TITLE:
Gold Mining and Mercury Bioaccumulation in a Floodplain Lake and Main Channel of the Tambopata River, Perú
AUTHORS:
Katherine A. Roach, Nicolas F. Jacobsen, Christine V. Fiorello, Amanda Stronza, Kirk O. Winemiller
KEYWORDS:
Fishes; Giant Otter; Gold Mining; Mercury; Methylmercury; Perú
JOURNAL NAME:
Journal of Environmental Protection,
Vol.4 No.1,
January
25,
2013
ABSTRACT:
Contamination of water bodies by
inorganic mercury (Hg[II]) used in placer mining of gold deposits in the Madre
de Dios Department, Perú, contributes to the bioaccumulation of methylmercury
(MeHg) in fish tissue. We measured MeHg and total Hg (THg) concentrations
(mg/kg wet weight [ww] tissue) of thirteen fish species from the Tambopata River, Perú, and the connected oxbow lake
Tres Chimbadas. We also used stable isotope analysis (δ15N and δ13C) to estimate trophic positions
of fishes. Average MeHg concentrations of fish species ranged from 0.042 mg/kg
ww (Satanoperca jurupari) to 0.463
mg/kg ww (Hoplias malabaricus) in the
main channel and from 0.090 mg/kg ww (Parauchenipterus sp.) to 1.282 mg/kg ww (Pimelodina
flavipinnis) in the lake. Spearman rank correlation indicated that trophic
position had no influence on MeHg concentrations of species in the main
channel, but in the lake, trophic positions of species were positively
associated with MeHg. Migrations of the pimelodid catfish surveyed from the
main channel are well documented. Because little gold mining occurs at our
study site, fishes from the main channel may be bioaccumulating MeHg from areas
where mining is widespread. Fish species that reside in the lake are relatively
sedentary and migration is limited by the brief period of floodplain inundation
and the long, narrow corridor that connects the lake to the main channel; lake
sediments are therefore the likely source for MeHg bioaccumulation. Five out of
the eight fish species surveyed from the main channel and two out of the five
species from the lake had MeHg levels higher than United States Environmental
Protection Agency fish tissue criterion for human consumption.