水体酸化条件下Cu(II)对斑马鱼胚胎的毒性效应

为评价由酸雨、酸性矿山排水等环境污染导致的水体酸化及水体重金属联合作用对水生生物的生态毒性效应,研究了不同pH值(pH=3、4、5、6、7和7.8)条件下Cu2+对斑马鱼胚胎发育的影响。结果表明,酸性水体及Cu2+单一存在时,酸对斑马鱼胚胎24h半数效应浓度值EC50为pH=3.65,Cu2+(pH=7.8)对斑马鱼胚胎24h-EC50为0.267mg·L-1;当水体酸化及水体中的Cu2+共存时,较低的pH对Cu2+的生物毒性起协同作用,表现为随溶液pH的降低,各浓度Cu2+对斑马鱼胚胎的24h凝结率显著增高(P24h致死率=0.001),而斑马鱼胚胎96h孵化率显著降低(P96h孵化率=0.002),且不同浓度的Cu2+之间的生物毒性效应存在显著性差异(P24h致死率=0.0321;P96h孵化率=0.0028)。这说明酸性水体和Cu2+都显著影响斑马鱼胚胎的发育,且Cu2+在酸性水体中对斑马鱼胚胎的毒性显著增强。因此,在受重金属Cu2+污染的地区,如同时受到酸雨或酸性矿山排水等较低pH值和Cu2+的双重胁迫,较低浓度的Cu2+就能够对水生生物的生殖发育及水生生态系统产生严重的影响和危害。     

Low-cost and efficient adsorbent derived from pyrolysis of Jatropha curcas seeds for the removal of Cu2+ from aqueous solutions

Biochar, is a low-cost material that can be used as an alternative adsorbent for the removal of heavy metals. In this study, a low-cost and efficient adsorbent synthesised from Jatropha curcas seeds was used for the uptake of Cu²⁺ from aqueous solutions. The as-prepared adsorbent was characterised by scanning electron microscopy and Brunauer–Emmett–Teller analysis post calcination at 500 °C, its BET surface area and total pore volume were 39.62?m²?g^?1 and 0.049?m³?g^?1, respectively. Subsequently, the effects of initial pH of the solution, contact time, and adsorbent material dosage on the adsorption of Cu²⁺ by the prepared adsorbent were investigated. The as-prepared adsorbent exhibited a high performance, with a maximum adsorption amount of 32.895?mg?g^?1 for Cu²⁺ at pH 5.0 and 25 °C, owing to the presence of ?OH, C=O, C–O, Si-O-Si, and O-Si-O on its surface. The predominant Cu²⁺ adsorption mechanism was assumed to be ion exchange. Notably, the Cu²⁺ adsorption could attain equilibrium within 90?min. In addition, the fact that the Langmuir model was a better fit than the Freundlich model for the isotherm data of Cu²⁺ adsorption by the as-prepared adsorbent suggested that the adsorption of Cu²⁺ was a monolayer adsorption process.     

Nano-titanium dioxide (TiO2)-induced changes affecting Cu2+-mediated alterations in bacterium Bacillus subtilis and α-amylase

Titanium dioxide (TiO₂) nanoparticles possess the potential to coexist with Copper (Cu²⁺) in soil. The individual and combined toxicity of these two chemicals was evaluated using the bacterium Bacillus subtilis, a known soil model bacterium. Cu²⁺ (6.25–50?µg?mL^?1) alone produced toxicity to bacteria as evidenced by the decreased cell viability and deceased α-amylase production. The addition of TiO₂ (50?mg?mL^?1) enhanced the Cu²⁺-induced decrease in cell viability but elevated amylase activity. TiO₂ did not markedly affect the growth rate and lag period. A primary cause of TiO₂ increasing Cu²⁺ toxicity is presumed to be associated with hydroxyl radical formation, while increased amylase activity is considered to arise from Cu²⁺ facilitating TiO₂ degradation ability.     

