Critical comment Comment on ‘‘Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA” by D. Naftz, C. Angeroth, T. Kenney, B. Waddell, N. Darnall, S. Silva, C. Perschon and J. Whithead With regard to the paper recently published in Applied Geochemistry by Naftz et al. (2008), the title of the paper is interesting because the authors have basically no Hg data, except for total and methyl Hg analyses of unfiltered waters and brine shrimp, that would provide for a discus- sion of the anthropogenic influences on Hg concentrations in the lake. Because of the lack of data, most of the discussion regarding Hg inputs and cycling associated with the lake is very speculative. I list several specific comments below. (1) The first two paragraphs of Section 3.4 contain no air concentration data, no air Hg deposition data, and no air–water flux data yet they suggest specific sources of Hg to the lake. This is not the objective science expected of a peer reviewed scientific article and misleading for those who expect scientific jour- nals to present unbiased scientific research. One of my graduate students spent 7–10 days during 5 dif- ferent periods collecting data representing different seasons at Great Salt Lake. She has a paper in press that has air Hg concentration data and presents esti- mated values of atmospheric deposition to the lake. She did detailed analysis of HYSPLIT back trajecto- ries to try and understand potential sources of Hg to the lake. She also collected water Hg data (Peterson and Gustin, 2008). The data collected and presented in her paper does not support the speculative hypotheses proposed in the Naftz manu- script in Section 3.4. (2) The authors discuss ‘‘abundance of Br and Cl in the MBL above GSL” with no references or data to sup- port this discussion. There is one paper in the litera- ture that did report on ClO and BrO concentrations measured one time and the values were 15 ppt and 6 ppt (respectively) and less (Stutz et al., 2002). Peterson and Gustin (2008) also report very low con- centrations of Br and Cl in air. These reported values are significantly below those reported in the litera- ture for areas where Hg depletion events are thought to occur (Lindberg et al., 2002; Peleg et al., 2007). (3) On page 1739 the authors discuss the high methyl Hg concentrations measured in the deep brine layer. Admittedly these concentrations are high, however the authors do not consider that the samples are unfiltered and the high concentrations could reflect high organic material content and the fact their samples were unfiltered. Peterson and Gustin (2008) found filtered sample Hg concentrations for Great Salt Lake waters to be significantly less than that of unfiltered samples. (4) Lastly, the authors suggest mixing of methyl Hg from the bottom brine layer to the surface. They only have limited data to suggest mixing and this data is not Hg data of any sort thus they present no evidence to support the statement – Additional evidence of mix- ing CH 3 Hg enriched water from the DBL with the UBL is provided by sediment traps.... I am sorry to see that this manuscript seems to have fallen easily through the peer review process. There is valuable information presented in the paper however the method of presentation is misleading to the readers and not unbiased scientific reporting. References Lindberg, S.E., Brooks, S., Lin, C.-J., Scott, K.J., Landis, M.S., Stevens, R.K., Goodsite, M., Richter, A., 2002. Dynamic oxidation of gaseous mercury in the arctic troposphere at polar sunrise. Environ. Sci. Technol. 36, 1245–1256. Naftz, D., Angeroth, C., Kenney, T., Waddell, B., Darnall, N., Silva, S., Perschon, C., Whithead, J., 2008. Anthropogenic influences on the input and biogeochemical cycling of nutrients and mercury in Great Salt Lake, Utah, USA. Appl. Geochem. 23, 1731–1744. Peleg, M., Matveev, V., Tas, E., Luria, M., 2007. Mercury Depletion Events in the Troposphere in Mid-Latitudes at the Dead Sea, Israel. Environ. Sci. Technol. 41, 7280–7285. 0883-2927/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.apgeochem.2008.08.002 Applied Geochemistry 23 (2008) 3852–3853 Contents lists available at ScienceDirect Applied Geochemistry journal homepage: www.elsevier.com/locate/apgeochem