Atmospheric Environment, Jan, 2013, Vol.64, p.242(9)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.atmosenv.2012.10.015 Byline: Weijun Shen (a), Huili Ren (a), G. Darrel Jenerette (b), Dafeng Hui (c), Hai Ren (a) Abstract: Acid deposition as a widely concerned environmental problem in China has been less studied in plantation forests compared to urban and secondary forests, albeit they constitute 1/3 of the total forested areas of the country. We measured the rainwater amount and chemistry outside and beneath the canopies of two widely distributed plantations (Acacia mangium and Dimocarpus longan) in the severe acid rain influenced Pearl River Delta region of southeastern China for two years. Our results showed that the frequency of acid rain was 96% on the basis of pH value 〈5.6. The volume-weighted mean (vwm) pH was 4.62 and higher in the dry (Oct.-Mar.) than in the wet (Apr.-Sep.) seasons. The major acidic anion was sulfate with vwm concentration of 140 [mu]eq l.sup.-1 and annual deposition flux of 110.3 kg ha.sup.-1 yr.sup.-1. The major neutralizing cations were calcium (94.8 [mu]eq l.sup.-1 and 28 kg ha.sup.-1 yr.sup.-1) and ammonium (41.2 [mu]eq l.sup.-1 and 11.7 kg ha.sup.-1 yr.sup.-1). Over 95% of these major acidic anions and neutralizing cations were derived from anthropogenic and terrestrial sources as a result of industrial, agricultural and forestry activities. Plantation canopy had marked impacts on rainwater chemistry, with the measured anion and cation concentrations being significantly enriched in throughfall (TF) and stemflow (SF) rainwater by 1.4 (for NO.sub.3.sup.-) to 20-fold (for K.sup.+) compared to those in bulk precipitation (BP). Dry deposition generally contributed about 13-22% of the total deposition while canopy leaching mainly occurred for K.sup.+ (〉88%) and NH.sub.4.sup.+ (10-38%). The two tree species showed distinct impacts on rainfall redistribution and rainwater chemistry due to their differences in canopy architecture and leaf/bark texture, suggesting that species-specific effects should not be overlooked while assessing the acid deposition in forested areas. Author Affiliation: (a) CAS Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, 723 Xinke Rd., Tianhe District, Guangzhou 510650, China (b) Department of Botany and Plant Sciences, Center for Conservation Biology, University of California Riverside, Riverside, CA 92521, USA (c) Department of Biological Sciences, Tennessee State University, Nashville, TN 37209, USA Article History: Received 18 July 2012; Revised 4 October 2012; Accepted 9 October 2012
Rivers ; Rain ; Sulfates ; Air Pollution ; Forest Management ; Ecosystems ; Plantations ; Acid Deposition ; Forests ; Rainwater
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