【大气磷沉降】L.M. Zamora J.M. Prospero D.A. Hansell J.M. Trapp. Atmospheric P deposition to the subtropical North Atlantic: sources properties and relationship to N deposition. Journal of Geophysical Research: Atmospheres 2013 DOI: 10.1002-jgrd.50187

Abstract

Biogeochemical studies show that the surface waters of the subtropical North Atlantic are highly phosphorus (P) stressed. Human activity may exacerbate phosphorus stress by enhancing atmospheric nitrogen (N) deposition and raising N:P ratios in deposition. However the magnitude of this effect is unclear in part because atmospherically-deposited phosphorus sources are not well known particularly the contribution from organic phosphorus. Here we report measurements of phosphorus in aerosols and wet deposition at Miami and Barbados. African dust is the major aerosol P source at both Miami and Barbados containing ~880 ppm total phosphorus and ~70 ppm soluble reactive phosphorus (SRP). Organic compounds contribute on average 28–44% of soluble phosphorus in precipitation. Because of dust transport seasonality phosphorus inputs to the North Atlantic are expected to be highly variable with 2–10 times more P deposition during summer than winter. Pollution is also an important contributor to total and soluble phosphorus in Miami aerosols and deposition. Estimated SRP deposition in Barbados and Miami is 0.21 and 0.13 μmol phosphorus m⁻² d⁻¹ respectively. Inorganic nitrogen in excess of Redfield ratio expectations in deposition was very different between the sites totaling 21–30 and 127–132 μmol nitrogen m⁻² d⁻¹ in Barbados and Miami respectively; the high deposition rates at Miami are linked to pollutants. Including soluble organic nitrogen and phosphorus halved estimates of excess nitrogen in Barbados wet deposition. Thus the organic phosphorus fraction is important in the assessment of the magnitude of biogeochemical change of the North Atlantic caused by atmospheric deposition.

【温室气体对对流层臭氧的影响】C. Lang D. W. Waugh M. A. Olsen A. R. Douglass Q. Liang J. E. Nielsen L. D. Oman S. Pawson R. S. Stolarski. The impact of greenhouse gases on past changes in tropospheric ozone. Journal of Geophysical Research: Atmospheres 2012117(D23)

Abstract

The impact of changes in the abundance of greenhouse gases (GHGs) on the evolution of tropospheric ozone (O₃) between 1960 and 2005 is examined using a version of the Goddard Earth Observing System chemistry-climate model (GEOS CCM) with a combined troposphere-stratosphere chemical mechanism. Simulations are performed to isolate the relative role of increases in methane (CH₄) and stratospheric ozone depleting substances (ODSs) on tropospheric O₃. The 1960 to 2005 increases in GHGs (CO₂ N₂O CH₄ and ODSs) cause increases of around 1–8% in zonal-mean tropospheric O₃ in the tropics and northern extratropics but decreases of 2–4% in most of the southern extratropics. These O₃ changes are due primarily to increases in CH₄ and ODSs which cause changes of comparable magnitude but opposite sign. The CH₄-related increases in O<