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Archives of Environmental Contamination and Toxicology (v.56, #4)

Observations on the Estrogenic Activity and Concentration of 17β-Estradiol in the Discharges of 12 Wastewater Treatment Plants in Southern Australia by C. Mispagel; G. Allinson; M. Allinson; F. Shiraishi; M. Nishikawa; M. R. Moore (pp. 631-637).

There is very little information on the overall level of estrogenic activity, or concentrations of specific hormonal compounds in wastewater treatment plant (WWTP) discharges in Australia, compared with Europe, Japan, and North America. To partly address this, in 2004, water samples were collected as “grab” or “spot” samples from 12 WWTP facilities across southern Victoria at the point at which effluent enters the environment, either as recycled water or direct discharge to the receiving water. The WWTPs were of a variety of treatment types and served a diverse range of rural and regional municipalities. For instance, of the 12 WWTPs, 3 served municipalities with populations greater than 100,000, 4 with populations between 20,000 and 100,000, and 5 with populations less than 5,000. The principal treatment process in six was an activated sludge system, and three were trickle-filter-based systems. The remaining plants fall into a “miscellaneous” category, each plant having a mixture of treatment processes within the overall systems. The estrogenic activity and 17β-estradiol concentrations of the samples were assessed using a yeast-based, in vitro reporter gene assay and enzyme-linked immunosorbant assays, respectively. Most of the effluents showed estrogenic activity in the assays (hER, no response: 7.9 ng/L EEQ; mER, no response: 44.5 ng/L EEQ). There was no correlation between estrogenic response and the results of a concurrent toxicity assay, suggesting that a lack of bioassay response was related to lack of estrogenic compounds, rather than the direct toxic effect of the sample. Estradiol concentrations were for the most part in the range 2–5 ng/L, with one sample at 18 ng/L. Despite the assurance our results might provide (of minimal impact in most cases if there is significant dilution), there is still a need for further extensive on-ground reassurance research to provide data for higher-level risk assessment by industry and government agencies. In particular, more research is warranted to verify the estrogenic activity and to expand the range of specific hormone/metabolites reported in these studies. Moreover, studies are required to determine if the estrogenic activity reported in this and other recent Australian studies is sufficient to induce a physiological effect in exposed aquatic organisms, especially Australian native fish.

Amino Acids as Precursors of Trihalomethane and Haloacetic Acid Formation During Chlorination by H. C. Hong; M. H. Wong; Y. Liang (pp. 638-645).

Twenty amino acids were chlorinated and examined for the formation of trihalomethane (THM) and haloacetic acid (HAA). The amino acids exhibited a high Cl₂ demand (3.4–10 mg Cl₂ mg^–1 C) but low THM formation (<4.19 μg mg⁻¹ C) except for tryptophan and tyrosine (45.8 − 147 μg mg⁻¹ C). Large variation in HAA yield occurred among the amino acids (from not detectable to 106 μg mg⁻¹ C). One group of amino acids, possessing chain structures, exhibited a slow increase in HAA formation (<6.2 μmol mol⁻¹ amino acid or <11.3 μg mg⁻¹ C) as the chlorine demand increased (3.4–8.9 mol Cl₂ mol⁻¹ amino acids). The other group of amino acids, containing ring structures (including tryptophan, tyrosine, histidine, phenylalanine, and proline) and two amino acids with chain structures (aspartic acid and asparagine), showed a fast increase in HAA formation (16–96 μmol mol⁻¹ amino acid or 27–106 μg mg⁻¹ C) with the increase in chlorine demand (5.2–15.9 mol Cl₂ mol⁻¹ amino acid). The ratios of TCAA to DCAA (mol/mol), derived from the amino acids, ranged between 0.01 and 1.10.

A Study of the Degradation of Organophosphorus Pesticides in River Waters and the Identification of Their Degradation Products by Chromatography Coupled with Mass Spectrometry by Xueheng Zhao; Huey-Min Hwang (pp. 646-653).

