<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Avila, Anna</style></author><author><style face="normal" font="default" size="100%">Rodà, Ferran</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Changes in atmospheric deposition and streamwater chemistry over 25 years in undisturbed catchments in a Mediterranean mountain environment.</style></title><secondary-title><style face="normal" font="default" size="100%">The Science of the total environment</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Alkalinity</style></keyword><keyword><style  face="normal" font="default" size="100%">Base cations</style></keyword><keyword><style  face="normal" font="default" size="100%">nitrogen</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Streamwater chemistry</style></keyword><keyword><style  face="normal" font="default" size="100%">Sulphate</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2012</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2012///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/22200374</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">434</style></volume><pages><style face="normal" font="default" size="100%">18 - 27</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Surface water chemistry has changed in response to reduced atmospheric deposition of sulphur and acidity in many regions of Europe and North America. Most of these studies come from acidic or low-alkalinity surface waters under high acidic deposition. Mediterranean climates offer a different biogeochemical context, characterised by streamwaters of higher alkalinity and low acid inputs. In this paper, we use surveys of streamwater chemistry conducted in 1981-1984 and again in 2007 in the Montseny natural park (NE Spain) to test whether streamwaters of these well-buffered catchments respond to changes in atmospheric deposition, which has declined for S during the last decades in NE Spain while remaining about stable for nitrogen. The 23 sampled streams drained heathland, beech forests and evergreen oak forests in relatively undisturbed small catchments underlain by silicate bedrock. Bulk deposition of sulphate at Montseny decreased by 54% while nitrate bulk deposition increased (non-significantly) by 30% in this period. Total N deposition is estimated in the range 15-30 kg N ha(-1) y(-1) for NE Spain. This is well above threshold values (e.g. 10 kg N ha(-1) y(-1)) reported as starting nitrogen saturation symptoms in forest ecosystems in Europe. Baseflow sulphate concentrations decreased on average by 47 μeq L(-1) or 29% of early 1980s concentrations. Baseflow mean nitrate concentrations increased significantly but only from 5.5 to 8.9 μeq L(-1). Thus, despite decades of high N deposition, these ecosystems appear to be still far from N saturation. Baseflow alkalinity and base cation concentrations increased substantially, probably a combined result of decreased S deposition, enhanced silicate weathering under current higher temperatures, reduced plant cation uptake as vegetation matures, and slightly drier conditions in the survey of 2007. Overall, these well-buffered catchments have shown sizable changes in baseflow chemistry in response to changed atmospheric deposition and other environmental changes.</style></abstract><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;publisher: Elsevier B.V.&lt;br/&gt;accession-num: 22200374</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Piñol, J</style></author><author><style face="normal" font="default" size="100%">Avila, a</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Streamwater pH, alkalinity, p CO 2 and discharge relationships in some forested Mediterranean catchments</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Hydrology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Catchments</style></keyword><keyword><style  face="normal" font="default" size="100%">montseny</style></keyword><keyword><style  face="normal" font="default" size="100%">prades</style></keyword><keyword><style  face="normal" font="default" size="100%">precipitation (voyant)</style></keyword><keyword><style  face="normal" font="default" size="100%">Streamwater chemistry</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1992</style></year></dates><volume><style face="normal" font="default" size="100%">131</style></volume><pages><style face="normal" font="default" size="100%">205-225</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The streamwater chemistry of four catchments at Prades and one catchment at Montseny (NE Spain) is described and the relationships between streamwater alkalinity, pH and pCO 2 with discharge and that between pH and alkalinity are highlighted. At Montseny, results from a subsurface seepage are also presented. The Prades and Montseny catchments have similar vegetation (dense forest of holm oak. Quercus ilex L.) and lithology (phyllites). However, the catchments differ strongly in their hydrological behaviour: only 8-15% of the rainfall passes to the stream from the two gauged Prades catchments, whereas the Montseny catchment provides 50% of rainfall to the stream. Hence the mineralization of streamwaters is much higher in the Prades catchments. All the streams studied show an inverse relationship between alkalinity and discharge. Although pH also decreases with discharge in the Montseny catchment. it remains high during high flows in the Prades catchments. The Prades streamwater chemistries are determined by the solubility equilibrium of calcite: at high flows alkalinity decreases and, as a result of calcite solubility controls, this change results in an increase in pH. Consequently, pH and log(alkalinity) are either negatively correlated or uncorrelated in the Prades streams. At Montseny, the relationship between pH and alkalinity is significantly positive: calcite solubility controls do not come into play. All waters analyzed show an excess pCO 2 (epC02) with respect to atmospheric concentrations. The highest epC02 values usually correspond to low flows. However, study of the variation of epCO2 during 15 individual storm events sampled at Montseny shows that epCO 2 increases with discharge. At Prades, the degassing of epCO 2 in the stream channel produces calcite precipitation.</style></abstract></record></records></xml>