Emissions of sulphur and oxidized nitrogen compounds in Europe have been reduced following a series of control measures during the last two decades. These changes have taken place during a period in which the primary gases and the wet deposition throughout Europe were extensively monitored. Since the end of the 1970s, for example land based sulphur emissions declined by between 90 and 70% depending on the region. Over the same period the total deposition of sulphur and its partitioning into wet and dry deposition have declined, but the spatial pattern in the reduction in deposition differs from that of emission and has changed with time. Such non-linearities in the emission-deposition relationship are important to understand as they complicate the process of assessing the effects of emission reduction strategies. Observed non-linearities in terrestrial sulphur emission-deposition patterns have been identified in north west Europe due to increases in marine emissions, and are currently slowing the recovery of freshwater ecosystems. Changes in the relative amounts of SO₂ and NH₃ in air over the last two decades have also changed the affinity of terrestrial surfaces for SO₂ and have therefore changed the deposition velocity of SO₂ over substantial areas. The consequence of this effect has been the very rapid reduction in ambient SO₂ concentration in some of the major source areas of Europe, where NH₃ did not change much. Interactions between the different pollutants, generating non-linearities are now being incorporated in long-range transport models to simulate the effects of historical emission trends and to provide projections into the future. This paper identifies non-linearities in emission deposition relationships for sulphur and nitrogen compounds in Europe using data from the EMEP long-rang transport model and measured concentration fields of the major ions in precipitation and of SO₂ and NO₂ in surface air.

On 1998, a settling pond of a pyrite mine in Aznalcóllar (SW Spain) broke open, spilling some 3.6 × 10⁶ m³ of water and 0.9 × 10⁶ m³ of toxic tailings into the Agrio and Guadiamar river basin 40 km downstream, nearly to Doñana National Park. The soils throughout the basin were studied for arsenic pollution. Almost all the arsenic penetrated the soils in the solid phase (tailings) in variable amounts, mainly as a result of the different soil structure. The chemical oxidation of the tailings was the main cause of the pollution in these soils. A study of the relationships between the main soil characteristics and arsenic extracted with different reagents (water, CaCl₂, acetic acid, oxalic–oxalate and EDTA) indicates a direct relationship with the total arsenic concentration. The highest amount of arsenic was extracted by oxalic–oxalate (24%–36% of the total arsenic), indicating the binding with the iron oxides.

In this study adsorption of arsenic (As) onto TiO₂ nanoparticles and the facilitated transport of As into carp (Cyprinus carpio) by TiO₂ nanoparticles was examined. Adsorption kinetics and adsorption isotherm were conducted by adding As(V) to TiO₂ suspensions. Facilitated transport of As by TiO₂ nanoparticles was assessed by accumulation tests exposing carp to As(V) contaminated water in the presence of TiO₂ nanoparticles. The results showed that TiO₂ nanoparticles had a significant adsorption capacity for As(V). Equilibrium was established within 30 min and the isotherm data was described by Freundlich isotherm. The KF and 1/n were 20.71 mg/g and 0.58, respectively. When exposed to As(V)-contaminated water in the presence of TiO₂ nanoparticles, carp accumulated considerably more As, and As concentration in carp increased by 132% after 25 days exposure. Considerable As and TiO₂ accumulated in intestine, stomach and gills of the fish, and the lowest level of accumulation was found in muscle. Accumulation of As and TiO₂ in stomach, intestine and gills are significant. Arsenic accumulation in these tissues was enhanced by the presence of TiO₂ nanoparticles. TiO₂ nanoparticles that have accumulated in intestine and gills may release adsorbed As and As bound on TiO₂ nanoparticles which cannot be released maybe transported by TiO₂ nanoparticles as they transferred in the body. In this work, an enhancement of 80% and 126% As concentration in liver and muscle after 20 days of exposure was found.