The degradation of selected organophosphorus pesticides (OPs), i.e., malathion and parathion, in river water, has been studied with solar simulator irradiation. The degradation of OPs and formation of degradation products were determined by chromatography coupled with mass spectrometry analysis. The effect of a photosensitizer, i.e., riboflavin, on the photolysis of OPs in a river-water environment was examined. There was no significant increase in the degradation rate in the presence of the photosensitizer. Degradation products of the OPs were identified with gas chromatography coupled with mass spectrometry (GC-MS) after derivatization by pentafluorobenzyl bromide (PFBB) and with high-performance liquid chromatography-mass spectrometry (HPLC-MS) with electrospray (ESI) or atomospheric pressure chemical ionization (APCI). Malaoxon, paraoxon, 4-nitrophenol, aminoparathion, O,O-dimethylthiophosphoric acid, and O,O-dimethyldithiophosphoric acid, have been separated and identified as the degradation products of malathion and parathion after photolysis in river water. Based on the identified transformation products, a rational degradation pathway in river water for both OPs is proposed. The identities of these products can be used to evaluate the toxic effects of the OPs and their transformation products on natural environments.

Assessment of Water Quality Using Chemometric Tools: A Case Study of River Cooum, South India by L. Giridharan; T. Venugopal; M. Jayaprakash (pp. 654-669).

Multivariate statistical techniques were applied to identify and assess the quality of river water. Thirty samples were collected from the River Cooum, and basic chemical parameters—such as pH, effect concentration, total dissolved solids, major cations, anions, nutrients, and trace metals—were evaluated. To evaluate chemical variation and seasonal effect on the variables, analysis of variance and box-and-whisker plots were performed. Cluster analysis was applied, and pre-monsoon and post-monsoon major and minor clusters were classified. The relations among the stations were highlighted by cluster analysis, which were represented by dendograms to categorize different levels of contamination. Cluster analysis clearly grouped stations into polluted and unpolluted regions. The analysis classified the upper part of the river course into one unpolluted cluster; the middle and lower parts of the river clustered together, reflecting the presence of pollution. Factor analysis revealed that water quality is strongly affected by anthropogenic activities, rock–water interaction, and saline water intrusion. Seasonal variations in water chemistry were clearly highlighted by both cluster and factor analysis. Factor-score diagrams were used successfully to delineate the stations under study by the contributing factors, and seasonal effects on the sample stations were identified and evaluated. These statistical approaches and results yielded useful information about water quality and can lead to better water resource management.

Desorption and Bioavailability of Spiked Pentabromo Diphenyl Ether and Tetrachlorodibenzo(p)dioxin in Contaminated Sediments by Arto J. Sormunen; Matti T. Leppänen; Jussi V. K. Kukkonen (pp. 670-679).

The relationship between desorption kinetics and bioavailability of sediment-associated 2,2′,4,4,5′ pentabromo diphenyl ether [¹⁴C] (BDE-99) and 2,3,7,8 tetrachlorodibenzo(p)dioxin [³H] (TCDD) was examined in the contaminated sediments. The desorption kinetics were measured in a sediment–water suspension using Tenax^® extraction, and bioaccumulation was examined by exposing Lumbriculus variegatus (Oligochaeta) to BDE-99 and TCDD spiked sediment in a 14-day kinetic study. Both chemicals had a high affinity to the finest particle size fraction (<20 μm) and the large, very slowly desorbing fraction (58–75%). The biota–sediment accumulation factors ranged between 1.9 and 4.4 for BDE-99 and between 1.4 and 2.8 for TCDD. The chemical outflux from the rapidly desorbing fraction and influx into organisms shows the connection between desorption and bioavailability. Despite this, normalization to the rapidly desorbing fraction was unable to reduce differences in bioavailability estimates between the chemicals. Thus, it is evident that chemical extraction in the mixed system (Tenax tubes) does not fully describe the bioavailable fraction that worms face in stagnant sediments in a similar way for all chemicals. However, when all desorbing domains were included in the calculation, the difference between the chemicals disappears. Desorbing fractions were also able to reduce variability in the biota–sediment accumulation factors between the tested sediments when organic carbon-based sediment chemical concentrations were modified by the desorbing fractions.

