| Popis: |
Trace metals in natural colloidal material (l-400nm) were investigated in the River Beaulieu, the Trent- Humber system and the Celtic Sea. Colloidal and truly dissolved ( Pb, Mn > Cu, Zn, Ni > Cd. Colloidal Fe, Pb and Mn all illustrated removal in the low salinity region of the estuary. Ni (mainly truly dissolved) showed somewhat conservative behaviour. Total dissolved Cd (and Zn) consistently showed a mid-estuarine maximum (truly dissolved), which was attributed to chloro-complex formation or ionic exchange with major seawater ions. For most metals, the positioning and intensity of the turbidity maximum zone (TMZ) appeared to have greatest control on their removal. Cu is controlled seasonally by input of organic ligands (truly dissolved/microcolloidal). The existence of separate organic and inorganic colloidal pools was proposed, which may have seasonally variable signatures. The presence of lower molecular weight |
