Pesticides in water and sediment from littoral area of Lake Biwa

Spatiotemporal variations, surface inventory, and cross regional impact of current-use organoamine pesticides in Chinese Marginal Seas

Current-use Organoamine Pesticides (CUOAPs) are a growing concern as emerging pesticide pollutants that were initially discovered on a large scale in Chinese Marginal Seas (CMSs). The highest level was detected in the East China Sea in the late spring and decreased in the following order: East China Sea (early spring) > the South China Sea > the Bohai Sea. The crucial role played by the Yangtze and Yellow rivers as significant terrestrial sources were established. The fluctuations in the land application and riverine input led to variations in the source, distribution, and seasonal patterns of CUOAPs. Terrestrial-exported CUOAPs were transported and redistributed spatially by the surface ocean currents, resulting in significant regional disparities. The results displayed a pronounced terrestrial source signature and a cross-regional impact. By the ocean current transport, CMSs will likely become a secondary source region for the surrounding seas.

Acute exposure of Isopyrazam damages the developed cardiovascular system of zebrafish (Danio rerio)

Isopyrazam (IPZ) is one of the broad-spectrum succinate dehydrogenase inhibitor fungicides (SDHIs). Although the potential bio-toxicity of SDHIs has been reported hourly, the specific effects focused on the cardiovascular system have remained unclear and piecemeal. Thus, we chose IPZ as a representative to observe the cardiovascular toxicity of SDHIs in zebrafish. Two types of transgenic zebrafish, Tg (cmlc2:GFP) and Tg (flk1:GFP) were used in this study. Healthy embryos at 6 hpf were exposed to IPZ solutions. The statistical data including survival rate, hatching rate, malformed rate, and morphological and functional parameters of the cardiovascular system at 48 hpf and 72 hpf demonstrated that IPZ could cause abnormalities and cardiovascular defects such as spinal curvature, dysmotility, pericardial edema, pericardial hemorrhage, and slowed heart rate, etc. At the same time, the activity of enzymes related to oxidative stress was altered with IPZ. Our results revealed that IPZ-induced cardiovascular toxicity and oxidative stress might be one of the underlying toxic mechanisms.

Distribution of organochlorine, organophosphates, carbamate, thiocarbamate, pyrethroids, and strobilurins in surface sediments of the Rio de Ondas watershed by GC-MS

The determination of some pesticides in surface sediments can provide important information about their distribution in the water column. This work aimed to determine the distribution of the classes of pesticides along the Ondas River's hydrographic basin (ORHB), in eighteen different points, during the dry and rainy periods. The pesticides were extracted from the sediment samples by solid-liquid extraction and then analyzed using a gas chromatograph coupled to mass spectrometry. After the development and validation of the method, nineteen pesticides from the group of organochlorine, organophosphates, carbamate and thiocarbamate, pyrethroids, and strobilurins were quantified in at least one point in the two collection periods, with accuracy varying between 86 and 126%. The average concentrations were 0.020 ng g^-1 (carbofuran) to 249.123 ng g^-1 (dimethoate) and 0.029 ng g^-1 (carbofuran and sulfotep) to 533.522 ng g^-1 in the dry and rainy periods, respectively. The results showed a wide distribution of pesticide residues in the ORHB, with higher levels for dimethoate, phenitrothion, and malathion, which may be related to their agricultural use in the region. In Brazil, it does not have specific legislation for maximum permitted values of pesticides in sediment, allowing for inappropriate or prohibited use and, consequently, affecting water quality.

Toxicity of the organophosphate insecticide sumithion to embryo and larvae of zebrafish

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The 24 h LC₅₀ value of sumithion for embryo was 0.235 mg L⁻¹.

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Several malformations were observed in embryos exposed to different concentrations of sumithion.

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The 24, 48 and 72 h LC₅₀ values of sumithion for larvae were 0.620, 0.475 and 0.341 mg L⁻¹, respectively.

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Different deformities were evident in the sumithion exposed larvae.

