Impact of biomass burning on ocean water quality in Southeast Asia through atmospheric deposition: field observations

Abstract

Atmospheric nutrients have recently gained considerable attention as a significant additional source of new nitrogen (N) and phosphorus (P) loading to the ocean. The effect of atmospheric macro nutrients on marine productivity depends on the biological availability of both inorganic and organic N and P forms. During October 2006, the regional smoke haze episodes in Southeast Asia (SEA) that resulted from uncontrolled forest and peat fires in Sumatra and Borneo blanketed large parts of the region. In this work, we determined the chemical composition of nutrients in aerosols and rainwater during hazy and non-hazy days to assess their impacts on aquatic ecosystem in SEA for the first time. We compared atmospheric dry and wet deposition of N and P species in aerosol and rainwater in Singapore between hazy and non-hazy days. Air mass back trajectories showed that large-scale forest and peat fires in Sumatra and Kalimantan were a significant source of atmospheric nutrients to aquatic environments in Singapore and SEA region on hazy days. It was observed that the average concentrations of nutrients increased approximately by a factor of 3 to 8 on hazy days when compared with non-hazy days. The estimated mean dry and wet atmospheric fluxes (mg/m<sup>2</sup>/day) of total nitrogen (TN) were 12.72 ± 2.12 and 2.49 ± 1.29 during non-hazy days and 132.86 ± 38.39 and 29.43 ± 10.75 during hazy days; the uncertainty estimates are represented as 1 standard deviation (1σ) here and throughout the text. The estimated mean dry and wet deposition fluxes (mg/m<sup>2</sup>/day) of total phosphorous (TP) were 0.82 ± 0.23 and 0.13 ± 0.03 for non-hazy days and 7.89 ± 0.80 and 1.56 ± 0.65 for hazy days. The occurrences of higher concentrations of nutrients from atmospheric deposition during smoke haze episodes may have adverse consequences on receiving aquatic ecosystems with cascading impacts on water quality

Atmospheric deposition—Another source of nutrients enhancing primary productivity in the eastern tropical Indian Ocean during positive Indian Ocean Dipole phases

“…Dugdale et al, 1989]. Therefore, additional nutrients from atmospheric deposition were likely responsible for the continued high PP postupwelling/postwildfire, and the atmospheric N deposited over the upwelling region during +IODs was perhaps slightly higher than that measured by Sundarambal et al [2010]. Whereas the estimates of atmospheric contributions to ePPt are probably prone to large uncertainty, all model combinations show that ePPt during +IODs was modulated by more than just elevated nutrient concentrations from upwelling.…”

“…Atmospheric aerosols on hazy days during 2006 wildfires in Sumatra contained the macronutrient N at levels 3 to 8 times those during nonhazy days, with the atmospheric inorganic N flux at about 90 mg-N m À2 d À1 on hazy days [Sundarambal et al, 2010]. How this atmospheric N flux can reconcile the differences between ePPt and ePPu (Table 1) is addressed in section 4.…”

“…Atmospheric deposition of nutrients from Indonesian wildfires potentially fertilizes marine environments adjacent to Sumatra [Abram et al, 2003;Sundarambal et al, 2010]. Atmospheric aerosols on hazy days during 2006 wildfires in Sumatra contained the macronutrient N at levels 3 to 8 times those during nonhazy days, with the atmospheric inorganic N flux at about 90 mg-N m À2 d À1 on hazy days [Sundarambal et al, 2010].…”

“…The mean atmospheric inorganic N flux during the 2006 +IOD from Sumatra wildfires was 90 mg N m À2 d À1 , with 10% of the flux as ammonia, although this was susceptible to oxidization to nitrate [see Sundarambal et al, 2010]. Assuming that this mean N flux was applicable over the main upwelling regions during both the 1997 and 2006 +IODs, the deposited N, if fixed by phytoplankton, would generate roughly 581 Gg C over the upwelling region during the 1997 +IOD and roughly 113 Gg C during the 2006 +IOD.…”

Assessing the regional impact of indonesian biomass burning emissions based on organic molecular tracers and chemical mass balance modeling

“…The sampling site was located in an open coastal area in the southern part of Singapore, and was not influenced by local pollution sources from the main island, but potentially by biomass burning emissions from Indonesia. Additional information about the sampling location has been reported previously (Sundarambal et al, 2010). Total suspended particle (TSP) samples were collected for 24 h three times per week, using a HighVolume Air Sampler (HVAS, model 3800 AFC, HI-Q Environmental Products Company, USA).…”