Accumulation of As, Pb, and Cu Associated with the Recent Sedimentary Processes in the Colorado Delta, South of the United States-Mexico Boundary by L. W. Daesslé; K. C. Lugo-Ibarra; H. J. Tobschall; M. Melo; E. A. Gutiérrez-Galindo; J. García-Hernández; L. G. Álvarez (pp. 680-692).

Sediment cores from the Colorado River (CR) remnant delta were used to assess the changing sedimentation and pollutant deposition processes in response to extensive human manipulation of the river. The cores are formed of alternating layers of clays and silts, with isolated sandy horizons. The clayey units are interpreted as periods of flood flows into this low gradient and meandering estuary after dam construction in the United States. The geochemistry of these sediments is particular because of the association of MnO with CaO rather than with the Fe₂O₃-rich clays. Past pollution of the CR delta by As, and probably also Pb and Cu, is recorded in some cores. Enrichment factors (EFs) >1 for these elements and their statistical association suggest anthropogenic inputs. The most likely sources for these element enrichments (especially As) are the arsenate-based pesticides used intensively in the area during the first half of the 20th century. The transport of these elements from the nearby agricultural lands into the present river reaches appears to have been driven in part by flooding events of the CR. Flushing by river and tide flows appear to be responsible of a lower pollutant deposition in the CR compared to the adjacent Hardy River (HR). Arsenic in the buried clay units of the HR has concentrations above the probable toxic effect level (PEL) for dwelling organisms, with maximum concentrations of 30 μg g⁻¹. Excess ²¹⁰Pb activities (²¹⁰Pb_xs) indicate that fluxes of this unsupported atmospheric isotope were not constant in this estuarine environment. However, the presence of ²¹⁰Pb_xs does indicate that these sediments accumulated during the last ~100 years. Aproximate sediment ages were estimated from the correlation of historic flooding events with the interpretation of the stratigraphic record. They are in fair agreement with the reported onset of DDT metabolites at the bottom of one core.

Sources of Arsenic and Fluoride in Highly Contaminated Soils Causing Groundwater Contamination in Punjab, Pakistan by Abida Farooqi; Harue Masuda; Rehan Siddiqui; Muhammad Naseem (pp. 693-706).

Highly contaminated groundwater, with arsenic (As) and fluoride (F⁻) concentrations of up to 2.4 and 22.8 mg/L, respectively, has been traced to anthropogenic inputs to the soil. In the present study, samples collected from the soil surface and sediments from the most heavily polluted area of Punjab were analyzed to determine the F⁻ and As distribution in the soil. The surface soils mainly comprise permeable aeolian sediment on a Pleistocene terrace and layers of sand and silt on an alluvial flood plain. Although the alluvial sediments contain low levels of F, the terrace soils contain high concentrations of soluble F⁻ (maximum, 16 mg/kg; mean, 4 mg/kg; pH > 8.0). Three anthropogenic sources were identified as fertilizers, combusted coal, and industrial waste, with phosphate fertilizer being the most significance source of F⁻ accumulated in the soil. The mean concentration of As in the surface soil samples was 10.2 mg/kg, with the highest concentration being 35 mg/kg. The presence of high levels of As in the surface soil implies the contribution of air pollutants derived from coal combustion and the use of fertilizers. Intensive mineral weathering under oxidizing conditions produces highly alkaline water that dissolves the F⁻ and As adsorbed on the soil, thus releasing it into the local groundwater.

Spatial Variability of Trace Metals and Inorganic Nutrients in Surface Waters of Todos Santos Bay, México in the Summer of 2005 During a Red Tide Algal Bloom by M. L. Lares; S. G. Marinone; I. Rivera-Duarte; A. Beck; S. Sañudo-Wilhelmy (pp. 707-716).

