Static Renewal System Research Articles

TOXICITY OF CHLORPYRIFOS TECHNICAL GRADE AND 20% EC TO THE FRESHWATER FISH, CHANNA PUNCTATA (BLOCH)

The toxicity studies of chlorpyrifos technical grade (TG) and 20% EC are conducted in the prevailing laboratory conditions of the fish Channa punctata in vivo to determine the median lethal concentrations i.e., LC50 values for 24, 48, 72 and 96 hrs duration by employing both static renewal and continuous flowthrough systems. The most preferred and palatable fish and mostly used pesticide the organophosphate are selected for study. The static renewal values are 6.02 µg/L, 5.82 µg/L, 5.62 µg/L, 5.38 µg/L for technical grade and for 20% EC 3.01 µg/L, 2.71 µg/L, 2.61 µg/L, and 2.51 µg/L for 24, 48, 72 and 96 hrs respectively. Similarly, for the continuous flow through system (CFTS) the values are 3.11 µg/L, 2.87 µg/L, 2.81 µg/L and 1.61 µg/L for technical grade and for 20% EC 1.91 µg/L, 1.81 µg/L, 1.61 µg/L and 1.41 µg/L respectively for 24, 48, 72 and 96 hrs. The toxicity is the concentration and duration dependent and the LC50 values in both methods decreased as well as concentrations also. The static renewal values are higher to CFTS and 20% EC is sufficiently toxic, which had synergistic effect on target and tested organism. The values are useful for data base and also in prescribing the permissible limits.

Effect of Probiotics-YUGE® on Survival and Growth of Heterobranchus bidorsalis Larvae Reared in Static-Renewal System

Effect of Probiotics-YUGE® on Survival and Growth of Heterobranchus bidorsalis Larvae Reared in Static-Renewal System

Developmental abnormalities and growth patterns in juvenile Oreochromis mossambicus chronically exposed to efavirenz

Efavirenz is an antiretroviral drug (ARV) used for the treatment of Human Immunodeficiency Virus (HIV/AIDS) infections. The effects efavirenz may have on mammals is known, however, little is known about the effects on non-target aquatic organisms, especially on growth and development of fish. Adult Oreochromis mossambicus were bred to produce newly fertilised eggs. These eggs were exposed to efavirenz using two concentrations (10.3 ng/L and 20.6 ng/L) over 60 days growth period. The growing juveniles were kept in a static renewal system under controlled laboratory conditions (27 ± 1 °C; day:night photoperiod of 14:10) to simulate an optimal growth environment similar to summer. The endpoints included changes in growth, growth rates and morphological development based on exposure to efavirenz. After morphological analyses were done at (i) 1-day post hatching, (ii) approximately two weeks post hatching, (iii) 30 days post hatching and (iv) 60 days post hatching abnormalities were reported. Efavirenz had no noticeable effect on length and weight, or growth parameters of the juveniles at all stages. Efavirenz however, influenced the morphological development of the juveniles by causing physical abnormalities (p > 0.05). Abnormalities included spinal deformities and alterations to the shape of the jaws.

Evaluation of silver nanoparticle acute and chronic effects on freshwater amphipod (Hyalella azteca).

Silver nanoparticles (AgNPs) are known to cause ecotoxic effects, but there are no existing derived ambient water quality criteria (AWQC) for these nanomaterials to protect freshwater aquatic life due to insufficient toxicological data. We exposed Hyalella azteca to silver nitrate, citrate-coated AgNPs (citrate-AgNPs), and polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) in a 10-day and 28-day water-only static renewal system with clean sand as a substrate for the amphipods and compared their point estimates with the United States Environmental Protection Agency (USEPA) AWQC for silver. We observed that all treatments decreased the survival, growth, and biomass of H. azteca, and the order of toxicity was AgNO3 > citrate-AgNPs > PVP-AgNPs. The LC50s of AgNO3, citrate-AgNPs, and PVP-AgNPs were 3.0, 9.6, and 296.0µg total Ag L-1, respectively, for the acute exposure and 2.4, 3.2, and 61.4µg total Ag L-1, respectively, for the chronic exposure. Acute and chronic EC20s of citrate-AgNPs ranged from 0.5 to 3.5µg total Ag L-1 while that of PVP-AgNPs ranged from 31.2 to 175µg total Ag L-1 for growth and biomass. Both Ag+ released from AgNPs and the nanoparticles contributed to the observed toxicity. The dissolution and toxicity of AgNPs were influenced by surface coating agents, particle size, and surface charge. Most point estimates for AgNPs were above AWQC for silver (4.1µg L-1) and the lowest concentration (0.12µg/L) at which Ag is expected to cause chronic adverse effects to freshwater aquatic life. Our study demonstrates that the current AWQC for silver, in general, is protective of freshwater aquatic life against AgNPs tested in the present study.

