A critical load data base was developed for Europe and Northern Asia using the latest data bases on soils, vegetation, climate and forest growth. Critical loads for acidity and nutrient nitrogen for terrestrial ecosystems were computed with the Simple Mass Balance model. The resulting critical loads are in accordance with critical loads from previous global empirical studies, but have a much higher spatial resolution. Critical loads of acidity are sensitive to both the chemical criterion and the critical limit chosen. Therefore a sensitivity analysis of critical loads was performed by employing different chemical criteria. A critical limit based on an acid neutralizing capacity (ANC) of zero resulted in critical loads that protect ecosystems against toxic concentrations of aluminium and unfavourable Al/Bc ratios, suggesting that ANC could be an alternative to the commonly used Al/Bc ratio. Critical loads of nutrient nitrogen are sensitive to the specified critical nitrate concentration, especially in areas with a high precipitation surplus. If limits of 3-6 mg N l⁻¹ are used for Western Europe instead of the widely used 0.2 mg N l⁻¹, critical loads double on average. In low precipitation areas, the increase is less than 50%. The strong dependence on precipitation surplus is a consequence of the simple modelling approach. Future models should explore other nitrogen parameters (such as nitrogen availability) instead of leaching as the factor influencing vegetation changes in terrestrial ecosystems.

In contaminated water reservoirs, the sorption and binding of radionuclides to solids (SR) determines their bioavailability and transport and thus human and ecosystem exposure. In this work, the influence of organic matter (OM) on binding of the radionuclides ⁹⁰Sr, ¹³⁷Cs, sum of ²³⁵U, ²³⁸U, and sum of ²³⁹Pu, ²⁴⁰Pu to solids are investigated, using experimental data derived from ecological monitoring of radioactive waste deposits in South Ural (Russia). OM in several surface water reservoirs mainly consists of humic substance (HS) which forms humates and fulvates with radionuclides and binds to solids via different mechanisms, such as coordinating bond or covalent bond. These processes are strongly dependent on the phase of HS, which can be colloidal or soluble high-molecular compounds. Based on the spatial distribution of radionuclides, SR and OM in waste deposits, we assumed a specific influence of humic acids (HA) on the binding of radionuclides to SR, and quantified it with invariant values of a modified partitioning coefficient. The mathematical form of this invariant value emphasizes a significant impact of the local mass of HA (mHA/V) and local surface area of SR (s = Ssorb/V) per volume V on the processes involved in binding radionuclides to SR. These processes may retard radionuclide migration into groundwater.

Inorganic nitrogen deposition and leaching in stream water were monitored from January, 2001 to December, 2004 in a subtropical evergreen mixed forest in central-south China. The seasonal concentration and flux of inorganic nitrogen in bulk precipitation and stream water, seasonal mean net retention of nitrogen and net flux of H⁺ transformed by nitrogen were estimated and quantified in Shaoshan forest. The research results show that the correlation coefficient of fluxes between bulk precipitation and stream water is significant, with a coefficient 0.916 at the 0.01 level. Mean fluxes of inorganic nitrogen input are 2.62 g m⁻² a⁻¹ and 0.516 g m⁻² a⁻¹ in form of bulk precipitation and dry deposition respectively, and output in stream water is around 0.22 g m⁻² a⁻¹, which indicates that most of nitrogen input is reserved in the forest. Net retention of nitrogen reaches 2.916 g m⁻² a⁻¹, just higher than other study plots over the world. Along with the translating of nitrogen ( [graphic removed] and [graphic removed] ), H⁺ is imported to the forest ecosystem at the same time. At our study plots, net flux of H⁺ transformed by nitrogen is about 73.57 mmol m⁻² a⁻¹. The positive value suggests that Shaoshan forest is still a finer buffering system to nitrogen deposition and it is far from nitrogen saturation in spite of the high nitrogen deposition.

