Yamashita, N. and Sase, H. and Kobayashi, R. and Peng, Leong Kok and Hanapi, Jamal Mohd and Uchiyama, S. and Urban, S. and Ying-Ying, Toh and Muhamad, Maznorizan and Gidiman, Jikos and Chappell, Nick A. (2014) Atmospheric deposition versus rock weathering in the control of streamwater chemistry in a tropical rain-forest catchment in Malaysian Borneo. Journal of Tropical Ecology, 30 (5). pp. 481-492. ISSN 0266-4674
Full text not available from this repository.Abstract
Uncertainty about the H+ buffering capacity in tropical rain forest limits our ability to predict the future effect of anthropogenic deposition on the streamwater chemistry. Export ofmajor ions to the stream and the ion-fluxes via rainfall, throughfall, litter-leachate and soil-water pathways were observed to examine the source of streamwater nutrients in a small catchment in Sabah, Malaysia. The streamwater and the ion-fluxes were measured for 3.75 and 2 y, respectively, by collecting water twice a month and setting ion-exchange-resin columns. Streamwater pH ranged from 6.5 to 7.6 and was not sensitive to water discharge controlling base cations. The NO3--N, Ca2+ and Mg2+ fluxes were low in atmospheric depositions (0.6, 0.5 and 0.3 kg ha−1 y−1, respectively) andmarkedly increased in litter layer. The NO3− flux decreased drastically from subsoil (70 kg ha−1 y−1) to the stream (1.4 kg ha−1 y−1) whereas the Ca2+ and Mg2+ fluxes were not different between subsoil (38 and 18 kg ha−1 y−1) and stream (30 and 15 kg ha−1 y−1). Neutral pH in tropical streams was mainly due to the base cation leaching with deep chemical weathering in deeper strata, and a rapid decrease in NO3− leaching from the subsoil to the stream.