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We assessed the contamination, dynamics, and health risks of the pesticides cyanazine, simetryn, fenarimol, isoprothiolane, diazinon, irgarol, fenitrothion, and diuron in marine samples (seawater, sediments, plankton, fish, and other edible organisms) at various locations in the Seto Inland Sea in Japan in 2016 and 2017. Pesticide concentrations were highest at sampling sites close to the coastline, and mean concentrations in seawater were slightly higher in surface water than in bottom water. All eight pesticides were detected in plankton. Diazinon concentrations (77-387 ng/g dw) were highest in sediments and cyanazine was the most frequently detected pesticide (88%, n = 17) in sediments. Only cyanazine (2.7-41.9 ng/g dw), simetryn (1.0-34.3 ng/g dw), and diazinon (6.3-308.8 ng/g dw) were detected in fish and other edible marine organisms. Based on the calculated bioconcentration factor, the results showed that plankton, fish, and marine animals bioaccumulated pesticides. The highest hazard quotients were calculated for diazinon in red seabream and greenling, indicating a possible risk to consumers. It is, therefore, imperative to promote strict implementation of pollution control, integrated pest management practices, and policy formulation on pesticides. Usage of diazinon must be controlled and monitored to ensure large residues do not reach aquatic ecosystems and marine coastlines.

Organic anion transporting polypeptide (OATP) 1B1 (gene, solute carrier organic anion transporter family member 1B1 [SLCO1B1]) and OATP1B3 (SLCO1B3) serve as transporters for hepatic uptake of important endogenous substances and several commonly prescribed drugs. Inactivation of both proteins together causes Rotor syndrome. How this OATP1B1/1B3 defect disturbs bile acid (BA) metabolism is largely unknown. In this study, we performed detailed BA analysis in 3 patients with genetically diagnosed Rotor syndrome. We found that BAs glucuronidated at the C‐3 position (BA‐3G) accounted for 50% or more of total BAs in these patients. In contrast but similarly to healthy controls, only trace amounts of BA‐3G were detected in patients with constitutional indocyanine green excretory defect (OATP1B3 deficiency) or sodium‐taurocholate cotransporting polypeptide (NTCP; gene, solute carrier family 10 member 1 [SLC10A1]) deficiency. Therefore, substantial amounts of BA‐3G are synthesized in hepatocytes. The cycling pathway of BA‐3G, consisting of excretion from upstream hepatocytes and uptake by downstream hepatocytes by OATP1B1/1B3 may exist to reduce the burden on upstream hepatocytes. Conclusion: Detailed BA analysis revealed glucuronidated bile acidemia in patients with Rotor syndrome. Further exploration of the physiologic role of glucuronidated BAs is necessary.

A total of 23 road-dust and 9 house-dust samples were collected from Alexandria and Kafr El-Sheikh cities, Egypt in 2016 to investigate heavy metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination, spatial distribution, sources, and health risks. The mean concentrations (mg kg−1) of Cd (road-dust (RD) = 0.33, house-dust (HD) = 0.77), Cu (RD = 80, HD = 141), Pb (RD = 70, HD = 260), and Zn (RD = 169, HD = 771) in Alexandria and Zn (RD = 192, HD = 257) in Kafr El-Sheikh were higher than corresponding background (background refers to generic earth crust shale values given in the literature) levels. Whereas average concentrations (mg kg−1) of Co, Cr, Mn, and Ni (Alexandria: RD = 2.7, 24.3, 251, 14.4; HD = 3.2, 29.2, 237, 25.1 and Kafr El-Sheikh: RD = 6.6, 31.9, 343, 20.2; HD = 8.6, 33.4, 438, 23.2) in both cities were much lower than their background values. Spatially, for most heavy metals, the high concentrations were observed in areas characterized with increased anthropogenic activities, heavy traffic, and high population density. Contamination indices revealed moderate contamination (Cd and Cu) to high contamination (Pb: only house-dust from Alexandria), which posed low (most metals) to moderate ecological risk (Cd and Pb). Correlation analysis and factor analysis classified the studied metals in two groups as: natural input (Co, Cr, Mn, Ni, and Fe) and anthropogenic sources (Cd, Cu, Pb, and Zn). The noncancerous risks posed by studied metals ranged from 0.0001 (Cd) to 0.15 (Pb) and were insignificant. The cancerous risk of Pb (1.4 × 10−4) for children on exposure to house-dust form Alexandria exceeded the guideline values and was considered unacceptable, whereas the cancerous risks of other studied metals were acceptable for both subpopulations. The results of health risk revealed that children are facing higher risk than adults.

