Nitrate anthropogenic influences

We focus on temperate shelf seas because these are not only best studied, but also most subject to anthropogenic influence. Most of our examples are taken from studies in northwest European waters, because it is these that we know best. The aim of this chapter is to review recent improvements in knowledge of the sources and sinks of nutrients in the shelf seas of northwest Europe, and to consider, especially, the influence of ratios of nutrient elements on the floristic composition of the phytoplankton in these seas. We deal mainly with the macronutrient elements nitrogen, phosphorus and silicon, and to some extent with iron. The acronym DAIN (Dissolved Available /norganic Mtrogen) is a convenient way to refer to nitrate, nitrite and ammonium, excluding di-nitrogen which is not available to most phytoplankters. 

The first three components suggest regional sources of acidic anthropogenic aerosol, the marker elements of a copper smelter, and seasalt, respectively. The fourth component or the ammonium In component three do not provide a ready Interpretation of a known emission or meteorological source of variability. The negative correlation of nitrate with component two Is consistent with separate Influences of the copper smelter and automobile emissions. 

Aldehydes are emitted directly into the atmosphere from a variety of natural and anthropogenic sources and are also formed in situ from the atmospheric degradation of volatile organic compounds (VOCs). The atmospheric fate of aldehydes is controlled by photolysis and reaction with hydroxyl (OH) or nitrate (NO3) radicals and, in the case of unsaturated compounds, reaction with ozone (Atkinson, 1994). The photolysis of aldehydes is of particular importance because it is a source of free radicals in the troposphere, and thus may significantly influence the oxidizing capacity of the lower atmosphere (Finlayson-Pitts and Pitts, 1986). 

Furthermore, the marine influence in the region was manifested in several locations by a clear chloride deficit due to the reaction of sea salt with acidic anions like sulfates and nitrates (Kocak et al. 2004a, b Kouyoumdjian and Saliba 2006 Saliba et al. 2007). It has been reported that PMio composition along the Mediterranean coast (i.e. Erdemli, Turkey) contained up to 90% of sea salt and mineral dust, whereas PM2.5 mainly contained anthropogenic pollutants emitted locally and/or transported from neighboring locations (Hassanien and Abdel-Latif 2008 Kocak et al. 2007a, b, 2009). 

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