Photodegradation of the insecticide fipronil in aquatic environments: photo-dechlorination processes and products.

Fipronil (FIP) is a phenylpyrazole insecticide that, along with neonicotinoid insecticides, is regularly used worldwide. Photodegradation of FIP in aqueous systems is thought mainly to involve the reaction of desulfinylation to give fipronil desulfinyl (FIP-desulfinyl); however, little is known about further degradation reactions. We investigated FIP photodegradation by analyzing photodegradation products by liquid chromatography and liquid chromatography high-resolution tandem mass spectrometry using an Orbitrap instrument. A wide range of products, including dechlorinated compounds, was detected, and the structures were identified. FIP-desulfinyl has previously been found to be an important and persistent FIP photodegradation product; however, we also found that FIP-desulfinyl was photochemically decomposed to a didechlorinated product via a monodechlorinated product. The main photodegradation pathway was probably similar to that of ethiprole, which has a similar skeleton. The photodegradation rate constant was 22.6 times lower for FIP-desulfinyl (0.00372 min-1) than FIP (0.0839 min-1). The photodegradation rate constant was lower for the newly found didechlorinated product (0.001 min-1 or below) than FIP-desulfinyl, suggesting that the product is persistent in aquatic environments and could be an important indicator of long-term FIP contamination.

Distribution and phylogeny of mercury methylation, demethylation, and reduction genes in the Seto Inland Sea of Japan.

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.

Contamination, dynamics, and health risk assessment of pesticides in seawater and marine samples from the Seto Inland Sea, Japan.

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.

Migration of terephthalate from scraps of poly(ethylene terephthalate) (PET) in water and artificial seawater.

We report the migration of terephthalate and some low molecular weight organic compounds from poly(ethylene terephthalate) (PET) scraps in Milli-Q water and artificial seawater (ASW). The photochemical processes and the subsequent dark reactions were investigated using PET scraps obtained from postconsumer bottles of commercial non­carbonated mineral water. Concentrations of terephthalate exponentially increased with irradiation time, reaching approximately 6-8 µmol L-1 in ASW after 80 h irradiation. The photochemical migrations of compounds related to terephthalate were also observed. Concentrations of terephthalate and related compounds reached higher concentrations in ASW than in Milli-Q water. After 80 h irradiation, two dark experiments were conducted: one on the solutions after irradiation without PET scraps, and the other on photochemically damaged PET scraps. In ASW in the dark without PET scraps, the terephthalate concentration increased, and concentrations of other compounds related to terephthalate also changed. The results suggested that terephthalate was generated by hydrolytic reaction in dark ASW from the scission products of PET which were generated during the irradiation of PET scraps. Photochemically damaged PET scraps released terephthalate and related compounds in the dark. The half-life of the photo-irradiated PET scraps in the dark is approximately 205 years. Our results show that PET bottles in marine environments can continuously release terephthalate and other low molecular weight organic compounds during the day at the sunny surface, at the dark ocean floor, and during the night.

Dynamics and Mass Balance of Polycyclic Aromatic Hydrocarbons in and Around the Seto Inland Sea, Japan.

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.

Optical properties of dissolved organic matter in Japanese rivers and contributions to photoformation of reactive oxygen species.

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 (1O2)) were assessed. The lowest and highest mean dissolved organic carbon concentrations were for the Ohta River (0.95 (mg C) L-1) and Yamato River (2.85 (mg C) L-1), respectively, and the concentrations correlated with some optical parameters. Absorption ratios (e.g., the E2:E3 and A280/A350 ratios) and the spectral slope S275-295 indicated that DOM from the Yodo and Kokubu rivers had the lowest and highest molecular weights, respectively. PARAFAC models and DOM excitation-emission matrices were used to assess the sources and fates of DOM in the rivers. The PARAFAC model indicated that the main types of fluorescent DOM in the rivers were terrestrial humic-like (TH-L) and tryptophan-like (TP-L) substances. The Kokubu River contained other compounds such as fluorescent whitening agents, autochthonous humic-like substances, and extracellular polymeric substances. Statistically significant relationships between the dissolved organic carbon and TH-L, TP-L, and extracellular polymeric substance concentrations suggested that TH-L, TP-L, and extracellular polymeric substances are important contributors to total DOM in the rivers. TH-L and TP-L substances strongly contribute to ROS photoformation, but TH-L substances play roles in both ROS generation and scavenging. Comprehensive models for estimating the photoformation rates of different ROS (in M s-1) were established by integrating the contributions of the relevant major and minor sources. Examples are ROH (10-12) = 21.0 [NO2-]_µM + 0.460 [TH-L]_QSU + 10.9, RNO (10-12) = 67.9 [NO2-]_µM + 35.2 [a300]_m-1 - 2.51 [TH-L]_QSU - 0.765 [TP-L]_QSU - 8.14, and R1O2 (10-9) = 3.81 [a300]_m-1 - 0.101 [TP-L]_QSU + 11.1.