Dissolved and particulate metals (Ag, Cd, Co, Cu, Ni, and Zn) and nutrients (PO₄, NO₃, and H₄SiO₄) were measured in Todos Santos Bay (TSB) in August 2005. Two sources producing local gradients were identified: one from a dredge discharge area (DDA) and another south of the port and a creek. The average concentrations of dissolved Cd and Zn (1.3 and 15.6 nM, respectively) were higher by one order of magnitude than the surrounding Pacific waters, even during upwelling, and it is attributed to the presence of a widespread and long-lasting red tide coupled with some degree of local pollution. A clear spatial gradient (10 to 6 pM), from coast to offshore, of dissolved Ag was evident, indicating the influence of anthropogenic inputs. The particulate fraction of all metals, except Cu, showed a factor of ~3 decrease in concentrations from the DDA to the interior of the bay. The metal distributions were related to the bay’s circulation by means of a numerical model that shows a basically surface-wind-driven offshore current with subsurface compensation currents toward the coast. Additionally, the model shows strong vertical currents over the DDA. Principal component analysis revealed three possible processes that could be influencing the metal concentrations within TSB: anthropogenic inputs (Cd, Ag, and Co), biological proceses (NO₃, Zn, and Cu), and upwelling and mixing (PO₄, H₄SiO₄, Cd, and Ni). The most striking finding of this study was the extremely high Cd concentrations, which have been only reported in highly contaminated areas. As there was a strong red tide, it is hypothesized that the dinoflagellates are assimilating the Cd, which is rapidly remineralized and being concentrated on the stratified surface layers.

Bioindication of Trace Metals in Brachythecium rutabulum Around a Copper Smelter in Legnica (Southwest Poland): Use of a New Form of Data Presentation in the Form of a Self-Organizing Feature Map by A. Samecka-Cymerman; A. Stankiewicz; K. Kolon; A. J. Kempers (pp. 717-722).

Concentrations of the elements Al, Be, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn were measured in the terrestrial moss Brachythecium rutabulum and the soil on which it grew. Soil and moss plants were sampled at sites situated 1.5, 3, 6, 9 and 15 km to the north, south, east and west of the Legnica copper smelter (SW Poland). The self-organizing feature map (SOFM) or Kohonen network was used to classify the soil and moss samples according to the concentrations of the elements. The self-organizing map yielded distinct groups of B. rutabulum and soil samples, depending on the distance from and direction to the source of pollution. When the map-identified groups of sites with similar soil metal concentrations were combined with the map-identified groups of sites with similar metal concentrations in B. rutabulum, these maps were found to correspond closely. The SOFMs accurately represented the least polluted, moderately polluted and severely polluted sites, reflecting the distribution of metals that is typical of the smelter area, caused by the prevailing westerly and northerly winds.

Relationship Between Proline and Hg²⁺-Induced Oxidative Stress in a Tolerant Rice Mutant by Feijuan Wang; Bin Zeng; Zongxiu Sun; Cheng Zhu (pp. 723-731).

There has been little agreement regarding the mechanism by which proline reduces heavy metal stress. The present work examines the relationship between Hg²⁺-induced oxidative stress and proline accumulation in rice and explores the possible mechanisms through which proline protects against Hg²⁺ stress. The effect of proline on alleviation of Hg²⁺ toxicity was studied by spectrophotography and enzymatic methods. Hg²⁺ induced oxidative stress in rice by increasing lipid peroxidation. Pretreatment of the rice with 2 mM proline for 12 h profoundly alleviated Hg²⁺-induced lipid peroxidation and minimized H₂O₂ accumulation. Proline pretreatment significantly reduced (p < 0.01) the Hg²⁺ content in rice leaves. A comparison of the effects of proline pretreatment on H₂O₂ accumulation by Hg²⁺ and aminotrazole suggested that proline protected cells from Hg²⁺-induced oxidative stress by scavenging reactive oxygen species. The present work demonstrates a protective effect of proline on Hg²⁺ toxicity through detoxifying reactive oxygen species, rather than chelating metal ions or maintaining the water balance under Hg²⁺ stress.

Exposure to Lead and Mercury in Young Larvae Induces More Severe Deficits in Neuronal Survival and Synaptic Function than in Adult Nematodes by X.-J. Xing; Q. Rui; M. Du; D.-Y. Wang (pp. 732-741).