Using Passive Samplers to Track per and Polyfluoroalkyl Substances (PFAS) Emissions From the Paper Industry: Laboratory Calibration and Field Verification

Per and polyfluoroalkyl substances (PFAS) are becoming more stringently regulated and as such, a more diverse suite of environmental monitoring methods is needed. In this work a polar organic chemical integrative sampler (POCIS) with a nylon membrane and a combination of Oasis WAX and Fluoroflash® sorbents was calibrated in the laboratory and deployed in the field. A static renewal system was used to determine sampling rates for 12 PFAS which ranged between 0.69 ± 0.27 to 5.68 ± 1.80 L/day. POCIS devices were deployed for 10 days in lake Tyrifjorden, Norway which is known to be contaminated by a closed down factory producing paper products, in order to track the evolution of the PFAS contamination in a river system draining into the lake. Th sampling campaign enabled the stretch of the river which was responsible for the emissions of PFAS to lake Tyrifjorden to be identified. Freely dissolved concentrations determined with the POCIS were lowest at the site considered to reflect a diffuse PFAS contamination and highest at the site located downstream the factory. Perfluorooctanesulfonic acid (PFOS), perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonamidoacetic acid (EtFOSAA) dominated the concentration profile at this site. Emissions of PFAS to lake Tyrifjorden were estimated to be 3.96 g/day for the sum of the 12 investigated PFAS.

Impact of silver nanoparticles exposure on neuro-behavior, hematology, and oxidative stress biomarkers of African catfish (Clarias gariepinus)

Recently, silver nanoparticles (AgNPs) established a prospective value in aquaculture; however, extensive use afflicts fish and environment. Therefore, the current study represents a premier report to investigate the acute exposure of African catfish, Clarias gariepinus (B.) to AgNPs and the ethological alterations in a static renewal system. Additionally, AgNPs impact on blood profile, stress, brain activity, and branchial oxidative stress parameters were evaluated. Fish (50.71 ± 3.85 g) were exposed to different concentrations (0, 6.25, 12.5, 25, 50, and 100 mg L−1) of AgNPs for 96-h without water exchange. Finney's probit analysis was used to estimate the 96-h LC50 value of AgNPs which recorded 21.38 mg L−1. In comparison to the control, the AgNPs exposed fish exhibited different ethological responses such as surfacing for gasping air, restlessness, slow swimming movement, aggressiveness, and nervousness and the scores of these behaviors and mortalities reached the high values with increasing AgNPs concentrations. There were marked reductions in hematological indices (RBCs, Hb, Hct, and WBCs), acetylcholine esterase (AChE) activity, and oxidative stress indices (superoxide dismutase (SOD), catalase (CAT), and reduced glutathione content (GSH)) of exposed groups in an AgNPs dose-dependent manner relative to the control group. On the contrary, the levels of stress-mediated indices (glucose and cortisol) and 8 hydroxy 2 deoxyguanosine (8OH2dG) were markedly decreased in all AgNPs exposed groups as compared with the control group and the reduction increased with increasing the exposure concentration. We concluded that AgNPs exposure of C. gariepinus induced marked alterations in behavior, blood profile, neurological, and branchial antioxidant parameters, and the 96-h LC50 of AgNPs was 21.38 mg L−1 and this provides a basis for future applying AgNPs as a safe therapeutic agent after considering the acute toxicity.

