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Publisher: Springer-Verlag (Total: 2352 journals)

 Aquatic Geochemistry   [SJR: 0.764]   [H-I: 39]   [4 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1573-1421 - ISSN (Online) 1380-6165    Published by Springer-Verlag  [2352 journals]
• The Speciation of Metals in Natural Waters
• Authors: Denis Pierrot; Frank J. Millero
Pages: 1 - 20
Abstract: The equilibria and rates of reactions of trace metals in natural waters are affected by their speciation or the form of the metal in the solution phase. Many workers have shown, for example, that biological uptake (Anderson and Morel in Limnol Oceanogr 27:789–813, 1982), the toxicity (Sunda and Ferguson in Trace metals in seawater, Plenum Press, New York, 1983) as well as the solubility (Millero et al. in Mar Chem 50:21–39, 1995; Liu and Millero in Geochim Cosmochim Acta 63:3487–3497, 1999) are affected by the speciation. For example, Fe(II) and Mn(II) are biologically available for marine organisms, while Fe(III) and Mn(IV) are normally not available. The speciation of metals also affects the rates of oxidation (Millero in Geochim Cosmochim Acta 49:547–553, 1985, Res Trends Curr Top Sol Chem 1:141–169, 1994; Sharma and Millero in Geochim Cosmochim Acta 53:2269–2276, 1989; Vazquez et al. in Geophys Res Lett 16:1363–1366, 1989) and reduction (Res Trends Curr Top Sol Chem 1:141–169, 1994; Millero et al. in Mar Chem 36:71–83, 1991) of metals in natural waters. The ionic interactions of metals are controlled by interactions with inorganic (Cl−, OH−, CO3 2−, etc.) and organic ligands (e.g., Fulvic and Humic acids). The speciation of metals is also affected by the oxidation potential (Eh) and the pH in the solution. In this paper we have developed a Pitzer Model (Pitzer in J Phys Chem 77:268–277, 1973, Activity coefficients in electrolyte solutions, 2nd edn, CRC Press, Boca Raton, 1991) that can be used to determine the speciation of trace metals in seawater and other natural waters. It is based upon the Miami Pitzer Model (Millero and Pierrot in Aquatic Geochem 4:153–199, 1998) that has been shown to predict reliable activity coefficients for the major components of seawater. The computer code (Pierrot in Ph.D. Thesis, University of Miami, Miami, Florida, 2002) for these calculations is described in detail, in this paper. It has been used in an earlier paper (Millero and Pierrot in Chemistry of marine water and sediments, Springer, Berlin, 2002) and more recently used to examine the effect of pH on the speciation of metals in seawater (Millero et al. in Oceanography 22(4):72–85, 2009).
PubDate: 2017-02-01
DOI: 10.1007/s10498-016-9292-4
Issue No: Vol. 23, No. 1 (2017)

• Assessment of the Hydrogeochemical Processes Affecting Groundwater Quality
in the Eocene Limestone Aquifer at the Desert Fringes of El Minia
Governorate, Egypt
• Authors: Reda G. M. Ibrahim; W. Berry Lyons
Pages: 33 - 52
Abstract: El Minia Governorate is within the Nile Valley and is surrounded by the Eocene limestone plateaus from the east and west. The present study focuses on the hydrogeochemistry of the Eocene limestone aquifer in both the eastern and western desert fringes of El Minia. Thirty groundwater samples from the Eocene aquifer (east and west of the Nile) and seven samples from post-Eocene aquifers in this area were analyzed to assess the groundwater geochemistry, isotopic compositions and the subsurface hydrology. Samples obtained from depths of 24–120 m were measured for major components, nutrients, oxygen-18, deuterium and carbon-13. The groundwater TDS (total dissolved solids) concentrations ranged from 530 to 2788 and 453 to 1903 mg/l at the western and eastern desert fringes, respectively. Values of Eocene aquifer water δ18O ranged from −8.31 to −0.44 and −2.07 to 0.55 ‰, and those of water δD ranged from −63.6 to −2.32 and −9.03 to 5.03 ‰ for the Eocene aquifer at the western and eastern side, respectively. Chemical analysis shows that the main chemical facies of the Eocene water are Ca–Mg–HCO3 and Ca–SO4. The chemical and isotopic data show that water–rock interaction (calcite dissolution and silicate weathering) and mixing between different water types control the major ion chemistry of Eocene aquifer water. The chemical composition of Eocene water has also evolved by evaporation and ion exchange. The present study indicates the need for regional chemical and isotopic study for the Eocene aquifer along the Nile Valley region to delineate the sources of recharge to this important aquifer.
PubDate: 2017-02-01
DOI: 10.1007/s10498-016-9298-y
Issue No: Vol. 23, No. 1 (2017)

