The top saline lake research of 2014

ResearchBlogging.org

The year 2014 was the specific year for saline lake research. First of all, because it was the year of triennial International Conference on Salt Lake Research. The meeting was held in China in July. I blogged about the conference before. Abstracts of the conference were published by the Acta Geologica Sinica, they can be downloaded and studied in details.

Now, it is time to analyze the research output. The traditional approach is to use the Web of Science and to make search for “salt lake or saline lake” and “salinity and lake”. The combined list of 690 papers published in year 2014 will be the database for brief analysis and selection of best papers.

The top 3 most active countries are the same as were the previous year – USA, China and Germany. England and Spain joined the top 5 which is the good sign of growing diversity of saline lake studies.

The top 5 most active countries. Saline lake research 2014

The top 5 journals where the largest numbers of salt lake science papers were published clearly demonstrated that microbiology and geology completely dominated this area of inland water studies.

The top 5 most popular journals. Saline lake research 2014

Web of Science Categories is a good indicator of research priorities. Geosciences and geography – this is the specific world of saline lakes that differs from the priorities in freshwater lakes studies.

The top 5 most popular Web of Science categories. Saline lake research 2014

It was interesting to reveal most active scientists. Dimitry Sorokin from Russia co-authored six (6) papers and this is enough to be at the top. The following list of five scientists (each of them is a coauthor of 5 papers) is a good demonstration of worldwide activities in salt lake research: Mohammad Ali Amoozegar from Iran; Luc Dendooven from Mexico; Renzo Perissinotto from South Africa; Cathrin Spröer from Germany and Antonio Ventosa from Spain.

The selection of the best papers was based on metrics and merits. Metric is the Web of Science impact factor of the journal were the paper was published. The list of 15 papers was created based on this metrics. Merit is the selection of the papers based on personal preferences of me, Hongwei Yin (Professor of Structural Geology and Salt Tectonics at the Nanjing University) and Aharon Oren (Professor of Microbial ecology at the Hebrew University of Jerusalem).

Year 2014. Top 5 papers in saline lake science

1. Dong-Ha Oh and Maheshi Dassanayake with colleagues compared the genome structures and transcriptomes of Schrenkiella parvula and its close relatives Arabidopsis thaliana and Brassica crop species. S. parvula completes its life cycle on the shores of Lake Tuz, Turkey, where soils accumulate high concentrations of different salts (Na+, K+, Mg2+, Li+, and borate) at concentrations lethal to Arabidopsis. Research revealed that the capacity of extremophyte S. parvula to tolerate multiple-ion stress most probably is enabled by its genome structure and transcriptome variations. Many stress-related ion transporter genes in S. parvula showed increased copy numbers and basal expression strengths compared with Arabidopsis. These results provide some insights into the mechanisms of plant ion stress tolerance.

Left: treatment of S. parvula (Sp) and Arabidopsis (At) with high concentrations of various salts – root growth of the seedlings. Right: differently expressed gene pairs between S. parvula (Sp) and Arabidopsis (At). Examples of networks representing gene ontology terms enriched in differently expressed gene pairs groups. Gene ontology terms are connected based on their ancestorchild relationships.

2. Andreas Kappler with several colleagues from Germany quantify the release of volatile halogenated organic compounds (VOX) from sediments from a hypersaline lake in Western Australia (Lake Strawbridge). VOX formation was observed in many environments ranging from forest soils to salt lakes. These substances contribute to ozone depletion and global warming. Field studies have provided evidence for direct biological (enzymatic) VOX formation. However, the relative contribution of abiotic and biotic processes to global VOX budgets is still unclear. Authors used microbially active and sterilized microcosms to understand the relative contributions of biotic and abiotic VOX formation. Experiments demonstrated that the release of organochlorines from Lake Strawbridge sediments was mainly biotic. In discussion authors note that the impact of salt lake sediments and salt-affected soils to organochlorine emission is also important with regard to global warming and decreasing rainfall. The increasing salinization of freshwater lakes is of major concern in many arid and semiarid environments. Salt lakes seem to act as a source of organochlorines. Future scenarios predict that existing salt-affected landscapes increase in size and that there is also the formation of new areas suffering from salinization.If these scenarios are realized, then there might be fundamental changes in the global VOX budgets with an increasing importance of salt lake sediments and salt affected soils.

Top: location of the sampling site, Lake Strawbridge, in South Western Australia, and its sediments. Bottom: biotic and abiotic chloromethane emission within the first 60 min of incubation from Lake Strawbridge sediments. Effect of different sterilization techniques on chloromethane formation from sediments collected from different depth. Biotic = unsterilized sediment, NaN3 = 150 mM sodium azide and a.c. = autoclaved sediment.