In the present study, we investigated the possibly neurotoxic effects of metal (Pb and Hg) exposure at different developmental stages on neuronal loss in the GABAergic nervous system and synaptic functions in the nematode Caenorhabditis elegans. Our data suggest that neuronal survival in GABAergic neurons and cholinergic transmission were relatively stable during development in nematodes. Moreover, neurodegeneration, as shown by the neuronal loss and dorsal/ventral cord gaps, was more severely induced by Pb and Hg exposure at the L1 through L3 larval stages than at the L4 larval and young-adult stages. Similarly, pre- and postsynaptic functions were more severely impaired by Pb and Hg exposure at the L1 through L3 larval stages than at the L4 larval and young-adult stages. Furthermore, both aldicarb and levamisole resistance were significantly correlated with neuronal loss, dorsal cord gap, and ventral cord gap in Pb- and Hg-exposed nematodes, suggesting that neuronal survival was noticeably correlated with synaptic function in metal-exposed nematodes during development. Therefore, younger (L1–L3) larvae show more sensitivity to neurotoxicity of neuronal survival and synaptic function than L4 larvae and young adult nematodes.

Assessment of the Genotoxicity of Endosulfan in Earthworm and White Clover Plants Using the Comet Assay by Wei Liu; Lu-Sheng Zhu; Jun Wang; Jin-Hua Wang; Hui Xie; Yan Song (pp. 742-746).

Endosulfan, as one of the most widely used organochlorine pesticides in the world, has increased the public concern about genotoxicity in soil ecosystems. The comet assay has been widely used in the fields of genetic toxicology and environmental biomonitoring. In the present study we conducted comet assay of endosulfan in earthworm (Eisenia foetida) and white clover (Trifolium repens L.), which are sensitive organisms suitable for acting as a bioindicator for agricultural ecosystems. Earthworms were exposed to endosulfan concentrations of 0.1, 1.0, and 10.0 mg/kg in the soil. White clover roots were immersed in hydroponic pots containing nutrient solutions of different endosulfan concentrations: 0.1, 1.0, and 10.0 mg/L. Tissues from each treatment were collected on the 7th, 14th, 21st, and 28th days of treatment process. Significant effects (p < 0.01) of both concentrations and times of exposure were observed. And endosulfan induced DNA damage in earthworm and white clover nuclei. The comet assay can be used as a reliable tool for early detection of endosulfan.

Purification and cDNA Cloning of a Cadmium-Binding Metallothionein from the Freshwater Crab Sinopotamon henanense by Wen-Li Ma; Tao Yan; Yongji He; Lan Wang (pp. 747-753).

Metallothioneins (MTs) are cysteine-rich, metal-binding proteins that are useful biomarkers for monitoring pollution by heavy metals. In this report, a novel cadmium (Cd)-binding MT (CdMT) from Sinopotamon henanense was purified using acetone precipitation (50–80%), followed by gel-filtration chromatography and anion-exchange chromatography. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis and time-of-flight mass spectrometry analysis showed that S. henanense CdMT existed as monomer and dimmer forms, with a monomer molecular weight of 6890 Da and a dimmer molecular weight of 13,766 Da. In addition, the full-length cDNA sequence of S. henanense CdMT was prepared from the gill RNA using reverse transcription–polymerase chain reaction and 3′ and 5′ rapid amplification of cDNA ends (RACE) methods. Sequence analyses indicated that the isolated cDNA (633 bp) contains an open reading frame of 177 bp that encodes a protein with 59 amino acids. The deduced amino acid sequence has 18 cysteine residues, implying that S. henanense CdMT binds six equivalents of bivalent metal ions (Cd) as opposed to the seven in its mammalian counterparts. The deduced molecular weight of MT without binding metals is 6218 Da. If six bound Cd atoms are counted, the deduced molecular weight of S. henanense CdMT would be 6892 Da, which is very similar to the molecular weight of the purified protein (6890 Da) determined by time-of-flight mass spectrometry analysis. These confirmed our results of MT purification. These present studies will be helpful to increase the database information of heavy-metal-induced MT in terms of crustaceans.

