Estuaries as filters: the role of tidal marshes in trace metal removal.
Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary.
Department of Biology, Ecosystem Management Research Group, University of Antwerp, Wilrijk, Belgium. johannes.teuchies@ua.ac.be
Johannes
J
Teuchies
Wouter
W
Vandenbruwaene
Roos
R
Carpentier
Lieven
L
Bervoets
Stijn
S
Temmerman
Chen
C
Wang
Tom
T
Maris
Tom J S
TJ
Cox
Alexander
A
Van Braeckel
Patrick
P
Meire
D001530:Belgium; D064308:Ecological Parameter Monitoring / Q000379:methods; D063366:Estuaries; D005374:Filtration; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry; D008670:Metals / Q000032:analysis* / Q000378:metabolism; D009426:Netherlands; D012621:Seasons; D014131:Trace Elements / Q000032:analysis* / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism; D053833:Wetlands
D008670:Metals; D014131:Trace Elements; D014874:Water Pollutants, Chemical