Wet Atmospheric Deposition of Inorganic N, P and Fe in the Northeastern Mediterranean and Contribution to Ecosystems
The atmospheric supply of nutrients to marine and terrestrial ecosystems has recently gained great importance because it is often found to have major contribution. This mode of transport is particularly important for oligotrophic ocean areas such as the Eastern Mediterranean, characterized with low productivity due to unusual phosphorus limitation, resulting in very high N:P molar ratios even in deep water. In order to estimate the magnitude of the atmospheric contribution to the soluble, bioavailable nutrient budget of the Northeastern Mediterranean coastal waters, inorganic nutrient (N, P, Fe) concentrations have been determined in rainwater samples collected at two urban and two suburban sites of the coastal city of Mersin during the period of December 2003-May 2005. A total of 246 samples covering all recorded precipitation events in the region were analyzed to determine pH, conductivity, major ions and the minor phosphate (PO4 3.) ion concentrations. Additionally, crustal trace elements (Al and Fe) have been analysed in soluble and particulate fractions of the samples. Evaluations are also made from the perspective of terrestrial ecosystems, particularly in respect to nitrogen saturation in forested and/or vegetated soils. The relative contributions of sulfate and nitrate to acidity of precipitation respectively are found to be 71% and 29%. However, either local or sporadic regional transport appears to account for about 99% of acidity to be neutralized primarily by the calcite content of atmospheric dust. As a result, rainwater has had alkaline character in most of the cases, with an average pH of 6.2. Even though rainwater acidity appears to be effectively neutralized in the region, the inorganic soluble N and S fluxes are estimated to be within the range of published critical loads, slightly exceeding the lower limits of landscape nitrogen and sulfur saturation. The annual supply to the coastal zone of soluble (bioavailable) inorganic N, P and Fe, respectively were calculated to be 0.54, 0.006 and 0.0016 g m-2 yr-1. The incorporation of soluble inorganic N and P, delivered via atmospheric wet deposition is expected to account respectively for about 25.7% and 2.0% of the mean annual new production in the Northeastern Mediteranean, based on these estimates. On the other hand, the ample supply of soluble iron via wet deposition is more than sufficient to support almost 100% of the new primary production in the region. If the calculated fluxes were to be uniformly distributed over the Cilician Basin (area=34,000 km2), the total atmospheric wet deposition of N and P would be comparable in magnitude to land-based freshwater fluxes of the same nutrients in the Northeastern Mediterranean.
critical loads dissolved Fe inorganic N inorganic P Northeastern Mediterranean.
Türkan (O)ZSOY Sermin (O)RNEKIN
Mersin University,Faculty of Science and Literature,Chemistry Department,Ciftlikk(o)y Campus,33343,M Mustafa Kemal University,Faculty of Science and Literature,Chemistry Department,Tayfur Somen Campus,
国际会议
2009 International Symposium on Environmental Science and Technology(2009环境科学与技术国际会议)
上海
英文
633-642
2009-06-02（万方平台首次上网日期，不代表论文的发表时间）