@article{fdi:010084653,
  title = {{I}n situ photochemical transformation of {H}g species and associated isotopic fractionation in the water column of high-altitude lakes from the {B}olivian {A}ltiplano},
  author = {{B}ouchet, {S}. and {T}essier, {E}. and {M}asbou, {J}. and {P}oint, {D}avid and {L}azzaro, {X}avier and {M}onperrus, {M}. and {G}u{\'e}dron, {S}t{\'e}phane and {A}cha, {D}. and {A}mouroux, {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{P}hotochemical reactions are major pathways for the removal of {H}g species from aquatic ecosystems, lowering the concentration of monomethylmercury ({MMH}g) and its bioaccumulation in foodwebs. {H}ere, we investigated the rates and environmental drivers of {MMH}g photodegradation and inorganic {H}g ({IH}g) photoreduction in waters of two high-altitude lakes from the {B}olivian {A}ltiplano representing meso- to eutrophic conditions. {W}e incubated three contrasting waters in situ at two depths after adding {H}g-enriched isotopic species to derive rate constants. {W}e found that transformations mostly occurred in subsurface waters exposed to {UV} radiation and were mainly modulated by the dissolved organic matter ({DOM}) level. {I}n parallel, we incubated the same waters after the addition of low concentrations of natural {MMH}g and followed the stable isotope composition of the remaining {H}g species by compound-specific isotope analysis allowing the determination of enrichment factors and mass-independent fractionation ({MIF}) slopes ({D}elta {H}g-199/{D}elta {H}g-201) during in situ {MMH}g photodegradation in natural waters. {W}e found that {MIF} enrichment factors potentially range from -11 to -19% and average -14.3 +/- 0.6% (1 {SE}). {T}he {MIF} slope diverged depending on the {DOM} level, ranging from 1.24 +/- 0.03 to 1.34 +/- 0.02 for the low and high {DOM} waters, respectively, and matched the {MMH}g {MIF} slope recorded in fish from the same lake. {O}ur in situ results thus reveal (i) a relatively similar extent of {H}g isotopic fractionation during {MMH}g photodegradation among contrasted natural waters and compared to previous laboratory experiments and (ii) that the {MMH}g {MIF} recorded in fish is characteristic for the {MMH}g bonding environment. {T}hey will enable a better assessment of the extent and conditions conducive to {MMH}g photodegradation in aquatic ecosystems.},
  keywords = {photodegradation ; photoreduction ; compound-specific isotope analysis ; enrichment factor ; dissolved organic matter ; fish ; {BOLIVIE} ; {ANDES}},
  booktitle = {},
  journal = {{E}nvironmental {S}cience and {T}echnology},
  volume = {56},
  numero = {4},
  pages = {2258--2268},
  ISSN = {0013-936{X}},
  year = {2022},
  DOI = {10.1021/acs.est.1c04704},
  URL = {https://www.documentation.ird.fr/hor/fdi:010084653},
}