The objective of this study was to examine the chemistry of trace elements in coalbed methane (CBM) discharge water reacting with semi-arid ephemeral stream channels in Powder River Basin, Wyoming. The study area consisted of two ephemeral streams, Burger Draw and Sue Draw. These streams are tributaries to the perennial Powder River, Wyoming. Samples were collected bimonthly from three CBM discharge points and seven channel locations in Burger Draw and Sue Draw. Samples were also collected bimonthly from the Powder River above and below the confluence of Burger Draw. Before sample collection, pH, temperature, dissolved oxygen (DO), and turbidity were measured in the field. Samples were transported to the laboratory and analyzed for dissolved trace elements including iron (Fe), manganese (Mn), boron (B), arsenic (As), selenium (Se), and fluoride (F). Results suggest pH of discharge water was 7.1 and increased significantly in the downstream channel of Burger Draw to 8.84 before joined with the Powder River. Temperature of CBM produced water at discharge points ranged between 20.3 and 22.7 [composite function (small circle)]C. Before discharge, DO concentrations of CBM produced water were between 1.42 and 1.5 mg/L. No significant differences in temperature, DO, and turbidity were found between Burger Draw flow and Powder River flow. However, significant differences were found within the sampling period in temperature and turbidity in flow of Burger Draw. The temperature, DO, and turbidity were all significantly different in Powder River within the sampling period. The CBM discharge water consisted of higher concentrations of F, Fe and B compared to other components. Significant changes were observed for Fe, Mn, and As; and seasonally for B. Dissolved Fe and Mn decreased, while As and Se increased in downstream channel flow. These findings will be useful in proper management of CBM produced water in semi-arid environments.

Hydrochemistry of an alluvial river was investigated employing the chemometric techniques such as cluster analysis (CA), principal component analysis (PCA), discriminant analysis (DA) and partial least square (PLS) with a view to extract information about the variables responsible for spatial and temporal variations in river hydrochemistry and water quality, the hidden factors explaining the structure of the hydro-chemical database of the river, factors/processes influencing the river hydro-chemistry. Analysis of spearman's correlation coefficient revealed non-significant correlation of the pollution indicator (BOD, COD, SO₄, F, NH₄-N, NO₃-N) variables with season and significant correlation with site, indicating contribution of the site-specific anthropogenic sources in the catchments. Spatial CA clustered the monitoring sites (10nos.) into three groups of relatively non-polluted sites, moderately polluted sites, and highly polluted sites. Temporal CA differentiated among the samples of monsoon and non-monsoon months. PCA rendered considerable data reduction, in terms of eight parameters explaining about 71% of the total variance and evolved six PCs. PCA grouped samples belonging to different seasons and sites distinctly correlating them with natural and anthropogenic variables. Temporal and spatial DA rendered 97 and 92% correct assignations of the samples, respectively, and revealed that temperature, pH, BOD, DO, alkalinity and Ca are the most significant variables to discriminate between the different seasons and account for most of the expected temporal variations in hydrochemistry of the river, whereas, hardness, DO, BOD, COD, Ca and Mg were the most significant discriminating variables in space. Spatial and temporal groupings of the samples were successfully achieved through PLS modeling. PLS showed that the summer season samples are dominated by PO₄, TDS, F, K, COD, BOD, Na, Cl, hardness and alkalinity, whereas, samples of winter season by DO, pH, NH₄-N and coliforms. Furthermore, PLS indicated site-specific dominance of anthropogenic contaminants suggesting for their pollution sources in the corresponding catchments of these sites.

The Erzgebirge, part of the so-called former “Black Triangle”, used to represent the strongest regional air pollution of Central Europe. To test the hypothesis of deposition enhancement with height, an altitudinal gradient along a N-S transect from the Elbe river lowlands to the Erzgebirge summit was chosen to investigate chemical composition, elevation-related variability, temporal changes, and seasonal patterns of ion concentrations from 1993 to 2002. The following questions were to be answered: (1) Which role does orography play on the composition of precipitation?, (2) Does fog occurrence overrule the orographic influence?, (3) Are there changes in the past 10 years, and if so, why?, (4) Do relevant seasonal changes occur and why? Air streams from westerly and to a lesser degree south-easterly directions prevail. The average precipitation was ion-poor (23 μS cm-¹ and acidic (pH 4.5). Sulphate still was the dominant anion (52.3-59.9 μeq L-¹, while NH⁺ ₄ determined the cations (41.9-62.2 μeq L-¹. Ion concentrations decreased with altitude to about 735 m a.s.l. and subsequently increased. The seeder-feeder effect largely explains the chemical composition of precipitation; enhanced in winter through snow crystals. Sub-cloud scavenging does not explain the observed patterns. Fog occurrence enhanced the observed effects at higher altitudes. Deposition amounts doubled from the lowlands to the Erzgebirge summit. From 1993 to 2002, acidity decreased by about 50%, mainly due to reduced SO₂ -emissions.

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.