This paper presents transformations of saturated hydrocarbons of petroleum type pollutants during ex situ bioremediation of soil on the pilot heap (halde), during a period of 6 months, within the grounds of Petroleum Refinery Pančevo (Serbia). Samples for analysis were taken in time intervals of 2 weeks (P₁-P₁₂ samples). Organic substance was extracted by Soxhlet's method and quantified. Isoprenoid aliphatics, in particular pristane and phytane, and polycyclic aliphatics of sterane and triterpane types in saturated hydrocarbon fractions were analysed by GC-MS (SIM method). Significant amounts of n-alkanes have not been detected. The MS-chromatogram revealed only marginal amounts of pristane and phytane in sample P₁. Pristane and phytane occurred in sample P₈, and in even higher quantities in the final sample P₁₂. The proceeding bioremediation process was accompanied by the decrease of the relative amounts of pentacyclic terpanes of hopane type, compared to tri- and tetracyclic terpanes. In the initial sample P₁ the distribution of steranes and hopanes follows a pattern, which is characteristic for crude oils. However, their identification by SIM method was not possible in samples P₈ and P₁₂ because of the reduced concentration. The observed changes in the alkane fractions' compositions may be considered as atypical, referring to the fact that during oil biodegradation under natural conditions, decomposition of isoprenoids occurs much easier and faster than decomposition of polycyclic alkanes of tri-, tetra- and pentacyclic terpane, sterane and diasterane types, after the decomposition of n-alkanes has been almost completed.

The partial phase transformation of nanometer TiO₂ powder from anatase phase to rutile phase was realized by heat-treatment and a new TiO₂ photocatalyst which could be excited by visible light was obtained. The heat-treated TiO₂ powder at different stage of transition crystal was characterized and monitored by XRD, TEM, FT-IR and UV-vis DRS methods. The test of photocatalytic activity of the heat-treated TiO₂ powder was carried out by the photocatalytic degradation of rhodamine B and acid orange II dyes, respectively, in aqueous solution under visible light irradiation. The results indicate that the nanometer TiO₂ photocatalyst heat-treated at 500°C for 60 min shows the highest photocatalytic activity, that is, it can effectively degrade the rhodamine B and acid orange II under visible light irradiation. The remarkable improvement of photocatalytic activity of heat-treated TiO₂ powder at 500°C for 60 min was mainly illustrated by the formation of special interphase between rutile and anatase phases, which not only restrains the recombination of photogenerated electrons and holes, but also reduces the adsorbability of nanometer anatase TiO₂ powder properly for various dyes. Additionally, the effects of dye-assisting chemicals such as Na₂CO₃ and NaCl on the photocatalytic degradation were also studied.

The chemical composition of precipitation in the city of Mersin on the Mediterranean coast of Turkey has been studied. Spatial and temporal variability of rainwater constituents have been determined from samples collected at two central and two suburban stations for the December 2003-May 2005 period. A total of 246 samples covering all precipitation events were analyzed to determine pH, conductivity, as well as major anion (Cl-, [graphic removed] , [graphic removed] ); major cation (H⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, [graphic removed] ) and formaldehyde (HCHO) concentrations. The pH varied within a range of 4.8-8.5, with only 8 out of 246 samples being acidic (pH < 5.6), and the remaining highly alkaline samples being neutralized by either [graphic removed] in rainwater, or by CaCO₃ resulting from wet deposition of atmospheric dust. The volume weighted mean ΣAnion/ΣCation ratio was 0.49. The equivalent concentration of major ionic species followed the order: [graphic removed] . Formaldehyde concentrations varied in the range of 0.01-17.9 μM, and was found to be dependent on precipitation volume. Relatively higher [graphic removed] , [graphic removed] , [graphic removed] and HCHO concentrations, mainly of anthropogenic origin, measured near the city center suggest increased pollution from local anthropogenic sources, e.g., residential heating, industrial and/or traffic emissions. In general, the results of this study suggest local precipitation chemistry is more strongly influenced by natural (mineral dust and marine) sources compared to anthropogenic ones.

In the present study, a three-dimensional Eulerian photochemical model was employed to estimate the impact that organic compounds have on tropospheric ozone formation in the Metropolitan Area of São Paulo (MASP). In the year 2000, base case simulations were conducted in two periods: August 22-24 and March 13-15. Based on the pollutant concentrations calculated by the model, the correlation coefficient relative to observations for ozone ranged from 0.91 to 0.93 in both periods. In the simulations employed to evaluate the ozone potential of individual VOCs, as well as the sensitivity of ozone to the VOC/NO x emission ratio, the variation in anthropogenic emissions was estimated at 15% (according to tests performed previously variations of 15% were stable). Although there were significant differences between the two periods, ozone concentrations were found to be much more sensitive to VOCs than to NO x in both periods and throughout the study domain. In addition, considering their individual rates of emission from vehicles, the species/classes that were most important for ozone formation were as follows: aromatics with a kOH > 2 x 10⁴ ppm⁻¹ min⁻¹; olefins with a kOH < 7 x 10⁴ ppm⁻¹ min⁻¹; olefins with a kOH > 7 x 10⁴ ppm⁻¹ min⁻¹; ethene; and formaldehyde, which are the principal species related to the production, transport, storage and combustion of fossil fuels.