Trace elements may present an environmental hazard in the vicinity of mining and smelting activities. However, the factors controlling their distribution and transfer within the soil and vegetation systems are not always well defined. Total concentrations of up to 15,195 mg . kg –¹ As, 6,690 mg . kg–¹ Cu, 24,820 mg . kg–¹ Pb and 9,810 mg . kg–¹ Zn in soils, and 62 mg . kg–¹ As, 1,765 mg . kg–¹ Cu, 280 mg . kg–¹ Pb and 3,460 mg . kg –¹ Zn in vegetation were measured. However, unusually for smelters and mines of a similar size, the elevated trace element concentrations in soils were found to be restricted to the immediate vicinity of the mines and smelters (maximum 2–3 km). Parent material, prevailing wind direction, and soil physical and chemical characteristics were found to correlate poorly with the restricted trace element distributions in soils. Hypotheses are given for this unusual distribution: (1) the contaminated soils were removed by erosion or (2) mines and smelters released large heavy particles that could not have been transported long distances. Analyses of the accumulation of trace elements in vegetation (median ratios: As 0.06, Cu 0.19, Pb 0.54 and Zn 1.07) and the percentage of total trace elements being DTPA extractable in soils (median percentages: As 0.06%, Cu 15%, Pb 7% and Zn 4%) indicated higher relative trace element mobility in soils with low total concentrations than in soils with elevated concentrations.

The research concerns the Wielkopolski National Park (West Poland), which suffered a huge human impact in the 1970s and 1980s owing to the nearby location of an industrial plant. Since then, fundamental technological changes that it introduced into its production of phosphate fertilizers have radically reduced the amount of pollution emitted. A three-year study (2002-2004) of fluorides in precipitation in open terrain and under tree crowns showed their concentrations to range from levels below the detection limit (0.003 mg/l) to 0.560 mg/l. Those registered under tree crowns were several times higher and indicated substantial dry deposition of fluorides on the trees. The highest values were recorded in 2003, with 43% of samples ranging from 0.01 to 0.05 mg/l, and with 51% of throughfall ranging from 0.10 to 0.50 mg/l. A strong connection was shown to exist between fluoride and sulphate concentrations in the precipitation. An analysis was made of the available data on F concentrations in the air and the dust levels around the factory, but these figures did not show an unequivocal effect on F concentrations in precipitation. A great similarity was found to occur between the fluoride content in rainwater in the Wielkopolski National Park and in the centre of the nearby Poznań metropolitan area, which indicates that there are also other F sources besides the local factory.

Four umbric A horizons from acid forest soils were acidified in a batch type experiment and its effect in the Al pools of the solid phase analysed by means of selective dissolution methods. The results showed that Al release accounted for the consumption of 85-99% of the added protons, and causes a decrease of 2-33% of the 'reactive' Al pool of the soil solid phase. In these A horizons, inorganic non-crystalline Al and high stability Al-humus complexes are the main sources of the dissolved Al. The contribution of the complexes with intermediate stability only was relevant in the more acid horizon developed from phyllites (P18-A). The increase of equilibration time from 96 to 720 h did not caused significant differences in the decrease of the 'reactive' Al pool suggesting the acid neutralising reactions occurred in less than 96 h. In most cases the quantity of released Al is in agreement with the decrease of the different reactive Al pools of the solid phase.

Groundwater contamination by leakage and spill of petroleum hydrocarbons from underground storage tanks has been a major environmental concern. Among various remediation alternatives, the vacuum-enhanced free product recovery (VFPR) is an important technology to extract light nonaqueous-phase liquids (LNAPLs) from subsurface. However, efficient design of a VFPR system was challenging to practitioners, since the process of hydrocarbon removal is costly and time consuming. To address such a problem, an integrated study system for optimizing the VFPR process was developed through coupling a numerical modeling system, a multivariate regression technique and nonlinear optimization model into a general framework. A two-dimensional multiphase flow simulation system was provided for modeling VFPR processes. An iterative stepwise-inference regression (ISIR) method was advanced for establishing a linkage between remediation actions and system responses. A nonlinear optimization model embedded with ISIR was then established for generating desired operating conditions. The results from a case study demonstrated that the established optimization model could effectively analyze tradeoffs between various environmental and economical considerations, and provide effective decision supports for site remediation practices. Compared with the conventional stepwise-cluster analysis method, the proposed ISIR method was more efficient and reliable in approximating relationships between remediation actions and system responses, and could significantly enhance the robustness of optimization solutions.

