@article{fdi:010053509,
  title = {{A}mazonian former gold mined soils as a source of methylmercury : evidence from a small scale watershed in {F}rench {G}uiana},
  author = {{G}u{\'e}dron, {S}t{\'e}phane and {G}rimaldi, {M}ichel and {G}rimaldi, {C}. and {C}ossa, {D}. and {T}isserand, {D}elphine and {C}harlet, {L}aurent},
  editor = {},
  language = {{ENG}},
  abstract = {{T}otal mercury ({H}g{T}) and monomethylmercury ({MMH}g) were investigated in a tropical head watershed (1 km(2)) of {F}rench {G}uiana. {T}he watershed includes a pristine area on the hill slopes and a former gold mined flat in the bottomland. {C}oncentrations of dissolved and particulate {H}g{T} and {MMH}g were measured in rain, throughfall, soil water and at three points along the stream. {S}amples were taken in-between and during 14 storm events at the beginning and middle of the 2005 and 2006 rainy seasons. {D}issolved and particulate {H}g{T} concentrations in the stream slightly increased downstream, while dissolved and particulate {MMH}g concentrations were low at the pristine sub-watershed outlet (median = 0.006 ng {L}-1 and 1.84 ng g(-1), respectively) and sharply increased at the gold mined flat outlet (median = 0.056 ng {L}-1 and 6.80 ng g(-1), respectively). {O}xisols, which are dominant in the pristine area act as a sink of {H}g{T} and {MMH}g from rain and throughfall inputs. {H}ydromorphic soils in the flat are strongly contaminated with {H}g (including {H}g droplets) and their structure has been disturbed by former gold-mining processes, leading to multiple stagnant water areas where biogeochemical conditions are favorable for methylation. {I}n the former gold mined flat high dissolved {MMH}g concentrations (up to 0.8 ng {L}-1) were measured in puddles or suboxic soil pore waters, whereas high dissolved {H}g{T} concentrations were found in lower {E}h conditions. {I}ron-reducing bacteria were suggested as the main methylators since highest concentrations for dissolved {MMH}g were associated with high dissolved ferrous iron concentrations. {T}he connection between saturated areas and stagnant waters with the hydrographic network during rain events leads to the export of dissolved {MMH}g and {H}g{T} in stream waters, especially at the beginning of the rainy season. {A}s both legal and illegal gold-mining continues to expand in {F}rench {G}uiana, an increase in dissolved and particulate {MMH}g emissions in the hydrographic network is expected. {T}his will enhance {MMH}g bio-amplification and present a threat to local populations, whose diet relies mainly on fish.},
  keywords = {{M}ercury ; {M}ethylmercury ; {T}ropical watershed ; {G}old placers ; {S}tream water ; {O}xisols ; {H}ydromorphic soils ; {GUYANE} {FRANCAISE} ; {AMAZONIE}},
  booktitle = {},
  journal = {{W}ater {R}esearch},
  volume = {45},
  numero = {8},
  pages = {2659--2669},
  ISSN = {0043-1354},
  year = {2011},
  DOI = {10.1016/j.watres.2011.02.022},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053509},
}