Distribution of heavy metals and pollution pathways in a shallow marine shelf: assessment for a future management

• Published in: International journal of environmental science and technology (Tehran) Vol. 11; no. 5
• Main Authors: Ruiz, F, González-Regalado, M.L, Muñoz, J.M, Abad, M, Toscano, A, Prudencio, M.I, Dias, M.I
• Format: Journal Article
• Language: English
• Published: Center for Environment and Energy Research and Studies (CEERS) 03-07-2015
• Subjects: Environmental pollution; Future assessment; Geoaccumulation indices; Inner shelf; Trace metals
• ISSN: 1735-1472

The spatial distribution and geoaccumulation indices of four heavy
metals were investigated in very shallow marine sediments of
southwestern Spain. Surface sediments were collected from 43 sites with
water depth ranging from 3 to 20 m. High to very high pollution levels
(Igeo>4 for zinc, lead and copper) were detected near the end of the
Huelva bank, whereas chromium shows a more hazardous distribution in
the southwestern Spanish littoral. Low to moderate heavy metal contents
(mainly zinc and lead) were also observed in other two areas at
different water depths (Isla Cristina-Piedras River: 10-18 m
water depth; Mazagón-Matalascañas: <10 m water
depth), whereas unpolluted to moderately polluted sediments were
detected in the very shallow zones (<8 m water depth) located
between the mouths of the Guadiana and the Piedras Rivers. A regional
scenario indicates a strong pollution of the adjacent marine areas by
polluted inputs derived from the Tinto-Odiel rivers, with a
partial transport of heavy metals by W-E littoral currents even
40 km eastward. The Guadiana River is an additional source of
zinc-lead contamination near the Spanish-Portuguese border,
mainly at water depths up to 10 m. All these rivers are affected by
acid mine drainage processes, derived from millennial mining
activities. This pollution affects the sediment quality even 40 km
eastward.