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Morten Madsen - One of the best experts on this subject based on the ideXlab platform.
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Transient liquid water and water activity at Gale crater on Mars
Nature Geoscience, 2015Co-Authors: F. Javier Martín-torres, María-paz Zorzano, Patricia Valentín-serrano, Osku Kemppinen, James Wray, M. Genzer, Edgard G. Rivera-valentin, Ari-matti Harri, Morten Madsen, Walter GoetzAbstract:Liquid water on equatorial Mars is inconsistent with large-scale climatic conditions. Humidity and temperature measurements by the Curiosity rover support the formation of subsurface liquid brines by hydration of Perchlorates during the night. Water is a requirement for life as we know it^ 1 . Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars^ 2 , in contrast with expectations from large-scale climate models. The presence of Perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover^ 3 , 4 , lowers the freezing temperature of water^ 5 . Moreover, Perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence^ 6 , 7 . Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere–soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms^ 8 . Perchlorates are widespread on the surface of Mars^ 9 and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.
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Transient liquid water and water activity at Gale crater on Mars
Nature Geoscience, 2015Co-Authors: F. Javier Martín-torres, María-paz Zorzano, Patricia Valentín-serrano, Osku Kemppinen, Insoo Jun, James Wray, M. Genzer, Edgard G. Rivera-valentin, Ari-matti Harri, Morten MadsenAbstract:Water is a requirement for life as we know it. Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars, in contrast with expectations from large-scale climate models. The presence of Perchlorate salts, which have been detected at Gale crater on equatorial Mars by theCuriosity rover, lowers the freezing temperature of water. Moreover, Perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence. Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere–soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms. Perchlorates are widespread on the surface of Mars and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.
F. Javier Martín-torres - One of the best experts on this subject based on the ideXlab platform.
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Transient liquid water and water activity at Gale crater on Mars
Nature Geoscience, 2015Co-Authors: F. Javier Martín-torres, María-paz Zorzano, Patricia Valentín-serrano, Osku Kemppinen, James Wray, M. Genzer, Edgard G. Rivera-valentin, Ari-matti Harri, Morten Madsen, Walter GoetzAbstract:Liquid water on equatorial Mars is inconsistent with large-scale climatic conditions. Humidity and temperature measurements by the Curiosity rover support the formation of subsurface liquid brines by hydration of Perchlorates during the night. Water is a requirement for life as we know it^ 1 . Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars^ 2 , in contrast with expectations from large-scale climate models. The presence of Perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover^ 3 , 4 , lowers the freezing temperature of water^ 5 . Moreover, Perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence^ 6 , 7 . Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere–soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms^ 8 . Perchlorates are widespread on the surface of Mars^ 9 and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.
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Transient liquid water and water activity at Gale crater on Mars
Nature Geoscience, 2015Co-Authors: F. Javier Martín-torres, María-paz Zorzano, Patricia Valentín-serrano, Osku Kemppinen, Insoo Jun, James Wray, M. Genzer, Edgard G. Rivera-valentin, Ari-matti Harri, Morten MadsenAbstract:Water is a requirement for life as we know it. Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars, in contrast with expectations from large-scale climate models. The presence of Perchlorate salts, which have been detected at Gale crater on equatorial Mars by theCuriosity rover, lowers the freezing temperature of water. Moreover, Perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence. Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere–soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms. Perchlorates are widespread on the surface of Mars and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.
Todd A. Anderson - One of the best experts on this subject based on the ideXlab platform.
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Uptake and elimination of Perchlorate in eastern mosquitofish
Chemosphere, 2005Co-Authors: Carrie M. Bradford, Todd A. Anderson, June-woo Park, Jacques Rinchard, Christopher W. TheodorakisAbstract:The purpose of this study was to investigate the uptake and elimination of Perchlorate in eastern mosquitofish (Gambusia holbrooki). Fish were exposed to 0.1–1000 mg/l sodium Perchlorate for 12 h, 1, 2, 5, 10, and 30 days, and Perchlorate was determined in whole body extracts. Perchlorate was not detected in mosquitofish exposed to the low concentrations of Perchlorate (0, 0.1, and 1 mg/l sodium Perchlorate), regardless of the exposure time, whereas it was detected when fish were exposed to 10, 100, and 1000 mg/l. The tissue concentrations were approximately 10 times less than that in the water. There was no difference in the uptake of Perchlorate depending upon the exposure time, however, a difference in Perchlorate uptake depending upon the concentration of the exposure dose (P < 0.001) was observed. Uptake (Ku) and elimination (Ke) rate constants were 0.09 l/mg day and 0.70 day � 1 , respectively. The halflife (T1/2) of Perchlorate was 0.99 day. Thus, it appears that Perchlorate is rapidly taken up and eliminated in eastern mosquitofish. These results are critical and may be used to develop models of fate, effects, and transport of Perchlorate in natural systems, as well as to assess ecological risk in affected ecosystems. 2005 Elsevier Ltd. All rights reserved.