Histopathological changes in Oreochromis mossambicus (Peters, 1852) ovaries after a chronic exposure to a mixture of the HIV drug nevirapine and the antibiotics sulfamethoxazole and trimethoprim

The burden of the human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS) infection has transformed the African continent into a major consumer of antiretrovirals (ARVs) drugs. In addition to HIV burden, the African continent has also a high incidence of tuberculosis (TB) and has been experiencing recurring outbreaks of several other viral, bacterial, and parasitic epidemic diseases. The novel severe acute respiratory syndrome coronavirus 2 (SARS-COV-2 or Covid-19) pandemic outbreak is adding to the continent’s infectious diseases burden as experts are predicting that it will be here for a long time. One of the consequences of these infectious diseases is that antiviral and antibiotic compounds have become some of the most consumed pharmaceuticals on the continent. Many of these drugs have been frequently detected in surface waters across Africa. There is limited information available on the adverse effects of the mixtures of different types of pharmaceuticals in African aquatic environments on fish reproduction. The present study investigated the effects of the ARV drug nevirapine (NVP - 1.48 and 3.74 μg/L) and its mixture with the antibiotic sulfamethoxazole (3.68 μg/L) and trimethoprim (0.87 μg/L) on O. mossambicus gonads using histopathological endpoints as biomarkers. The fish (n = 52) were exposed for 30 days in a static renewal system. Female O. mossambicus exposed to nevirapine (3.74 μg/L) and to NVP – antibiotic mixture recorded higher ovary indices. Statistically significant differences were found in female ovary indices between the fish exposed to NVP (3.74 μg/L) and the control fish (p = 0.002) as well as between the fish exposed to the NVP - antibiotic mixture and the control fish (p = 0.009). The main observed histopathological changes in the ovaries were increased vitellogenic oocyte atresia and vacuolation of the interstitial tissue in the fish exposed to NVP - antibiotic mixture. It is evident that the presence of NVP - antibiotics mixture in water triggered the observed histopathology in female fish ovaries. The detected abnormal high rate of atretic oocytes could result in impaired fish reproduction.

Exploring the sublethal genotoxic effects of class II organophosphorus insecticide quinalphos on freshwater fish Cyprinus carpio

The genotoxic effects of quinalphos (QP) were evaluated in the erythrocytes of Cyprinus carpio using the comet, micronucleus, and nuclear abnormality assays. The 96 h LC50 value of quinalphos, estimated by static renewal system, was 10.9 µL/L. On the basis of the LC50 value, two sublethal concentrations (1.09 and 2.18 µL/L) of the compound were used together with cyclophosphamide (5 mg/L) as the positive control. The fish were exposed for 35 d, and sampling was done at the end of 7, 14, 21, 28, and 35 d. Our results reveal a significant dose-dependent increase in the frequencies of DNA strand breaks, micronucleus, and nuclear abnormalities. Similar responses were also observed in fish exposed to the positive genotoxin cyclophosphamide. The collective findings demonstrated that quinalphos exerts a genotoxic effect on C. carpio. The results further confirmed that the comet, micronucleus, and nuclear abnormality assays are useful tools in determining the potential genotoxicity of pesticides towards aquatic organisms.

Nevirapine in African surface waters induces liver histopathology in Oreochromis mossambicus: A laboratory exposure study

Nevirapine (NVP) is one of the HIV antiretrovirals detected recurrently in African surface waters. Liver side effects in humans were reported. Because the effects on fish are unknown, this study investigated the potential effects of NVP on selected biometric indices and liver histology of Oreochromis mossambicus (Mozambique tilapia) in a chronic exposure. Adult fish were exposed to two concentrations of NVP (1.48 and 3.74 µg l−1) in a static renewal system under controlled conditions for 30 days. At the end of the exposure, each fish was weighed, the total length recorded, and blood collected from the caudal vein. A standard necropsy was done, selected organs were sampled and weighed, and biometric indices calculated. Liver tissue was processed for histological assessment. Results showed significant differences (p < 0.001) in hepatosomatic indices between the exposed fish and the control, as well as in spleen indices of the fish exposed to the higher NVP concentration (p = 0.008). Liver tissue of exposed fish showed significant histological changes (p < 0.001), including hepatocyte apoptosis, vacuolation, and a mild fibrosis around some of the veins and bile ducts. Nevirapine in African surface waters could have long-term negative effects on the health of fish.