Sumithion, a synthetic organophosphate, is widely used as an agricultural insecticide and for control of tiger bug (Cicindela spp.) in larval rearing for aquaculture. An experiment was conducted to examine the effects of sumithion on embryological and larval development of zebrafish Danio rerio. Fertilized egg (n = 100) and larvae (n = 100) were exposed to six concentrations of sumithion (0, 0.1, 0.2, 0.4, 0.8 and 1.6 mg L⁻¹) in three replicates. LC₅₀ values for embryos and larvae were calculated by probit analysis. The 24 h LC₅₀ value of sumithion for embryo was 0.235 (0.079-0.428) mgL⁻¹. Increasing sumithion concentrations decreased hatching success and increased embryonic mortality. In embryos, sumithion induced several malformations including immature yolk sac, dark yolk sac, yolk sac bud, broken eggshell and notochord, unhatched eggs. Larval LC₅₀ values at 24, 48 and 72 h of various doses of sumithion exposure were 0.620 (0.436-0.963), 0.475 (0.302-0.801) and 0.341 (0.177-0.617) mgL⁻¹, respectively. Various physical deformities, including edema, notochord deformity, yolk sac damage, body arcuation, lordosis and black pigmentation on the yolk sac were evident in response to different concentrations of sumithion. The results of the current study indicate that sumithion exerts developmental toxicity to zebrafish embryos and larvae. It is expected that current findings will increase sensitivity about the toxic effect of sumithion in early development, as well the possibility of similar actions induced by other insecticides and pesticides.

Increase in water temperature increases acute toxicity of sumithion causing nuclear and cellular abnormalities in peripheral erythrocytes of zebrafish Danio rerio

Global warming and indiscriminate usages of pesticides are notable concern to all. The present study has been conducted to evaluate the effects of high temperature on acute toxicity of sumithion in adult zebrafish. A 2-day renewal bioassay system was used to determine the 96 h LC₅₀ value of sumithion at three temperature regimes, such as 25 °C, 30 °C, and 35 °C. Blood glucose (mg/dL) level was measured in control (0.0 mg/L) and low concentration (1.0 mg/L) of sumithion during the determination of LC₅₀ in three temperature conditions. In addition, micronucleus (MN), erythrocytic nuclear abnormalities (ENA), and erythrocytic cellular abnormalities (ECA) tests were performed in the blood erythrocytes. The 96 h LC₅₀ value of sumithion for zebrafish was significantly lower at 35 °C, which indicates that the toxicity of sumithion increases at higher temperature. Blood glucose level was significantly increased by sumithion in all temperature conditions, while it was significantly higher in the highest (35 °C) temperature compared to the lowest (25 °C) temperature in both control and sumithion-treated fish. Similarly, frequencies of MN, ENA, and ECA were elevated by sumithion in all temperature conditions, whereas it was significantly raised in the highest (35 °C) temperature compared to the lowest (25 °C) temperature in both control and sumithion treated fish. With increasing temperature in exposure to sumithion, dissolved oxygen decreased significantly, whereas free CO₂ increased significantly. On the other hand, no distinct changes were observed in pH and total alkalinity during the experimental period. Therefore, it can be inferred that increasing temperature enhances the toxicity of sumithion in the zebrafish.

Evaluation of algal photosynthesis inhibition activity for dissolved organic matter with the consideration of inorganic and coloring constituents

The effect of waterborne ingredient on ecosystem has been of great interest. In the present study, the evaluation method using algal photosynthesis inhibition assay with dual-channel pulse amplitude modulation (PAM) system was established for a series of water samples to elucidate the potential effect of the total body of organic compounds including natural organic matter (NOM) on aquatic ecosystems. The more sensitive and less time-consuming monitoring method compared with algal growth inhibition assay was suggested, especially considering inorganic and coloring constituents. Algal photosynthesis inhibition activity was detected with high sensitivity for photosystem II (PSII) inhibitors, whereas the IC₁₀ of the other chemicals was over the environmental standard concentration for Chlamydomonas moewusii (Chlorophyceae) and Pheodactylum tricornutum (Diatomea). The photosynthesis inhibition activity of Lake Biwa dissolved organic matter (LBDOM) and fulvic acid (LBFA) was significantly detected at ≥10 times the concentration and >10 mgC L^-1, respectively, whereas prominent activity was confirmed for Suwannee River NOM (SRNOM) on the river original concentration (>30 mgC L^-1) for both algae. Significant inhibition activity was detected in both algae at least in twice-concentration for water samples from a wastewater treatment pilot plant. There was no great difference in the activity between sewage secondary effluent and its filtrate with ultrafiltration (UF), and physically washing water for the UF membrane.

Temporal trends in organophosphorus pesticides use and concentrations in river water in Japan, and risk assessment

We reviewed organophosphorus pesticide use in Japan between 1982 and 2016 using data from the National Institute of Environmental Studies. Organophosphorus pesticide concentrations in river water throughout Japan were taken from the literature, and risk assessments were performed for some organophosphorus pesticides based on risk quotients and hazard quotients. Assessments were performed for 20 common pesticides, including insecticides, fungicides, and herbicides. The amounts used decreased in the order: insecticides > herbicides > fungicides. Organophosphorus insecticide and fungicide use have decreased over the last four decades, but organophosphorus herbicide use has increased. During this period, annual organophosphorus pesticide use was the highest for chlorpyrifos (105,263 tons/year) and the lowest for glyphosate-sodium (8 tons/year). The ecotoxicological risk assessment indicated that diazinon and fenitrothion posed strong risks to the Japanese aquatic environment, and chlorpyrifos and malathion have moderate risks. None of the pesticides that were assessed posed significant risks to humans. Continued use of organophosphorus pesticides in Japan may cause strong risks to aquatic environments. These risks should be reassessed periodically.

