Contaminants adsorbed on microplastics (MPs) are a potential risk to aquatic environments. Several studies have demonstrated that polycyclic aromatic hydrocarbons (PAHs), which adsorb on MPs, can be ...photolyzed in aqueous solutions. We investigated photolysis of PAHs on MPs under sunlight conditions to estimate their environmental fate for the first time. The PAHs (25 ng each) were added to polyethylene powder, which was used as the MP sample. The MP sample was agitated in water with sunlight irradiation; thereafter, the concentration of the PAHs on the MP sample was determined by high-pressure liquid chromatography with a fluorescence detector. The half-life values of the PAHs were estimated between 3.4 × 102 (pyrene) and 3.2 × 104 min (benzjfluoranthene). These values are 0.5 (fluoranthene) to 25 (benzoapyrene) times larger than those in the aqueous phase. Additionally, the degradation of PAHs by OH radicals produced by the photolysis of nitrate was observed.
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•Photolysis of PAHs on polyethylene microplastics was observed for the first time.•The half-lives were from 3.4 × 102 (pyrene) to 3.2 × 104 min (benzojfluoranthene).•Existing of nitrate enhanced the photolysis via indirect photolysis.
A polar organic chemical integrative sampler (POCIS) was developed for the detection of linear alkylbenzene sulfonates (LASs), which are one of the most widely used chemicals globally and represent a ...type of surfactant agent. In the present study, the LASs were significantly sorbed onto the polyethersulfonate (PES) membrane, suggesting that the less sorptive polytetrafluoroethylene (PTFE) membrane is suitable for application in the POCIS device. Calibration experiments showed that the POCIS device with Oasis WAX as the sorbent and PTFE as the membrane filter had linear ranges > 28 d and sampling rates ranging from 0.035 ± 0.007 (tetradecylbenzenesulfonate) to 0.139 ± 0.024 (dodecylbenzenesulfonate) L d–1. Furthermore, this POCIS device was validated under non-steady-state conditions via both field and chamber tests. The time-weighted average concentrations of dodecylbenzenesulfonate measured using the POCIS agreed well with those obtained via grab sampling within 21% over the sampling period of 14 d in both the field and chamber tests. Therefore, the POCIS can be successfully applied in the detection of LASs in LAS-contaminated aquatic environments.
A Nankai Trough mega-earthquake with a magnitude of 8 to 9 on the Richter scale is predicted to occur with a probability of 70 to 80% within the next 30 years. Therefore, there are concerns about the ...risk to the health of residents due to the leakage of hazardous chemical substances from factories and business establishments associated with the earthquake. In this study, we attempted to estimate the stock amount of chemical substances subject to the PRTR Law at factories and business establishments in the area expected to be inundated by the tsunami caused by the earthquake.It was found that the chemical substance stock in the tsunami inundation area nationwide was 19.5 million tons, accounting for 87.1% of the total stock of the 23 prefectures concerned. In addition, it was found that this amount is equivalent to the amount of chemical substances released for about 93 years in the 23 prefectures concerned.
To evaluate post-depositional loss from the snow surface and subsequent redistribution of nitrate, we determined the spatial variation of nitrate concentrations, as well as δ15N and Δ17O values of ...nitrate in surface snow, sampled along a latitudinal transect in eastern Dronning Maud Land, East Antarctica. The NO3– concentrations of surface snow ranged from 40.0 to 130.8 μg L–1, showing no obvious trends with latitude, while the δ15N(NO3–) in surface snow increased from coastal sites to inland sites, ranging from –19.4 to 165.5‰. The relationship between the isotopic values (δ15N and Δ17O) of nitrate and snow accumulation rate are consistent with other traverses studied in East Antarctica (e.g., from Dumont d’Urville station to Vostok, and from East Antarctic coast to Dome Argus), implying that post-depositional loss and redistribution occur similarly throughout East Antarctica.
Continuous and simultaneous measurements of ammonia gas (NH
3
) and fine particulate ammonium (PM
2.5
NH
4
+
) were performed in two distinct urban areas: Osaka, Japan, and Ho Chi Minh City (HCMC), ...Vietnam. Measurements were performed using a new online instrument. Two measurement periods were conducted during February 11–March 12, 2015 (cold period), and July 1–September 14, 2015 (warm period), at the urban site in Osaka, while 17 days of measurements, from May 21 to June 8, 2015, were conducted at the urban site in HCMC. The average NH
3
concentration at the HCMC site was much higher than that at the Osaka site. The differences in the NH
3
levels between the two cities are a result of their different emission sources. Traffic emission is a significant contributor to the NH
3
levels within the urban area in Osaka. Conversely, the contribution of traffic emission to the NH
3
levels in the HCMC urban area is negligible. With a population of around 8.5 million people living in the urban area of HCMC, the high NH
3
level is due to human sources and poor waste management systems, especially because of the high temperature (30 °C) and dense population of the city (density up to 42,000 inhabitants per km
2
). In contrast to the NH
3
levels, the highest PM
2.5
NH
4
+
level occurred during the cold period at the Osaka site, and the average level at this site was higher than that at the HCMC site. The availability of atmospheric acids, low temperature, and high humidity facilitates the formation of ammonium. Our results indicate that NH
3
plays a key role in secondary inorganic aerosol formation; therefore, it contributes to a significant amount of PM
2.5
at the Osaka site. In contrast, the high levels of PM
2.5
observed at the HCMC site are likely from road traffic emission, mainly motorcycles, rather than secondary inorganic aerosol formation.
This study validated the chemicals monitoring ability of a polar organic chemical integrative sampler (POCIS) under non-steady-state conditions resulting from natural disasters and environmental ...accidents in aquatic environments via laboratory experiments. The goal of this work was to contribute toward monitoring the actual state of chemical contamination resulting from emergencies and natural disasters. A chamber replicating the chemical contamination of an aquatic environment established by a chemical exposure assessment model was set up in a clean booth. The concentrations of seven neonicotinoid pesticides were increased to a maximum of 1,000, 100, or 10 µg/L for one day and decreased by 50% per day thereafter. A POCIS was set up with polyethersulfone as the permeation membrane and a resin (Oasis hydrophilic-lipophilic balance) as the receiving phase. Calibration tests of the POCIS were also conducted. The results of this study led to the addition of six neonicotinoid pesticides to the list of POCIS-measurable targets. The results of the chamber experiments showed that a POCIS is a good tool for chemicals monitoring under non-steady-state conditions in an aquatic environment.
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