Speciation and sorption of mercury in two macro-tidal estuaries

摘要: Mercury speciation and partition were determined in two macro-tidal estuaries, the Loire Seine estuaries (France) during several cruises covering various hydrological conditions. Additional measurements performed freshwaters order to assess temporal variations of mercury inputs an annual cycle. In freshwater, average total ‘dissolved’ (< 0.8 μm) concentration [(HgT)D] was 4.1 ± 2.1 pM 11.5 9.7 Seine. Mean particulate [(HgT)p] 0.95 0.63 nmol g−1 5.4 2.6 The seasonal variation concentrations rivers are interpreted terms changes water sources flood events variable contribution colloidal materials. estuarine parts, (HgT)D generally varied from 2 6 1 3 Loire, while (HgT)P between 0.5 5 2.5 10 Because its high distribution coefficient (log Kd = 5–6) turbidity these environments, is mainly transported form as well mixing zones. Relationships suspended particles, dissolved organic carbon allow describe solid phases colloids, complexation solution sorption processes. Chlorocomplex formation does not play major role Hg mixing. Organic associations, through sulphydryl groups, seems be dominant processes governing studied. Primary production appears important dynamic. correlated with chlorophyll content particles flow regime river, elemental (Hg0) found related oxygen saturation rate both estuaries. Hg0 sufficient sustain a significant evasion flux atmosphere. Dimethylmercury detected at fentomolar level one cruise Baie de la hypoxia episode. Highest monomethylmercury (up 4% HgT) associated warmer rich freshwater. Candidate for methylated species discussed. Both appear affected by local anthropogenic inputs. However, river more deeply impacted human activities. Watershed yields calculated drainage basins. yield (41 mmol km−2 a−1) range what other urban areas, (9 it close values agricultural watersheds. spite within riverine adjacent coastal waters (la le Grand estuaire Loire) have been estimated half corresponding atmospheric depositions.