Health risk assessment and source apportionment of PM2.5-bound toxic elements in the industrial city of Siheung, Korea.

The emission sources and their health risks of fine particulate matter (PM2.5) in Siheung, Republic of Korea, were investigated as a middle-sized industrial city. To identify the PM2.5 sources with error estimation, a positive matrix factorization model was conducted using daily mean speciated data from November 16, 2019, to October 2, 2020 (95 samples, 22 chemical species). As a result, 10 sources were identified: secondary nitrate (24.3%), secondary sulfate (18.8%), traffic (18.8%), combustion for heating (12.6%), biomass burning (11.8%), coal combustion (3.6%), heavy oil industry (1.8%), smelting industry (4.0%), sea salts (2.7%), and soil (1.7%). Based on the source apportionment results, health risks by inhalation of PM2.5 were assessed for each source using the concentration of toxic elements portioned. The estimated cumulative carcinogenic health risks from the coal combustion, heavy oil industry, and traffic sources exceeded the benchmark, 1E-06. Similarly, carcinogenic health risks from exposure to As and Cr exceeded 1E-05 and 1E-06, respectively, needing a risk reduction plan. The non-carcinogenic risk was smaller than the hazard index of one, implying low potential for adverse health effects. The probable locations of sources with relatively higher carcinogenic risks were tracked. In this study, health risk assessment was performed on the elements for which mass concentration and toxicity information were available; however, future research needs to reflect the toxicity of organic compounds, elemental carbon, and PM2.5 itself.

Uncertainty-based concentration estimation of chlortetracycline antibiotics in swine farms and risk probability assessment for agricultural application of manure.

Consideration of livestock farming practices is necessary for the reliable prediction of veterinary antibiotics concentrations in livestock manure and soil and characterization of their ecological risks. This study aims to predict concentrations of chlortetracycline (CTC) generated from slurry pit and evaluate its ecological risk in soil based on the European Medicine Agency guidelines by considering slurry pit farm practices such as cleaning water volume and those uncertainties. Additionally, sensitivity analysis was conducted on the exposure estimation of CTC in soil employing the Monte Carlo simulation. The predicted environmental concentrations of CTC in the slurry pit and soil were in a range of 0.54-5.64 mg/kgmanure and 3.42-67.59 µg/kgsoil, respectively, for a 90 % confidence level. The predicted ranges included the measured values reported in previous studies. The probability of risk quotient (RQ) exceeding one was estimated at 9.3 % based on the Monte Carlo simulation. The four most influential factors on the exposure to CTC in soil were identified as nitrogen in fertilizer/compost, cleaning water volume, ratio of sick pigs requiring antibiotics, and pit emptying cycles. The results indicate that the ecological risk of CTC in the soil is possible and can be controlled by slurry pit farm practices.

Assessment on landfill liners as the barrier against C60 nanoparticles.

Owing to the increasing usage of nanomaterials, it is imperative to assess their potential impacts on natural systems, and in particular, investigate if existing barriers can prevent nanomaterial emission in landfills because they will be disposed in landfills at the end of their useful lives. This study inspected the behavior of colloidal fullerene (nC60) in and around landfill liner materials. Sorption isotherm experiments using either natural soil or high density polyethylene geomembrane as sorbents showed that nC60 was readily removed by sorption to soil and precipitation, while there was no sorption to geomembrane. To investigate transport through soil, nC60 was injected into columns of compacted soil layers with a thickness of 3.3-4.2 cm and hydraulic conductivity <1 × 10-7 cm/s. The nanoparticles rarely passed through the layers owing to self-aggregation and/or screening by the soil layer. When they were detected in the effluent, breakthrough curves of an extraordinary shape were produced, which is presumably attributed to surface modification of collectors by deposited nC60. However, simulation using the obtained mass transport parameters showed that it is unlikely that nC60 from disposed C60-containing products would overcome compacted clay liners; therefore, its migration to the ambient environment would be negligible.