Trialkylamines and coprostanol as tracers of urban pollution in waters from enclosed seas: The Mediterranean and Black Sea

The occurrence and distribution of two domestic pollution markers, namely t rialkylamines (TAMs, CH3NR1R2, where R-1 and R-2 = n-C14H29, n-C16H33 or n- C18H37) and coprostanol (COP, 5 beta(H)-cholestan-3 beta-ol) in the open se awaters from the western Mediterranean and the northwestern Black Sea is re ported for the first time. Riverine transport (i.e. Danube in the Black Sea and Ebro and Rhone in the Mediterranean) is the main source of domestic po llution in both seas. The TAM concentrations in the suspended particulate m atter (SPM) collected at riverine affected seawater in each area reflects t he pattern of cationic surfactant usage, the population, and its wastewater management practices in the watershed reaching the highest concentrations at the Danube estuary (average value 119 ng L-1) followed by the Ebro (53.3 ng L-1) a nd Rhone (1.2 ng L-1) estuaries. Coprostanol concentrations were consistently lower than TAMs and maximized at the Rhone River mouth (8.9 n g L-1) followed by the Danube (average value 2.4 ng L-1) and the Ebro (0.52 ng L-1) estuaries. In the dissolved phase (DP), TAMs and COP exhibited hig her concentrations in the Black Sea (TAMs = 16.6 ng L-1-10 mu g L-1; COP = <0.1-1.6 ng L-1) than in the Mediterranean (TAMs = 0.2-1.6 ng L-1; CDP = 0. 1-1.2 ng L-1). Negative gradients of concentrations of both molecular marke rs in accordance with the coast distance were steeper in the case of COP, a nd enrichment in TAM concentrations was observed at frontal areas. Partitio ning of COP favored the particulate phase according to its high hydrophobic ity, but because TAMs behave as amphiphilic organic cations, in the Black S ea with low salinity and high dissolved organic carbon (DOC) they occurred preferentially in the dissolved phase. Vertical profiles of TAMs and copros tanol show a surface enrichment, depth-depletion, and bottom-enrichment whe n resuspension is favored. Therefore, TAMs are proposed as molecular marker s to assess the long-range transport of domestic pollution into the open se a.