Agricultural soils high in both fluoride (F) and phosphate (P) are common due to long-term accumulation of F from multi-sources and extensive application of phosphate fertilizers. Iron (Fe) and aluminum (Al) (hydro)oxides in acidic soils serve as main geochemical sinks of both P and F, influencing their transport and bioavailability. Though sorption of P and F in their single-ion system has been extensively investigated, studies on co-sorption of F and P on soils are very limited. In this study, the batch technique was used to investigate mutual effects of F and P on their co-sorption/desorption in an acidic red soil with high contents of Fe and Al (hydro)oxides. Results indicate that, in F-P coexisting system, a decrease in pH enhances the sorption of both F and P. An increase in F concentration suppresses P sorption due to competitive effect. However, F sorption can be improved in the presence of P due to surface precipitation of (Al,Fe)-F-P. Sorption of F and P follows both the Langmuir and Freundlich isotherms. Different orders of F and P addition into the soil have no appreciable effect on P sorption, but exert significant impact on F sorption. The presence of F has no measurable effect on P desorption, while the stability of F in the presence of P can be significantly diminished in comparison with that in the absence of P, which would lead to an improvement of F mobility.

Many national exposure programmes have been performed in tropical and subtropical climates during the last 50 years. However, ambitious programmes involving more than a few countries are scarce. In this paper a recently formed network of test sites is described involving 12 test sites in Asia (India, Vietnam, Thailand, Malaysia and China including Hong Kong) and four test sites in Africa (South Africa, Zambia and Zimbabwe). This effort is part of the 2001-2004 Swedish International Development Agency (SIDA) funded Programme on Regional Air Pollution in Developing Countries (RAPIDC). Corrosion attack after one (2002-2003) year of exposure (carbon steel, zinc, copper, limestone and paint coated steel) are presented together with environmental data (SO₂, NO₂, HNO₃, O₃, particles, amount and pH of precipitation, temperature and relative humidity) for all the test sites. The obtained corrosion values are substantially higher than expected for limestone, higher than expected for carbon steel and lower than expected for zinc compared to values calculated using the best available dose-response functions.

A greenhouse experiment with two levels of Cd (0.5 and 10 mg Cd kg-¹, in the form of CdCl₂), and five salinity levels of irrigation water (0, 8.6, 17.1, 34.2 and 68.4 mM NaCl) in triplicate was conducted to determine the effect of NaCl-induced salinity on the solubility and availability of Cd in clay loam and sandy calcareous soils. Corn seeds (Zea mays L.) were sown in pots. Forty-five days after planting, the shoots were harvested, and their Cd concentration was determined. The post-harvest electrical conductivity (ECe), pH, and concentrations of cations and anions were determined in soil saturation paste extracts. Increasing irrigation water salinity resulted in significant increases in the total soluble Cd concentration in both studied soils. A positive correlation was found between the total soluble Cd and the chloride concentration in the soil solution.Solution speciation, calculated with MINEQL+ (a chemical equilibrium modeling system), predicted that Cd was present mainly as free Cd²⁺ ions followed by CdCl⁺ and [graphic removed] in the soils irrigated with deionized water. However, Cd species in the soil solution were significantly altered by increasing chloride concentration, with Cd-chloro complexes becoming the dominant Cd species in the soil solution. Increasing the salinity level resulted in significant decreases in the shoot dry matter and increases in the shoot Cd concentration. Shoot Cd concentration was positively correlated with both the total Cd and Cd-chloro complexes in the soil solution.

Phytoextraction is a promising technology that uses hyperaccumulating plants to remove inorganic contaminants, primarily heavy metals, from soils and waters. A field experiment was conducted to evaluate impacts of a mixture of chelators (MC) upon the growth and phytoextraction of heavy metals by the hyperaccumulator Sedum alfredii Hance in a co-planting system in a paddy soil that was historically irrigated with Pb and Zn contaminated mining wastewaters. The co-planting system used in this study was comprised of a Zn- and Cd-hyperaccumulator (S. alfredii) and a low-accumulating crop (Zea mays). Results showed that yields of S. alfredii were significantly increased with the addition of the MC and by co-planting with Z. mays. Our study further revealed that concentrations of Zn, Pb, and Cd in the corn grains of Z. mays conform to the Chinese hygiene standards for animal feeds and in the other parts of Z. mays conform to the Chinese organic fertilizer standards. The uptake of Zn, Cd, and Pb by S. alfredii was significantly increased with the addition of MC. The uptake of Zn by S. alfredii was also significantly enhanced by co-planting with Z. mays, but the interaction between MC and co-planting was not significant, meaning the effects of the two types of treatments should be additive. When the MC was applied to the co-planting system in the soil contaminated with Zn, Cd, and Pb, the highest phytoextraction rates were observed. This study suggested that the use of the hyperaccumulator S. alfredii and the low-accumulating crop Z. mays in the co-planting system with the addition of the MC was a more promising approach than the use of a single hyperaccumulator with the assistance of EDTA (ethylenediaminetetraacetic acid). This approach not only enhances the phytoextraction rates of the heavy metals but also simultaneously allows agricultural practices with safe feed products in the metal-contaminated soils.

