The objectives of this work were to characterize and compare the chemical composition of the water-soluble fraction of the PM₁₀ particles (Dp < 10μm) in two sites: one inside the Metropolitan Area of São Paulo (MASP) and another, 250km apart, inside the State Park of Serra do Mar (CUNHA) part of the Atlantic Forest Reserve, both located in São Paulo State, Brazil. The atmospheric particles were collected during dry and wet season. The morphologic parameters of the particles were characterized for the different size fractions of the collected material. In the aqueous extract of the particulate fine fraction the major ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl-, NO₃ -, NH₄ ⁺, SO₄ ²-) and trace elements (Al, Mn, Fe, Pb, Cd, Zn, Ti, Ni, Cu, Co, Ba) were determined. The morphological characteristics of the particles collected within the MASP are typical of polluted environment while in CUNHA there is no evidence of this type of contribution. Regarding the solute concentrations it was observed that the most abundant major ions and trace elements were K⁺, Ca²⁺, Na⁺, Cl- and Pb, for CUNHA and NO₃ -, SO₄ ²-, NH₄ ⁺ and Mn, Ni, Pb, Co, Cd and Ba for MASP. These differences are associated with the different sources of the particles. In the urban area they are predominantly of pollution origin, mainly from vehicle emissions, and road dust suspension, while in the State Park they are mainly of biogenic, terrigenous and oceanic origins. For these reasons the CUNHA region can be considered to be a regional reference site for studies concerning eventual disturbances in the Cunha background site, derived from transported pollution.

Zinc toxicity thresholds for reclamation plants are largely unknown. As a result, ecological risk assessments often rely on toxicity thresholds for agronomic species, which may differ from those of restoration species. Our objective was to provide Zn toxicity thresholds for forb species that are commonly used in reclamation activities. We used a greenhouse screening study where seedlings of yarrow (Achillea millefolium L.), Bigelow's tansyaster (Machaeranthera bigelovii (Gray) Greene var. bigelovii), blue flax (Linum perenne L. var. Appar), alfalfa (Medicago sativa L. var. Ladak), Palmer's penstemon (Penstemon palmeri Gray), and Rocky Mountain penstemon (Penstemon strictus Benth. var. Bandera) were grown in sand culture and exposed to increasing concentrations of Zn. Lethal concentrations (LC50 - substrate Zn concentration resulting in 50% mortality), effective concentrations (EC50 - substrate Zn concentration resulting in 50% biomass reduction), and phytotoxicity thresholds (PT50 - tissue Zn concentration resulting in 50% biomass reduction) were then determined. Phytotoxicity thresholds and effective concentrations for these reclamation species were relatively consistent between species. Our estimates of PT50-shoot for these species range from 1258 to 3214 mg Zn kg-¹ . Measures of EC50-plant for these restoration forbs ranged from 82 to 214 mg Zn L-¹ . These thresholds might be more useful for risk assessors working on reclamation sites than those based on non-reclamation species that are widely used.

Litterfall can be an important flux of mercury (Hg) to soils in forested landscapes, yet typically the only available data to evaluate Hg deposition is from precipitation Hg monitoring. Litterfall was collected at 39 sampling sites in two small research watersheds, in 2003 and 2004, and analyzed for total Hg. Four vegetation classes were designated in this study as hardwoods, softwoods, mixed and scrub. The mean litter Hg concentration in softwoods (58.8 ± 3.3 ng Hg g-¹ was significantly greater than in mixed (41.7 ± 2.8 ng Hg g-¹ and scrub (40.6 ± 2.7 ng Hg g-¹, and significantly lower than in hardwoods (31.6 ± 2.6 ng Hg g-¹. In contrast, the mean weighted litter Hg flux was not significantly different among vegetation classes. The lack of a significant difference in litter Hg flux between hardwoods and softwoods was attributable to the large autumnal hardwood litter Hg flux being balanced by the higher softwood litter Hg concentrations, along with the higher chronic litterfall flux throughout the winter and spring in softwoods. The estimated annual deposition of Hg via litterfall in Hadlock Brook watershed (10.1 μg m-² and Cadillac Brook watershed (10.0 μg m-² was greater than precipitation Hg deposition and similar to or greater than the magnitude of Hg deposition via throughfall. These results demonstrate that litterfall Hg flux to forested landscapes can be at least as important as precipitation Hg inputs.

A cross-disciplinary research project has been implemented because of increased awareness of the potential environmental effects caused by dispersion of metals from external applications into the environment. The work comprises a 4-year (1998-2002) field exposure of grades 304 and 316 stainless steels, and a laboratory percolation study simulating 20-25 years of chromium and nickel containing runoff water interactions with soil. Total metal annual release rates varied between 0.2 and 0.7 mg m-² yr-¹ for Cr, between 0.1 and 0.8 mg m-² yr-¹ for Ni and between 10 and 200 mg m-² yr-¹ for Fe. Most Cr and Ni is present in an ionic form as a result of the limited presence of organic matter at the immediate release situation. Metal ion concentrations in the runoff water are far below reported ecotoxic concentrations. Studies of the environmental interaction between runoff water from stainless steel and soil show the majority of released Cr and Ni to be retained and their concentrations in percolation water to be very low (0.5-1 μg L-¹ and 1-5.5 μg L-¹ for Cr and Ni, respectively). Speciation calculations showed Cr to be primarily complexed to dissolved organic carbon while Ni also was present in an ionic form in the solution phase. Soil extractions showed Cr and Ni to be very strongly retained within the soil.

