With the aim of understanding the origin of acid rains in South China, we analyzed rainwaters collected from Guangzhou, China, between March 2005 and February 2006. The pH of rainwater collected during the monitoring period varied from 4.22 to 5.87; acid rain represented about 94% of total precipitation during this period. The rainwater was characterized by high concentrations of SO42-, NO3-, Ca2+, and NH4+. SO42- and NO3-, the main precursors of acid rain, were related to the combustion of coal and fertilizer use/traffic emissions, respectively. Ca2+ and NH4+ act as neutralizers of acid, accounting for the decoupling between high SO42- concentrations and relatively high pH in the Guangzhou precipitation. The acid rain in Guangzhou is most pronounced during spring and summer. A comparison with acid precipitation in other Chinese cities reveals a decreasing neutralization capacity from north to south, probably related to the role and origin of alkaline bases in precipitation. A north-to-south decreasing trend in the neutralization capacity of precipitation in China.

The influences of macronutrient additions on nickel (Ni) uptake and distribution in the subcellular structures and macromolecular components of the dinoflagellate Prorocentrum donghaiense Lu were examined using a radioisotope tracer method. The results showed that nitrate addition enhanced the uptake of Ni by P. donghaiense, whereas phosphate addition inhibited Ni uptake at high-Ni concentration. Nitrate or phosphate addition significantly affected Ni distribution in the subcellular structures and components. The majority of Ni was found in the soluble substances (>70%) and in the proteins (55.0-79.6%) of the algal cells. Urea reduced the Ni content in the amino acid-carbohydrate but elevated its content in proteins, and shown significantly correlated with the protein content of the algal cells. Thus, nutrient enrichment could influence both metal uptake and its distribution in the subcellular structures and components of the phytoplankton, as well as its subsequent transfer in marine food chains. Macronutrient additions significantly affected nickel uptake and distribution in the subcellular substructures and components of the dinoflagellate.

Rainwater has been used as drinking water in Thailand for centuries especially in the rural parts and is accepted as an important water resource. From past to present, the quality of rainwater has changed with the landuse of the landscape, and its water quality is influenced by a diverse range of conditions such as the management of pollutant sources, the catchment condition, wind and meteorological conditions, and the location of rainwater collection points. In this study, the quality of rainwater collected off roofs at several locations was examined. Granular activated carbon (GAC) filtration was used as a pretreatment to microfiltration (MF) to remove the dissolved organic matter (DOC). After an initial adsorption period, the biofilm that formed on the GAC (biofilter) was found to remove DOC by up to 40%, 35%, and 15% for bed filter depths of 15, 10, and 5 cm, respectively. Biofilters also removed nitrate and phosphate by more than 80% and 35%. The hollow fiber membrane microfiltration with pore size of 0.1 μm was used to treat the effluent from biofiltration to remove the microorganisms/pathogens in the rainwater. Although there was no significant additional removal of DOC by MF, the biofilter removed all microorganisms. The use of biofilters as pretreatment to MF/UF could remove a higher amount of DOC, remove microorganisms, increase the membrane treatment efficiency, and reduce membrane fouling.

PM2.5 and PM10 samples were collected in the urban atmosphere of Elche (southeastern Spain) between December 2004 and November 2005. The samples were analyzed for mass and water-soluble inorganic ions (Na⁺, [graphic removed] , K⁺, Ca²⁺, Mg²⁺, Cl⁻, [graphic removed] and [graphic removed] ) with the aim of investigating the influence of the climatic and geographic features of a coastal semiarid area on the contribution of these species to PM levels. Secondary inorganic ions ( [graphic removed] , [graphic removed] , [graphic removed] ) were the major components in the fine fraction (PM2.5), accounting for 40% of the total mass. The relationship between non-marine [graphic removed] and [graphic removed] indicated that fine sulfate particles were completely neutralized by ammonium. In the coarse fraction (PM10-2.5), nitrate (as NaNO₃ and Ca(NO₃)₂), together with crustal (CaCO₃) and marine species (NaCl) accounted for almost 50% of the total mass. Fine sulfate and coarse nitrate showed summer maximums. In contrast, the concentrations of fine [graphic removed] were lowest in the warm period. Ammonium presented both winter and summer maximums. The levels of marine ions, except for coarse Cl⁻, were highest in summer when the dominant wind flow is from the sea. No significant seasonal variations were observed for coarse Ca²⁺ and [graphic removed] . The concentrations of all inorganic ions increased during Saharan dust events, in particular, fine [graphic removed] and [graphic removed] and coarse [graphic removed] . Coarse calcium was proved not to be a good tracer for this type of episode in our region since the average levels of this cation are elevated and the relative increase in its concentrations during African events was not as high as expected.