Massive digital gene expression analysis reveals different predictive profiles for immune checkpoint inhibitor therapy between adenocarcinoma and squamous cell carcinoma of advanced lung cancer.

BACKGROUND: Immune checkpoint inhibitors prolong the survival of non-small cell lung cancer (NSCLC) patients. Although it has been acknowledged that there is some correlation between the efficacy of anti-programmed cell death-1 (PD-1) antibody therapy and immunohistochemical analysis, this technique is not yet considered foolproof for predicting a favorable outcome of PD-1 antibody therapy. We aimed to predict the efficacy of nivolumab based on a comprehensive analysis of RNA expression at the gene level in advanced NSCLC. METHODS: This was a retrospective study on patients with NSCLC who were administered nivolumab at the Kansai Medical University Hospital. To identify genes associated with response to anti-PD-1 antibodies, we grouped patients into responders (complete and partial response) and non-responders (stable and progressive disease) to nivolumab therapy. Significant genes were then identified for these groups using Welch's t-test. RESULTS: Among 42 analyzed cases (20 adenocarcinomas and 22 squamous cell carcinomas), enhanced expression of MAGE-A4, BBC3, and OTOA genes was observed in responders with adenocarcinoma, and enhanced expression of DAB2, HLA-DPB,1 and CDH2 genes was observed in responders with squamous cell carcinoma. CONCLUSIONS: This study predicted the efficacy of nivolumab based on a comprehensive analysis of mRNA expression at the gene level in advanced NSCLC. We also revealed different gene expression patterns as predictors of the effectiveness of anti PD-1 antibody therapy in adenocarcinoma and squamous cell carcinoma.

Blocking EP4 down-regulates tumor metabolism and synergizes with anti-PD-1 therapy to activate natural killer cells in a lung adenocarcinoma model.

Prostaglandin E2 (PGE2), a product of the cyclooxygenase (COX) pathway, is produced by tumors and surrounding stromal cells. It stimulates tumor progression, promotes angiogenesis and suppresses the anti-tumor response. Pharmacological inhibition of PGE2 synthesis has been shown to suppress tumor initiation and growth in vivo. In the current study, we demonstrated that the growth of the Ptgs2-deficient 3LL lung adenocarcinoma cell line was down-regulated in vivo through natural killer (NK) cell activation and a reduction in the population of polymorphonuclear leukocyte-myeloid-derived suppressor cells (PMN-MDSCs) and tumor-associated macrophages (TAMs). On the basis of these results, the therapeutic effect of ONO-AE3-208 (EP4i), an inhibitor of EP4 (a PGE2 receptor), combined with anti-PD-1 antibody was evaluated. EP4i, but not anti-PD-1 antibody, decreased tumor metabolism including glycolysis, fatty acid oxidation and oxidative phosphorylation. EP4i induced IFNγ production from only NK cells (not from T cells) and a shift from M2-like to M1-like macrophages in TAMs. These effects were further enhanced by anti-PD-1 antibody treatment. Although CD8 T-cell infiltration was increased, IFNγ production was not significantly altered, even with combination therapy. Tumor hypoxia was ameliorated by either EP4i or anti-PD-1 antibody treatment, which was further affected by the combination. Normalization of tumor vessels was significant only for the combination therapy. The results indicated a novel effect of EP4i for the metabolic reprogramming of tumors and revealed unique features of EP4i that can synergize with anti-PD-1 antibody to promote IFNγ production by NK cells, polarize TAMs into the M1 phenotype, and reduce hypoxia through normalization of the tumor vasculature.