Sulfate (SO₄ ²-), nitrate (NO₃ -) and ammonium (NH₄ ⁺) concentrations in precipitation as measured at NADP sites within the Ohio River Valley of the Midwestern USA between 1985 and 2002 are quantified and temporal trends attributed to changes/ variations in (i) the precipitation regime, (ii) emission patterns and (iii) air mass trajectories. The results indicate that mean SO₄ ²- concentrations in precipitation declined by 37-43% between 1985 and 2002, while NO₃ - concentrations decreased by 1-32%, and NH₄ ⁺ concentrations exhibited declining concentrations at some sites and increasing concentrations at others. The change in SO₄ ²- concentrations is in broad agreement with estimated reductions in sulfur dioxide emissions. Changes in NO₃ - concentrations appear to be less closely related to variations in emissions of oxides of nitrogen and exhibit a stronger dependence on weekly precipitation volume. Up to one quarter of the variability in log-transformed weekly NO₃ - concentrations in precipitation is explicable by variations in precipitation volume. Trends in annual average log-transformed SO₄ ²- concentrations exhibit only a relatively small influence of variability in weekly precipitation amount but at each of the sites considered the variance explanation of annual average log-transformed SO₄ ²- by sampling year was increased by removing the influence of precipitation volume. Annual mean log-transformed ion concentrations detrended for precipitation volume (by week) and emission changes (by year) exhibit positive correlations at all sites, indicating that the residual variability of SO₄ ²-, NO₃ - and NH₄ ⁺ may have a common source which is postulated to be linked to synoptic scale variability and air mass trajectories.

Sediment cores collected in eutrophic subalpine Lake Bled (NW Slovenia) were analyzed sedimentologically in terms of grain size, mineralogy and sedimentation rates, and geochemically in terms of metals and nutrients. Surficial sediment is composed of dark gyttya type clayey silt with 5%-10% of organic matter. The sediment below is fine laminated and composed of homogenous silt and clayey silt: Mineralogically, low-Mg calcite prevails, followed by dolomite, quartz, partially of diatomaceous origin, and feldspar. Clay minerals are composed of muscovite/illite and chlorite. Authigenic minerals are pyrite and 'lake chalk' (low-Mg calcite). Lake sediment is especially polluted by Pb, Zn and P. Higher contents were found in the northwestern and eastern parts due to the particle input by local inflows. Increasing eutrophication and pollution, indicated by Cd, Cu, V, Cr, Co and total N and P enrichment in the top layers of the cores, started almost 100 years B.P., and especially 50 years ago.

A benthic in situ flume and a 1D biogeochemical sediment model to evaluate solute fluxes across the sediment-water interface have been developed. The flume was successfully used to determine oxygen and nutrient fluxes at various locations of the Neckar River in Germany. The experimental results were linked with vertical pore water concentration profiles and independently verified with the model. By combining experimental and model results we assessed the influence of dissolved oxygen concentrations in the water column and the availability of degradable organic matter on sediment oxygen demand. The results and the derived relations can be used to parameterize the sediment module of large scale water quality models, allowing one to assess the influence of sediment-water interactions on various aspects of river water quality. Moreover, the biogeochemical sediment model can help to improve the general understanding of the processes governing solute concentrations and fluxes in sediments and across their interfaces.

Danish rivers carry >50% of the phosphorus (P) transport as particulate P (PP). In five of six rivers sampled in November 1998 iron-bound P made up > 59% of PP and loosely adsorbed P ranged between 2% and 13%. This fraction could potentially be released in 14[per thousand] seawater. The behaviour of dissolved and particulate P fractions was studied during seven month in a 2 km long estuary with low freshwater retention time and low tidal range. The river carried ~10% of PP as loosely adsorbed P but increased concentrations of dissolved inorganic P (DIP) relative to the estuarine mixing line was only observed in the summer month with low freshwater flow and was more likely due to DIP release from the bottom sediment. Instead estuarine particles were always enriched with oxidized iron (ox.Fe) and iron-bound P as well as loosely adsorbed P and during May-September this coincided with increasing concentration of PP in estuary. We suggest that flocculation of ox.Fe and adsorption of DIP onto the particles with subsequent transport seawards is a major loss process for P during the summer month. During winter month where 85% of the run-off occurs the dominant process in the estuary is sedimentation of larger particles, however, a comparison of river particles with surface sediment clearly reveals that most PP is mobilized again from the bottom sediments.

The process of eutrophication in form of intense plant growth has been observed in some lakes and water streams at the Plitvice Lakes National Park in central Croatia. Here we investigate whether this phenomenon is a consequence of anthropogenic pollution or due to naturally produced organic matter in the lakes. We applied chemical analysis of water at two springs and four lakes (nutrients, dissolved organic carbon (DOC), trace elements) and measurements of surface lake sediments (mineral and organic fraction analyses, trace elements) in four different lakes/five sites. The chemical composition of water does not indicate recent anthropogenic pollution of water because the concentrations of most trace elements are below detection limits. The concentrations of DOC and nutrients are slightly higher in the area of increased eutrophication-plant growth. Also the content of organic matter in the sediment is at the highest level in areas with highest C/N ratio indicating that the organic fraction of this sediment is mainly of terrestrial origin. There is no significant difference among the trace element concentration in the upper segment of all cores, deposited approximately during last 50 years when higher anthropogenic influence is expected due to development and touristic activity, and the lower part of the cores, corresponding to the period approximately 100-200 years before present. The content of trace elements and organic matter in sediments decreases from the uppermost lake downstream. According to our results there is no indication of recent anthropogenic pollution in water and sediment. Higher concentrations of DOC in water as well as phosphorus and some other elements in the lake sediment can be a consequence of input of natural organic matter to the lake water.