The present study aims to understand the hydrochemistry vis-à-vis As-exposure from drinking groundwater in rural Bengal. The characteristic feature of the groundwaters are low Eh (range, -151 to -37 mV; mean, -68 mV) and nitrate (range, 0.01-1.7 mg/l; mean, 0.14 mg/l) followed by high alkalinity (range, 100-630 mg/l; mean, 301 mg/l), Fe (range, 0.99-38 mg/l; mean, 8.1 mg/l), phosphate (range, 0.01-15 mg/l; mean, 0.54 mg/l), hardness (range, 46-600 mg/l; mean, 245 mg/l) and sulphate (range, 0.19-88 mg/l; mean, 7.2 mg/l), indicating reducing nature of the aquifer. The land use pattern (sanitation, surface water bodies, sanitation coupled with surface water bodies and agricultural lands) demonstrates local enrichment factor for As/Fe in groundwater. Among these, sanitation is the most prevailing where groundwater is generally enriched with As (mean, 269 μg/l) and Fe (mean, 9.8 mg/l). Questionnaire survey highlights that ~70% of the villagers in the study area do not have proper sanitation. This demonstrating the local unsewered sanitation (organic waste, anthropogenic in origin) could also cause As toxicity in rural Bengal. In the agricultural lands, higher mean values of alkalinity, phosphate, sulphate, hardness and electrical conductivity was observed, and could be linked with the excessive use of fertilizers for agricultural production. Bio-markers study indicates that the accumulation of As in hair and nail is related with the construction of exposure scenario with time dimension. The strength and weakness of the on-going West Bengal and Bangladesh drinking water supply scenario and achievability towards alternative options are also evaluated.

The concentrations of Pb, Cd, Cr, Mn and Fe were evaluated in leaves, stem and root of the Scirpus americanus and Typha latifolia aquatic macrophytes, which were collected from Tanque Tenorio, an artificial lagoon highly polluted by municipal and industrial wastewater. Some S. americanus and T. latifolia plants were collected from four different sites within Tanque Tenorio. The sites were chosen regarding their proximity with the main channel discharging wastewater into the lagoon. The results showed that S. americanus and T. latifolia have the ability to extract Pb, Cd, Cr, Mn and Fe from their water surroundings; on the whole, the roots presented higher concentrations of heavy metals than the stem and the leaves. The highest accumulation of heavy metals was observed in plants growing at the site near the channel entering the lagoon. S. americanus accumulated more Pb, Cr, Mn and Fe than T. latifolia; Cd concentrations were comparably the same in both species. This study provides information in relation to aquatic plants growing in polluted waters, which accumulate heavy metals. These findings are of interest pertaining to the removal processes for treating aquatic systems with heavy metal content.

In order to estimate acute-to-chronic toxicity ratios (ACRs) relevant to a coldwater stream community, we exposed rainbow trout (Oncorhynchus mykiss) to cadmium (Cd), lead (Pb), and zinc (Zn) in 96-h acute and 60+ day early-life stage (ELS) exposures. We also tested the acute and sublethal responses of a mayfly (Baetis tricaudatus) and a midge (Chironomus dilutus, formerly C. tentans) with Pb. We examine the statistical interpretation of test endpoints and the acute-to-chronic ratio concept. Increasing the number of control replicates by 2 to 3x decreased the minimum detectable differences by almost half. Pb ACR estimates mostly increased with increasing acute resistance of the organisms (rainbow trout ACRs <[almost equal to] mayfly < Chironomus). The choice of test endpoint and statistical analysis influenced ACR estimates by up to a factor of four. When calculated using the geometric means of the no- and lowest-observed effect concentrations, ACRs with rainbow trout and Cd were 0.6 and 0.95; Zn about 1.0; and for Pb 3.3 and 11. The comparable Pb ACRs for the mayfly and Chironomus were 5.2 and 51 respectively. Our rainbow trout ACRs with Pb were about 5-20x lower than earlier reports with salmonids. We suggest discounting previous ACR results that used larger and older fish in their acute tests.