Heavy metals in aquatic macrophytes drifting in a large river

Abstract

Macrophytes drifting throughout the water column in the Detroit River were collected monthly from May to October 1985 to estimate the quantities of heavy metals being transported to Lake Erie by the plants .Most macrophytes (80-92% by weight) drifted at the water surface . Live submersed macrophytes made up the bulk of each sample . The most widely distributed submersed macrophyte in the river, American wildcelery (Yallisneria americana), occurred most frequently in the drift . A total of 151 tonnes (ash-free dry weight) of macrophytes drifted out of the Detroit River from May to October . The drift was greatest (37 tonnes) in May . Concentrations of heavy metals were significantly higher in macrophytes drifting in the river than in those growing elsewhere in unpolluted waters . Annually, a maximum of 2 796 kg (eight heavy metals combined) were transported into Lake Erie by drifting macrophytes . The enrichment of all metals was remarkably high (range : 4000 x to 161000 x ) in macrophytes, relative to their concentration in water of the Detroit River . Detroit River macrophytes are thus a source of contaminated food for animals in the river and in Lake Erie .

Effects of macrophytes on the fate of mercury in aquatic systems

“…Such a synergism promoting the photoreduction of Hg(II) simultaneously is in line with the large differences observed between day and night emission of Hg(0) in the field . More generally, both IHg and MeHg in macrophytes might be dispersed by drifting or hydrochory as well as through herbivory .…”

Bioconcentration of chlorinated aromatic hydrocarbons in aquatic macrophytes

“…Their decay may release chemicals back to the water and/or to the sediments. It has further been found that drifting macrophytes can act as a vehicle for chemical transport in rivers (2).…”

Adaption of egg and larvae sampling techniques for lake sturgeon and broadcast spawning fishes in a deep river

“…Due to the numerous surface buoys marking our gear in these areas, we received complaints about these obstacles interfering with angling and boating and frequently lost gear due to boats accidentally running them over, or tampering by disgruntled anglers and boaters who would cut buoy lines or remove the gear completely. In addition, uprooted mats of submersed aquatic macrophytes (Manny et al., 1991), tree branches, and other items regularly float downstream and tend to catch on the float line. When enough of this material accumulated on the gear during the time period between inspections (typically 1 week), it created enough weight and drag to pull the floats underwater.…”