The Eco-physiological assessments of variable parameters known to be essential for proper plant growth and health were determined in cucumber plants exposed to short term treatments in 42 days using two broad classification types; Photo Fenton solution generating OH radicals and simulated acids. Solutions containing different classification of scavengers of OH radicals and mannitol were employed as Controls. Results indicated that the acid rain and photo Fenton solution both decreased the photosynthetic rate (Amax), stomatal conductance (gs), photochemical efficiency of PSII in the dark (Fv/Fm), SPAD chlorophyll and they imparted severe foliar injuries on cucumber leaves. The acids treatments have the highest negative impact followed by the photo Fenton Solution. The mechanisms of phytotoxicity of the two solutions may be through OH radical and other Reactive Oxygen Species (ROS) generation. The addition of mannitol, catechin hydrate and tea solutions to the acids and photo Fenton solution mixtures all mitigated the negative effects of the duo on the cucumber plants. Mannitol at dosage applied in the present study can be adjudged to be the best in the amelioration of the negative effects of the fumigants. Future plant protection from deleterious impacts of atmospheric and hydrospheric pollutants can employ mannitol as scavengers of ROS.

Background and Objectives: Identification of microbial community composition is very important for understanding the degradation kinetics of pollutants in water. This study was conducted to isolate and to identify the microbial communities of Kurose River water and to investigated the biodegradation kinetics of fenitrothion by identified microbial strains. Materials and Methods: Microbial community composition was investigated using differential display-denaturing gradient gel electrophoresis (DGGE). Identification of microbial isolates was carried out using 16S rRNA gene sequence analysis. Biodegradation of fenitrothion was carried out using High-performance liquid chromatography and gas chromatography-mass spectrometry analysis. Results: The results showed that the degradation of fenitrothion in Kurose River water occurred because of various bacterial isolates. Moreover, the degradation rate of fenitrothion in Kurose River water at different sampling sites depended on the microbial content and the chemical composition of the water. The bacteria isolated from the Kurose River identified as Pseudomonas putida and Flavobacterium sp. The degradation rate of fenitrothion by the isolated bacteria was lower in river water than in artificial growth media. The identified degradation products of fenitrothion were amino-fenitrothion and 3-methyl-4-nitrophenol. Conclusion: The microbial community and chemical composition of the Kurose River water significantly affect the fate and biodegradation kinetics of fenitrothion. Molecular identifications of microbial community structures of aquatic systems are very useful for interpretation of the fate and degradation kinetics of fenitrothion.

Mercury (Hg) adversely affects human and environmental health. To evaluate the mercury (Hg) speciation (methylation, demethylation, and reduction) of microorganisms in coastal seawater, we analyzed the microbial functional gene sets involved in Hg methylation (hgcA and hgcB), demethylation (merB), and reduction (merA) using a metagenomic approach in the eastern and western parts (the Kii and Bungo channels, respectively) of the Seto Inland Sea (SIS) of Japan. We determined the concentration of dissolved total mercury (dTHg) and methylated mercury (dMeHg) in seawater. The metagenomic analysis detected hgcAB, merA, and merB in both channels, whereas the phylogenies of these genes differed between them. A correlation between Hg concentration (both dTHg and dMeHg) and the relative abundance of each gene was not observed. Our data suggests that microbial Hg methylation and demethylation could occur in the SIS and there could be a distinct microbial Hg speciation process between the Kii and Bungo channels.

This study conducted an integrated approach combining monitoring and risk assessment of pesticides in Kurose River and its catchment area, Japan. Water samples (n = 168) were collected every month for 1 year (March 2016 to February 2017). Pesticides (cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon) were extracted by Sep-Pack C18 cartridges and analyzed using a reversed-phase HPLC-UV system. The pesticides were also determined in non-target organisms Red algae (Audouinella sp.) and diatoms (Cocconeis placentula) from the river. Based on the residual concentrations, an ecotoxicological risk assessment was conducted using the risk quotient (RQ) index. The human health carcinogenic and non-carcinogenic risk assessments were evaluated using hazard quotients (HQ). Results showed that cyanazine was the most commonly detected (64%), followed by simetryn (58%), and diazinon (57%) in all the sample sites (n = 12). Except for isoprothiolane, the pesticides were highest in spring followed by summer, autumn and winter. Based on extreme values (ex), non-acceptable ecotoxicological risk was obtained for diazinon (RQ

Polycyclic aromatic hydrocarbons (PAHs) were analyzed to elucidate the distribution, ecological risk, pathways, and fluxes of these pollutants in and around the Seto Inland Sea, an industrialized coastal region of Japan. High molecular weight PAHs (5-6 rings) were primarily found in regions close to the bay estuaries, and their proportions decreased at distances further from the estuaries (offshore areas), where low molecular weight PAHs (2-4 rings) were more ubiquitous. Screening-level risk assessments revealed that the PAHs found in the sediments should have no adverse effects on benthic communities. A mass balance for PAHs in the Seto Inland Sea, calculated based on data collected in the field and published literature findings, showed the PAH flux into the Seto Inland Sea from atmospheric deposition were ca. 6 times higher than that from riverine inflows. Comparison of the amount of the PAH mass flux between the Seto Inland Sea and the sea of the Europe and Asian countries indicated that the Seto Inland Sea is less polluted than the Gulf of Lion, the Mediterranean Sea, and the Bohai Sea, China and more polluted than the Yellow Sea. This paper is the first to determine the fluxes of PAHs in the coastal region of Japan.

