Abstract Title: | Mercury Storage in Tropical Peatlands: Evaluation of a Global Archive |
Presenter Name: | N. Roxanna Razavi |
Company/Institution: | SUNY ESF |
Session: | Special Session - Mercury in the Southern Hemisphere |
Day and Session: | Wednesday 27th July - Session Two |
Start Time: | 11:30 UTC |
Co-Authors: | N. Roxanna Razavi,Louis J. Lamit,Erik A. Lilleskov,Nathan Basiliko,Alex Cobb,Jhon del Aguila Pasquel,Jennifer Farmer,Alison Hoyt,Jyrki Jauhiainen,Mari Knnen,Thu Pham Quang,Jasmine Rutherford,Graeme Spiers,Matt Warren,Shaun Watmough,Geoffrey Zahn,Charles Driscoll,Charles Harvey |
Abstract Information :
Peat is an important mercury (Hg) sink, but absolute concentrations and estimates of Hg stored in tropical peat are lacking. Tropical peatlands contain ~30% of global peat reserves and are under severe human pressures from conversion to agriculture and gold mining. Here we quantify the Hg content of tropical peat swamp forests from a global archive and provide a first estimate of Hg stored in tropical peatlands. We found a range of total Hg concentrations (15 ? 912 ng/g dry weight (dw), mean = 200 ng/g dw, n = 295). Highest concentrations were proximate to a natural point source (204 ? 912 ng/g dw, mean = 547 ng/g dw, n = 18, Hawaii, USA) and potential gold mining activities (283 ? 566 ng/g dw, mean = 363 ng/g dw, n = 16, Bonzale, Republic of Congo). A depth effect was observed at some sites with lower concentrations found in deeper peat, but at other sites no gradient was observed with depth. Percent carbon, but not nitrogen or sulfur, were significant predictors of Hg concentrations with variation at the regional level. Other trace metals including lead and cadmium were positively related to Hg concentrations. For sites with published area and bulk density estimates (Central Kalimantan, Cuvette Centrale in the Congo, and the Peruvian Amazon), we found a wide range in Hg stocks of 9 ? 59 mg/m2 in the upper 70 cm, with higher estimates equivalent to published stocks in boreal peatlands of Canada. The destruction of tropical peat forests has important implications for the exposure of global ecosystems and human populations to toxic Hg.