Wet deposition of major ions in a rural area impacted by biomass burning emissions

Autor(es)

Coelho, Cidelmara H. ^[1] ; Allen, Andrew G. ^[2] ; Fornaro, Adalgiza ^[3] ; Orlando, Eduardo A. ^[1] ; Grigoletto, Tahuana L. B. ^[1] ; Campos, M. Lucia A. M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Quim, Fac Filosofia, BR-14040901 Ribeirao Preto, SP - Brazil

^[2] UNESP Univ Estadual Paulista, Inst Quim, BR-14800900 Araraquara, SP - Brazil

^[3] IAG USP, BR-05508090 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Atmospheric Environment; v. 45, n. 30, p. 5260-5265, SEP 2011.
• Citações Web of Science: 27

Resumo

This work concerns the influence of industrialized agriculture in the tropics on precipitation chemistry. A total of 264 rain events were sampled using a wet-only collector in central Sao Paulo State, Brazil, between January 2003 and July 2007. Electroneutrality balance calculations (considering H(+), K(+), Na(+), NH(4)(+), Ca(2)(+), Mg(2)(+), Cl(-), NO(3)(-), SO(4)(2-), F(-), PO(4)(3-), H(3)CCOO(-), HCOO(-), C(2)O(4)(2-) and HCO(3)(-)) showed that there was an excess of cations (similar to 15%), which was attributed to the presence of unmeasured organic anion species originating from biomass burning and biogenic emissions. On average, the three ions NH(4)(+), NO(3)(-) and H(+) were responsible for >55% of the total ion concentrations in the rainwater samples. Concentrations (except of H(+)) were significantly higher (t-test; P = 0.05), by between two to six-fold depending on species, during the winter sugar cane harvest period, due to the practice of pre-harvest burning of the crop. Principal component analysis showed that three components could explain 88% of the variance for measurements made throughout the year: PC1 (52%, biomass burning and soil dust resuspension); PC2 (26%, secondary aerosols); PC3 (10%, road transport emissions). Differences between harvest and non-harvest periods appeared to be mainly due to an increased relative importance of road transport/industrial emissions during the summer (non-harvest) period. The volume-weighted mean (VWM) concentrations of ammonium (23.4 mu mol L(-1)) and nitrate (17.5 mu mol L(-1)) in rainwater samples collected during the harvest period were similar to those found in rainwater from Sao Paulo city, which emphasizes the importance of including rural agro-industrial emissions in regional-scale atmospheric chemistry and transport models. Since there was evidence of a biomass burning source throughout the year, it appears that rainwater composition will continue to be affected by vegetation fires, even after sugar cane burning is phased out as envisaged by recent Sao Paulo State legislation. (C) 2011 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 03/01532-4 - Biogeoquímica de metais em ambientes aquáticos e na atmosfera. Parte I: Especiação química de metais em águas de chuva
• Beneficiário: Maria Lúcia Arruda de Moura Campos
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 09/07415-6 - Proposta para pesquisador visitante
• Beneficiário: Arnaldo Alves Cardoso
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• Processo FAPESP: 03/01194-1 - Estudo dos ácidos carboxílicos e aldeídos na deposição úmida na região metropolitana de São Paulo
• Beneficiário: Adalgiza Fornaro
• Modalidade de apoio: Auxílio à Pesquisa - Regular