Precipitation samples were collected at two coastal sites on the Korean Peninsula, Kangwha on the western coast and Yangyang on the eastern coast, from September 1991 to February 1997. The samples were analyzed for concentrations of major ions, in addition to pH and electrical conductivity. The annual volume-weighted mean pH values were 4.89 and 5.05 at Kangwha and Yangyang, respectively. The pH was generally lower at Kangwha than that at Yangyang, especially during the winter, because of reduced neutralizing inputs and greater acid inputs in winter. Dominant ions were different with NH₄ ⁺ and SO₄ ²⁻ most important at Kangwha and Na⁺ and Cl⁻ at Yangyang. Neglecting sea salt components, nss-SO₄ ²⁻ and NO₃ ⁻ were important anions and nss-Ca²⁺ and NH₄ ⁺ were important cations at both sites. Concentrations of these ions were 1.2–1.6 times higher at Kangwha than at Yangyang. Annual mean concentrations of these ions varied little during the study, while larger seasonal variations were observed. Annual mean nss-SO₄ ²⁻/NO₃ ⁻ ratios at Kangwha and Yangyang were 2.8 and 2.6. The 5 yr annual mean values of nss-SO₄ ²⁻/NO₃ ⁻ showed no trend at Kangwha but a decreasing tendency at Yangyang. The decreasing trend is similar to the decreasing trend in emissions of SO₂/NOₓ in South Korea. Regional differences in chemical composition between Kangwha and Yangyang appear to be associated with long-range transport of acidic gases and alkaline dust originated from other regions.

This study investigated the intrinsic perchlorate (ClO₄ ⁻)degradation kinetics of sediments and soils from multiple sites in microcosm studies, including the influence of varying nitrate concentration (NO₃ ⁻-N from 1 to 22.8 ppm) and up to 300 ppm sulfate. The first-order degradation rates and lag times of both ClO₄ ⁻ and NO₃ ⁻ degradation were site-specific and dependent on environmental conditions such as organic substrate availability, nitrate, initial ClO₄ ⁻ concentration, and prior ClO₄ ⁻ exposure. At an initial ClO₄ ⁻ concentration of 5 ppm, ClO₄ ⁻ degradation rates ranged from 0.13 to 0.46 day⁻¹, and lag times of ClO₄ ⁻ degradation ranged from 0 to 60.0 days; while NO₃ ⁻ degradation occurred at rates ranging from 0.03 to 1.42 day⁻¹, with lag times ranging from 0 to 29.7 days. Under the same treatment conditions, NO₃ ⁻ degradation rates were relatively higher than that of ClO₄ ⁻. Perchlorate degradation rates remained constant at both lower (0.5 ppm) and higher (5 ppm) ClO₄ ⁻ concentrations. Generally, ClO₄ ⁻ rates were affected by the availability of organic substrate, which was represented here by Total Volatile Solids (TVS) of sediments and soils, and not by NO₃ ⁻. Nitrate did increase the lag time of ClO₄ ⁻ degradation, which may account for the persistence of ClO₄ ⁻ in the environment, especially when ClO₄ ⁻ is typically ppb levels in the environment compared to ppm levels of NO₃ ⁻. This study showed rapid intrinsic ClO₄ ⁻ degradation in sediments and soils of contaminated sites, and highlighted the potential for natural attenuation of ClO₄ ⁻ in the environment.

This work aims to identify the sources of nitrogencontamination in nitrate vulnerable zones (NVZs) of Spain by means of the nitrogen isotope method. Three categories of nitrogen sources (synthetic fertilisers, animal wastes, and sludges and effluents from waste-water treatment plants) from three NVZs were analysed for their nitrogen isotopic composition (δ¹⁵N) in order to assess the applicability of the method to the identification of these N sources. The mean δ¹⁵N values were: +1.48‰ for synthetic fertilisers, +15.98‰ for animal wastes and +11.52‰ for sludges and effluents. The synthetic fertiliser sources were significantly different from the organic sources and so, the method can be used for their identification. The highest variability was found within the animal waste category. The range of values found for the different kinds of animal wastes (+5.86 to +36.74) was very wide and overlappedthe range found for sludges and effluents from waste-water treatmentplants (+4.57 to +20.18). Accordingly, these two nitrogen sources areisotopically indistinguishable.