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.

Typical mid-winter anthropogenic air pollution episodes are caused when pollutants are trapped in the lower atmospheric boundary layer due to the generation of surface inversion favored by synoptic conditions. We analyzed the optical properties of atmospheric aerosol particles obtained during one such episode using a sun/sky radiometer at two measurement sites: one located in the densely populated and industrialized central part of Israel, and the other in a reference site, about 150 km away. Aerosol optical thickness and volume size distributions showed an increased burden of fine aerosol particles in the central part of Israel. In order to verify the local origin and anthropogenic nature of the effect, the analysis was accompanied by examinations of the synoptic conditions, air mass backward trajectories, and conventional in situ air pollution measurements made by a ground-based sampling station. This case study shows the ability of optical measurements to track urban and industrial atmospheric air pollution expressed by high concentration of fine aerosol particles. In addition, it emphasizes the role of local Israeli air pollution sources and may explain the difference in the properties of long-term aerosol optical observations between the two sites. The advantages of the optical method presented are speed (almost instantaneous), automated measurement, and sensitivity to aerosol particle concentration as well as aerosol size fraction. The drawback is that the optical measurements discussed deal only with aerosol particles and cannot distinguish between different types of pollutant gases.

Interactions between Zn and Cd on the accumulation of these metals in coontail, Ceratophyllum demersum were studied at different metal concentrations. Plants were grown in nutrient solution containing Cd (0.05–0.25 mg l⁻¹) and Zn (0.5–5 mgl⁻¹). High concentrations of Zn caused a significant decrease in Cd accumulation. In general, adding Cd solution decreased Zn accumulation in C. demersum except at the lowest concentration of Zn in which the Zn accumulation was similar to that without Cd. C. demersum could accumulate high concentrations of both Cd and Zn. The influence of humic acid (HA) on Cd and Zn accumulation was also studied. HA had a significant effect on Zn accumulation in plants. 2 mg l⁻¹ of HA reduced Zn accumulation at 1 mg l⁻¹ level (from 2,167 to 803 mg kg⁻¹). Cd uptake by plant tissue, toxicity symptoms and accumulation at 0.25 and 0.5 mg l⁻¹, were reduced (from 515 to 154 mg kg⁻¹ and from 816 to 305 mg kg⁻¹, respectively) by addition of 2 mg l⁻¹ of HA. Cd uptake reached a maximum on day 9 of treatment, while that of Zn was observed on day 15. Long-term accumulation study revealed that HA reduced toxicity and accumulation of heavy metals.

The consequences of nitrogen (N) enrichment for terrestrial and freshwater ecosystems are of increasing concern in many areas due to continued or increasing high emission rates of reactive N. Within terrestrial ecosystems various conceptual frameworks and modelling approaches have been developed which have enhanced our understanding of the sequence of changes associated with increased N availability and help us predict their future impacts. Here, some recent findings are described and their implications for these conceptual frameworks and modelling approaches discussed. They are: (a) an early loss of plant species that are characteristic of low N conditions as N availability increases and a loss of species with high N retention efficiencies (so called N 'filters'), (b) suppression of microbial immobilisation of deposited [graphic removed] due to increased [graphic removed] availability in the early stages of N saturation, (c) the early onset of [graphic removed] leaching due to these changes (a and b above) in both plant and microbial functioning, (d) reduced sensitivity of vegetation to N additions in areas with high historical N deposition, (e) delayed changes in soil C:N changes due to increased net primary productivity and reduced decomposition of soil organic matter. Some suggestions of early indicators of N saturation are suggested (occurrence of mosses; [graphic removed] ratio in surface soils) which indicate either a shift in ecosystem function and/or structure.

CH₄ concentrations in both the surface and bottom waters of Jiaozhou Bay were determined during four surveys in 2003, which showed variability with both seasons and tidal cycles. Atmospheric fluxes of CH₄ in Jiaozhou Bay showed obvious seasonal and spatial variations, with the highest values occurring in summer and the lowest in winter. The annual emission of CH₄ from Jiaozhou Bay was estimated to be [graphic removed] . CH₄ in the water column of Jiaozhou Bay was found to come from several land-sources including riverine water input, sewage water input and groundwater input. The spatial and temporal variation in distributions and atmospheric fluxes of CH₄ in Jiaozhou Bay was influenced mainly by the input of polluted river waters and the sewage effluents along the eastern coast, which highlights the effects of human impacts on CH₄ emission rates.

