环境科学与生态学最新文献

Personal air sampling (PAS) is used to assess worker intake of airborne radioactivity in operations processing minerals containing naturally occurring radionuclides. Subsequent alpha particle counting of the PAS filter may be affected by self-absorption of the alpha particles in the dust matrix or filter, depending on the dust loading on the filter and the size of particles collected. This review investigates the potential for self-absorption on air sampling filters via a literature review and by applying a formula to correct past PAS data from the mineral sand industry. The findings indicate that PAS estimates of intake were consistently under-stated by at least 40% across work categories engaged in the operation and maintenance of mineral sand separation plants. An alpha particle self-absorption greater than 50% was derived when dust loading on the PAS filter exceeded 3 mg·cm^-2. The findings demonstrate that historical PAS data in industries where self-absorption effects are neglected can substantially underestimate worker radionuclide intakes and doses, with important implications for retrospective dose assessment.

Emissions from diesel-powered irrigation pumps (DIPs) in Nepal's agriculture sector contribute to climate change and local air pollution. This study presents the emission estimation using emission factors (EFs) for energy use in DIPs and estimates the contribution of DIPs to the GHGs emission in Nepal using both the bottom-up and top-down approaches. It involves analyzing data on the number of DIPs, the amount of fuel used for irrigation, hours of operations, and efficiency of the pumps. The various EFs for the DIPs were collected from the previous research reports and articles. The activity data for the bottom-up approach was collected from a telephone survey, field sampling, and review of the existing documents. The country-specific EFs for energy use in DIPs developed in Nepal by previous studies using sample measurements were used in this study. The estimated number of DIPs for 2024 is about 51,137 (1.5 to 9 hp; average 5 hp DIPs), operating an average of 192 h per year in Nepal. The DIPs consume 5891 m³ (kL) of fuel per year and emit 14,674 tons of CO₂, 20.9 tons of CH₄, 0.18 tons of N₂O, 71.3 tons of NO_x, 52.2 tons of non-methane volatile organic carbon (NMVOC), 332.0 tons of CO, 54.4 tons of PM_2.5, 40.30 tons of organic carbon (OC), 17.8 tons of black carbon (BC), and 0.6 tons of SO₂ each year. The number of solar-powered irrigation pumps (SIPs) is 3129, which is about 2% of total irrigation pumps in Nepal. Farmers are providing encouraging feedback on the use of SIPs in their small-sized farms. The study shows that the number of electricity-powered pumps has increased rapidly by replacing the DIPs after the mid-2010s due to increased access to the grid electricity. The assessment is expected to support identifying opportunities to reduce emissions through improvements in technology, management practices, and other strategies.

This study investigates radon concentrations in groundwater from 20 locations in Iluagba, Kogi State, Nigeria, analyzed using a liquid scintillation counter. Radon levels ranged from 10.6-43.1 Bq/L (average 24.1 Bq/L). Although below the World Health Organisation (WHO) limit of 100 Bq/L, about 90 % exceeded the United States Environmental Protection Agency (USEPA) advisory level of 11.1 Bq/L, indicating potential long-term health risks. The annual effective dose (AED) was highest in infants (up to 163.5 µSv/y), with seven samples exceeding the WHO reference dose of 100 µSv/y. Excess lifetime cancer risk (ELCR) values for all age groups surpassed the USEPA safety threshold (1.0 × 10^-⁴), identifying infants as the most vulnerable group. Organ-specific analysis showed the lungs received substantially higher doses than the stomach, confirming inhalation as the primary exposure route. While strong correlations (r ≈ 1.0) validated internal data consistency, the elevated radiological risk remains the key concern. Compared with other Nigerian regions, Iluagba exhibits moderate to high exposure levels. These findings underscore the need for targeted radon mitigation, community education, and routine groundwater monitoring to safeguard public health in Kogi State.