Amlexanox enhances the antitumor effect of anti-PD-1 antibody.

Cancer immunotherapy, especially treatment with monoclonal antibodies (mAbs) that block programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) signaling, has attracted attention as a new therapeutic option for cancer. However, only a limited number of patients have responded to this treatment approach. In this study, we searched for compounds that enhance the efficacy of anti-PD-1 mAb using mixed lymphocyte reaction (MLR), which is a mixed culture system of the two key cells (dendritic and T cells) involved in tumor immunity. We found that amlexanox enhanced production of interferon (IFN)-γ, an indicator of T cell activation, by anti-PD-1 mAb. Amlexanox also induced PD-L1 expression in dendritic cells in MLR, whereas it did not stimulate interleukin-2 production by Jurkat T cells. These results suggest that amlexanox acts on dendritic cells, not T cells, in MLR. Furthermore, it enhanced the antitumor effect of the anti-PD-1 mAb in vivo in a mouse tumor-bearing model. The combination of amlexanox and anti-PD-1 mAb increased the expression of Ifng encoding IFN-γ, IFN-γ-related genes, Cd274 encoding PD-L1, and cytotoxic T cell-related genes in tumors. In conclusion, amlexanox stimulates the antitumor effect of anti-PD-1 mAb by acting on dendritic cells, which in turn activates cytotoxic T cells in tumors.

Heavy metals in urban dusts from Alexandria and Kafr El-Sheikh, Egypt: implications for human health.

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.

Immune Checkpoint Blockade Improves Chemotherapy in the PyMT Mammary Carcinoma Mouse Model.

Despite the success of immune checkpoint blockade in cancer, the number of patients that benefit from this revolutionary treatment option remains low. Therefore, efforts are being undertaken to sensitize tumors for immune checkpoint blockade, which includes combining immune checkpoint blocking agents such as anti-PD-1 antibodies with standard of care treatments. Here we report that a combination of chemotherapy (doxorubicin) and immune checkpoint blockade (anti-PD-1 antibodies) induces superior tumor control compared to chemotherapy and immune checkpoint blockade alone in the murine autochthonous polyoma middle T oncogene-driven (PyMT) mammary tumor model. Using whole transcriptome analysis, we identified a set of genes that were upregulated specifically upon chemoimmunotherapy. This gene signature and, more specifically, a condensed four-gene signature predicted favorable survival of human mammary carcinoma patients in the METABRIC cohort. Moreover, PyMT tumors treated with chemoimmunotherapy contained higher levels of cytotoxic lymphocytes, particularly natural killer cells (NK cells). Gene set enrichment analysis and bead-based ELISA measurements revealed increased IL-27 production and signaling in PyMT tumors upon chemoimmunotherapy. Moreover, IL-27 signaling improved NK cell cytotoxicity against PyMT cells in vitro. Taken together, our data support recent clinical observations indicating a benefit of chemoimmunotherapy compared to monotherapy in breast cancer and suggest potential underlying mechanisms.

A fluorescence method for the determination of photochemically generated peroxynitrite in seawater.

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.

S1PR4 ablation reduces tumor growth and improves chemotherapy via CD8+ T cell expansion.

Tumor immunosuppression is a limiting factor for successful cancer therapy. The lipid sphingosine-1-phosphate (S1P), which signals through 5 distinct G protein-coupled receptors (S1PR1-5), has emerged as an important regulator of carcinogenesis. However, the utility of targeting S1P in tumors is hindered by S1P's impact on immune cell trafficking. Here, we report that ablation of the immune cell-specific receptor S1PR4, which plays a minor role in immune cell trafficking, delayed tumor development and improved therapy success in murine models of mammary and colitis-associated colorectal cancer through increased CD8+ T cell abundance. Transcriptome analysis revealed that S1PR4 affected proliferation and survival of CD8+ T cells in a cell-intrinsic manner via the expression of Pik3ap1 and Lta4h. Accordingly, PIK3AP1 expression was connected to increased CD8+ T cell proliferation and clinical parameters in human breast and colon cancer. Our data indicate a so-far-unappreciated tumor-promoting role of S1P by restricting CD8+ T cell expansion via S1PR4.