Batch experiments were performed to denitrify groundwater using sawdust as a carbon source at Marydale, South Africa. Alkalinity, pH, electrical conductivity, nitrate, nitrite, ammonia, SO ₄ ²⁻ , heterotrophic plate count (HPC), dissolved organic carbon (DOC), potassium and chloride were monitored. Two soil depths, 75 to 100 and 165 to 200 cm, respectively, from the Marydale area were used as matrix material during denitrification based on contrasting chemical composition with respect to major ion composition and moisture to consider different denitrification rates for varying soil depths. Different N to C ratios were used to evaluate the denitrification efficiency and the least undesirable products, e.g., elevated SO ₄ ²⁻ , H₂S and other reduced compounds. DOC is directly proportional to the N to C ratio used. Nitrite was produced for most of the treatments as incomplete denitrification occurred. The incubation periods were 28 and 43 days, respectively. N to C ratios were 12.6:1, 24:1, 34:1 and 54:1. Longer incubation period and higher N to C ratio resulted in total removal of both nitrate and nitrite. The reaction was carbon-limited for lower N to C ratios. The denitrification rate was proportional to the carbon availability at any time during the experiment. There was no significant difference in denitrification using heterogeneous and homogeneous particle sizes for sawdust. Soil depth of 75-100 cm displayed a greater denitrification rate than 165-200-cm soil depth due to higher initial soil nitrate concentration. The method showed some specificity, as DOC, nitrite, nitrate, alkalinity and HPC were the only parameters that showed a change in concentration over the duration of the denitrification experiment under constant temperature and nitrogen gas atmosphere. DOC and HPC were unacceptable for domestic use, but methods such as boiling or chlorinating water can rid it of bacteria.

Background, aim, and scope The Arctic holds large stores of minerals, and extracted materials are provided to the world's economy; in this sense, the Arctic issue associated with mining is not local but global. In a part of the Arctic region (the Kola Peninsula, 66-70° N and 28-41° E), metal levels are generally elevated in the lake sediment. There is a question as to what results in elevated metal levels--a natural process (naturally abundant minerals) or an anthropogenic process (mining and metallurgy). In terms of solving this question, Staroe lake located on the Kola Peninsula was researched as a case study. Materials and methods The following parameters were determined in relation with Staroe lake: (1) the current quality of the lake's water--each 1,000-ml sample was collected at a surface point and a deep point (near the bottom layer), and the collected samples were directly analyzed after filtration; (2) atmospheric bulk deposition--bulk deposition was collected using a set of three rainwater samplers near the lake. In addition, bulk deposition was collected in a background site (250 km to the southwest of the smelter complex) as a reference; and (3) sediment profile (plus principal component analysis)--lake-bottom sediment was collected by an open-gravimetric column sampler equipped with an automatic diaphragm. After collection, the sample columns were cut at a 1-cm interval for analysis. Eigenvalues and variances by factor were calculated from the correlation coefficients. Results The obtained data show that (1) naturally poor elements (Cu, Ni, Si, and SO₄ ²⁻) dominantly influence the lake's water quality; (2) they are transported from the anthropogenic sources to the study lake through the atmospheric pathway; (3) mainly the contents of Cu, Ni, Sr, and Ca have influenced the sediment quality since the 1950s, corresponding to the industrial movement; and (4) Cu, Ni, and Sr originate from an anthropogenic source (smelter), and Ca originates from both natural and anthropogenic sources. Discussion As compared with the Russian standard (San Pin 2.1.980-00), the contents of NO₃ ⁻ (50.3 ± 0.1 mg l⁻¹) and particulates (2.3 ± 0.2 mg l⁻¹) exceeded the standard levels (0.7 mg l⁻¹ NO₃ ⁻ and 45 mg l⁻¹ particulates); Staroe lake may be slightly contaminated. However, the contamination factor (comparison with the background data) implies that Staroe lake is considerably contaminated. There is a strong possibility that fine overburden detritus (<0.1 mm diameter) may be transported from an open pit to the study lake by natural forces such as wind. Although it is difficult to suppose that one factor dominantly affects the sediment quality, it follows from a factor analysis that factors 1 and 2 account for about 70% of the total variance: Factor 1 is the most dominant, and factor 2 is the second most dominant in the variability of sediment quality. It is considered that Cu, Sr, and Ni in factor 1 originate from anthropogenic sources because they are poor in sediment rocks. Conclusions The field survey conducted in Staroe lake can give the following answers to the key objectives: (1) The present water quality is affected by Cu, Ni, Si, and SO₄ ²⁻ in light of the contamination factor, and these elements originate from anthropogenic sources (the smelter and the open pit) and are transported to the lake through the atmospheric pathway; (2) the sediment profile and statistic analysis show that the lake quality has been influenced by deposition of metals since the 1950s; and (3) Cu, Ni, Sr, and Ca have influenced the sediment quality in light of the most dominant factor--Cu, Ni, and Sr originate from an anthropogenic source, whereas Ca comes from both natural and anthropogenic sources. Recommendations and perspectives The presented lake survey shows that the dispersion of human-related pollutants via the atmospheric pathway takes place in the Arctic region. If the current pollution continues without countermeasures, the high-latitude environment may lose its original characteristics; hence, this subject is important when considering how to implement a wide range of environmental protection measures in the Arctic.