Eighty soil cores were collected from a residential area adjacent to an automobile battery manufacturing facility to determine the level and variability of lead concentrations in the soil. Results of ICP-MS on HNO₃ digestions showed lead concentrations in the residential soil as high as 2760 mg kg⁻¹. High variability of lead concentrations of two to three times over short distances, less than a meter, indicated the necessity of remediating the entire soil area based on a clean-up level of 400 mg kg⁻¹. To delineate areas of soil requiring no remediation at a high level of confidence would have required a more extensive soil sampling survey. High lead concentrations in the residential soil to a depth of approximately 15 cm indicated remediationof residential soil to at least this depth may be necessary. Overall, the high variability of lead concentrations in the residential soil was consistent with a soil having been disturbed by residential activity and illustrated the difficulty in using a single sample per residentialyard for making correct remediation decisions.

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.

Input-output budgets for dissolved inorganic nitrogen (DIN) are summarized for 24 small watersheds at 15 locations in the northeasternUnited States. The study watersheds are completely forested, free of recent physical disturbances, and span a geographical region bounded by West Virginia on the south and west, and Maine on the north and east. Total N budgets are not presented; however, fluxes of inorganic N in precipitation and streamwater dominate inputs and outputs of N at these watersheds. The range in inputs of DIN in wet-only precipitation from nearby National Atmospheric Deposition Program (NADP) sites was 2.7 to 8.1 kg N ha⁻¹ yr⁻¹ (mean = 6.4 kg N ha⁻¹ yr⁻¹; median = 7.0 kg N ha⁻¹ yr⁻¹). Outputs of DIN in streamwater ranged from 0.1 to 5.7 kg N ha⁻¹ yr⁻¹ (mean = 2.0 kg N ha⁻¹ yr⁻¹; median = 1.7 kg N ha⁻¹ yr⁻¹). Precipitation inputs of DIN exceeded outputs in streamwater at all watersheds, with net retention of DIN ranging from 1.2 to 7.3 kg N ha⁻¹ yr⁻¹ (mean = 4.4 kg N ha⁻¹ yr⁻¹; median = 4.6 kg N ha⁻¹ yr⁻¹). Outputs of DIN in streamwater were predominantly NO₃-N (mean = 89%; median = 94%). Wet deposition of DIN was not significantly related to DIN outputs in streamwater for these watersheds. Watershed characteristics such as hydrology, vegetation type, and land-use history affect DIN losses and may mask any relationship between inputs and outputs. Consequently, these factors need to be included in the development of indices and simulation models for predicting 'nitrogen saturation' and other ecological processes.

To date there have only been a few studies that measured mercury emissions from background substrate worldwide, and only a small amount of mercury flux data, from background substrate, exists for the Western United States. Because of this, the database of mercury emissions from background units < 0.1 mg kg⁻¹ mercury) is incomplete. This study focused on the collection of in-situ mercury flux data from representative lithologic units in Nevada. Measured mercury fluxes from substrate with background mercury concentration throughout Nevada were low (mean 2.0 ± 4.1 ng m⁻² hr⁻¹), and ranged from –3.7 to 9.3 ng m⁻² hr⁻¹. The mean measured mercury flux is slightly higher than those measured from background substrate from various locations throughout the world. The mean mercury flux from in-situ mercury measurements from substrate located near altered geologic units across Nevada was 15.5 ± 24.2 ng m⁻² hr⁻¹. These mercury fluxes are higher than the values applied in published global models for naturally enriched geologic units.

Concentrations of ozone and nitrogen oxides, together with air temperature and solar radiation intensity, were measured at several heights on a tower standing through the canopy of a red pine forest in summer and in autumn. In the summer observation, the diurnal variation patterns of ozone concentration both above and below the canopy were all similar and parallel to the solar radiation intensity. Using the data collected immediately above the canopy, deviation from the Leighton relationship and variations of concentration sums [O₃] + [NO] and [NO₂] + [NO] were examined, and as a result, it was supposedthat ozone was photochemically formed there in the daytime, probably because hydrocarbons emitted from pine trees broke the photostationary state among ozone and nitrogen oxides. The vertical temperature profile exhibited an inversion at the leaf-layer, which must have hindered vertical mixing of the air and made the trunk space more or less isolated from the upper atmosphere. These observations led to an idea that the similarity of the ozone variation pattern at every height was caused by the photochemical formation that proceeded simultaneously above and below the canopy rather than by vertical transport. Such situations of ozone formation were supported by observation of two maximums in the ozone vertical profile, one immediately above the canopy and another in the trunk space. Another feature of the ozone profile was a deep minimum in the leaf layer, which indicated ozone deposition onto leaf surfaces. This study thus revealed concurrence of ozone formation and deposition, and left two potentially important implications worthy of further investigation: (1) a forest is not always a sink but can be a source of ozone in sunlit conditions, and (2) deposition of ozone to trees can take place not only from outside but also from inside of a forest. In the autumn observation, however, the ozone formation was barely recognizable above the canopy and no longer found in the trunk space; in addition, the ozone concentration minimum in the leaf layer disappeared, suggesting that the deposition or removal was dependent on temperature.

