Geochemistry of contrasting stream types, Taylor Valley, Antarctica

2020 ◽  
Vol 133 (1-2) ◽  
pp. 425-448
Author(s):  
Russell S. Harmon ◽  
Deborah L. Leslie ◽  
W. Berry Lyons ◽  
Kathleen A. Welch ◽  
Diane M. McKnight
Keyword(s):  
Dissolved Oxygen ◽  
Austral Summer ◽  
Mineral Dissolution ◽  
Silicate Mineral ◽  
Cation Composition ◽  
Taylor Valley ◽  
Low Concentrations ◽  
Hyporheic Zones ◽  
Dry Valley ◽  
Geochemical Fingerprint

Abstract The McMurdo Dry Valley region is the largest ice-free area of Antarctica. Ephemeral streams flow here during the austral summer, transporting glacial meltwater to perennially ice-covered, closed basin lakes. The chemistry of 24 Taylor Valley streams was examined over the two-decade period of monitoring from 1993 to 2014, and the geochemical behavior of two streams of contrasting physical and biological character was monitored across the seven weeks of the 2010–2011 flow season. Four species dominate stream solute budgets: HCO3–, Ca2+, Na+, and Cl–, with SO42–, Mg2+, and K+ present in significantly lesser proportions. All streams contain dissolved silica at low concentrations. Across Taylor Valley, streams are characterized by their consistent anionic geochemical fingerprint of HCO3 > Cl > SO4, but there is a split in cation composition between 14 streams with Ca > Na > Mg > K and 10 streams with Na > Ca > Mg > K. Andersen Creek is a first-order proglacial stream representative of the 13 short streams that flow <1.5 km from source to gage. Von Guerard is representative of 11 long streams 2–7 km in length characterized by extensive hyporheic zones. Both streams exhibit a strong daily cycle for solute load, temperature, dissolved oxygen, and pH, which vary in proportion to discharge. A well-expressed diurnal co-variation of pH with dissolved oxygen is observed for both streams that reflects different types of biological control. The relative consistency of Von Guerard composition over the summer flow season reflects chemostatic regulation, where water in transient storage introduced during times of high streamflow has an extended opportunity for water-sediment interaction, silicate mineral dissolution, and pore-water exchange.

scholarly journals Diurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica

2019 ◽  
Vol 98 ◽  
pp. 01020
Author(s):  
Russell S. Harmon ◽  
Deborah L. Leslie ◽  
W. Berry Lyons ◽  
Kathleen A. Welch ◽  
Diane M. McKnight
Keyword(s):  
Dissolved Oxygen ◽  
Hyporheic Zone ◽  
Austral Summer ◽  
Ephemeral Streams ◽  
Secondary Effects ◽  
Order Stream ◽  
Taylor Valley ◽  
Dry Valley ◽  
Direct Reflection ◽  
Algal Mat

Numerous ephemeral streams flow within the McMurdo Dry Valley Region of Antarctica that transport glacial meltwater to perennially ice-covered, closed-basin lakes during the austral summer. The diurnal behavior for two Taylor Valley streams of different character was examined during the summer of 2010-11. Andersen Creek is a short, 1st-order proglacial stream, whereas Von Guerard Stream is a long, high-order stream with an extensive hyporheic zone that has a substantial cyanobacterial algal mat community in its middle reaches. Both streams display strong daily cycles for temperature, electrical conductivity, dissolved oxygen, and pH. Conductivity varies in concert with flow, with solute dilution occurring during the daily high-flow pulse. Dissolved oxygen co-varies strongly with pH at Andersen Creek but not for Von Guerard Stream. Each stream has a distinct geochemical character that for Andersen Creek is a direct reflection of its glacial source, unmodified by secondary effects, whereas that for Von Guerard Stream is modulated by its resident algal mat community and through extensive hyporheic zone interaction and exchange.