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A cleanup method for Perchlorate determination in urine.
Talanta, 2005Co-Authors: Qiuqiong Cheng, Jaclyn E. Cañas, Todd A. AndersonAbstract:There is increasing concern about Perchlorate exposure because of Perchlorate's potential effects on organisms as a thyroid hormone disruptor, as well as its contamination of the environment being much more widespread than previously thought. Perchlorate is excreted primarily into urine, therefore, evaluating Perchlorate residues in urine should be a reasonable approach for determining exposure and if successful could be used as an effective biomarker of Perchlorate exposure. Since the presence of ions and other biomolecules in matrices like urine usually confounds accurate determination of Perchlorate by ion chromatography, it is necessary to develop efficient methods for Perchlorate determination in these matrices. We developed a method that reduces the background signal of urine, which is typically the problem with the analysis of biological fluids and tissues by ion chromatography. Relatively high recovery of Perchlorate was shown. In cow urine samples spiked with Perchlorate at 2.5, 10, and 100 μg/L, Perchlorate recoveries were 67% ± 2.5, 77% ± 3.6, and 81% ± 1.7 (mean ± S.D.), respectively. In addition, the detection limit was as low as 12.6, 12.3, and 18.7 μg/L in cow, vole, and human urine samples, respectively.
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Perchlorate occurrence in the texas southern high plains aquifer system
Ground Water Monitoring and Remediation, 2005Co-Authors: Andrew W Jackson, Todd A. Anderson, Srinath Rajagopalan, Srinivasa Kumar Anandam, Tom Lehman, Ken Rainwater, Moira Ridley, R W TockAbstract:In the spring of 2002, the Texas Commission on Environmental Quality determined that Perchlorate (ClO4 � ) was present in ground water from the McMillan and Paul Davis well fields that supply potable water for the city of Midland. Researchers began a large-scale sampling program to determine the source(s) and distribution of Perchlorate in the area’s ground water. This document summarizes the findings of a large-scale investigation in nine counties carried out from July to December 2002. This program included public water system (PWS) wells and private wells in Andrews, Borden, Dawson, Ector, Gaines, Glasscock, Howard, Martin, and Midland counties, which occupy a total area of 23,960 km 2 . Water samples were tested for Perchlorate and a suite of common ions. From a total of 254 wells sampled in the nine counties, 179 wells (70%) had detectable Perchlorate concentrations (>0.5 ppb) and 88 wells (35%) had Perchlorate concentrations equal to or above 4 ppb. The highest Perchlorate concentration found at a private well was 58.8 ppb in Dawson County, while the highest concentration detected for a well in PWS was 45.6 ppb in city of Midland, Midland County. Perchlorate positively correlated (a < 0.0001) with Cl � ,F � ,B r � ,S O4 2� ,M g 2+ , and K + but not with NO2 � ,N O3 � , Na + ,o r Ca 2+ . Research to date has identified the most likely sources to be (1) a natural mineralogical impurity; (2) agricultural fertilizers containing Perchlorate; (3) in situ generation of Perchlorate by electrochemical reactions; or (4) some combination of the three. This study suggests that there may be significant sources other than the traditional industrial processing of Perchlorate, and the distribution of Perchlorate in ground water is likely more widespread than previously suspected.
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the origin of naturally occurring Perchlorate the role of atmospheric processes
Environmental Science & Technology, 2005Co-Authors: Purnendu K Dasgupta, Todd A. Anderson, Andrew W Jackson, Kalyani P Martinelango, Kang Tian, Richard W Tock, Srinath RajagopalanAbstract:Perchlorate, an iodide uptake inhibitor, is increasingly being detected in new places and new matrices. Perchlorate contamination has been attributed largely to the manufacture and use of ammonium Perchlorate (the oxidizer in solid fuel rockets) and/or the earlier use of Chilean nitrate as fertilizer (∼0.1% Perchlorate). However, there are regions such as the southern high plains (Texas Panhandle) where there is no clear historical or current evidence of the extensive presence of rocket fuel or Chilean fertilizer sources. The occurrence of easily measurable concentrations of Perchlorate in such places is difficult to understand. In the southern high plains groundwater, Perchlorate is better correlated with iodate, known to be of atmospheric origin, compared to any other species. We show that Perchlorate is readily formed by a variety of simulated atmospheric processes. For example, it is formed from chloride aerosol by electrical discharge and by exposing aqueous chloride to high concentrations of ozone. ...