Drainage water from agricultural fields with applied manure can degrade the bacterial quality of surface and groundwater. The impact of conventional tillage (CT) and zero tillage (ZT) practices on Escherichia coli (E.coli) discharge through artificially drained soils is not well understood. Consequently, two field trials were conducted during 2002–2004. The first trial involved fall applications of beef manure while the second involved spring applications of dairy manure. Both surface and subsurface drainage water were monitored in the first trial while only subsurface drainage water was monitored in the second. Under fall applied beef manure (trial 1), no differences (p > 0.05) were observed in E.coli concentrations (cfu/100 ml) in combined drainage water under both tillage systems. However, during 2003–2004, subsurface drainage water under ZT had higher E.coli concentrations and loads than drainage water under CT. When the combined (surface + subsurface) annual E.coli loads were considered, CT loads were greater than ZT during 2002–2003 with an opposite situation during 2003–2004. Overall, annual E.coli loads were similar under ZT (4.7 × 10¹⁰ cfu/ha) and CT (4.8 × 10¹⁰ cfu/ha). Spring dairy manure application (trial 2) produced significant (p > 0.03) tillage effect on E.coli loads in subsurface drainage water only during the second year. During the study period, ZT plots (1.55 × 10¹⁰ cfu/ha) discharged 5× more E.coli than CT (0.23 × 10¹⁰ cfu/ha). A longer duration of ZT practices resulted in higher subsurface flow volumes and subsequently greater loads of E.coli discharge in both trials.

The importance of the chemical composition in evaluating groundwater flow is discussed. Two different geological environments, a felsic volcanic region around San Luis Potosí (SLPB), Mexico, and a sedimentary basin, part of the Pannonian Basin (PB), in Hungary, were chosen to explore the effect of local, intermediate and regional groundwater flows on the chemical evolution of water in different geological circumstances. In the study areas contrasting stable isotopes and groundwater temperature values, as well as the chemical composition of groundwater were convenient tools to propose groundwater flow direction and to study contamination processes in the different groundwater flow systems. Results indicate that regardless of the geological framework variability of the chemical composition of the shallow (<100 m) groundwater is significant; at depth the chemical content of groundwater becomes homogeneous, and the concentrations are smaller than at shallow depths. The Cl- and NO- ₃ concentrations indicate mainly up- and downward vertical flow directions suggesting local flow systems in the shallow layers. The linear regression between Cl- and Na⁺ suggests that evaporation processes are the main control of the Cl- concentration. Deviations from the regression line suggest processes such as pollution at shallow depths in both study areas. Based on the distribution of Ca⁺², Mg⁺² and Na⁺, a lateral flow can be traced. The large dimensions of the geological units involved with the regional flow systems implies a long groundwater flow path, also these flows remain isolated from anthropogenic contamination, then groundwater has not been altered by human influence, although in the SLPB a communication between the local and intermediate flows has been found. Recharge areas of the local and intermediate flow systems are more vulnerable to contamination processes than the discharge areas, where the expected low dissolved oxygen content of ascending water could play a control. Differences in the lithology between the PB (sedimentary basin) and the SLPB (felsic volcanic basin) explain the contrasting saturation indices calculated for chalcedony and calcite and the lack of the expected development of HCO- ₃, SO-² ₄ Cl- facies and contrasting aerobic/oxidizing conditions.

The objectives of this study are: (1) Evaluate the capacity of Indian mustard (Brassica juncea) for uptake and accumulation of Cs and Sr natural isotopes. (2) Identify foliar structural and other physiological changes (biomass, relative water content etc.) resulted from the accumulation of these two elements. (3) Monitor the Cs and Sr uptake and bioaccumulation process by spectral reflectance. Potted Indian mustard plants were exposed to different concentrations of Cs (50 and 600 ppm) and Sr (50 and 300 ppm) natural isotopes in solution form for 23 days. Bioaccumulation of Cs and Sr were found in the order of leaves > stems > roots for both Cs- and Sr-treated plants. The highest leaf and root Sr accumulations are observed to be 2,708, and 1,194 mg kg⁻¹, respectively; and the highest leaf and root Cs accumulations are 12,251, and 6,794 mg kg⁻¹, respectively. High translocation efficiency for both elements is documented by shoot/root concentration ratios greater than one. Biomass decreases were observed for plants treated with higher concentration of Cs or Sr. Cs accumulation affected the pigment concentration and internal structure of the leaf and the spectral characteristics of plants. Within the applied concentration range, Sr accumulation resulted in no significant changes in relative water content (RWC), leaf structural and spectral characteristics of mustard plants. Cs shoot concentration showed significant negative correlation with relative water content (RWC; r = −0.88*) and normalized difference vegetative index (NDVI) value (r = −0.68*) of plant shoots. The canopy spectral reflectance and NDVI analysis clearly revealed (p < 0.05) the stress caused by Cs accumulation.