An Introduction to “Microbial Biogeochemistry: A Special Issue of \u3ci\u3eAquatic Geochemistry\u3c/i\u3e Honoring Mark Hines”

(First paragraph) This issue of Aquatic Geochemistry is dedicated to the memory of Dr. Mark E. Hines (Fig. 1) and his contributions to the fields of microbial biogeochemistry and aquatic geochemistry. Mark passed away in March of 2018, and through his career as a researcher, teacher, mentor, colleague, and university administrator, he greatly influenced the lives of all around him. We hope that this volume will serve not only as a memory of Mark, but also as a way to recognize his significant influences and major contributions in the fields of carbon, sulfur, and trace element biogeochemistry

The fate of minor alkali elements in the chemical evolution of salt lakes

Alkaline earth elements and alkali metals (Mg, Ca, Na and K) play an important role in the geochemical evolution of saline lakes as the final brine type is defined by the abundance of these elements. The role of major ions in brine evolution has been studied in great detail, but little has been done to investigate the behaviour of minor alkali elements in these systems despite their similar chemical affinities to the major cations. We have examined three major anionic brine types, chloride, sulphate, and bicarbonate-carbonate, in fifteen lakes in North America and Antarctica to determine the geochemical behaviour of lithium, rubidium, strontium, and barium. Lithium and rubidium are largely conservative in all water types, and their concentrations are the result of long-term solute input and concentration through evaporation and/or sublimation. Strontium and barium behaviours vary with anionic brine type. Strontium can be removed in sulphate and carbonate-rich lakes by the precipitation of carbonate minerals. Barium may be removed in chloride and sulphate brines by either the precipitation of barite and perhaps biological uptake

Nitrate Plus Nitrite Concentrations in a Himalayan Ice Core

The measurement of chemical constituents in glacial ice has been useful in discerning historic trends in chemical deposition and hence paleo-atmospheric records in remote areas (Thompson and Mosley - Thompson, 1981; Johnson and Chamberlain, 1981; Ng and Patterson, 1981; Neftel et al., 1982). However, delineating the sources of the deposited chemical species in question is not always straightforward. This has been especially true for nitrate. Although it is now believed that man-made emissions are responsible for a high percentage of nitrate being deposited in remote areas of the Northern Hemisphere, numerous natural sources, named and unnamed, have also contributed to the precipitated nitrate burden in these regions (Risbo et al., 1981; Herron, 1982). Most of the data available for glacial ice has been obtained from polar glaciers. We present nitrate plus nitrite data froma 16.6m core collected at 4908m on Sentik Glacier in the Nun Kun portion of the Ladakh Himalayas, India. To our knowledge this is the longest record of nitrate concentrations reported from an alpine glacie

Source and climatic implication of the reactive iron and reactive silicate concentration found in a core from Meserve Glacier, Antartica

Glaciochemistry has recently provided a useful tool in the study of snow accumulation rates (Herron and Langway, 1979; Bulter et al., 1980 Warburton and Young, 1981; Mayewski et al., in press) and the elucidation of long-term climatic change (Delmas et al., 1980; Thompson and Mosley-Thompson, 1981) as well as the definition of aerosol/precipitation source areas (Warburton and Linkletter, 1978). Recent glaciochemical work from Antarctica has suggested that although cations associated with seasalt(Na, Mg, Ca and K) decrease in concentration as one proceeds inland, crustally-derived chemical species such as Al and Fe remain relatively constant in snow and ice (Boutron and Martin, 1980; Herron and Langway, 1979; Johnson and Chamberlain, 1981; Warburton and Young, 1981). This paper presents the first data suggesting that there is in some cases a local source for the crustally-derived material that enters Antarctic precipitation

Examination of Selected Microparticles from the Sentik Glacier Core, Ladakh, Himalayas

Several characteristics and interpretive comments are reported for microparticles from selected samples in the Sentik Glacier core. Four basic morphologic groups are defined: Platy, angular, biogenic, and anomalous

Acidity of Recent Himalayan Snow

Surface snows collected at various elevations in the Indian Himalayas were analyzed in the field for pH as part of a broader study of the chemistry. The pH values are lower than the predicted ≅5.6 for unpolluted precipitation. Analysis of NO3 + NO2, Cl, SO4 and NH4 indicate that these low pH values are not completely due to the presence of strong mineral acids. The strong correlation of pH with elevation (i.e. temperature) suggests that the low pH values are due to the snow being supersaturated with CO2