has led to increasing environmental problems associated not only with gaseous emissions, but also with the disposal of ash residues. In particular, use of low quality coals with high ash content results in huge quantities of both fly and bottom ashes to be disposed of. A main problem related to coal ash disposal is the heavy metal content of the residue. In this regard, experimental results of numerous studies indicate that toxic trace metals may leach when fly and bottom ashes are in contact with water. In this study, fly and bottom ash samples obtained from thermal power plants, namely Yenikoy, Kemerkoy and Yatagan, located at the southwestern coast of Turkey, were subjected to toxicity tests such as the extraction (EP) and toxicity characteristic leaching (TCLP) procedures of the US Environmental Protection Agency (USEPA) and the so-called 'Method A' extraction procedure of the American Society of Testing and Material (ASTM). The geochemical composition of ash samples showed variations depending on the coal burned in the plants. Furthermore, the EP, TCLP and ASTM toxicity tests showed variations such that the ash samples were classified as 'toxic waste' based on EP and TCLP results whereas they were classified as 'non-toxic' based on ASTM results, indicating test results are pH dependent. When the extraction results were compared with the chemical composition of water samples obtained in the vicinity of the thermal power plants, it was found that the results obtained using the ASTM procedure cannot be used to predict subsurface contamination whereas the EP and TCLP procedures can be used.