Because pesticide-contaminated water can harm living organisms, pesticide residues need to be monitored, their sources need to be identified, and the risks they pose should be assessed. In this study, the sources, fluxes, and discharges of, and risks from, pesticides were monitored and assessed during the rice-growing season (from April to October) in the Kurose and Ashida Rivers in Hiroshima, Japan. Water samples were collected monthly, subjected to solid-phase extraction, and then analyzed by gas chromatography–mass spectrometry and high-performance liquid chromatography to determine the presence and concentrations of pesticides. The fluxes of the detected pesticides were also estimated at each site in the Kurose and Ashida rivers, and the discharges of these pesticides from different sources were determined. The potential ecotoxicological risks from the detected pesticides to the aquatic systems were also evaluated. Thirteen pesticides were detected in the Kurose River. Of these, the mean concentrations of diroun (970 ng/L) and butamifos (4.7 ng/L) were the highest and the lowest, respectively. Eleven compounds were detected in the Ashida River. Again, the mean concentration of diuron (860 ng/L) was the highest, while that of flutolanil (5.5 ng/L) was the lowest. The pesticide fluxes were the highest in the Ashida and Kurose Rivers in October and May, respectively. The main sources of pesticide discharges were rice paddies, orchards, and vegetable fields. The results of the ecotoxicological risk assessment indicated that fenitrothion, diuron, dichlorvos, and benthiocarb posed high risks to the aquatic environment in the Ashida and Kurose Rivers.

The study assessed heavy metals (Cd, Cu, Fe, Mn, Pb and Zn) and physico-chemical parameters in water, sediments and fish from an endorheic lake (Lake Chilwa) in Malawi. It was observed that pH (max. 9.7), EC (max. 2936 μS/cm), TDS (max. 2119 mg/L), NO3− (max. 6.6 mg/L) and PO43− (max. 1.3 mg/L) were higher in the dry season than in the rainy season. Pb was not detected in all samples. However, the rest of heavy metals were detected with significant values of Mn and Cu in fish (Mn: 0.015–1.18 mg/kg dry weight, dw; Cu: 0.41–0.92 mg/kg dw) and sediment (Mn: 2.25–10.66 mg/kg dw; Cu: n.d–1.63 mg/kg dw). The concentrations of heavy metals in fish samples were below the maximum limits for edible fish recommended by Food and Agriculture Organization/World Health Organization: Cd (0.1 mg/kg), Cu (3 mg/kg), Fe (43 mg/kg), Pb (0.2 mg/kg), Mn (2–9 mg/kg) and Zn (60 mg/kg). The calculated target hazard quotients (ranged from 0.001 to 1.07) indicated no human risks from fish consumption. Furthermore, dry season values for Mn, Cu and Zn in sediments were significantly higher (p

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.

In this study, the kinetics of photocatalytic removal of imidacloprid, a systemic chloronicotinoid insecticide, from water using two advanced oxidation systems (ZnO(normal)/H2O2/artificial sunlight and ZnO(nano)/H2O2/artificial sunlight) were investigated. Moreover, the effects of pH, insecticide concentration, catalyst concentration, catalyst particle size, and water type on the photocatalytic removal of imidacloprid were evaluated. Furthermore, total mineralization of imidacloprid under these advanced oxidation systems was evaluated by monitoring the decreases in dissolved organic carbon (DOC) concentrations and formation rate of inorganic ions (Cl− and NO2−) with irradiation time using total organic carbon (TOC) analysis and ion chromatography to confirm the complete detoxification of imidacloprid in water. The degradation rate of imidacloprid was faster under the ZnO(nano)/H2O2/artificial sunlight system than the ZnO(normal)/artificial sunlight system in both pure and river water. The photocatalytic degradation of imidacloprid under both advanced oxidation systems was affected by pH, catalyst concentration, imidacloprid concentration, and water type. Almost complete mineralization of imidacloprid was only achieved in the ZnO(nano)/H2O2/artificial sunlight oxidation system. The photogeneration rate of hydroxyl radicals was higher under the ZnO(nano)/H2O2/artificial sunlight system than the ZnO(normal)/H2O2/artificial sunlight system. Advanced oxidation processes, particularly those using nanosized zinc oxide, can be regarded as an effective photocatalytic method for imidacloprid removal from water.This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

The optical properties of dissolved organic matter (DOM) from five rivers (Kokubu, Kurose, Ohta, Yamato, and Yodo) in Japan were investigated and contributions of DOM to photoformation of three reactive oxygen species (ROS) (hydroxyl radicals (OH), nitric oxide radicals (NO), and singlet oxygen (