Assessing the potential effects of nevirapine in South African surface water on fish growth: A chronic exposure of Oreochromis mossambicus

Aquatic environments around the world have become mixtures of different types of pollutants, including pharmaceuticals. The presence of pharmaceuticals in aquatic environments has raised concerns regarding the possibility of unintended effects on aquatic animals. South Africa is currently the largest consumer of HIV antiretroviral drugs (ARVs) worldwide. Nevirapine (NVP), a first-line ARV, has been associated with serious liver toxicity in humans and has been repeatedly detected in South African surface water. We investigated the potential effect of NVP on the growth of larvae and juveniles of the Mozambique tilapia (Oreochromis mossambicus) through a chronic laboratory exposure. Larval and early juvenile stages were exposed to the highest reported environmental relevant concentration of NVP in South African surface water (1.48 μg/L) for 60 days in a static renewal system. Body mass and total length measurements were recorded and analysed for individuals aged 1, 5, 30 and 60 days. In total, 455 fish were assessed. The growth parameters of larvae exposed to NVP were not statistically significantly different (p&gt;0.05) from those of control larvae. However, the juveniles exposed to NVP showed a slightly lower mean growth rate between the 30th and 60th day compared with the control fish. These results suggest that the concentration of NVP in South African surface water has no significant detrimental effects on fish growth during the first 2 months of their life. Further studies to investigate the effects on all life stages of fish are needed as it is evident that the growth rate of exposed fish could be affected after this stage.&#x0D; Significance:&#x0D; &#x0D; This study was the first to investigate the effect of an antiretroviral drug in surface water on fish growth.&#x0D; Chronic exposure to the highest environmentally relevant concentration of nevirapine in South African waters did not affect the growth of early life stages of Mozambique tilapia.&#x0D; The levels of antiretrovirals in aquatic systems should be monitored closely as their consumption is likely to increase in the future.&#x0D;

Interactions between Crassostrea virginica larvae and Deepwater Horizon oil: Toxic effects via dietary exposure

The Deepwater Horizon (DWH) disaster released crude oil in the Gulf of Mexico for 87 days, overlapping with the reproductive season and recruitment of the oyster Crassostrea virginica. The pelagic larval life stages of C. virginica are particularly vulnerable to contaminants such as polycyclic aromatic hydrocarbons (PAHs) and oil droplets. Based on their lipophilic properties, PAHs and oil droplets can adsorb onto phytoplankton and filter-feeding C. virginica larvae may be exposed to these contaminants bound to suspended sediment, adsorbed onto algal and other particles, or in solution. This study examined the effects of exposure of C. virginica larvae to algae mixed with DWH oil. In a 14-day laboratory exposure, 5 day-old C. virginica larvae were exposed to Tisochrysis lutea mixed with four concentrations of unfiltered DWH oil (HEWAF) in a static renewal system. Larval growth, feeding capacity, abnormality and mortality were monitored throughout the exposure. Total PAH (n = 50) content of the water medium, in which larvae were grown, were quantified by GC/MS-SIM. Oil droplets were observed bound to algae, resulting in particles in the size-range of food ingested by oyster larvae (1–30 μm). After 14 days of exposure, larval growth and survival were negatively affected at concentrations of tPAH50 as low as 1.6 μg L−1. GC/MS-SIM analysis of the exposure medium confirmed that certain PAHs were also adsorbed by T. lutea and taken up by oyster larvae via ingestion of oil droplets and/or contaminated algae. Long-term exposure to chronic levels of PAH (1.6–78 μg tPAH50 L−1) was shown to negatively affect larval survival. This study demonstrates that dietary exposure of oyster larvae to DWH oil is a realistic route of crude oil toxicity and may have serious implications on the planktonic community and the food chain.

