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At least 19 recordsLinked to original sources
PubMed2001

Large groundwater strontium flux to the oceans from the Bengal Basin and the marine strontium isotope record.

Strontium concentration and isotopic data for subsurface flowing groundwaters of the Ganges-Brahmaputra (G-B) delta in the Bengal Basin demonstrate that this is a potentially significant source of strontium to the oceans, equal in magnitude to the dissolved strontium concentration carried to the oceans by the G-B river waters. The strontium concentrations of groundwaters are higher by a factor of about 10 than typical G-B river waters and they have similar 87Sr/86Sr ratio to the river waters. These new data suggest that the present contribution of the G-B system to the rise in 87Sr/86Sr ratio in seawater is higher by at least a factor of 2 to 5 than the average over the past 40 million years.

Journal Article↗
PubMedDate not supplied

Strontium isotopic identification of water-rock interaction and ground water mixing.

87Sr/86Sr ratios of ground waters in the Bighorn and Laramie basins' carbonate and carbonate-cemented aquifer systems, Wyoming, United States, reflect the distinctive strontium isotope signatures of the minerals in their respective aquifers. Well water samples from the Madison Aquifer (Bighorn Basin) have strontium isotopic ratios that match their carbonate host rocks. Casper Aquifer ground waters (Laramie Basin) have strontium isotopic ratios that differ from the bulk host rock; however, stepwise leaching of Casper Sandstone indicates that most of the strontium in Casper Aquifer ground waters is acquired from preferential dissolution of carbonate cement. Strontium isotope data from both Bighorn and Laramie basins, along with dye tracing experiments in the Bighorn Basin and tritium data from the Laramie Basin, suggest that waters in carbonate or carbonate-cemented aquifers acquire their strontium isotope composition very quickly--on the order of decades. Strontium isotopes were also used successfully to verify previously identified mixed Redbeds-Casper ground waters in the Laramie Basin. The strontium isotopic compositions of ground waters near Precambrian outcrops also suggest previously unrecognized mixing between Casper and Precambrian aquifers. These results demonstrate the utility of strontium isotopic ratio data in identifying ground water sources and aquifer interactions.

Environmental Monitoring↗
PubMed2001

Application of strontium isotopes for tracing landfill leachate plumes in groundwater.

We are evaluating strontium isotopes as alternative tracers of landfill leachate in groundwater. The municipal landfill studied here is located in southeastern France. This landfill has no bottom liner, and wastes are placed directly on the ground. Based on the evaluation of chloride concentration, the plume extends a maximum of 4,600 m. Strontium isotopic composition characterizes two sources: natural groundwater (87Sr/86Sr = 0.708175) and landfill leachate contamination (87Sr/86Sr = 0.708457). The evolution of mixing ratios obtained with strontium reveals a second source of groundwater contamination: fertilizers (87Sr/ 86Sr = 0.707859). These results suggestthat isotopic signatures can be used to provide useful information on sources of groundwater contamination where conventional water quality parameters may yield ambiguous results.

Environmental Monitoring↗
PubMed2000

Local or nonlocal? A research of strontium isotope ratios of teeth and bones on skeletal remains with artificial deformed skulls.

The analysis of strontium isotopic composition of teeth and bone served as an approach to determine nonlocal individuals with artificially deformed skulls in Teuton and Gepid sites. A differing Sr-isotopic composition between tooth and bone from the same skeleton reveals a residence change between early childhood and the last ten years before death. The results show that most Teuton and Gepid individuals investigated are local habitants.

Bone and Bones↗
PubMed2006

Early African Diaspora in colonial Campeche, Mexico: strontium isotopic evidence.