In this study, we experimentally investigated the magnitude of the peroxynitrite sink: a radical-radical consumption mechanism for photochemically generated nitric oxide (NO) in surface seawater that describes NO reactions with co-generated superoxide (O2-) to yield peroxynitrite (ONOO-). Measurements of photochemically generated NO, O2- and ONOO- were conducted on seawater samples obtained from the Seto Inland Sea, Japan. Nitrite, dissolved organic carbon, chromophoric dissolved organic matter and pH were also measured in the same samples using standard analytical methods. The average photoformation rates of NO, O2- and ONOO- were: 1.78 × 10-12 M s-1, 7.19 × 10-10 M s-1 and 9.0 × 10-10 M s-1, respectively, and the average steady-state concentrations were: 67.28 × 10-12 M, 2.69 × 10-12 M and 2.26 × 10-11 M, respectively. Further evaluation of the experimental data indicated that the existence of ONOO- in seawater strongly depends on, and is limited by, photoformed NO. Seawater alkalinity favored the consumption of photoformed NO· via the peroxynitrite sink. The magnitude of average sinks (%) calculated from kinetic estimates and experimental data were: 0.17% and 0.11%, respectively. These results show that the consumption of photochemically generated NO· via the peroxynitrite sink is not significant in surface seawater. Therefore, we propose that sea-to-air efflux across the marine boundary layer is the major sink of photochemical NO· and can be regarded as a non-anthropogenic contributor to daytime atmospheric NOx concentrations.

Chromophoric-dissolved organic matter (CDOM) acts as the precursor to singlet oxygen (1O2) in natural waters, while water acts as the main scavenger. In this study, we showed that 1O2 in coastal seawater can be successfully predicted from CDOM parameters. The 1O2 steady-state concentration [1O2]ss and photoformation rate (R1O2) varied by a factor of 6 across 13 sampling stations in the Seto Inland Sea, Japan, ranging from 1.2 to 8.2 × 10-14 M and 3.32 to 22.7 × 10-9 M s-1, respectively. Investigation of CDOM optical properties revealed that CDOM abundance measured as the absorption coefficient at 300 nm (a300) had the strongest correlation (r = 0.96, p < 0.001) with [1O2]ss, while parameters indicative of CDOM quality (e.g., spectral slope) did not influence [1O2]ss. A linear relationship between [1O2]ss and a300, normalized to a sunlight intensity of 0.91 kW/m2, was derived as [1O2]ss (10-14 M) = 2.12(a300) + 0.48. This was then used to predict [1O2]ss using a300 values from a subsequent, independent sampling exercise conducted 2 years after the first sampling. There was a good agreement (r = 0.93, p < 0.001) between the predicted values and the experimentally determined values based on a 95% prediction interval plot. Kinetic estimations using [1O2]ss suggest that 1O2 mediates the degradation of tetrabromobisphenol A in surface seawater (t1/2 = 0.63 days) while also contributing to the indirect photolysis of methyl mercury. The findings from this study suggest that large-scale modeling of 1O2 generation in surface seawater from CDOM parameters is possible with useful environmental significance for determining the fate of pollutants.

Hydrogen peroxide (H2O2) is a reactive oxygen species formed in natural water. It is reportedly toxic to aquatic organisms with a predicted no-effect concentration (PNEC) of about 380 nM. In this study, a countrywide investigation of H2O2 concentrations in selected rivers across Japan was conducted to identify rivers that pose toxicity concerns. Twelve rivers with a total catchment area of 13,646 km2 were selected from different prefectures. Spatial and temporal variation studies showed that the H2O2 concentrations (avg. 320 nM, n = 111) varied by two orders of magnitude (range 21–2929 nM) across the rivers. The Yamato River in Osaka and Nara prefectures and the Kokubu River in Chiba Prefecture had the highest concentrations at 276–669 nM and 236–2929 nM, respectively. >75% of the data from the two rivers were either close to or exceeded the PNEC. Most of the results for the other rivers were less than the PNEC. There was a clear seasonal variation in the H2O2 concentrations, with the highest values obtained in summer because of high solar irradiation. The H2O2 concentration had the highest positive correlation (r = 0.61, p

Peroxynitrite (ONOO−) is a reactive species which can degrade several classes of organic compounds via both oxidation and nitration reactions. Despite the fact that the photochemical precursors; superoxide (O2·−) and nitric oxide (NO·) radicals, have been measured in seawater under simulated solar radiation, there is no published report on actual measurements of photoformed peroxynitrite in seawater. Hence, this attempt was made to develop a fluorescence method by using coumarin boronic acid (CBA) as a chemical probe. CBA reacts with ONOO− to yield fluorescent 7-hydroxycoumarin (COH). COH was determined by reversed‒phase isocratic HPLC with fluorescence detection at excitation/emission wavelengths of 332/475 nm, respectively. COH standards calibration is linear in range of (0.25–100) × 10−9 M. The detection limit, defined as 3σ of the lowest ONOO- photo-formation rates obtained within 10- min irradiation, was 1.66 × 10−12 M s−1. This method is very precise as coefficient of variation for triplicate measurements of COH photo-formation rates was a maximum of 0.052. Experimental procedures were optimized to handle potential interference by hypochlorite, and the method was applied to measure ONOO− in 13 surface seawater samples obtained from the Seto Inland Sea, Japan. ONOO− photo-formation rates, steady‒state concentrations and lifetimes were determined to be (0.06–5.13) × 10−9 M s−1, (0.98–6.11) × 10−11 M and (0.01–0.16) s, respectively.