Hatching success and survival of fish early life stages in a chronic exposure to nevirapine: a case study of the Mozambique tilapia

ABSTRACTThe anti-retroviral nevirapine has been detected in surface waters throughout South Africa and its effects on non-target aquatic animals are still unknown. The aim was to investigate the potential effects of nevirapine on the hatching success and survival of Oreochromis mossambicus early life stages through a chronic exposure. The exposer started with newly fertilized O. mossambicus eggs and concluded 30 days after hatching. Environmental relevant concentration of nevirapine (1.48 µg/l) was used in a static renewal system and a controlled environment (27 ± 1°C; 14:10 day/night cycle). The main endpoints assessed included hatching success and survival; a morphological assessment was also done on whole individual on day 1 and 30 post-hatching to identify any physical abnormality. Nevirapine had no noticeable effects on the hatching success and survival of O. mossambicus larvae; no statistically significant differences were observed between the control and the nevirapine exposed fish (p > 0.05).

Role of the Nrf2-ARE pathway in perfluorooctanoic acid (PFOA)-induced hepatotoxicity in Rana nigromaculata

Perfluorooctanoic acid (PFOA) is widely distributed in various environmental media and is toxic to organisms. This study demonstrated that PFOA induces hepatotoxicity in the frog and evaluated the role of CYP3A and the Nrf2-ARE signaling pathway in regulating responses to PFOA-induced hepatotoxicity. Rana nigromaculata were exposed to 0, 0.01, 0.1, 0.5, or 1 mg/L PFOA solutions in a static-renewal system for 14 days. Liver tissue samples were collected 24 h after the last treatment. Hepatic histology was observed by HE staining and transmission electron microscopy. The oxidative stress levels in the liver were measured. The expression levels of CYP3A, Nrf2, NQO1, and HO-1 mRNA were measured by quantitative reverse transcription–polymerase chain reaction. PFOA-treated frog liver tissue exhibited diffuse cell borders, cytoplasmic vacuolization, broken nuclei, nuclear chromatin margination, and swollen mitochondria. In addition, the livers of PFOA-treated frogs showed a significantly elevated content of reactive oxygen species, malondialdehyde, glutathione and glutathione S-transferase activity compared to the livers of control frogs. However, the glutathione peroxidase activities concomitantly decreased in PFOA-treated frogs compared to those in the control group. Furthermore, compared with control frogs, the expression levels of CYP3A, Nrf2, and NQO1 mRNA significantly increased in PFOA-treated frogs. HO-1 mRNA expression remarkably increased only in groups treated with 0.5 or 1 mg/L PFOA. Our results indicate that PFOA induces hepatotoxicity in a dose-dependent manner. Furthermore, the results of the comparison analysis between different gender groups illustrated that PFOA is more toxic to female frogs than male frogs. Our results demonstrated that PFOA causes liver damage and that CYP3A enhances PFOA-induced female frogs hepatotoxicity are more virulent than male through biotransformation, and the activation of the Nrf2-ARE pathway is induced to protect against hepatotoxicity in Rana nigromaculata, all of which provide the scientific basis for the protection of amphibians against environmental contaminants.

Improvements and cost-effective measures to the automated intermittent water renewal system for toxicity testing with sediments

The push to make bioassays more sensitive has meant an increased duration of testing to look at more chronic endpoints. To conduct these longer bioassays through the use of traditional bioassay methods can be difficult, as many traditional bioassays have employed manual water changes, which take considerable time and effort. To that end, static-renewal systems were designed to provide researchers a technique to ease the manual water change burden. One of the most well-known static-renewal designs, the static intermittent renewal system (STIR) was produced by the United States Environmental Protection Agency in 1993. This system is still being used in laboratories across the globe today. However, these initial designs have become rather dated as new technologies and methods have been developed that make these systems easier to build and operate. The following information details changes to the initial design and a proof of concept experiment with the benthic invertebrate, Chironomus tepperi, to validate the modifications to the original system.