An Ecological Risk Assessment of the Exposure and Effects of 2,4-D Acid to Rainbow Trout (Onchorhyncus mykiss) by J. F. Fairchild; K. P. Feltz; A. L. Allert; L. C. Sappington; K. J. Nelson; J. A. Valle (pp. 754-760).

Numerous state and federal agencies are increasingly concerned with the rapid expansion of invasive, noxious weeds across the United States. Herbicides are frequently applied as weed control measures in forest and rangeland ecosystems that frequently overlap with critical habitats of threatened and endangered fish species. However, there is little published chronic toxicity data for herbicides and fish that can be used to assess ecological risk of herbicides in aquatic environments. We conducted 96-h flowthrough acute and 30-day chronic toxicity studies with swim-up larvae and juvenile rainbow trout (Onchorhyncus mykiss) exposed to the free acid form of 2,4-D. Juvenile rainbow trout were acutely sensitive to 2,4-D acid equivalent at 494 mg/L (95% confidence interval [CI] 334–668 mg/L; 96-h ALC₅₀). Accelerated life-testing procedures, used to estimate chronic mortality from acute data, predicted that a 30-day exposure of juvenile rainbow trout to 2,4-D would result in 1% and 10% mortality at 260 and 343 mg/L, respectively. Swim-up larvae were chronically more sensitive than juveniles using growth as the measurement end point. The 30-day lowest observable effect concentration (LOEC) of 2,4-D on growth of swim-up larvae was 108 mg/L, whereas the 30-day no observable effect concentration (NOEC) was 54 mg/L. The 30-day maximum acceptable toxicant concentration (MATC) of 2,4-D for rainbow trout, determined as the geometric mean of the NOEC and the LOEC, was 76 mg/L. The acute:chronic ratio was 6.5 (i.e., 494/76). We observed no chronic effects on growth of juvenile rainbow trout at the highest concentration tested (108 mg/L). Worst-case aquatic exposures to 2,4-D (4 mg/L) occur when the herbicide is directly applied to aquatic ecosystems for aquatic weed control and resulted in a 30-day safety factor of 19 based on the MATC for growth (i.e., 76/4). Highest nontarget aquatic exposures to 2,4-D applied following terrestrial use is calculated at 0.136 mg/L and resulted in a 30-day safety factor of 559 (e.g., 76/0.163). Assessment of the exposure and response data presented herein indicates that use of 2,4-D acid for invasive weed control in aquatic and terrestrial habitats poses no substantial risk to growth or survival of rainbow trout or other salmonids, including the threatened bull trout (Salvelinus confluentus).

An Ecological Risk Assessment of the Acute and Chronic Toxicity of the Herbicide Picloram to the Threatened Bull Trout (Salvelinus confluentus) and the Rainbow Trout (Onchorhyncus mykiss) by J. F. Fairchild; K. P. Feltz; L. C. Sappington; A. L. Allert; K. J. Nelson; J. Valle (pp. 761-769).

We conducted acute and chronic toxicity studies of the effects of picloram acid on the threatened bull trout (Salvelinus confluentus) and the standard coldwater surrogate rainbow trout (Oncorhynchus mykiss). Juvenile fish were chronically exposed for 30 days in a proportional flow-through diluter to measured concentrations of 0, 0.30, 0.60, 1.18, 2.37, and 4.75 mg/L picloram. No mortality of either species was observed at the highest concentration. Bull trout were twofold more sensitive to picloram (30-day maximum acceptable toxic concentration of 0.80 mg/L) compared to rainbow trout (30-day maximum acceptable toxic concentration of 1.67 mg/L) based on the endpoint of growth. Picloram was acutely toxic to rainbow trout at 36 mg/L (96-h ALC50). The acute:chronic ratio for rainbow trout exposed to picloram was 22. The chronic toxicity of picloram was compared to modeled and measured environmental exposure concentrations (EECs) using a four-tiered system. The Tier 1, worst-case exposure estimate, based on a direct application of the current maximum use rate (1.1 kg/ha picloram) to a standardized aquatic ecosystem (water body of 1-ha area and 1-m depth), resulted in an EEC of 0.73 mg/L picloram and chronic risk quotients of 0.91 and 0.44 for bull trout and rainbow trout, respectively. Higher-tiered exposure estimates reduced chronic risk quotients 10-fold. Results of this study indicate that picloram, if properly applied according to the manufacturer’s label, poses little risk to the threatened bull trout or rainbow trout in northwestern rangeland environments on either an acute or a chronic basis.