A total of 23 road-dust and 9 house-dust samples were collected from Alexandria and Kafr El-Sheikh cities, Egypt in 2016 to investigate heavy metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination, spatial distribution, sources, and health risks. The mean concentrations (mg kg

This study investigated spatio-temporal variations of selected pesticide residues in the Kurose River in Higashi-Hiroshima city (Hiroshima Prefecture), Japan. Water samples were collected from the river at seven sites every month for 1 year (March 2016 to February 2017). Pesticide residues were extracted from the samples by a solid phase extraction using Sep Pack C18 cartridges. Once extracted, the samples were analyzed for cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon using a reversed-phase high-performance liquid chromatography ultraviolet visible (HPLC-UV Vis) system. The limits of detection were 3.60, 4.10, 2.80, 6.50, and 7.30 ng L-1 for cyanazine, simetryn, fenarimol, isoprothiolane, and diazinon, respectively. Good recovery rates (88%–102%), and mean percent relative standard deviation range (1.00%–5.70%) (n = 6) were obtained with a spiking at 0.20 µg L-1. The maximum concentrations of 282, 391, 60, 1086, and 1194 ng L-1 were obtained for cyanazine, simetryn, isoprothiolane,...

Okinawa Island, located in Southern Japan, has a higher prevalence rate of hepatitis C virus subtype 1a (HCV-1a) infection than that in mainland Japan. Okinawa has a history of US military occupation after World War II. To elucidate the transmission history of HCV-1a in Okinawa, 26 whole-genome sequences were obtained from 29 patients during 2011-2016. Phylogenetic trees were reconstructed to identify the origin and characteristics of HCV-1a in Okinawa with epidemiological information. A phylogenetic tree based on whole-genome sequencing revealed that all of the samples were located below the US branches. Additionally, we identified one cluster comprised of 17 strains (Okinawa, n = 16; United States, n = 1). The majority of the patients in this cluster were people who inject drugs (PWID), indicating the presence of a people who inject drugs (PWID) cluster. Subsequently, Bayesian analyses were employed to reveal viral population dynamics. Intriguingly, a phylodynamic analysis uncovered a substantial increase in effective population size of HCV-1a from 1965 to 1980 and a slight increase in mid-2000, which were associated with an increase in illicit drug use in Okinawa. The estimated divergence time of the PWID cluster was 1967.6 (1964.2-1971.1). These findings suggest that HCV-1a was introduced into Okinawa from the United States in the late 1960s, coincident with the Vietnam War. Subsequently, HCV-1a might have spread among the Japanese population with the spread of injecting drug use. Our study provides an understanding of HCV transmission dynamics in Okinawa, as well as the key role of PWID in HCV transmission.

A non-enzymatic fluorescence method for the determination of hydrogen peroxide (H2O2) was investigated. This method is based on the hydroxylation reaction of terephthalate (TP) by hydroxyl radical formed from reaction between H2O2 and Fe(II), resulting in the formation of a strongly fluorescent 2-hydroxyterephthalate (HTP). Under optimized conditions, a 3 nM detection limit and 1.0% precision at 200 nM were obtained. This was sensitive enough to determine the concentrations of H2O2 in coastal marine environments. The slopes of the calibration curve in seawater were nearly the same as those in Milli-Q water, suggesting that the fluorescent intensity was not affected by coexisting sea salts. However, the presence of nitrite at more than 10 μM interfered with the formation of HTP. The developed method was successfully applied to determine the concentrations of H2O2 in Osaka Bay on the research vessel. The results obtained in Osaka Bay demonstrated that H2O2 was photochemically produced via the photolysis of dissolved organic matter supplied from the river with fresh water at the surface layer.

A review of Japan’s fungicide usage from the 1960s to recent times was conducted using data from the National Institute of Environmental Studies, Japan. A total of 16 commonly used fungicides were assessed and these are: captan, chlorothalonil, fenarimol, ferbam, fosetyl-Al, iprodione, isoprothiolane, mancozeb, mepronil, metalaxyl, myclobutanil, pencycuron, thiophanate-methyl, tolclofos-methyl, triadimefon and trifloxystrobin. The assessment revealed that the most used fungicide within the period (1962–2014) was chlorothalonil with a maximum usage amount of 1795 tons/year. The least used was found to be myclobutanil with a maximum usage amount of 8 tons/year within the same reporting period. Generally, the usage of most of the fungicides peaked between the 1980s to early 2000s. For most of these fungicides, their usage amounts have decreased in recent times. However, the continuous usage of these fungicides has a potential to cause problems in the environment ranging from mere irritations to being very toxic to human beings and organisms.