Alteration in DNA structure, molecular responses and Na+ -K+ -ATPase activities in the gill of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) in response to sub-lethal verapamil

The ecotoxicological consequences of residues from pharmaceutical drugs on aquatic biota have necessitated the development of sensitive and reliable techniques to assess the impact of these xenobiotics on aquatic organisms. This study investigated the alteration in DNA structure, molecular responses and the activities of Na+ -K+ -ATPase and antioxidant enzymes in the gill of Nile tilapia, Oreochromis niloticus, exposed to long-term effects at the concentrations (0.14, 0.28 and 0.57mgL−1) of verapamil in static renewal system for 15, 30, 45 and 60 days. Evaluation of DNA structure, using single cell gel electrophoresis, revealed certain degree of DNA damages in the gill in a time and concentration-dependent relationship. Transcription of mRNA of superoxide dismutase (sod), catalase (cat) and heat shock protein (hsp70) genes in the gill of the fish showed the genes were up-regulated. Na+-K+-ATPase activity was inhibited in a concentration and time dependent manner. The indices of oxidative stress biomarkers (lipid peroxidation and carbonyl protein) as well as superoxide dismutase, glutathione peroxidase, glutathione-S-transferase were elevated in the treated fish in comparison to the control. Further, the level of reduced glutathione and catalase activity were inhibited at 0.28mgL−1 after day 30. Long-term exposure to sub-lethal concentration of verapamil can cause DNA damages, molecular effects and oxidative stress in O. niloticus. The biomarkers analysed can be used as early warning signals in environmental biomonitoring and assessment of drug contamination in aquatic ecosystem.

Cd2+对Cypridopsis vidua（介形纲）肠壁结构的毒性效应

Cypridopsis vidua is one of the few ostracods which can surrive from heavy pollution water. The toxic effects of Cd2+ on C. vidua and its intestinal ultrastructure were examined using a static renewal system. The LC50 values for cadmium in C. vidua were 5.00, 2.01, 0.46 and 0.14 mg/L at 24, 48, 72 and 96 h exposure respectively, and the safe concentration of Cd2+ for long-term C. vidua survival was less than 0.014 mg/L. To observe the structure changes of its intestinal, four Cd2+ concentrations were set up, and two of them were below the safe concentration of Cd2+ (0.001 and 0.004 mg/L) and the other concentrations were above its safe concentration (0.016 and 0.064 mg/L). The experiment lasted for 7 days. When microstructure of C. vidua was observed, the gastrointestinal orga-nization was not damaged below the safe concentration; while the degree of injury showed a certain amount of time and dose effects in 24-72 hours above the safe concentration, and some structures among those surviving animals were slightly recovered in 7 days under same concentration. Sub-microscopic analysis of intestinal cells of C. vidua in two concentrations (0.004 and 0.064 mg/L) groups showed, different degrees of structure damage were found in the cell membrane, cytoplasm and organelles, which worsened with increasing Cd2+ con-centrations. Among these cellular structures, the damage to the membrane system of the cell was especially serious.

Selection of food combinations to optimize survival, growth, and reproduction of the amphipod Hyalella azteca in static‐renewal, water‐only laboratory exposures

Although standardized sediment toxicity testing methods have been developed for the amphipod Hyalella azteca, no standardized chronic water-only toxicity testing methods have been established. Furthermore, optimal feeding and water quality conditions for culturing and toxicity testing with this species remained unclear. The objective of the present study was to determine the food or combination of foods that best promotes survival, growth, and reproduction of the US Lab strain of Hyalella azteca under 42-d, water-only, static-renewal testing conditions. The authors conducted 7 42-d control (no toxicant) tests with various combinations of food (including Tetramin, yeast-cereal leaves-trout chow, diatoms, wheatgrass, alfalfa, and maple leaves) and substrate types (clean "unconditioned" Nitex screens vs "conditioned" Nitex screens that were colonized by live biofilms). Over all treatments, survival ranged from 18% to 96%, dry weight per individual from 0.084 mg to 1.101 mg, and reproduction from 0 young/female to 28.4 young/female. Treatments that included Tetramin tended to result in better performance than those that did not. In particular, treatments that included Tetramin and either conditioned screens or diatoms consistently had high survival, weight, and reproduction values as well as low variability among replicates (measured as coefficient of variation). A ramped Tetramin plus diatom suspension feeding regime appears to have the greatest potential to produce consistently good performance across laboratories using static-renewal systems. Environ Toxicol Chem 2016;35:2407-2415. © 2016 SETAC.