Groundwater seeps in Taylor Valley Antarctica: an example of a subsurface melt event

2005 ◽  
Vol 40 ◽  
pp. 200-206 ◽  
Author(s):  
W. Berry Lyons ◽  
Kathleen A. Welch ◽  
Anne E. Carey ◽  
Peter T. Doran ◽  
Diana H. Wall ◽  
...  
Keyword(s):  
Austral Summer ◽  
Geochemical Data ◽  
Decadal Time Scale ◽  
Stream Flows ◽  
Unusual Event ◽  
The North ◽  
Taylor Valley ◽  
Dry Valley ◽  
Geochemical Models ◽  
Sources Of Solutes

AbstractThe 2001/02 austral summer was the warmest summer on record in Taylor Valley, Antarctica, (∼78° S) since continuous records of temperature began in 1985. The highest stream-flows ever recorded in the Onyx River, Wright Valley, were also recorded that year (the record goes back to the 1969/70 austral summer). In early January 2002, a groundwater seep was observed flowing in the southwest portion of Taylor Valley. This flow has been named ‘Wormherder Creek’ (WHC) and represents an unusual event, probably occurring on a decadal time-scale. The physical characteristics of this feature suggest that it may have flowed at other times in the past. Other groundwater seeps, emanating from the north-facing slope of Taylor Valley, were also observed. Little work has been done previously on these very ephemeral seeps, and the source of water is unknown. These features, resembling recently described features on Mars, represent the melting of subsurface ice. The Martian features have been interpreted as groundwater seeps. In this paper we compare the chemistry of the WHC groundwater seep to that of the surrounding streams that flow every austral summer. The total dissolved solids content of WHC was ∼6 times greater than that of some nearby streams. The Na : Cl and SO4 : Cl ratios of the seep waters are higher than those of the streams, but the Mg : Cl and HCO3 : Cl ratios are lower, indicating different sources of solutes to the seeps compared to the streams. The enrichment of Na and SO4 relative to Cl may suggest significant dissolution of mirabilite within the previously unwetted soil. The proposed occurrence of abundant mirabilite in higher-elevation soils of the dry valley region agrees with geochemical models developed, but not tested, in the late 1970s. The geochemical data demonstrate that these seeps could be important in ‘rinsing’ the soils by dissolving and redistributing the long-term accumulation of salts, and perhaps improving habitat suitability for soil biota. The H4SiO4 concentration is 2–3 times greater in WHC than in the surrounding streams, indicating a large silicate-weathering component in the seep waters.

scholarly journals The seasonal evolution of albedo across glaciers and the surrounding landscape of the Taylor Valley, Antarctica

2019 ◽  
Author(s):  
Anna Bergstrom ◽  
Michael Gooseff ◽  
Madeline Myers ◽  
Peter T. Doran
Keyword(s):  
Austral Summer ◽  
Short Wave ◽  
Desert Ecosystem ◽  
Dry Valleys ◽  
Seasonal Evolution ◽  
Taylor Valley ◽  
Incoming Radiation ◽  
Dry Valley ◽  
Summer Temperatures ◽  
Surrounding Landscape

Abstract. The McMurdo Dry Valleys (MDVs) of Antarctica are a polar desert ecosystem consisting of alpine glaciers, ice-covered lakes, streams, and expanses of vegetation-free rocky soil. Because average summer temperatures are close to 0 °C, glacier melt dynamics in particular, but the Dry Valley ecosystem in general, are closely linked to the energy balance. A slight increase in incoming radiation or change in albedo can have large effects on the timing and volume of melt water. However, we have yet to fully characterize the seasonal evolution or spatial variability of albedo in the valleys. In this study, we aim to understand the drivers of landscape albedo change within and across seasons. To do so, we used a camera, gps, and short wave radiometer from a helicopter-based platform to fly transects 4–5 times a season along Taylor Valley over three seasons. We coupled these data with incoming radiation measured at 6 meteorological stations distributed along the valley to calculate the distribution of albedo across individual glaciers, lakes, and the soil surfaces. We hypothesized that albedo would decrease throughout the austral summer with ablation of snow patches and ice and increasing sediment exposure on the glacier and lake surfaces. However, small snow events (

