Atmospheric Ionic Deposition in Tropical Sites of Central Sulawesi Determined by Ion Exchange Resin Collectors and Bulk Water Collector

S Köhler,R Herrera,C Gutzler,H F Jungkunst,G Gerold

doi:10.1007/s11270-012-1211-8

Abstract

In the light of global change, the necessity to monitor atmospheric depositions that have relevant effects on ecosystems is ever increasing particularly for tropical sites. For this study, atmospheric ionic depositions were measured on tropical Central Sulawesi at remote sites with both a conventional bulk water collector system (BWS collector) and with a passive ion exchange resin collector system (IER collector). The principle of IER collector to fix all ionic depositions, i.e. anions and cations, has certain advantages referring to (1) post-deposition transformation processes, (2) low ionic concentrations and (3) low rainfall and associated particulate inputs, e.g. dust or sand. The ionic concentrations to be measured for BWS collectors may easily fall below detection limits under low deposition conditions which are common for tropical sites of low land use intensity. Additionally, BWS collections are not as independent from the amount of rain fallen as are IER collections. For this study, the significant differences between both collectors found for nearly all measured elements were partly correlated to the rainfall pattern, i.e. for calcium, magnesium, potassium and sodium. However, the significant differences were, in most cases, not highly relevant. More relevant differences between the systems were found for aluminium and nitrate (434–484 %). Almost five times higher values for nitrate clarified the advantage of the IER system particularly for low deposition rate which is one particularity of atmospheric ionic deposition in tropical sites of extensive land use. The monthly resolution of the IER data offers new insights into the temporal distribution of annual ionic depositions. Here, it did not follow the tropical rain pattern of a drier season within generally wet conditions.

Highlights

Human impact on atmospheric depositions is high (Pye et al 2009; Fan et al 2009; Aas et al 2007) and depositions of nitrogen (N), sulphur (S), phosphorus (P) and potassium (K) have considerable influence on ecosystems (Cinderby et al 1998; Adams 2003; Rockström et al 2009)
The relative comparison revealed 3, 7 and 14 % higher values for the ion exchange resins (IER) collectors compared to the bulk water collectors (BWS) collectors for Mg, Ca and Na, respectively
Mayer et al (2000), Veneklaas (1990) and Boy et al (2008) reported, for Latin America, similar ranges for Al (0.12–5.2 kg ha−1 a−1), Ca (13–76 kg ha−1 a−1), Na (11–31 kg ha−1 a−1), Mg (2.2–3.2 kg ha−1 a−1) and K (6.9–8.3 kg ha−1 a−1) as we found for Central Sulawesi but with the IER collectors

Summary

Introduction

Human impact on atmospheric depositions is high (Pye et al 2009; Fan et al 2009; Aas et al 2007) and depositions of nitrogen (N), sulphur (S), phosphorus (P) and potassium (K) have considerable influence on ecosystems (Cinderby et al 1998; Adams 2003; Rockström et al 2009). An excess of N leads to a multitude of undesirable reactions of the affected ecosystems, which can be: (a) acidification (Adams 2003), (b) contamination of ground and surface water (Curtis et al 2009) and (c) increasing greenhouse gas emissions, for example N2O (Veldkamp et al 2008). Another major impact of atmospheric N deposition is the associated loss of richness of species (Phoenix et al 2006). Simple economic methods have multiple advantages for poor and remote tropical regions

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Results

Discussion

Conclusion