Construction activities around Campeche's central park led to the discovery of an early colonial church and an associated burial ground, in use from the mid-16th century AD to the late 17th century. Remains of some individuals revealed dental mutilations characteristic of West Africa. Analyses of strontium isotopes of dental enamel from these individuals yielded unusually high (87)Sr/(86)Sr ratios, inconsistent with an origin in Mesoamerica, but consistent with an origin in West Africa in terrain underlain by the West Africa Craton, perhaps near the port of Elmina, a principal source of slaves for the New World during the 16th century. These individuals likely represent some of the earliest representatives of the African Diaspora in the Americas.

Africa, Western↗
PubMed2005

Sulfur and strontium isotope geochemistry of tributary rivers of Lake Biwa: implications for human impact on the decadal change of lake water quality.

To study the deterioration of the water quality in Lake Biwa, Japan, over the last 40 years, we measured the concentrations and isotopic ratios of sulfur and strontium of water in 41 inflowing rivers and one discharging river. The concentrations of SO4 and Sr of inflowing rivers at downstream sites were generally high in the southern urban area and in the eastern area, where a large agricultural plain is situated, but low in the northern and western areas, whose watersheds are mountainous and with low population density. SO4 and Sr concentrations are also lower at upstream sites, which are closer to mountainous areas. Thus, the inflowing river receives large amounts of SO4 and Sr as it flows across the plain, where human activity levels are high. The delta34S or 87Sr/86Sr values of most eastern rivers at downstream sites are lower than those of water in Lake Biwa, and values become more uniform as the proportion of the plain area in the watershed increases. River water in other areas has higher values of delta34S or 87Sr/86Sr than the lake water. This result indicates that the decadal decrease of delta34S and 87Sr/86Sr in the lake water has been caused mainly by the increased flux of SO4 and Sr from rivers in the eastern plain. We assume that in the plain, sulfur, nitrogen, and organic compounds induced by human activities generate sulfuric, nitric, and organic acids in the water, which accelerate the extraction of Sr from bedrocks, leading to the generation of Sr in the river water in the area.

Environmental Monitoring↗
PubMed2006

Use of strontium isotopes to identify buried water main leakage into groundwater in a highly urbanized coastal area.

Previous studies indicate that the local aquifer systems in the Mid-Levels, a highly urbanized coastal area in Hong Kong, have commonly been affected by leakage from water mains. The identification of leakage locations was done by conventional water quality parameters including major and trace elements. However, these parameters may lead to ambiguous results and fail to identify leakage locations especially where the leakage is from drinking water mains because the chemical composition of drinking water is similar to that of natural groundwater. In this study, natural groundwater, seepage in the developed spaces, leakage from water mains, and parent aquifer materials were measured for strontium isotope (87Sr/86Sr) compositions to explore the feasibility of using these ratios to better constrain the seepage sources. The results show that the 87Sr/86Sr ratios of natural groundwater and leakage from water mains are distinctly different and thus, they can provide additional information on the sources of seepage in developed spaces. A classification system based on the aqueous 87Sr/86Sr ratio is proposed for seepage source identification.

Cities↗
PubMed1991

Strontium isotopic variations of Neoproterozoic seawater: implications for crustal evolution.