Protective Effect of High Alkalinity Against the Deleterious Effects of Chronic Waterborne Cadmium Exposure on the Detection of Alarm Cues by Juvenile Silver Catfish (Rhamdia quelen) by Daiani Kochhann; Ana Paula S. Benaduce; Carlos E. Copatti; Karina R. Lorenzatto; Márcia F. Mesko; Érico M. M. Flores; Valderi L. Dressler; Bernardo Baldisserotto (pp. 770-775).

The objective of the present study was to analyze the effect of chronic cadmium (Cd) exposure at two alkalinity levels (63 and 92 mg l⁻¹ CaCO₃) on the antipredatory behavior of juvenile silver catfish (Rhamdia quelen) exposed to conspecific skin extract and predator odor. At an alkalinity of 63 mg l⁻¹ CaCO₃, 30 days of exposure to either 4.5 or 8.0 μg l⁻¹ Cd impaired the catfish’s antipredatory response to alarm cues. However, silver catfish exposed to 4.5 μg l⁻¹ Cd at an alkalinity of 92 mg l⁻¹ CaCO₃ responded to skin extract and predator odor. In catfish exposed to 8.0 μg l⁻¹ Cd at the same alkalinity, only the number of feeding bites decreased, and this occurred only for specimens exposed to predator odor. Our results show that higher alkalinity protected against the deleterious effects of Cd on alarm cue detection but only in the larvae exposed to the lowest waterborne Cd level.

Toxic Effects of Copper on Antioxidative and Metabolic Enzymes of the Marine Gastropod, Onchidium struma by Xiao-bo Li; Xue-li Hou; Qian Mao; Yun-long Zhao; Yong-xu Cheng; Qun Wang (pp. 776-784).

The goals of this study were to evaluate the acute and sublethal toxicity of copper (Cu²⁺) on the marine gastropod, Onchidium struma, and to examine the utility of enzymatic parameters as indicators of Cu²⁺ exposure. In a semistatic renewal test, the 96-hour median lethal concentration of Cu²⁺ for O. struma, 74.80 mg/L, was higher than that for other intertidal species. The activities of the antioxidative enzymes, Cu/Zn superoxide dismutase (Cu/Zn-SOD) and catalase (CAT), and those of the metabolic enzymes-acid phosphatase (ACP), alkaline phosphatase (AKP), glutamic-oxaloacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT) -in both hepatopancreas and muscle were determined after a 1-week exposure to Cu²⁺ (range 1.35 to 4.20 mg/L). The activities of both Cu/Zn-SOD and CAT were higher in hepatopancreas than muscle. In addition, there was a negative correlation between Cu²⁺ concentration and Cu/Zn-SOD activity in hepatopancreas, whereas a positive correlation was observed for CAT activity. Concentration-dependent changes in ACP and AKP activity showed a similar trend in hepatopancreas, increasing then decreasing and, finally, a slight increase. In contrast, ACP activity was positively correlated with Cu²⁺ across the concentration range tested. In both hepatopancreas and muscle, both GOT and GPT were activated by lower concentrations of Cu²⁺ and inhibited at higher concentrations.

Demographic Responses to Multigeneration Cadmium Exposure in Two Strains of the Freshwater Gastropod, Biomphalaria glabrata by Christopher J. Salice; Thomas J. Miller; G. Roesijadi (pp. 785-795).

