Mercury bioaccumulation in temperate forest food webs associated with headwater streams.
Sci Total Environ
; 665: 1125-1134, 2019 May 15.
Article
em En
| MEDLINE
| ID: mdl-30893744
ABSTRACT
The soils and food webs associated with mid to high elevation, forested, headwater streams in northeastern North America are potential hotspots for mercury (Hg) methylation and bioaccumulation, but are not well studied. Our goals were to quantify total Hg (THg) and methyl Hg (MeHg) concentrations in soils and terrestrial food webs associated with headwater streams of northern hardwood forests to identify predictors of small-scale spatial variation in Hg bioaccumulation. We sampled soil characteristics that promote Hg methylation including pH, sulfur and calcium content, and organic matter. To assess spatial variation, we sampled at high (~700â¯m asl) and mid elevations (~500â¯m asl), both adjacent to (<1â¯m) and away from (>75â¯m) three replicate headwater streams in each of two watersheds of the White Mountains region, New Hampshire, USA. Soils of these forested watersheds differed significantly in pH and the content of calcium, sulfur, organic matter and THg. Conditions for methylation were more favorable in the upland forest sites compared to streamside sites. Significant bioaccumulation of THg occurred in all measured components of the food web, including insects, spiders, salamanders, and birds. Trophic position, as determined by δ15N, was the best predictor of both THg and MeHg bioaccumulation across the sampled taxa and was also a better predictor than spatial location. However, the degree of bioaccumulation at which MeHg significantly affects animal behavior, reproduction or survival is unknown for most taxa in terrestrial habitats, particularly for invertebrates. These findings show that Hg methylation and bioaccumulation is not limited to areas traditionally classified as wetlands or to areas with exceptionally high THg inputs, but that it is a widespread and important phenomenon in the moist deciduous forests of eastern North America.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Vertebrados
/
Poluentes Químicos da Água
/
Compostos de Mercúrio
/
Cadeia Alimentar
/
Invertebrados
/
Mercúrio
Tipo de estudo:
Prognostic_studies
/
Risk_factors_studies
Limite:
Animals
País/Região como assunto:
America do norte
Idioma:
En
Revista:
Sci Total Environ
Ano de publicação:
2019
Tipo de documento:
Article