The lead content and isotopic composition of british coals and their implications for past and present releases of lead to the UK environment

More than 60 coal samples, predominantly from the principal coalfields of England and Wales (25) and Scotland (30), were analysed for lead by AAS and for stable lead isotopes by ICPMS. While the average lead content of Scottish coal, 23.9mg kg^–1, was more than double that of coal from England and Wales, 11.0mg kg^–1, the corresponding mean ²⁰⁶Pb/²⁰⁷Pb ratios (± 1 s.d.) were nearly identical, at 1.181±0.011 and 1.184±0.006, respectively. In the light of the lead isotopic signatures of British coals and of both indigenous (²⁰⁶Pb/²⁰⁷Pb 1.17) and imported Australian (²⁰⁶Pb/²⁰⁷Pb 1.04) lead ores, an approach based on estimated lead emissions from these sources and the deconvolution of the historical lead and ²⁰⁶Pb/²⁰⁷Pb records preserved in lake sediments, peat bogs and archival herbage material indicates that coal combustion became an increasingly significant contributor to atmospheric lead deposition in the UK during the period 1830–1930, especially after the onset of Englands decline as a major location of lead mining and smelting in the late19th Century. Since 1930 and the introduction of leaded petrol, the atmospheric ²⁰⁶Pb/²⁰⁷Pb ratio in the UK has been strongly influenced by carexhaust emissions of comparatively ²⁰⁶Pbdepleted lead of predominantly Australian origin, counterbalanced to some extent by coalcombustion emissions of lead, although these have fallen dramatically since the mid1950s. Nevertheless, with the introduction and substantial uptake of unleaded petrol in the UK during the last decade, even the declining releases from coal, along with contributions from other sources, are continuing to affect the atmospheric lead content and ²⁰⁶Pb/²⁰⁷Pb ratio.     

Effects of lead and selected pyrethroids/piperonyl butoxide alone and in combination on Na,K‐ATPase

In vitro effects of Pb²⁺, the pyrethroid insecticides cypermethrin, fenvalerate and the syner‐gist piperonyl butoxide on sodium‐potassium‐activated adenosine triphosphatase (Na,K‐ATPase) from dog kidney were determined. Pb²⁺ with an estimated IC50 value of 5.2 μM was found to be a potent inhibitor of Na,K‐ATPase activity, whereas Na,K‐ATPase was less sensitive to the pyrethroids tested and piperonyl butoxide. Investigation with circular dichroism (CD) spec‐troscopy showed that inhibition occurs through conformational changes of the α‐subunit of the enzyme. The kinetic characteristics of inhibition of Na,K‐ATPase with varying substrate (ATP) concentrations as well as with varying Na⁺ concentrations exhibited a competitive type of inhibition with Pb²⁺ in the μM range. With Pb²⁺ alone in the enzyme assay no conformational changes of the protein could be observed which confirmed the assumption that Pb²⁺ can bind to the Na⁺ binding site of the α‐subunit. Uncompetitive type of inhibition occurred with varied K⁺ concentrations demonstrating that this cation binding site is not affected directly by Pb²⁺.

Complete reversal of Pb²⁺ by DTT confirms that a possible target for interaction of this heavy metal ion with Na, K‐ATPase are specific SH groups.

Synergistic effects could only be determined with higher Pb²⁺ concentrations of 3, 5 and 7 μM plus piperonyl butoxide while all other combinations with this heavy metal plus organic substances where of the additive type. With CD spectroscopy also only additive effects were observed. These results demonstrate that higher concentrations of piperonyl butoxide favor the binding of Pb²⁺ to the Na⁺ binding site by conformational changes of the protein.     

Soil organic matter chemistry. Part 1. Characterization of several humic preparations by proton and carbon‐13 nuclear magnetic resonance spectroscopy

Both laboratory and commercial preparations of humic substances (HSs) such as fulvic acids and humic acids along with HC1‐HF preparation of Manitoba peat soil organic matter were characterized using Fourier Transformation (FT) proton (¹H) and carbon‐13 (¹³C) nuclear magnetic resonance (NMR) spectroscopy. All the samples were dissolved in a solution of 0.4 N NaOD in D₂O. In the case of ‘H‐NMR spectroscopy, all the investigated humic samples displayed resonance absorption peaks in the region of 1–4 ppm indicating the likely presence of aliphatic protons in the preparations. However, with the exception of one fulvic acid preparation (extracted from Manitoba Carrol clay‐loam soil with 0.5 N NaOH), ¹H‐NMR spectra of all other samples provided evidence for strong aromatic character. The aliphatic and aromatic characteristics of such samples of HSs were further confirmed with the aid of ¹³C‐NMR spectra.     

铜离子对中国花鲈幼鱼的毒性研究

为给中国花鲈(Lateolabrax maculatus)养殖提供污染生物学的理论数据,研究了中国花鲈幼鱼的铜离子中毒症状和半致死浓度(LC50);检测了幼鱼肝脏的谷胱甘肽(GSH)和丙二醛(MDA)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷丙转氨酶(GPT)和谷草转氨酶(GOT)活力;分析了铜离子胁迫对...     