3. Boaz Lazar from the Hebrew University with colleagues established the history of the deepest part of the Dead Sea by direct measurements of the chemical and isotopic composition of pore-fluids that were extracted from cores drilled by International Continental Scientific Drilling Program in the deep basin of the Dead Sea. The vertical profiles of chloride and oxygen isotopes in pore brines reveal the history of the Dead Sea. The summary diagram presents three major lake settings: (a) The highest stand of the last glacial predecessor of the modern Dead Sea (Lake Lisan) that contained two thick brine layers (epilimnion and hypolimnion), each∼200m deep; (b) Drop in lake level, formation of northern freshwater lakes, Kinneret (Sea of Galilee) and Baisan, active mixing between the epilimnion and the hypolimnion that pushed the epilimnion/hypolimnion interface downward and triggered massive gypsum precipitation; (c) Further drop in lake level, full overturn and the disappearance of the epilimnion and the onset of post glacial halite precipitation.

The history of the Dead Sea

4. Daniel Nelson and Julian Sachs investigated the influence of salinity on hydrogen isotopic compostion in two algal lipids (dinosterol and brassicasterol) from a wide range of globally distributed lakes with different salinities. Results demonstrated that salinity is the dominant factor responsible for modulating the deuterium/protium ratio in biosynthesis of many algal lipids in saline and hypersaline environments. This finding can be used for quantitative reconstructions of salinity and lake water isotope changes in the past.

Salinity vs. deuterium/protium ratio for dinosterol and brassicasterol. Data are also grouped by sub-region and plotted in color, with regression lines that correspond to the symbol color.

5. Wayne Wurtsbaugh and Erin F. Jones published the research where they link the complex stratification patterns of Great Salt Lake (USA), food web interactions and mercury bioaccumulation through the food web. An anoxic, sulfide-rich deep brine layer in the south arm of the Great Salt Lake accumulates high levels of total mercury and methylmercury. High mercury levels of brine shrimp (Artemia franciscana) in the mixed layer are passed to waterfowl, creating a human health hazard. Authors hypothesized that high mercury levels in Artemia are due to exposure when mercury is mixed into the upper layer or when they feed on mercury-rich organic matter in the chemocline separating the two layers. To test the hypothesis they conduct laboratory experiments with aquaria and chemically stratified tubes. In aquaria growth experiments with 0%, 10%, or 25% deep brine water, Artemia exposed to progressively higher concentrations of mercury had significantly less mercury. In column experiments simulating a lake with a deep brine layer, Artemia grazed in the chemocline, but they also had lower mercury concentrations than Artemia in controls without a deep brine layer. This was due to detrital dilution of the mercury because the deep brine layer has very high particulate organic carbon. Consequently, although Artemia are exposed to the high concentrations of methylmercury generated in the deep layer, the detrimental effect is partially ameliorated by detrital dilution of the mercury.

Left: experimental columns used to test whether the presence of a deep brine layer increased mercury uptake of Artemia franciscana. Right: relationship between mean total mercury concentrations in the water and mercury content of Artemia franciscana grown in the experimental aquaria with different proportions of deep brine layer water from the Great Salt Lake and the relationship between the mercury to particulate organic carbon (POC) ratio and mercury accumulation in the Artemia.

References

Oh, D., Hong, H., Lee, S., Yun, D., Bohnert, H., & Dassanayake, M. (2014). Genome Structures and Transcriptomes Signify Niche Adaptation for the Multiple-Ion-Tolerant Extremophyte Schrenkiella parvula PLANT PHYSIOLOGY, 164 (4), 2123-2138 DOI: 10.1104/pp.113.233551

Ruecker A, Weigold P, Behrens S, Jochmann M, Laaks J, & Kappler A (2014). Predominance of biotic over abiotic formation of halogenated hydrocarbons in hypersaline sediments in Western Australia. Environmental science & technology, 48 (16), 9170-8 PMID: 25073729

Lazar, B., Sivan, O., Yechieli, Y., Levy, E., Antler, G., Gavrieli, I., & Stein, M. (2014). Long-term freshening of the Dead Sea brine revealed by porewater Cl− and δO18 in ICDP Dead Sea deep-drill Earth and Planetary Science Letters, 400, 94-101 DOI: 10.1016/j.epsl.2014.03.019

Nelson, D., & Sachs, J. (2014). The influence of salinity on D/H fractionation in dinosterol and brassicasterol from globally distributed saline and hypersaline lakes Geochimica et Cosmochimica Acta, 133, 325-339 DOI: 10.1016/j.gca.2014.03.007

Erin F. Jones and Wayne A. Wurtsbaugh (2014). The Great Salt Lake’s monimolimnion and its importance for mercury bioaccumulation in brine shrimp (Artemia franciscana) Limnology and Oceanography, 59 (1), 141-155

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