Nutrient-rich, highly acidic leachate draining from a coastalphosphogypsum storage site located at a phosphate fertilizer manufacturing company posed potentially harmful environmental effects to the coastal ecosystem. This study evaluated the chemical characteristics of the phosphogypsum and the hydrogeological characteristics of the surroundings. Hydraulic and chemical properties of the leachate draining from the site were also evaluated. The leachate is nutrient-rich and very acidic and discharges into the sea. The leachate and seawater are hydraulically connected through highly-permeable riprap placed at the toe of the stack. The chemical quality of the leachate and its drainage rate showed large variations depending on the location of the well, indicating heterogeneous hydraulic conditions. A vertical barrier system consisting of horizontal drainage wells and vertical leachate-collecting wells is suggested, in order to contain and collect the leachate. A back-up system of soil-bentonite cut-off walls is suggested to control leachate discharge to the sea.

The effect of selected nutrient amendments and temperature on the biodegradation of pentachlorophenol (PCP) within a soil biopile was studied on a laboratory scale. This was accomplished by monitoring microbial populations, the concentration of PCP and the release of inorganic chloride ions in the contaminated soil. It was found that temperatures of 10, 15 and 20 °C had no significant effect on microbial populations and the percentage of PCP remaining in the soil. However, the nutrient amendments did have a significant effect on the parameters measured. The dairy manure, ammonium nitrate fertilizer and control treatments all experienced some fluctuations in the amount of PCP remaining in the soil over the incubation period and may have been due to the release of initially unextractable bound residues. PCP decreased by 76% in the municipal solid waste compost amended soil, while the concentration of inorganic chloride ions increased. The municipal solid waste compost treatment had significantly higher bacterial and fungal populations. Based on the results of this study municipal solid waste compost may be used as an effective supplemental nutrient amendment for the degradation of PCP in soil biopiles.

Soil solution chemistry is a powerful tool for studying many aspects of soil science. Among several isolation techniques, centrifugation appears most promising as a method of extracting the soil solution in the laboratory. However, some operational conditions must be defined. The present work reports the influence of sample storage on the observed composition of the soil solution of two Brazilian soils submitted to different managements. Since metal speciation in soil solution significantly influences metal bioavailability, a second experiment was conducted to evaluate the effects of storage on Fe, Al, and Mn speciation by size exclusion chromatography (HPLC-SEC). The results showed that the effects of soil handling prior to solution extraction had a significant effect on soil solution composition, mainly when the sample was dried and rewetted. Only the samples that were kept refrigerated (4 °C) for 15 days led to results comparable to those obtained from fresh soils. However, considering the patterns of the UV detection chromatograms and metal distribution, only field moist samples should be used in studies related to Al, Mn, and Fe speciation in the studied soils.

Chlorothalonil, a halogenated benzonitrile compound, is one of the most widely used fungicides in the world. Anaerobic microcosm assays were established to evaluate the combined effect of the initial content of carbon (6.3, 9.45 and 12.6 mg g⁻¹), nitrogen (0.6, 1.8 and 3 mg g⁻¹)and chlorothalonil (432, 865 and 1298 ηg g⁻¹) on the biodegradation of this fungicide by microbiota from an agricultural tropical soil. A Box-Behnken experimental design was used and chlorothalonil depletion was followed by HPLC with UV detection. The initial carbon content and fungicide dose were found to have a significant effect on removal efficiency. After 25 days of incubation, a high chlorothalonil depletion was observed in all biologically active microcosms (56–95%) although abiotic loss in a sterile blank was also notable (37%). The results suggest a high potential for chlorothalonil biodegradation under anaerobic conditions by indigenous microbial communities from soil that has been continuously exposed to high doses of the fungicide.