We propose a simple, efficient and selective hydroxyl radical generation system based on the photolysis of submicromolar concentrations of nitrite using a high-power ultraviolet light emitting diode (UV-LED). Hydroxyl radical formation by the 6.75-W UV-LED was at least 10 times greater than that by a 300-W Xe lamp. In the UV-LED system, the hydroxyl radical formation rate from nitrite was about four orders of magnitude larger than that from nitrate and two orders of magnitude larger than that from hydrogen peroxide. Such efficient and selective hydroxyl radical formation can be attributed to the overlap of the emission spectrum of the UV-LED and absorption of nitrite. The system was used to determine the reaction rate constants between hydroxyl radicals and chemicals based on the competition method with terephthalate as the hydroxyl radical probe. The reaction rate constants between hydroxyl radicals and some low-molecular-weight organic compounds and inorganic halide salts with various reaction rate constants were determined. The values obtained ranged from 105 to 1010 M−1 s−1, and agreed well with previously reported values. The potential of the developed method to determine the reaction rate constants of hydroxyl radicals is discussed.

The fate of carbaryl in the Seto Inland Sea (west Japan) was predicted using a mass distribution model using carbaryl concentrations in river and sea water samples, degradation data, and published data. The predicted carbaryl concentrations in water in Kurose River and the Seto Inland Sea were 4.320 and 0.2134 μg/L, respectively, and the predicted concentrations in plankton, fish, and sediment were 0.4140, 2.436, and 1.851 μg/g dry weight, respectively. The carbaryl photodegradation and biodegradation rates were higher for river water (0.330 and 0.029 day−1, respectively) than sea water (0.23 and 0.001 day−1, respectively). The carbaryl photodegradation rates for river and sea water (0.33 and 0.23 day−1, respectively) were higher than the biodegradation rates (0.029 and 0.001 day−1, respectively). The hydrolysis degradation rate for carbaryl in sea water was 0.003 day−1, and the half-life was 231 days. Land (via rivers) was the main source of carbaryl to the Seto Inland Sea. The model confirmed carbaryl is distributed between sediment, plankton, and fish in the Seto Inland Sea. Degradation, loss to the Open Ocean, and sedimentation are the main carbaryl sinks in the Seto Inland Sea, accounting for 43.81, 27.90, and 17.68%, respectively, of total carbaryl inputs. Carbaryl source and sink data produced by the model could help in the management of the negative impacts of carbaryl on aquatic systems and human health., This research was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (grant number 16KT0149).

Reactive oxygen species (ROS) including singlet oxygen (1O2) and hydroxylradicals (radical dotOH) photogenerated in natural waters play important roles in indirect photolysis of man-made pollutants. This study was conducted to investigate how the generation of these two ROS influences the degradation of two highly toxic insecticides (methomyl and carbaryl) in river water. To accomplish this, the reaction rate constants of 1O2 and radical dotOH with carbaryl and methomyl were determined; the degradation rate constants of the tested insecticides in ultrapure water (direct photolysis) and in river water in the presence and absence of 1O2 and radical dotOH scavengers were also measured. The rate constants for the reaction of radical dotOH with carbaryl and methomyl were found to be (14.8 ± 0.64) × 109 and (4.68 ± 0.52) × 109 M−1 s−1, respectively. The reaction rate constant of 1O2 with carbaryl (2.98 ± 0.10) × 105 M−1 s−1, was much higher than that of methomyl (, The Japan Society for the Promotion of Science (JSPS) is acknowledged for funding an invitation research fellowship provided to Professor Aly Derbalah at Hiroshima University, Japan. This study was supported by JSPS KAKENHI grant number 16KT0149 and 161T05622, Japan.

Airborne infectious diseases such as the new Coronavirus 2019 (COVID-19) pose serious threat to human health. Indoor air pollution is a problem of global environmental concern as well. Singlet oxygen (1O2) is a reactive oxygen species that plays important role in bacteria/virus inactivation and pollutant degradation. In this study, we found that commercially available filters typically deployed in air purifier and air conditioning units, when impregnated with Rose Bengal (RB) as a 1O2 sensitizer, can be used for heterogeneous gas-phase generation of 1O2. It was confirmed that irradiation of the RB filter under oxygen gas stream produced 1O2, which was measured using furfuryl alcohol trapping method followed by HPLC analysis. It was also observed that the amount of 1O2 generated increases as the light intensity increased. Similarly, the sensitizer loading also positively influenced the 1O2 generation. The heterogeneous gas-phase generation of 1O2 can find potential applications in air purifier and air conditioning units for the purpose of bacteria/virus inactivation and/or pollutant degradation thereby improving indoor air quality., Graphical abstract Unlabelled Image, Highlights • Gas-phase singlet oxygen (1O2) generation from Rose Bengal-impregnated filter • A simple experimental set-up for gas phase 1O2 estimation from impregnated filter • Sensitizer loading and light intensity were the most important factors. • Potential application of 1O2 for indoor bacteria/virus inactivation in air