The Bagmati River in Kathmandu valley, Nepal, was studied to understand the influence of human and geochemical processes on changes in river chemistry (nutrients, organic matter, and major cations and anions) along the drainage network. Population density appeared to drive variation in the chemistry of surface waters at 10 stations in the Bagmati River. For all constituents studied, concentrations increased with distance downstream and many parameters showed strong relationships with human population density adjacent to the river. The composition of river water suggests that sewage effluent entering the river has a major effect on water quality. Concentrations of most solutes were highest during summer and lower during the winter monsoon season. The contribution of chemical weathering processes to water quality of the Bagmati appears to be minor within the Kathmandu valley. Dominant cations and anions when expressed in equivalents per liter were [graphic removed] and [graphic removed] along the entire Bagmati drainage system. Ammonium contributed almost all nitrogen in the total dissolved nitrogen fraction and the concentration of nitrate was negligible, probably due to rapid denitrification and limited nitrification within the stream channel under conditions of relatively low oxygen. Decreases in sulfate along the stream channel may also be due to the reduction of sulfate to sulfide due to heavy organic matter loading. Water quality is unacceptable for any use and the whole ecosystem is severely affected due to human activities within the urban areas of the drainage basin.

A glass house study was conducted to investigate the accumulation of arsenic in tissues of five widely cultivated rice (Oryza sativa L.) varieties of Bangladesh namely BRRI dhan 28, BRRI dhan 29, BRRI dhan 35, BRRI dhan 36, BRRI hybrid dhan 1. Arsenic concentrations were measured in straw, husk and brown and polish rice grain to see the differential accumulation of arsenic among the rice varieties. The results showed that the concentrations of arsenic in different parts of all rice varieties increased significantly (p < 0.05) with the increase of its concentrations in soil. The rice varieties did not showed significant differences in arsenic accumulation in straw, husk, brown and polish grain when the concentrations of arsenic in soil was low. However, at higher concentrations of arsenic in soil, different rice varieties showed significant differences in the accumulations of arsenic in straw, husk and grain. Significantly higher concentrations of arsenic in straw and husk of rice were observed in BRRI hybrid dhan 1 compared to those of other verities. The BRRI dhan 28 and 35 concentrated significantly higher amount of arsenic in brown and polish rice grain compared to those of other rice varieties. The results imply that arsenic translocation from root to shoot (straw) and husk was higher in hybrid variety compared to those of non-hybrid varieties. Arsenic concentrations in brown and polish rice grain of five rice varieties were found to follow the trend: BRRI dhan 28 > BRRI dhan 35 > BRRI dhan 36 > BRRI dhan 29 > BRRI hybrid dhan 1. The order of arsenic contents in tissues of rice was: straw > husk > brown rice grain > polish rice grain.

Aerosol samples were collected during the wintertime from Nov. 24, 1998 to Feb. 12, 1999 in Beijing, China. Chemical composition was determined using several analytical techniques, including inductive coupled plasma atomic emission spectroscopy (ICP-AES), graphite furnace atomic absorption spectroscopy (GFAAS) and flame atomic absorption spectroscopy (FAAS) for trace elements, ion chromatography (IC) for water-soluble ions and CHN elemental analyzer for organic carbon (OC) and elemental carbon (EC). The average concentration of aerosol was 375 ± 169 μg m⁻³, ranging from 136 to 759 μg m⁻³. Multilinear regression (MLR) analysis was performed and crustal matter, secondary particles and organics were identified as three major components of aerosol in wintertime in Beijing, accounting for 57.3% ± 9.8%, 13.4% ± 8.0%, and 22.8% ± 5.9% of the total concentration, respectively. Based on performance evaluation, Al, SO₄ ²⁻ and OC were selected as tracers of the three components, with the regression coefficients of 23.5, 1.78 and 1.26, respectively. A regression constant of 19.6 was obtained, which accounts for other minor components in aerosol. On average 93.5% of the total aerosol concentration, ranging from 82% to 105%, was explained by crustal matter, secondary particle and organics. Meteorological conditions are important factors that can influence the concentration level and chemical composition of aerosols. Wind would be favorable for the pollutant dilution, leading to low aerosol levels, whereas too strong a wind may cause regional soil dust and local road dust to be resuspended resulting in a high contribution of crustal matter. Circuitous air movement, high RH% and low wind speed facilitated the secondary particle formation, not only inorganic salts, such as sulfate and nitrate, but also secondary organic carbon in a similar way.