Effects of penthiopyrad on the development and behaviour of zebrafish in early-life stages

The agricultural use of succinate dehydrogenase inhibitor (SDHI) fungicides has increased dramatically in the US and Europe. As the SDHI fungicides, boscalid, flutolanil and thifluzamide had been reported to induce a series of toxic effects on zebrafish. However, the toxic effects of penthiopyrad on zebrafish have not been reported yet. This study aimed to assess the acute toxicity of penthiopyrad to zebrafish in early-life stages and investigate behavioural response of larvae and the effects on lipid metabolism and pigmentation under sub-lethal exposure of penthiopyrad. Based on results of the acute toxicity tests of zebrafish embryo and larvae, penthiopyrad had an acute toxicity to early-life stages of zebrafish and induced a series of deformities during development. Based on the results of sub-lethal exposure for 8 days, penthiopyrad resulted in significant decreases in swimming velocity, acceleration speed, distance moved and inactive time of larvae at 0.3, 0.6 and 1.2 mg/L. Penthiopyrad induced the disorders of lipid metabolism via affecting fatty acid synthesis and β-oxidation, in accordance with remarkable changes in the content of triglycerides and cholesterol and the expression of key genes (hmgcrα, pparα1, srebf1, cyp51 and acca1) at 1.2 mg/L. In addition, the disorder of melanin synthesis and distribution was caused by penthiopyrad in larvae in accordance with changes in body colour and related gene expression at 8 dpe.

Impacts of isopyrazam exposure on the development of early-life zebrafish (Danio rerio)

Isopyrazam (IPZ) is a broad spectrum succinate dehydrogenase inhibitor fungicide. Little is known about its potential ecological risks of aquatic organisms recently. The present study examined the embryonic development effects of zebrafish exposed to IPZ under static condition using a fish embryo toxicity test. The lowest observed effect concentration of IPZ was 0.025 mg/L in 4-day exposure. Developmental abnormalities, including edema, small head deformity, body deformation and decreased pigmentation, and mortality were observed in zebrafish embryos of 0.05 mg/L and higher concentrations, which shown concentration dependency. The heart rate of zebrafish was disrupted by IPZ. Moreover, enzyme and gene experiments shown that IPZ exposure caused oxidative stress of zebrafish. Furthermore, it induced a decrease of succinate dehydrogenase (SDH) enzyme activity and gene transcription level in zebrafish larvae. It can be speculated that IPZ may have a lethal effect on zebrafish, which is accompanied by decreased SDH activity, oxidative stress, and abnormality. These results provide toxicological data about the IPZ on aquatic non-target organisms, which could be useful for further understanding potential environmental risks.

The embryonic developmental effect of sedaxane on zebrafish (Danio rerio)

The succinate dehydrogenase inhibitor (SDHI) fungicides have been extensively used in agriculture, and some of their potential ecological risks to aquatic organisms have been demonstrated recently. Sedaxane (SDX) is a broad spectrum SDHI fungicide. Despite being extensively used in environment, little is known about its potential developmental effect in zebrafish embryo. This study examined the effects of which SDX triggered in zebrafish through embryonic development assessments. Results show that SDX induced mortality, hatch delay and failure in zebrafish embryos, which were concentration dependent. In addition, several developmental abnormalities were observed at 2 mg/L and higher concentrations, including edema, microcephaly, body deformation, and swim bladder not fully inflated. SDX exposure influenced reactive oxygen species, malondialdehyde, peroxidase, glutathione S-transferase, superoxide dismutase and glutathione in live larvae, which indicated that oxidative stress was caused in zebrafish. Furthermore, SDX induced decrease of succinate dehydrogenase activity in zebrafish larvae. These results provide toxicological data of SDX on developing zebrafish embryo, which could be help for further understanding the potential risk on the environment.