The photo-Fenton reaction is a key source of the highly reactive hydroxyl radical (HO) that is produced by the reaction of simultaneous photo-induced generation of Fe(2)(+)-dissolved organic matter (DOM) with H2O2 in sunlit surface waters as well as in the treatment of organic pollutants in the advanced oxidation processes (AOPs). Concentrations of both H2O2 and Fe(2)(+)-DOM were dependent on time and total solar intensity flux, and their levels were highest in the diurnal samples collected at noon compared with the samples collected during the period before sunrise and after sunset. H2O2 and Fe(2)(+)-DOM concentrations during monthly readings were also found higher in comparison with the diurnal samples, shortly before sunrise or after sunset. A π-electron bonding system is formed between Fe and the functional groups in DOM (Fe-DOM), through electron donation from the functional groups of DOM to an empty d-orbital of Fe. The π-electron is loosely bound and is highly susceptible to a rapid excitation upon light exposure that will provide better understanding of the formation of aqueous electrons, superoxide radical anions, H2O2 and finally, photo-Fenton reactions, too. Our results imply that simultaneous generation of H2O2 and Fe(2)(+)-DOM upon sunlight exposure during the daytime is most likely to be the key photo-Fenton reaction pathway, taking place in surface waters.

Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO2 that adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3−, and CO32−) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO2 itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different timescales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena.

A mass distribution model was used to predict the fate of Diuron, Irgarol 1051 and Fenitrothion in Seto Inland Sea which is located in western Japan. This was done by using concentration, degradation, and literature data. Diuron and Irgarol 1051 in Seto Inland Sea are mainly derived from antifouling paints used for ships and boats. On the other hand Fenitrothion exclusively comes from land via rivers and atmospheric deposition. The total inputs/yr to Seto Inland Sea were found to be 104 tons, 7.65 tons and 5.14 tons for Diuron, Irgarol 1051 and Fenitrothion, respectively. The pesticide residence times were 0.26 yr, 0.36 yr and 0.17 yr for Diuron, Irgarol 1051 and Fenitrothion, respectively. Photodegradation was faster than biodegradation. In seawater, the half-life ranges were 37.9-57.3 d for photodegradation. In the same seawater the half-life ranges were 1650-2394 d for biodegradation. Photodegradation is effective in surface water (0-5 m depth) while biodegradation occurs throughout the entire water column. Plankton and fishes accumulate these pesticides significantly. The pesticides are deposited (sorbed and buried with) sediments (between 74 and 87% of total input amounts). The open ocean is an important sink accounting for between 8 and 17% of the total pesticide input amounts while photo- and biodegradation accounts for a small percentage.

Organic matter in marine sediment is mainly categorized into three fractions depending on degradability: labile, semi labile and refractory. The degradability of coastal marine sediments depends on the properties of the organic matter contained in the sediments. The purpose of this study was to quantify labile and refractory organic matter in coastal marine sediments with different characteristics collected from the Seto Inland Sea, and to discover the factors controlling the degradability of organic matter. Refractory organic matter content in sediments ranged from 4.7–21.4 mg g−1, a percent composition equivalent to 72–97% of TOC. In contrast, labile and semi-labile content were 0.1–1.4 mg g−1 and 0.1–2.3 mg g−1, respectively, a percent composition equivalent to 0.5–12.9% and 1.8–17.1% of TOC, respectively. Approximately 93% of refractory organic matter was categorized into humin. Organic matter originated from marine phytoplankton settled on the surface of sediments and changed to humin or a refractory organic matter. This study contributes to a better understanding of the organic matter degradation characteristics of coastal marine sediments and provides important parameters for estimating carbon budget and carbon cycling in coastal sea systems.

Diurnal changes of H2O2 in river water during mid-summer were investigated. H2O2 in river water increased with the increase in intensity of solar radiation in the morning, and reached a maximum at 14:00, although solar radiation reached a maximum around 12:00. In the afternoon, a gradual decrease in H2O2 was observed, and H2O2 reached a minimum just before sunrise. Degradation rate constants determined using unfiltered river water samples were 0.081–0.161 h−1, corresponding to a half-life of 4.3–8.5 h. We simulated diurnal changes in H2O2 using a simple formation, accumulation, and degradation model for static water using formation and degradation rate constants. The results of the modeling suggested that in situ degradation rate constants in rivers could be faster than those determined for unfiltered river water samples. Experiments using river sand indicated that riverbed sand could play an important role in H2O2 decay in rivers. We discussed the decomposition process of H2O2 in rivers.