量子点对Cu2+诱导L02细胞毒性的影响及机理研究

量子点(QDs)和Cu~(2+)可能共存于肝脏,对肝细胞产生联合毒性,威胁人体健康。本研究以人胚肝细胞(L02)为研究对象,考察了低/无毒的QDs(3.6%的细胞致死率)对Cu~(2+)诱导L02细胞毒性的影响及相关机理,为其可能的健康和环境风险提供参考。结果显示,QDs的加入使得Cu~(2+)的细胞毒性有了很大的提高,细胞存活率最高下降了26.0%,两者表现为协同作用;另外QDs存在使得Cu~(2+)细胞蓄积量增大,伴随着Cu~(2+)天然解毒蛋白CTR1和ATP7A等表达水平的升高,从侧面印证了Cu~(2+)的蓄积量增加对细胞的影响;同时,QDs的存在使得细胞乳酸脱氢酶(lactate dehyfrogenase,LDH)泄露相对于Cu~(2+)单独处理组提高,暗示QDs可能破坏了细胞膜,导致Cu~(2+)在细胞内蓄积量增加,从而使细胞毒性增加,两者的联合毒性表现为协同作用。     

Sorption of cadmium(II) and copper(II) by soil humic acids: temperature effects and sorption heterogeneity

Sorption by humic acids is known to modify the bioavailability and toxicity of metals in soils and aquatic systems. The sorption of cadmium(II) and copper(II) to two soil humic acids was measured at pH 6.0 using ion-selective electrode potentiometric titration at different temperatures. Sorption reactions were studied with all components in aqueous solution, or with the humates in suspension. Adsorption reactions were described using a multiple site-binding model, and a model assuming a continuous log-normal distribution of adsorption constants. Adsorption of Cu²⁺ was more favourable than adsorption of Cd²⁺. The log-normal distribution model provided the closest fit to observations and allowed parameterisation of adsorption data using a mean adsorption constant (log K _μ). Sorption of Cd²⁺ to dissolved humic acids increased slightly in extent and sorption affinity with increasing temperature, but the effect was small (log K _μ 2.96–3.15). A slightly greater temperature effect occurred for sorption of Cd²⁺ to solid-phase humic acids (log K _μ 1.30–2.08). Sorption of copper(II) to both aqueous- and colloidal-phase humates showed more pronounced temperature dependence, with extent of sorption, and sorption affinity, increasing with increasing temperature (log K _μ 3.4–4.9 in solution and 1.4–4.5 in suspension). The weaker adsorption of Cd²⁺ than Cu²⁺, and smaller temperature effects for dissolved humates than suspended humates, suggested that the observed temperature effects had a kinetic, rather than thermodynamic, origin. For any metal-to-ligand ratio, free metal ion concentration, and by inference metal bioavailability, decreased with increasing temperature. The consistency of the data with kinetic rather than thermodynamic control of metal bioavailability suggests that equilibrium modelling approaches to estimating bioavailability may be insufficient.     

Solid phase extraction of trace metals from environmental samples using Amberlite XAD-7 loaded with 2-hydroxy-propiophenone-4-phenyl-3-thiosemicarbazone and determination by inductively coupled plasma–atomic emission spectrometry

A method for the solid phase extraction of trace metals, namely Co, Cu, Pb, Ni and Zn, from environmental and biological samples using column Amberlite XAD-7 loaded with 2-hydroxy-propiophenone-4-phenyl-3-thiosemicarbazone (HPPPTSC) and determination by inductively coupled spectrometry (ICP–AES) has been developed. The reagent has the capacity to form chelate complexes with the metals because of three binding sites in the reagent molecule. The optimum experimental conditions for the quantitative sorption of five metals, pH, effect of flow rate, concentration of eluent, sorption capacity and the effect of diverse ions on the preconcentration of analytes have been investigated. The sorption capacity of the resin has 83, 127, 35, 88 and 85?µmol?g^?1 for Co²⁺, Cu²⁺, Pb²⁺, Ni²⁺ and Zn²⁺, respectively. The preconcentration factors for Co²⁺, Cu²⁺, Pb²⁺, Ni²⁺ and Zn²⁺ were 100, 110, 120, 140 and 150, respectively. The accuracy of the proposed procedure was evaluated by standard reference materials. The achieved results were in good agreement with certified values. The proposed method was applied for the determination of trace metals in river water and plant leaves.     