Aquatic passive sampling of perfluorinated chemicals with polar organic chemical integrative sampler and environmental factors affecting sampling rate.

A modified polar organic chemical integrative sampler (POCIS) could provide a convenient way of monitoring perfluorinated chemicals (PFCs) in water. In the present study, the modified POCIS was calibrated to monitor PFCs. The effects of water temperature, pH, and dissolved organic matter (DOM) on the sampling rate (R s) of PFCs were evaluated with a static renewal system. During laboratory validation over a 14-day period, the uptake kinetics of PFCs was linear with the POCIS. DOM and water temperature slightly influenced POCIS uptake rates, which is in consistent with the theory for uptake into POCIS. Therefore, within a narrow span of DOM and water temperatures, it was unnecessary to adjust the R s value for POCIS. Laboratory experiments were conducted with water over pH ranges of 3, 7, and 9. The R s values declined significantly with pH increase for PFCs. Although pH affected the uptake of PFCs, the effect was less than twofold. Application of the R s value to analyze PFCs with POCIS deployed in the field provided similar concentrations obtained from grab samples.

A Comparative Study on The Acute Toxicity Bioassay of Dimethoate and Lambda-cyhalothrin and Effects on Thyroid Hormones of Freshwater Teleost Fish Labeo rohita (Hamilton)

Dimethoate (organophosphate insecticide) and Lambda-cyhalothrin (synthetic pyrithroid) aretwo frequently used pesticides due to their high effectiveness and rapid breakdown into environmentally safeproducts. The aim of this present study was to assess and compare the acute toxicity of Dimethoate(Rogor30%EC) and Lambda-cyhalothrin (5%EC) on Labeo rohita (Hamilton). Acute toxicity bioassay wascarried out in a static renewal system to assess the toxicity. The fishes were exposed to different concentrationof dimethoate and Lambda-cyhalothrin to determine the LC50 values for 96hrs. The mortality data obtainedwere analyzed by SPSS 16.0 based on Finney’s Probit Analysis Statistical method. The 96h LC50 values forDimethoate and Lambda-cyhalothrin were found to be 24.55 μl/L and 0.7 μl/L respectively. Effects of thesetwo insecticides on serum T3, T4 and TSH were investigated under sub-lethal toxicities which cause decrease inthe serum T3, T4 and increase in TSH level. It shows significant difference from control fish (p < 0.05)..

Sensitivity of freshwater pulmonate snail Lymnaea luteola L., to silver nanoparticles

Toxicity of nanoparticles depends on many factors including size, shape, chemical composition, surface area and surface charge. Silver nanoparticles (AgNPs) are likely to enter the aquatic ecosystems because of their multiple applications and pose a health concern for humans and aquatic species. Therefore, we used a freshwater snail Lymnaea luteola L (L. luteola) to investigate the acute toxicity and genotoxicity of AgNPs in a static-renewal system for 96h. AgNPs caused molluscicidal activity in L. luteola, with 96-h median lethal concentrations (LC50) (48.10μgL−1). We have observed that AgNPs (36μgL−1) elicited a significant (p<0.01) reduction in glutathione, glutathione-s-transferase and glutathione peroxidase with a concomitant increase in malondialdehyde level and catalase in digestive gland of L. luteola. However, a significant (p<0.01) induction in DNA damage was observed by the alkaline single cell gel electrophoresis in digestive gland cells treated with AgNPs for 24 and 96h. These results demonstrate that silver nanoparticles are lethal to freshwater snail L. luteola. The oxidative stress biomarkers and comet assay can successfully be used as sensitive tools of aquatic pollution biomonitoring.