Heterogeneity and potential aquatic toxicity of hydrogen peroxide concentrations in selected rivers across Japan.

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 < 0.01, n = 111) with the product of dissolved organic carbon and solar radiation intensity, which suggests that these two factors in combination are important in determining the H2O2 concentrations in river water. It was also observed that bigger rivers had lower H2O2 concentration and vice-versa. This shows that the size of a river may influence its H2O2 concentration. This study is the first countrywide survey of H2O2 concentrations in different rivers and evaluation of their relationship with the PNEC. The data provide insight on the factors influencing the concentrations of H2O2 in river water.

Singlet Oxygen Photogeneration in Coastal Seawater: Prospect of Large-Scale Modeling in Seawater Surface and Its Environmental Significance.

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.

Carbaryl residue concentrations, degradation, and major sinks in the Seto Inland Sea, Japan.

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.

Factors controlling the degradation of hydrogen peroxide in river water, and the role of riverbed sand.

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.

Photoformation of reactive oxygen species and their potential to degrade highly toxic carbaryl and methomyl in river water.

Reactive oxygen species (ROS) including singlet oxygen (1O2) and hydroxylradicals (OH) 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 OH 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 OH scavengers were also measured. The rate constants for the reaction of OH with carbaryl and methomyl were found to be (14.8 ±â€¯0.64) × 109 and (4.68 ±â€¯0.52) × 109 M-1 s-1, respectively. The reaction rate constant of 1O2 with carbaryl (2.98 ±â€¯0.10) × 105 M-1 s-1, was much higher than that of methomyl (<104 M-1 s-1). Indirect photolysis by OH accounted for 63% and 62%, while 1O2 accounted for 26% and 30% and direct photolysis accounted for 1.4% and 7% of methomyl and carbaryl degradation, respectively. The high degradation rate in river water demonstrated by both insecticides suggests that indirect photolysis mediated by OH is an important means of their degradation in river water. In addition, kinetic calculations of OH-mediated degradation rate constants of the compounds agrees with their experimentally-determined values thereby confirming the importance of OH towards their degradation.

Persistent organic pollutants are still present in surface marine sediments from the Seto Inland Sea, Japan.

Although persistent organic pollutants (POPs) are currently banned or strictly controlled under the Stockholm Convention on Persistent Organic Pollutants, POPs are still distributed worldwide due to their environmental persistence, atmospheric transport, and bioaccumulation. Herein we investigated the current concentrations of POPs in the sediments from Seto Inland Sea, Japan and sought to clarify the factors currently controlling the POPs concentration of the surface sediments from Seto Inland Sea. The concentrations of hexachlorocyclohexane isomers (HCHs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), and chlordane isomers (CHLs) in sediments from Seto Inland Sea were <0.002-1.20 ng g-1, 0.01-2.51 ng g-1, and 0.01-0.48 ng g-1, respectively. Resuspension increased the concentrations of HCHs, HCB, and DDTs in the surface sediment with the release of historically contaminated pollutants accumulated in a lower layer. We speculate that CHLs in air that were removed by atmospheric deposition affects the concentration of CHLs in surface sediments.

Identifying sulfur species adsorbed on particulate matters in exhaust gas emitted from various vessels.

Ship fuels are highly associated with the emission of particulate matter and sulfur. Sulfur adsorbed on particulate matter in exhaust gases from fuels is generally considered to be sulfate. However, other chemical species of sulfur adsorbed on particulate matter in ship exhaust gases are not well known. The purpose of this study is to identify sulfur species adsorbed on particulate matter in ship exhaust gases using X-ray absorption fine structure. Particulate matter and soot samples were collected from a container carrier, a tugboat, an electric propulsion vessel, training vessels, and a marine engine, and sulfur species of particulate matter and soot were identified by X-ray absorption fine structure analysis. Sulfur emission adsorbed on particulate matter and sulfur species did not change between high and middle loads. In this study, sulfonate derived from fuel or oxidation of sulfide in fuel was identified in addition to sulfate. Total sulfur and sulfate concentrations in soot increased with increasing fuel sulfur content. The concentration of organosulfurorganosulfurs in soot such as thiophen and sulfonate, which originated mainly from fuel and engine oil, tended to increase with increasing fuel sulfur content.