Environmental contextPolycyclic aromatic hydrocarbons are carcinogenic environmental contaminants that tend to migrate into the sediments in oceans and seas. Their vertical distribution in sediments from the Seto Inland Sea matched their emission over time, which in turn reflected changes in energy sources and industrial activities in Japan. This study shows that human activities on land directly and significantly influence the concentration of polycyclic aromatic hydrocarbons in sediments. AbstractSeventeen polycyclic aromatic hydrocarbons (PAHs) were identified in sediment cores collected at several locations in the Seto Inland Sea in 2015 and 2016 to understand their spatial distribution and potential emission sources. PAHs were analysed using gas chromatography–mass spectrometry. The age of the sediment cores was analysed using radioisotopic dating techniques to reconstruct historical PAH emissions. The total concentrations of 17 PAHs in the sediment cores of Osaka Bay in 2015 were in the range of 108–2810ng g−1 dry weight (dw) with a mean concentration of 1050ng g−1 dw. The total concentrations of 17 PAHs in sediment cores from the Seto Inland Sea in 2016 were in the range of 52.6–941ng g−1 dw with a mean concentration of 313ng g−1 dw. The spatial distribution of PAHs showed the highest concentration in Osaka Bay and the lowest in Kii Channel in 2016. The horizontal PAH distribution showed a decreasing trend in concentrations from the estuary offshore to Osaka Bay and Aki-Nada. The vertical PAH distribution revealed that levels were higher before the 1980s–1990s, when oil consumption and industrial activities in the Osaka region reached a maximum in the 20th century. The diagnostic ratios of PAHs and a principal component analysis revealed three main emission sources of PAHs, industry, biomass burning and traffic activities.

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in road and aerial dust to assess their concentration, composition profile, distribution, emission sources, and potential human health risks. Sixteen priority PAHs and Benzo [e]pyrene (BeP) were analyzed in 13 aerial dust samples from Jalalabad, and 78 road dust samples from Kabul and Jalalabad cities, Afghanistan. The mean concentration of ∑17PAHs in road dust from Kabul and Jalalabad were 427 μg kg−1 and 288 μg kg−1, respectively whereas ∑17PAHs in aerial dust from Jalalabad averaged 200 μg kg−1. Fluoranthene (Flu), Chrysene (Chr), Benzo [b]fluoranthene (BbF), Benzo [k]fluoranthene (BkF) and BeP were major individual PAH species. The composition patterns of the PAHs were dominated by 5-6-ring PAHs (51% in road dust from Kabul; 44% in road dust from Jalalabad; and 44% in aerial dust) followed by 4-ring and 2-3-ring PAHs. Source apportionment of the road dust PAHs by the molecular diagnostic ratios (MDR) and principal component analysis (PCA), indicated signatures of PAHs sources (including vehicular exhaust, coal/wood combustion and oil spill). The Benzo [a]pyrene (BaP) toxicity equivalent values (BaPeq17PAHs) for road dust were 75 μg kg−1 (Kabul) and 36 μg kg−1 (Jalalabad); and 35 μg kg−1 for aerial dust (Jalalabad). BaP and Dibenz [a,h]anthracene (DahA) together contributed > 50% of the BaPeq associated cancer risk. All incremental lifetime cancer risk (ILCR) due to human exposure to road and aerial dust PAHs were in the order of 10−7, which is one-fold lower than the threshold (10−6). The noncancerous risk (Hazard Index

Superoxide radical (O2(•-)) is an important reactive oxygen species in seawater. Measurements of its production rates and steady-state concentrations generated by photochemical processes have been a Herculean task over the years. In this study, a probe - 3'6'-(diphenylphosphinyl)fluorescein (PF-1) - was used to trap photochemically generated O2(•-) in seawater, thereby yielding fluorescein. The fluorescein produced was measured by an isocratic fluorescence HPLC at excitation/emission wavelengths of 490/513 nm, respectively. The reaction rate constant of PF-1 with O2(•-) (kPF-1) was pH-dependent: (3.2-23.5) × 10(7) M(-1) s(-1) at pHTOT 7.65-8.50. By applying appropriate equations, both the production rate and the steady-state concentration of O2(•-) generated by photochemical reactions in the seawater were quantified. Under the optimized experimental conditions, fluorescein standards (3-50 nM) exhibited linearity in the seawater by HPLC. The photoformation of fluorescein, due to the reaction of PF-1 with the O2(•-) photochemically produced in the seawater, was linear within the 20 min irradiation. The detection limit of the fluorescein photoformation rate was 0.03 pM s(-1), defined as 3σ of the lowest standard fluorescein concentration per 20 min irradiation. Using this value, the yield of fluorescein, and the fraction of O2(•-) that reacted with PF-1 in the seawater, the detection limit of the O2(•-) photoformation rate was 1.78 pM s(-1). Superoxide measurements using the proposed method were relatively unaffected by the potential interfering species in seawater. Application of the proposed method to ten (10) seawater samples from the Seto Inland Sea, Japan, resulted in measured O2(•-) photoformation rates of 3.1-8.5 nM s(-1), with steady-state concentrations ranging (0.06-0.3) × 10(-10) M. The method is simple, requires no technical sample preparation, and can be used to analyze a large number of samples.