Isolation and characterisation of cadmium-resistant bacteria from an industrially polluted coastal ecosystem on the southeast coast of India

A total of 35 bacterial strains were isolated from the industrially polluted Cuddalore coast, on the southeast coast of India. Of these, 17 strains were cadmium resistant and the remainder were sensitive. Six strains (C-1, C-8, C-10, C-12, C-14 and N-1) were selected based on high levels of cadmium tolerance (>150 mg L^?1) and were termed highly cadmium-resistant bacteria (HCRB). These HCRB were identified on the basis of morphological, biochemical and partial sequencing of their 16S rRNA genes. The antibiotic-susceptibility patterns and minimum inhibitory concentrations (MIC) of different metals (Cu²⁺, Pb²⁺ and Zn²⁺) against each HCRB were determined. Among the isolates, C-14 showed high degrees of metal and antibiotic resistance compared with other HCRB. Growth rates of HCRB at two different Cd²⁺ concentrations (50 and 100 mg L^?1) and under different metal conditions (Cd²⁺, Cu²⁺ and Pb²⁺) were also investigated. HCRB growth rates were lower in the metal-treated condition than in the untreated condition. Isolates C-14 and N-1 removed>80% of Cd²⁺ from cadmium-treated broth. However, isolate C-14 removed 92.3% of Cd²⁺ compared with 86.5% for isolate N-1. Bacteria showing residual growth rates under metal stress conditions might be useful in metal removal applications under growing conditions.     

Utilization of fly ash in adsorption of heavy metals from wastewater

The aim of this study was to assess the toxicity reduction of wastewaster after treatment with fly ash. Fly ash is a waste material which is formed as a result of coal burning in power plants, but has the potential to adsorb heavy metal ions. The present study examined the adsorption capacity of fly ash to adsorb Pb²⁺, Cu²⁺, and Zn²⁺ from waste water under different conditions of contact time, pH, and temperature. Uptake of metal ions by fly ash generally rose with increasing pH. At lower temperatures the uptake of heavy metal adsorption were enhanced. Significant reduction in Pb²⁺ (79%), Cu²⁺ (53%), and Zn²⁺ (80%) content was found after treatment with fly ash of waste water treatment. Using the microtox test toxicity of the effluent was reduced by 75% due to removal of Pb²⁺ ion by the fly ash. Data indicated that fly ash generated by power plants may be used beneficially to remove metals from waste water.     

Oxidized multiwalled carbon nanotubes modified with 2-(2-hydroxy-5-nitrophenyl)-4,5-diphenyl imidazole for solid phase extraction and preconcentration of some metal ions

In this work, a new procedure for the enrichment of the trace amount of Cu²⁺, Ni²⁺, Co²⁺, Pb²⁺, Fe²⁺, and Zn²⁺ ions based on the utilization of multiwalled carbon nanotubes (MWCNT) modified with 2-(2-hydroxy-5-nitrophenyl)-4,5-diphenyl imidazole as chelating agent prior to their determination by flame atomic absorption spectrometry has been described. The influence of effective parameters including pH, amount of ligand and MWCNT, composition of eluent, and coexisting ions on recoveries of understudy metal ions was examined. At the optimum pH of 5.0, all metal ions were quantitatively sorbed onto the proposed solid phase and completely desorbed with 8?mL of 5.0?mol?L^?1 HNO₃. The detection limit of Cu²⁺, Co²⁺, Ni²⁺, Pb²⁺, Fe²⁺, and Zn²⁺ ions was 1.7, 2.4, 2.3, 2.9, 2.8, and 1.4?µg?L^?1, while the preconcentration factor was 63 for Cu²⁺ and 94 for the other metal ions and relative standard deviations between 1.8 less than 3.0%. The proposed procedure was applied for the analysis of various samples.     

A Preliminary Study on Soil–Gas Radon Geochemistry According to Different Bedrock Geology in Korea

Three study areas of Kwanak campus (Seoul National University), Boeun (Choongbuk) and Gapyung (Kyonggi) were selected and classified according to their bedrock types in order to investigate soil–gas radon concentrations. The mean values of radon concentrations decreased in the order of Gapyung (40BqL^–1) > Kwanak campus (30BqL^–1) > Boeun (22BqL^–1), and decreased in the order of granite gneiss > banded gneiss > granite > black slate–shale > mica schist > shale–limestone > phyllite schist according to bed rock types. Variation in radon emanation with water content in soils and with soil grain size was assessed by the modified Morse (1976) 3min method. Soil–gas radon concentrations increased with increasing water content in the range of less than about 6–16wt.%, but decreased above 6–16wt.%. Radon concentrations also increased with decreasing soil grain size. Radioactivity analysis of radionuclides of ²³⁸U series in some soil samples indicated their possible radioactive disequilibrium between ²²⁶Ra and ²³⁸U due to the differing geochemical behaviour of intermediate radionuclides. Thus, a radioactive isotope geochemical approach should be necessary for soil–gas radon study.     