A life table response experiment (LTRE) was used to quantify the population-level effects of continuous, multigeneration cadmium exposure on two strains of the freshwater gastropod, Biomphalaria glabrata: the parasite-resistant BS90 and parasite-susceptible NMRI strains. Snails were exposed to waterborne cadmium for three consecutive generations. Survival, growth, and reproduction were measured empirically and incorporated into a stage-based, deterministic population model. Cadmium significantly affected hatching success, time to maturity, and juvenile and adult survival in both strains. There were significant effects of generation on fecundity, hatching success, time to maturity and juvenile survival in NMRI, and time to maturity and adult survival in BS90. Cadmium significantly affected the population growth rate, λ, in BS90. Cadmium, generation, and the cadmium × generation interaction had significant effects on λ in NMRI. At the high cadmium exposure, λ for NMRI showed a decrease from generation 1 to generation 2, followed by an increase from generation 2 to generation 3. The λ value in high-cadmium BS90 steadily decreased over the three generations, while NMRI at this same concentration was similar to the controls. The results indicate that strain-specific differences in response to multigeneration cadmium exposure are evident in B. glabrata. Moreover, effects seen in the first generation are not necessarily indicative of effects in subsequent generations. Changes in λ over the course of the three-generation exposure suggest that acclimation and/or adaptation to cadmium may have occurred, particularly in NMRI at the high cadmium exposure level.

Long-Term Effects of Ammonia on the Behavioral Activity of the Aquatic Snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca) by Álvaro Alonso; Julio A. Camargo (pp. 796-802).

An appropriate approach to assess the effect of toxicants on aquatic animals is to monitor behavioral endpoints, as they are a link between physiological and ecological processes. A group that can be exposed long-term to low toxic concentrations is benthic macroinvertebrates, as their mobility in aquatic ecosystems is relatively limited. Therefore, the study of behavioral long-term effects in this group is suitable from an ecological point of view, as behavioral effects can appear before mortality. During the last decades there has been an increase in ammonia concentrations in freshwater ecosystems, threatening aquatic animals. The present study focuses on the long-term effects (40 days) of nonionized ammonia on the behavioral activity of the aquatic snail Potamopyrgus antipodarum. One control and three ammonia concentrations (0.02, 0.07, and 0.13 mg N–NH₃/L) were used in triplicate, and the activity of snails (as mean time to start normal movement) and immobility were recorded for each treatment after 0, 10, 20, 30, and 40 days of continuous exposure to nonionized ammonia. The results show that P. antipodarum presented a high tolerance to lethal long-term effects of nonionized ammonia, as no animal died during the bioassay. However, the behavioral activity of snails was a very sensitivity endpoint, as a mean nonionized ammonia concentration of 0.07 mg N–NH₃/L affected P. antipodarum. The results are discussed and compared with the available literature on long-term effects of ammonia on freshwater macroinvertebrates. Additionally, the ammonia water quality criteria, NOECs, LOECs, and long-term LCs are discussed on the basis of the current available data for freshwater macroinvertebrates.

Organochlorine Pesticide and Polychlorinated Biphenyl in Feathers of Resident and Migratory Birds of South-West Iran by Reza Dahmardeh Behrooz; Abbas Esmaili-Sari; Seyed Mahmoud Ghasempouri; Nader Bahramifar; Seyed Mehdi Hosseini (pp. 803-810).

Persistent organochlorine pesticides (OCPs), such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), α-, β-, and γ-hexachlorocyclohexane (HCH) isomers, together with polychlorinated biphenyl (PCB) congeners (IUPAC Nos. 28, 52, 101, 138, 153, and 180) were determined in tail feathers from 35 birds belonging to 15 species, all originating from the southwest of Iran (Khuzestan, coast of the Persian Gulf) and kept in museum collections. The patterns of organochlorine contaminants (OCs) in birds varied depending on their migratory behavior. Resident birds contained higher median PCB concentrations (

Impact of Waterborne Copper on the Structure of Gills and Hepatopancreas and its Impact on the Content of Metallothionein in Juvenile Giant Freshwater Prawn Macrobrachium rosenbergii (Crustacea: Decapoda) by Na Li; Yunlong Zhao; Jian Yang (pp. 811-812).

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Archives of Environmental Contamination and Toxicology (v.56, #4)