Pesticide residues in muscles of some marine fish species and seaweeds of Iskenderun Bay (Northeastern Mediterranean), Turkey

Pesticide residues in muscles of nine marine fish and four seaweed species of Iskenderun Bay (Northeastern Mediterranean) have been investigated. In sampled fish species, two herbicides, three insecticides, two fungicides, and one synergist were identified and quantified. Metribuzin DADK, propamocarb HCl, and piperonyl butoxide (PBO) were detected in all the muscles of sampled fish species. Metribuzin DADK was the most abundant pesticide residue in fish muscles and the highest metribuzin DADK concentration was found in sardine (311.20 μg/kg). Propamocarb HCl concentrations varied greatly among species; from 0.530 ± 0.020 μg/kg in striped sea bream to 34.170 μg/kg in sea bass. The level of PBO ranged from 0.001 μg/kg for fourlined terapon to 0.013 μg/kg for sardine. No measurable oxamyl residue was found in any of the muscles of sampled fish species (except sardine). In seaweeds, two herbicides and two insecticides were identified and quantified. Metribuzin DADK was the most abundant and found in Cystoseira corniculata (5.01 mg/kg), Corallina elongata (0.703 mg/kg), and Jania rubens (3.85 mg/kg). Molinate was a minor contaminant and only found in Corallina elongata (0.002 mg/kg). Pyrethrin I was determined only in Padina pavonia to be 0.567 mg/kg. Pyrethrine II was found in Padina pavonia and Corallina elongate to be 1.214 and 0.229 mg/kg, respectively. The most hazardous pesticide residues of organochlorines and organophosphorus were not detected in both sampled fish muscles and seaweeds. There are no clear maximum residue limits for the detected eight pesticide residues declared for fish muscle by European Union MRL (2017). In conclusion, it can be considered that observed concentrations of pesticides in sampled nine marine fish species do not have a potential health risk for consumers. Some of the detected pesticide residues can be toxic for algae and aquatic life and regular monitoring studies are therefore essential to control the pesticide concentrations of aquatic biota in the region.

Photocatalytic degradation of molinate in aqueous solutions

In this study, the degradation of molinate through heterogeneous photocatalysis, using two different types of the semiconductor TiO2 as photocatalyst, as well as through homogeneous treatment, applying the photo-Fenton reaction, has been investigated. As far as heterogeneous photocatalysis is concerned, the degradation of the pesticide follows apparent first-order kinetics, while the type of the catalyst and the pH value of the solution affect the degradation rate. The effect of the addition of electron scavengers (H2O2 and K2S2O8) was also studied. In the case of photo-Fenton-assisted system, the degradation also follows pseudo-first-order kinetics. Parameters such as iron's and electron scavenger's concentration and inorganic ions strongly affect the degradation rate. The extent of pesticide mineralization was investigated using dissolved organic carbon (DOC) measurements. The toxicity of the treated solution was evaluated using the Microtox test based on the luminescent bacteria Vibrio fischeri. The detoxification and mineralization efficiency was found to be dependent on the system studied, and although it did not follow the rate of pesticide disappearance, it took place in considerable extent. The study of the photodegradation treatment was completed by the determination of the intermediate by-products formed during the process, which was carried out using LC-MS/MS technique and led to similar compounds with both processes.

Part I: temporal and spatial distribution of multiclass pesticide residues in lake waters of Northern Greece: application of an optimized SPE-UPLC-MS/MS pretreatment and analytical method

The present work describes the application of an analytical procedure, utilizing ultra performance liquid chromatography (UPLC) coupled with mass spectrometry instrumentation, for the determination of 253 multiclass pesticides, classified in six different groups. Solid phase extraction was applied for the isolation and pre-concentration of target compounds in water samples. Surface waters of the lakes located in Northern Greece (Volvi, Doirani, and Kerkini), were collected in two time periods (fall/winter 2010 and spring/summer 2011) and analyzed, applying the developed analytical methods. Spatial distribution of detected pesticides was visualized using interpolation methods and geographical information systems (GIS). Pesticides with maximum concentrations were amitrole, propoxur, simazine, chlorpyrifos, carbendazim, triazophos, disulfoton-sulfone, pyridaben, sebuthylazine, terbuthylazine, atrazine, atrazine-desethyl, bensulfuron-methyl, metobromuron, metribuzin, rotenone, pyriproxyfen, and rimsulfuron. In Lake Kerkini, mainly carbamates and triazines were determined at elevated concentrations, near the coastal point of the NW side of the lake. Seasonal variations were strong among the applied pesticide classes and determined concentrations, indicating the contribution of pesticide application patterns and rainfall. Lake Doirani exhibited organophosphate pesticides at higher concentrations mainly at coastal points, while triazines emerged as the main pollutant during spring sampling. Lake Volvi exhibited the highest pesticide concentrations, mostly triazines and ureas at the central part of the lake. The occurrence of extreme values and nonconstant seasonal variations indicated that the concentrations were increased disproportionately during the second sampling, as a result of the varying contribution of pollution sources right after the application period. In all cases, the total concentration of pesticides increased during the second sampling period.