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Perchlorate accumulation in forage and edible vegetation
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Andrew W Jackson, Philip N. Smith, Preethi Joseph, Patil Laxman, Lu Yu, Todd A. AndersonAbstract:The accumulation of Perchlorate in vegetation is becoming a concern, with increasing numbers of sites reporting the presence of Perchlorate in groundwater and surface water. This study investigated potential Perchlorate uptake and distribution by a variety of forage and edible crops in both the laboratory and the field. Perchlorate concentrations in soybean leaves grown in the greenhouse were significantly higher than Perchlorate concentrations in soybean seeds and pods. Perchlorate concentrations in alfalfa grown in sand were significantly lower than those in alfalfa grown in soil. The concentration of Perchlorate in tomato was lower in the fruit than the leaves. Commercially grown wheat and alfalfa samples all contained Perchlorate, 0.72−8.6 mg/kg of fresh weight (FW) in the wheat stems, 0.71−4.4 mg/kg of FW in the wheat heads, and 2.9 mg/kg of FW in alfalfa. All field garden samples tested (including cucumber, cantaloupe, and tomato) that were irrigated with Perchlorate-tainted water contained perchlor...
Walter Goetz - One of the best experts on this subject based on the ideXlab platform.
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Transient liquid water and water activity at Gale crater on Mars
Nature Geoscience, 2015Co-Authors: F. Javier Martín-torres, María-paz Zorzano, Patricia Valentín-serrano, Osku Kemppinen, James Wray, M. Genzer, Edgard G. Rivera-valentin, Ari-matti Harri, Morten Madsen, Walter GoetzAbstract:Liquid water on equatorial Mars is inconsistent with large-scale climatic conditions. Humidity and temperature measurements by the Curiosity rover support the formation of subsurface liquid brines by hydration of Perchlorates during the night. Water is a requirement for life as we know it^ 1 . Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars^ 2 , in contrast with expectations from large-scale climate models. The presence of Perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover^ 3 , 4 , lowers the freezing temperature of water^ 5 . Moreover, Perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence^ 6 , 7 . Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere–soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms^ 8 . Perchlorates are widespread on the surface of Mars^ 9 and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.
Osku Kemppinen - One of the best experts on this subject based on the ideXlab platform.
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Transient liquid water and water activity at Gale crater on Mars
Nature Geoscience, 2015Co-Authors: F. Javier Martín-torres, María-paz Zorzano, Patricia Valentín-serrano, Osku Kemppinen, James Wray, M. Genzer, Edgard G. Rivera-valentin, Ari-matti Harri, Morten Madsen, Walter GoetzAbstract:Liquid water on equatorial Mars is inconsistent with large-scale climatic conditions. Humidity and temperature measurements by the Curiosity rover support the formation of subsurface liquid brines by hydration of Perchlorates during the night. Water is a requirement for life as we know it^ 1 . Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars^ 2 , in contrast with expectations from large-scale climate models. The presence of Perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover^ 3 , 4 , lowers the freezing temperature of water^ 5 . Moreover, Perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence^ 6 , 7 . Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere–soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms^ 8 . Perchlorates are widespread on the surface of Mars^ 9 and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.
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Transient liquid water and water activity at Gale crater on Mars
Nature Geoscience, 2015Co-Authors: F. Javier Martín-torres, María-paz Zorzano, Patricia Valentín-serrano, Osku Kemppinen, Insoo Jun, James Wray, M. Genzer, Edgard G. Rivera-valentin, Ari-matti Harri, Morten MadsenAbstract:Water is a requirement for life as we know it. Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars, in contrast with expectations from large-scale climate models. The presence of Perchlorate salts, which have been detected at Gale crater on equatorial Mars by theCuriosity rover, lowers the freezing temperature of water. Moreover, Perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence. Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere–soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms. Perchlorates are widespread on the surface of Mars and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.
