The sources and forms of phosphorus in marine aerosol particles and rain from Northern New Zealand

Various forms of phosphorus were measured in marine aerosol particles and rain samples collected from the northern tip of the North Island of New Zealand. Approximately 58 % of the total phosphorus in the aerosol particles was organic and 7 % was soluble in deionized water. The remaining 35 % was not released by treatment with potassium persulfate, and it was defined as a refractory fraction. Stepwise regression analyses suggested that (1) the concentrations of organic phosphorus in the aerosol particles were related to those of sodium, which was regarded as sea salt tracer, (2) the concentrations of water soluble phosphorus were correlated with those of aluminum, which was considered an indicator of crustal material and (3) total phosphorus was derived from the ocean and from the earth's crust. The mass particle-size distribution of the refractory and organic phosphorus combined was similar to that of sodium and aluminum. However, on submicrometer particles the concentrations of all forms of phosphorus appeared to increase relative to those of sodium, suggesting that small particle phosphorus may be derived from a non-marine source, possibly weathered crustal material or wind blown fertilizer. The wet deposition rates for water soluble and organic phosphorus were calculated to be 0.30 and 0.61 μg cm ⁻² y ⁻¹, respectively. The dry deposition of these two forms of phosphorus combined (0.14 μg cm ⁻² y ⁻¹ ) was clearly lower than the wet deposition rate. Total deposition of phosphorus to the site was estimated to be 1.5μgcm⁻²y⁻¹.