Is chloride a conservative ion in forest ecosystems?

• Published in: Biogeochemistry Vol. 107; no. 1-3; pp. 125 - 134
• Main Authors: Svensson, Teresia, Lovett, Gary M, Likens, Gene E
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01.02.2012; Springer; Springer Netherlands; Springer Nature B.V
• Subjects: atmospheric deposition; biogeochemical cycles; Biogeochemistry; Biogeosciences; Catchment; Chloride; Chlorides; Chlorine; coasts; data collection; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Ecological function; Ecosystems; Environmental Chemistry; Exact sciences and technology; Forest ecosystems; Forest soils; forested watersheds; Forests; Geochemistry; ions; Life Sciences; Mass balance; Soil; Soil and rock geochemistry; Soil ecology; Soil pollution; Soil water; Soils; Surficial geology; Throughfall; Tracer; Vegetation; Watershed; Watersheds; Mass balance; Catchment; Chloride; Chlorine; Tracer; Watershed; Soil; chlorides; mass balance; tracers; vegetation; halides; forests; chlorine; drainage basins; ecosystems; ions; soils; retention
• ISSN: 0168-2563; 1573-515X; 1573-515X
• DOI: 10.1007/s10533-010-9538-y

Chloride (Cl−) has often been assumed to be relatively unreactive in forest ecosystems, and is frequently used as a conservative tracer to calculate fluxes of water and other ions. Recently, however, several studies have detailed cycling of Cl− in vegetation and soils. In this study Cl− budgets are compiled from 32 catchment studies to determine the extent to which Cl− is conserved in the passage through forest ecosystems. Chloride budgets from these sites vary from net retention (input > output) to net release (output > input). In the overall data set, including those sites with very high inputs of seasalt Cl−, there was a strong correspondence between inputs and outputs. However, sites with low Cl− deposition (<6 kg ha−1 year−1) consistently showed net release of Cl−, suggesting an internal source or a declining internal pool. The results indicate that Cl− may be a conservative ion in sites with high Cl− deposition, but in sites with low deposition Cl− may not be conservative. We discuss the possible causes of the Cl− imbalance and reasons why Cl− may not be conservative in ecosystem functions.