A geologic classification scheme was combined with elevation to test hypotheses regarding watershed sensitivity to acidic deposition using available regional spatial data and to delimit a high-interest area for streamwater acidification sensitivity within the Southern Appalachian Mountains region. It covered only 28% of the region, and yet included almost all known streams that have low acid neutralizing capacity (ANC ≤20 μeq l⁻¹) or that are acidic (ANC ≤0). The five-class geologic classification scheme was developed based on recent lithologic maps and streamwater chemistry data for 909 sites. The vast majority of the sampled streams that had ANC ≤20 μeq l⁻¹ and that were totally underlainby a single geologic sensitivity class occurred in the siliceous class, which is represented by such lithologies as sandstone and quartzite. Streamwater acid-base chemistry throughout the region was also found to be associated with a number of watershed features that were mapped for the entire region, in addition to lithology and elevation, including ecoregion, physiographic province, soils type, forest type and watershed area. Logistic regression was used to model the presence/absence of acid-sensitive streams throughout the region.

A multi-media monitoring field investigation, which included atmospheric, road sediment and soil samples, was carried out at two highway study sites to identify past and present Pb sources. Past Pb anthropogenic sources such as paint and leaded gasoline were linked to significant Pb accumulation in roadside soils at both sites through Pb isotopic analyses. This was achieved by identifying the distinct Pb isotopic composition in older versus newer Pb accumulation at different depths across the soil profile. Older Pb accumulations exhibited lower ²⁰⁶Pb/²⁰⁷Pb isotopic ratios, consistent with Canadian Pb-bearing ores, whereas newer Pb accumulations reflected a mixture of the ²⁰⁶Pb/²⁰⁷Pb ratios of road sediment samples, with the Pb isotopic signature of uncontaminated soil. Isotopic analyses were also helpful in identifying road sediment as an important current source of Pb in roadside soils, by comparing the isotopic signatures derived from road sediment and atmospheric dustfall. The known association of Pb with anthropogenic sources was used to indirectly relate other metals (Cu, Mn, Zn) to the same source by the Enrichment Ratio method. Significant positive correlations at the 90-95% confidence level were found between Cu, Zn and Pb Enrichment Ratios in roadside and dust deposition samples. Weaker correlations were found between Mn and Pb, at the highway study site with the least amount of traffic. However, correlations between these two metals were significant at the 90% confidence level for the busier highway site highlighting Mn potential anthropogenic source. An isotopic tracer study is suggested to further investigate the process of Mn redistribution in the environment due to exhaust fuel emissions. More research is needed regarding the potential impact from using a Mn-based fuel additive.

The determination of stomatal ozone fluxes is essential to assess the potential damage to plants due to ozone uptake. This parameter is not accessible directly with measurements, but can be deduced through algorithms using observational data. Total ozone fluxes and water vapour fluxes are generally used. Water vapour fluxes give an indication on stomatal aperture, which is the controlling factor of ozone uptake by vegetation. In this work, a series of observations made during the growing season over an onion field are used to show the equivalence of two algorithms found in the literature to derive ozone stomatal fluxes and both based on the similarity between ozone stomatal fluxes and water vapour stomatal fluxes. One of these algorithms uses the Penman-Monteith approach, where the water vapour pressure deficit is calculated using air temperatures; the second calculates, with another formulation, the water vapour deficit from the leaf temperature. The two approaches lead to the same results if applied properly, as shown in this work, both theoretically and numerically.

Trace metal levels in the otoliths of the juvenile chum salmon Oncorhynchus keta were examined by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Life history transect analyses showed that all otoliths had a central region with low Zn/Ca ratios (mean, 0.35-0.68 x 10-⁴), and thereafter the ratios increased abruptly in the freshwater growth zone (mean: 1.72-1.90 x 10-⁴) toward the edge of otolith. In regard to otolith Sr/Ca ratios, all specimens showed slightly higher values in the otolith core region, and thereafter the ratios showed constant values or values that decreased gradually toward the edge of the otolith in the freshwater growth zone (mean, 3.33-4.58 x 10-³). An abrupt increase was found in some specimens to 5-7 x 10-³ in the maximum levels around the otolith edge. The relationship between Sr/Ca and Zn/Ca ratios at each ablation in otoliths in both juvenile and adult salmons showed a significant correlation. Otolith Zn/Ca and Sr/Ca ratio patterns were seen to reflect the levels in ambient water environment. Thus, these findings indicate that Zn, like Sr, in teleost otoliths is an excellent tracer for reconstructing the ambient aquatic environmental conditions which individual fish have experienced.

The objective of this study was to identify and quantify volatile organic compounds (VOCs) produced during composting of poultry litter. The VOCs produced from in-vessel composting with a controlled aeration system were tested using the F-ITR method by VOC analyzer. Alkanes and alkylated benzenes were emitted in the highest amounts from poultry litter, while aldehydes, terpenes, ketones were emitted in much lesser amounts. Studies showed that VOCs generation was the greatest early during the composting process and greatly reduced thereafter. Composting temperatures were found to affect VOCs. All VOCs were least with the high temperatures generated during composting.

The simulation of ecosystems by mesocosms might be affected by artefacts due to the scale reduction implied in such experiments. The physico-chemical properties of water leaching out of mesocosms made of only 50 kg of agricultural soil were measured to demonstrate that they constitute reproducible systems. The soils were artificially contaminated with lead, atrazine, benzo(a)pyrene and Phenochlor. Physico-chemical parameters (redox potential, conductivity, pH, dissolved oxygen) and major ions were monitored in the leachates for six months. Even though these changed with time, in each sampling campaign they were similar for all of the mesocosms despite possible independent development of microbial and biological activity.