Characteristics of Environmental Geochemistry in the Arseniasis Area of the Inner Mongolia of China

In China, endemic arseniasis attributable to the geological-geochemistry environment is mainly found in the plain of the Great Bend of the Yellow River and the Hu-Bao plain in the Inner Mongolia Autonomous Region, in the Datong basin of Shanxi Province, the floodplain of the northern side of the Tian Mountain of Xinjiang Uygur Autonomous Region, and in the southwest coastal plain of Taiwan. These areas share many similar characteristics including widespread occurrences, a large population being affected, and the magnitude of risk involved. The population living in these areas is estimated to be around 5.5 × 10⁵, of which of 2.5 × 10⁵ are resident in Inner Mongolia. Based on our systematic research and comparison of various areas, we found the different types of arseniasis are often associated with different regions. The neural arseniasis is distributed in Xinjiang Uygur Autonomous Region and Shanxi Province, caused by inorganic arsenic in drinking water while the cycling-obstacle arseniasis is mainly found in Inner Mongolia and Taiwan, associated with organic arsenic in water. The distribution of arsenic affected villages in Inner Mongolia exhibits orientation and focus on low-lying land in the subsiding centre of the Great Bend basin, which was enriched with humus in the lake and limnetic deposits. Much CH₄ gas can be detected in the water of shallow and deep wells in these villages. Some of the wells with higher concentrations of CH₄ can even be ignited. This is a typical reductive geochemical environment. We tested the total amount of arsenic (As), As³⁺, and methyl arsenate in all types of water sources. It is found that the number of arseniasis cases is not clearly related to the total amount of arsenic (As) in the water. However, it is related to the ratio of As³⁺ plus methyl arsenic to the total amount of arsenic (As). The higher the ratio, the higher the number of people affected and the more serious the illness. The statistical results also indicate that good drinking water accounts for 60% of the drinking water source while the arsenic contaminated water makes up about 25% of the drinking water in the study area. This research reveals that the local geochemical environment is responsible for the spreading of the endemic arseniasis in the area and thus suggests a new direction of how to prevent such disease.     

重金属对禾谷镰刀菌的生长及毒素合成的影响

以禾谷镰刀菌为研究对象,研究了常见重金属(Cu、Pb、Zn、Cd)对禾谷镰刀菌菌株生长及其毒素合成的影响。研究结果表明,重金属对菌株的生长和其产毒能力均产生影响。Cu~(2+)和Cd~(2+)对菌株生长影响较大,随着浓度的增加对生长的抑制作用增强,当离子浓度分别为20 mg·L~(-1)和40 mg·L~(-1)时,能够完全抑制菌株生长。Zn~(2+)在0~160 mg·L~(-1)浓度范围内促进菌株生长,在10 mg·L~(-1)浓度下促进毒素合成。Pb~(2+)在察氏培养基中对菌株生长的影响没有明显规律可循,但是,随着Pb~(2+)浓度增加,抑制毒素合成作用增强。     

Kinetic and mechanism studies of the adsorption of lead onto waste cow bone powder (WCBP) surfaces