Correlation between Chlorophyll-a Concentration and Environmental Factors in Jihongtan Reservoir

2011 ◽  
Vol 356-360 ◽  
pp. 959-962
Author(s):  
Ji Ping Ma ◽  
Cui Jie Rui ◽  
Jian Hua Ge ◽  
Yu Hua Liu ◽  
Zhi Wen Song ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Environmental Factors ◽  
Dissolved Oxygen ◽  
Statistical Method ◽  
Chlorophyll A ◽  
Potassium Permanganate ◽  
Total Nitrogen ◽  
Average Concentration ◽  
Low Concentrations ◽  
High Concentrations

Based on the Jihogntan reservoir’s monitoring data from 2006 to 2009, eutrophication of Jihongtan reservoir was assessed. The result showed that the nutrition level of the Jihongtan reservoir was middle in recent years. The average concentration of chlorophyll-a(Chla) was higher in summer and autumn than in spring and winter. The correlation between concentration of Chla and some environmental factors was studied by statistical method, and seasonal variation of Chla and the extent of eutrophication were also analyzed. The results showed that the correlations between Chla and total nitrogen(TN), dissolved oxygen(DO) and transparency were significantly negative, and that between Chla and total phosphorus(TP), temperature(T) and potassium permanganate index(COD Mn) were significantly positive. The growth of phytoplankton was promoted by TP and TN at low concentrations, and inhibited by TN at high concentrations.

Latent disciplinal clashes concerning the batch dissolution of minerals, and their wider implications

2018 ◽  
Vol 15 (2) ◽  
pp. 113 ◽  
Author(s):  
Victor W. Truesdale ◽  
Jim Greenwood
Keyword(s):  
Large Scale ◽  
Dissolution Kinetics ◽  
Mineral Dissolution ◽  
Atomic Scale ◽  
Rate Equations ◽  
Silicate Mineral ◽  
Waste Products ◽  
Calcite Dissolution ◽  
Macro Scale ◽  
Made In

Environmental contextMineral dissolution kinetics are important to understand natural processes including those increasingly used to store waste carbon dioxide and highly radio-active nuclides, and those involved in the amelioration of climate change and sea-level rise. We highlight a mistake made in the fundamental science that has retarded progress in the field for over 40 years. Its removal suggests improved ways to approach dissolution studies. AbstractMineral dissolution kinetics are fundamental to biogeochemistry, and to the application of science to reduce the deleterious effects of humanity’s waste products, e.g. CO2 and radio-nuclides. However, a mistake made in the selection of the rate equation appropriate for use at the macro-scale of the aquatic environment has stymied growth in major aspects of the subject for some 40 years. This paper identifies the mistake, shows how it represents a latent disciplinal clash between two rate equations, and explores the misunderstandings that resulted from it. The paper also briefly explores other disciplinal clashes. Using the example of calcite dissolution, the paper also shows how the phenomenon of ‘non-ideal’ dissolution, which is prevalent in alumino-silicate mineral dissolution, as well as with calcite, has obscured the clash. The paper provides new information on plausible mechanisms, the absence of which has contributed to the problem. Finally, it argues that disciplinal clashes need to be minimised so that a rigorous description of dissolution at the large scale can be matched to findings at the atomic, or near-atomic, scale.