We report high precision Sr isotopic data on carbonates from the Neoproterozoic Shaler Group, Victoria Island, Northwest Territories, Canada. Lithostratigraphic correlations with the relatively well-dated Mackenzie Mountains Supergroup constrain Shaler deposition to approximately 770-880 Ma, a range corroborated by 723 +/- 3 Ma lavas that disconformably overlie Shaler carbonates and by Late Riphean microfossils within the section. Samples with low 87Rb/86Sr ratios (<0.01) were selected for Sr isotopic analysis. Delta 18O, Mn, Ca, Mg, and Sr data were used to recognize altered samples. The altered samples are characterized by high Mn/Sr (> or = 2) and variable delta 18O; most are dolomites. The data indicate that between ca. 790-850 Ma the 87Sr/86Sr ratio of seawater varied between 0.70676 and 0.70561. The samples show smooth and systematic variation, with the lowest 87Sr/86Sr value of 0.70561 at ca. 830 Ma. The low 87Sr/86Sr ratio of carbonates from the lower parts of our section is similar to a value reported for one sample from the Adrar of Mauritania (approximately 900 Ma), West African Craton. Isotopic ratios from the upper part of the Shaler section are identical to values from the lower part of the Neoproterozoic Akademikerbreen Group, Spitsbergen. Although a paucity of absolute age determinations hinders attempts at the precise correlation of Neoproterozoic successions, it is possible to draw a broad outline of the Sr isotopic composition of seawater for this period. Indeed, the Sr isotope data themselves provide a stratigraphic tool of considerable potential. Data from this study and the literature are used to construct a curve of the 87Sr/86Sr ratio of Neoproterozoic seawater. The new data reported in this study substantially improve the isotopic record of Sr in seawater for the period 790-850 Ma. The Sr isotope composition of seawater reflects primarily the balance between continental Sr input through river input and mantle input via hydrothermal circulation of seawater through mid-ocean ridges. Coupling of Nd and Sr isotopic systems allows us to model changes in seafloor spreading rates (or hydrothermal flux) and continental erosion. The Sr hydrothermal flux and the erosion rate (relative to present-day value) are modeled for the period 500-900 Ma. The results indicate that the hydrothermal flux reached a maximum value at ca. 830 Ma. In contrast, a large peak in erosion rate is indicated at ca. 570 Ma. The peaks in hydrothermal flux and erosion rate are most likely related to developments in the Pan-African and related orogenic events, whose initial development is characterized by production of juvenile crust during supercontinental break up and rifting. The time ca. 570 Ma is characterized by continent-continent collision and production of recycled crust. Sr isotope data from Proterozoic carbonates offer a valuable resource for understanding large-scale crust dynamics.

Africa, Western↗
PubMed2005

Strontium isotope and major ion chemistry of the rainwaters from Guiyang, Guizhou Province, China.

Twenty-two rainwater samples from Guiyang city, southwestern China, have been analyzed for their chemical compositions and 87Sr/86Sr ratios, with a main purpose to get a better understanding of the general features of rainwater in Guiyang city and their correspondences to human activities. The rainwaters studied are almost acidic (pH=4.53) and show big changes in major ion composition. Ca2+ and Mg2+ are the principal cations in the rainwaters and their mean values are 56.6 micromol/L (12.5-163.8 micromol/L) and 12.8 micromol/L (4.5-47.3 micromol/L ), respectively. The sum of Ca2+ and Mg2+ accounts for 78%-96% of the total cations in the studied rainwaters. Na+ was the least abundant of the major cations with a mean content of 4 micromol/L (0.9-7.8 micromol/L). SO4(2-) is the predominant anion, with a mean content of 94 micromol/L (33.5-279.4 micromol/L), coming next is NO(3-) with a mean content of 48 micromol/L (2.1-251.8 micromol/L). SO4(2-) and NO(3-) together account for 77%-99% of the total anions. Ca2+ and Mg2+ in the rainwater are most likely from dissolution of carbonate minerals in dust or aerosol, unlike K+ that shows more contribution of anthropogenic sources to the rainwater. Na+ does not vary in concentration with Cl-. Significant enrichment of Cl- relative to Na+ as compared with sea water indicates negligible contribution of marine source, which is supported by the evidence that the total rainwater samples show lower 87Sr/86Sr ratios (ranging from 0.707934 to 0.709080) than sea water. The rainwater samples are characterized by high contents of NO(3-), SO4(2-), and Cl- relative to Na+, as compared to the rainwater from other areas in the world, suggesting that the anions (NO(3-), SO4(2-), and Cl-) have mainly of anthropogenic sources. Sr isotope shows potential to trace sources of contaminants when combined with other chemical factors: covariation of 87Sr/86Sr ratio with Cl-/Na+ in the rainwater suggest presence of at least two anthropogenic sources for the rainwater samples studied. The coal-combustion industries are probably the major atmospheric contaminant sources in Guiyang city.

Acid Rain↗