This study examines the adsorption isotherms, kinetics and mechanisms of Pb²⁺ sorption onto waste cow bone powder (WCBP) surfaces. The concentrations of Pb²⁺ in the study range from 10 to 90 mg/L. Although the sorption data follow the Langmuir and Freundlich isotherm, a detailed examination reveals that surface sorption or complexation and co-precipitation are the most important mechanisms, along with possibly ion exchange and solid diffusion also contributing to the overall sorption process. The co-precipitation of Pb²⁺ with the calcium hydroxyapatite (Ca-HAP) is implied by significant changes in Ca²⁺ and PO₄ ^3? concentrations during the metal sorption processes. The Pb²⁺ sorption onto the WCBP surface by metal complexation with surface functional groups such as ≡ POH. The major metal surface species are likely to be ≡ POPb⁺. The sorption isotherm results indicated that Pb²⁺ sorption onto the Langmuir and Freundlich constant q _max and K _F is 9.52 and 8.18 mg g^?1, respectively. Sorption kinetics results indicated that Pb²⁺ sorption onto WCBP was pseudo-second-order rate constants K ₂ was 1.12 g mg^?1 h^?1. The main mechanism is adsorption or surface complexation (≡POPb⁺: 61.6%), co-precipitation or ion exchange [Ca_3.93 Pb_1.07 (PO₄)₃ (OH): 21.4%] and other precipitation [Pb 50 mg L^?1 and natural pH: 17%). Sorption isotherms showed that WCBP has a much higher Pb²⁺ removal rate in an aqueous solution; the greater capability of WCBP to remove aqueous Pb²⁺ indicates its potential as another promising way to remediate Pb²⁺-contaminated media.     

In vitro and in vivo inhibition of Ca2+-Mg2+-ATPase activity by cadmium in post larvae of Penaeus monodon

Ca²⁺-Mg²⁺-ATPase is a membrane-bound enzyme and is responsible for regulating cytosolic free calcium. In vitro and in vivo effects of cadmium were studied on Ca²⁺-Mg²⁺-ATPase activity in plasma membrane/mitochondrial fraction of Penaeus monodon post larvae. In vitro studies revealed a concentration-dependent decrease in enzyme activity with an IC₅₀ value of 11.02?µM. In vivo experiments were conducted by exposing the post larvae to 1/10th (0.12?ppm) and 1/5th (0.24?ppm) of LC₅₀ values of cadmium for 30 days. Both ATPase activity and metal accumulation were estimated in post larvae exposed to 0.12 and 0.24?ppm of cadmium at different intervals of 24?h, 48?h, 96?h, 10 days and 30 days. ATPase activity showed a gradual decrease in post larvae on exposure to both the sub-lethal concentrations with respect to their controls and the decrease was significant (p?相似文献   

Arsenic tissue concentration of immature mice one hour after oral exposure to gold mine tailings

A potentially high bioavailability of arsenic in gold mine tailings from a site in northern California has been suggested by solubility studies. To help address this issue, an in vivo dosing study was conducted using 12dayold Swiss Webster mouse pups (n=8/group). A sample of sizefractionated mine tailings from the site (<20m particle size, 691g g^–1 arsenic) was prepared as an aqueous suspension and administered by gavage in a volume that provided 4mg As/kg body weight. The control group received the same volume of a commercial soil (1g g^–1 As) of similar particle size (<60m). No mortality or toxic signs were noted in either group. Tissue samples were collected 1h after gavage, freezedried, microwavedigested and analysed for arsenic by ICP/MS (detection limit 2ng As g^–1 dry weight). Arsenic concentrations (ng As g^–1 dry weight) in tissues from the pups who received mine tailings were significantly higher than in control tissues. The mean elevation in arsenic concentration was highest in the liver (3364% of control, p<0.0001), followed by blood (818 of control, p<0.0001), skin (207% of control, p=0.07), and brain (143% of control, p<0.0001). The carcass arsenic concentration (excluding the GI tract, liver, brain and skin) was 138 of control (p=0.02). The data indicate uptake of arsenic from weathered mine tailings by the immature mouse pups after oral exposure.     

Alterations in serum electrolyte levels after dimethoate exposure and recovery in the freshwater air-breathing catfish,Heteropneustes fossilis (Bloch)

Dimethoate, a moderately toxic insecticide, has a wide range of agricultural and domestic applications. Like other organophosphates, dimethoate has anticholinesterase activity. Fish are non-target organisms, inadvertently exposed to pesticides and their metabolic products. The present study includes short-term (96 h) and long-term (36 d) effects of dimethoate exposure on some serum electrolytes Ca²⁺, Mg²⁺, and Pi in the freshwater air-breathing catfish Heteropneustes fossilis. The concentration of dimethoate for short-term exposure was 2.24 mg L^?1 (75% of 96 h LC₅₀) and for long-term exposure 0.75 mg L^?1 (25% of 96 h LC₅₀). The study includes the recovery pattern in serum electrolytes after placing the fish in pesticide-free water. Fish show hypocalcemia, hypermagnesemia, and hyperphosphatemia after short-term and long-term exposure to dimethoate. When placed in pesticide-free water, these electrolytes exhibit recovery towards normalization, indicating significant (p < 0.05) recovery.