Measuring silicate mineral dissolution rates using Si isotope doping

2016 ◽  
Vol 445 ◽  
pp. 146-163 ◽  
Author(s):  
Chen Zhu ◽  
Zhaoyun Liu ◽  
Yilun Zhang ◽  
Chao Wang ◽  
Augustus Scheafer ◽  
...  
Keyword(s):  
Mineral Dissolution ◽  
Silicate Mineral ◽  
Dissolution Rates ◽  
Si Isotope

Laboratory evidence for microbially mediated silicate mineral dissolution in nature

1996 ◽  
Vol 132 (1-4) ◽  
pp. 11-17 ◽  
Author(s):  
William J. Ullman ◽  
David L. Kirchman ◽  
Susan A. Welch ◽  
Philippe Vandevivere
Keyword(s):  
Mineral Dissolution ◽  
Silicate Mineral ◽  
Laboratory Evidence

Influence of denitrification reactor retention time distribution (RTD) on dissolved oxygen control and nitrogen removal efficiency

2015 ◽  
Vol 72 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Massimo Raboni ◽  
Renato Gavasci ◽  
Paolo Viotti
Keyword(s):  
Dissolved Oxygen ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Plug Flow ◽  
Oxygen Control ◽  
Low Concentrations ◽  
Dissolved Oxygen Control ◽  
Denitrification Reactor ◽  
Do Concentration ◽  
Mixed Reactor

Abstract Low concentrations of dissolved oxygen (DO) are usually found in biological anoxic pre-denitrification reactors, causing a reduction in nitrogen removal efficiency. Therefore, the reduction of DO in such reactors is fundamental for achieving good nutrient removal. The article shows the results of an experimental study carried out to evaluate the effect of the anoxic reactor hydrodynamic model on both residual DO concentration and nitrogen removal efficiency. In particular, two hydrodynamic models were considered: the single completely mixed reactor and a series of four reactors that resemble plug-flow behaviour. The latter prove to be more effective in oxygen consumption, allowing a lower residual DO concentration than the former. The series of reactors also achieves better specific denitrification rates and higher denitrification efficiency. Moreover, the denitrification food to microrganism (F:M) ratio (F:MDEN) demonstrates a relevant synergic action in both controlling residual DO and improving the denitrification performance.

scholarly journals Evaluation of the Potential for Dissolved Oxygen Ingress into Deep Sedimentary Basins during a Glaciation Event

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-20 ◽  
Author(s):  
Sergio A. Bea ◽  
Danyang Su ◽  
K. Ulrich Mayer ◽  
Kerry T. B. MacQuarrie
Keyword(s):  
Dissolved Oxygen ◽  
Reactive Transport ◽  
Large Scale ◽  
Sedimentary Basins ◽  
Mineral Dissolution ◽  
Depth Of Penetration ◽  
Glacial Meltwater ◽  
Oxidation Rates ◽  
High Concentrations ◽  
Oxygen Ingress

Geochemical conditions in intracratonic sedimentary basins are currently reducing, even at relatively shallow depths. However, during glaciation-deglaciation events, glacial meltwater production may result in enhanced recharge (Bea et al., 2011; and Bea et al., 2016) potentially having high concentrations of dissolved oxygen (O2). In this study, the reactive transport code Par-MIN3P-THCm was used to perform an informed, illustrative set of simulations assessing the depth of penetration of low salinity, O2-rich, subglacial recharge. Simulation results indicate that the large-scale basin hydrostratigraphy, in combination with the presence of dense brines at depth, results in low groundwater velocities during glacial meltwater infiltration, restricting the vertical ingress of dilute recharge waters. Furthermore, several geochemical attenuation mechanisms exist for O2, which is consumed by reactions with reduced mineral phases and solid organic matter (SOM). The modeling showed that effective oxidative mineral dissolution rates and SOM oxidation rates between 5 × 10−15 and 6 × 10−13 mol dm−3 bulk s−1 were sufficient to restrict the depth of O2 ingress to less than 200 m. These effective rates are low and thus conservative, in comparison to rates reported in the literature. Additional simulations with more realistic, yet still conservative, parameters reaffirm the limited ability for O2 to penetrate into sedimentary basin rocks during a glaciation-deglaciation event.

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