Bromine in rainfall, cloud water, stream water and groundwater were measured in the upper River Severn catchments at Plynlimon in midWales using two analytical procedures for bromide determination: a colorimetric method and, later, ion chromatography. Discrepancies between the methods indicated that the colorimetric method was measuring more than just bromide so it was dissolved labile bromine (DLBr) (Neal et al. 2007). This paper reports the variation in DLBr and bromide across the Plynlimon region and assesses the differences between these two measures. The average DLBr concentration in the streams ranges between 18.3 and 27.8 mgl -1 compared with a rainfall average concentration of 15.6 mg l 1 . The corresponding bromide concentrations in the streams are 13.818.6 mg l -1 and 13.2 mg l -1 in rainfall. For cloud water, throughfall and stemflow, DLBr concentrations are an order of magnitude higher than in rainfall and the concentrations are strongly correlated with chloride. Average values of bromide in rainfall and cloud water are similar to those of DLBr and are strongly correlated with chloride: unfortunately, no bromide measurements were taken in throughfall and stemflow. These results indicate that marine aerosol inputs are high and that the DLBr in these inputs is dominated by bromide. For cloud water, DLBr was correlated with dissolved organic carbon (DOC) as well as with chloride; hence, there may well be an organic-associated component. Within the streams draining the forested areas, DLBr increases with time as DOC increases. DLBr concentrations in the streams are correlated with DOC in most cases and, to a lesser degree, with chloride. However, for bromide there is no correlation with DOC, but a weak correlation with chloride remains and the gradient is higher than for the DLBr case. Increasing concentrations of both DLBr and DOC may well reflect the wetting up of the catchments as transpiration diminshes as the trees age as well as through felling. In groundwater, only DLBr has been measured, and its concentration is similar to that for the streams. However, in the groundwater zone, DLBr is poorly correlated with DOC concentrations, in which DOC is largely converted to CO 2 . Atmospheric inputstream output flux estimates indicate a net uptake of bromide by the catchment of around 30%, matched by a corresponding release of DOC-associated bromine.

Abstract. Data on the water quality of streams draining a range of acidic and acid sensitive, mainly afforested, upland catchments in mid- and north-Wales and northern-England are described to investigate the acidification effects of conifer harvesting in relation to natural variability. Most sites show a large range in pH and major cation and major anion concentrations. The waters draining from the smaller catchments are more acidic and aluminium bearing reflecting a higher proportion of runoff from the acidic soils in each area. However, there is often a less acidic component of runoff under base-flow conditions due to ground-water contributions particularly within the larger streams. Higher concentrations of nitrate occur for sites which have been felled although declines in concentration occur several years after felling. Multiple regression analysis reveals the importance of cation exchange and within catchment acidification associated with sulphate and nitrate generation. Sulphate also has a component associated with weathering but the patterns vary from catchment to catchment. Analysis of the influence of changing anion concentrations associated with tree harvesting reveals that the acidification induced by increases in nitrate can be offset or reversed by the lowering of chloride and sulphate concentrations due to decreased atmospheric scavenging by the vegetation, reduced evapotranspiration and increased surface runoff diluting the acidity generated. It is concluded that contemporary UK forestry guidelines with an emphasis on phased harvesting of catchments over several years and careful harvesting methodologies can alleviate most problems of stream acidification associated with felling activities and in some cases can reverse the acidification pattern.

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No abstract available. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.6.01.2008" target="_blank">10.2204/iodp.sd.6.01.2008</a>

Total 105.8 2.5744 O 3.86 Less O ~-F 4.2 0.2625 101.6 2.3119 f = 2.1627 MW = 219.73 COMMUNICATIONS 143 suggest that water and carbon dioxide are very minor constituents of the triplite. Consequently, the empirical formula of the triplite was derived from the analytical data assuming only oxygen and fluorine as anions and is (Mnl.4.3Fe0.43Mg0.12Ca0.03)~2.o 1P0.9703.86Fl.14 or, ideally, (Mn,Fe,Mg, Ca)zPO4F. The density calculated from the unit cell contents and parameters following the procedure outlined by Mandarino (1981) is 3.847 g/cm 3. The density measured by means of the Berman microbalance is 3.83(1) g/cm 3 at 22 ~ Notes: Analyst: Pete J. Dunn (see text for operating conditions). Accuracy of data: 4-15 ~ of the amount present for F, _+ 3 ~ for all other constituents. Number of ions calculated on the basis of oxygen + fluorine = 5. regarding the evolved gases because more than one product was evolved at any given time. Between 100 ~ and 675 ~ a weight loss consisting of CO2 and H20 amounted to 0.4 wt. ~. The run was continued to 1000 ~ but the weight loss was not complete at this temperature. Between 675 ~ and 1000 ~ the weight loss was 3.3 wt. ~ and H20 , HF, and POF~-were detected by the mass spectrometer. Additional substances with masses of 28, 47, 76, and 104 were also detected. The presence of fluorine is thought to promote the evolution of unusual products during thermal analysis. The TGA data Acknowledgements. Drs D. A. McAuslan formerly of Shell Canada Resources Limited and P. M. Kavanagh of Riocanex Inc. kindly gave permission to publish these results. The following members of the Royal Ontario Museum's Department of Mineralogy and Geology contributed to this study: Mr R. A. Ramik carried out the thermogravimetric analysis; Mrs C. Peat prepared the X-ray powder diffraction pattern and Mrs M. F. Grzedzielski measured it.