• Impact of Cyanobacterial Associate and Heterotrophic Bacteria on Dissolved
Organic Carbon and Metal in Moss and Peat Leachate: Application to
Permafrost Thaw in Aquatic Environments
• Authors: Liudmila S. Shirokova; Joachim Labouret; Melissa Gurge; Emmanuelle Gérard; Irina S. Ivanova; Svetlana A. Zabelina; Oleg S. Pokrovsky
Abstract: In the boreal and subarctic zone, the moss and peat interactions with rainwater and snowmelt water in shallow surface ponds control the delivery of dissolved organic matter (DOM) and metal to the rivers and further to the Arctic Ocean. The transformation of peat and moss leachate by common aquatic microorganisms and the effect of temperature on DOM mineralization by heterotrophs remain poorly known that does not allow predicting the response of boreal aquatic system to ongoing climate change. We used experimental approach to quantify the impact of boreal aquatic bacteria P. reactans, and two culturable bacteria extracted from a thaw lake of the permafrost zone (Bolshezemelskaya tundra, NE Europe): Iodobacter sp. and cyanobacterial associate dominated by order Chroococcales (Synechococcus sp). The interaction of these bacterial cultures with nutrient-free peat and moss leachate was performed in order to (1) quantify the impact of temperature (4, 25 and 45 °C) on peat leachate processing by heterotrophs; (2) compare the effect of heterotrophic bacteria and cyanobacterial associate on moss and peat leachate chemical composition, and (3) quantify the DOC and metal concentration change during cyanobacterial growth on leachate from frozen and thawed peat horizon and moss biomass. The efficiency of peat DOM processing by two heterotrophs was not modified by temperature rise from 4 to 45 °C. The DOC concentration decreased by a factor of 1.6 during 3 days of moss leachate reaction with Iodobacters sp. or cyanobacterial associate at 25 °C. The SUVA245 increased twofold suggesting an uptake of non-aromatic DOM by both microorganisms. The growth of cyanobacteria was absent on peat leachate but highly pronounced on moss leachate. This growth produced tenfold decrease in P concentration, a factor of 1.5–2.0 decrease in DOC, a factor of 4 and 100 decrease in Fe and Mn concentration, respectively. Adsorption of organic and organo-mineral colloids on bacterial cell surface was more important factor of element removal from organic leachates compared to intracellular assimilation and/or Fe oxyhydroxide precipitation. Overall, we demonstrate highly conservative behavior of peat leachate compared to moss leachate in the presence of culturable aquatic bacteria, a lack of any impact of heterotrophs on peat leachate and their weak impact on moss leachate. A very weak temperature impact on DOM processing by heterotrophs and lack of difference in the biodegradability of DOM from thawed and frozen peat horizons contradict the current paradigm that the warming of frozen OM and its leaching to inland waters will greatly affect microbial production and C cycle. Strong decrease in concentration of P, Fe and Mn in the moss leachate in the presence of cyanobacterial associate has straightforward application for understanding the development of thermokarst lakes and suggests that, in addition to P, Fe and Mn may become limiting micronutrients for phytoplankton bloom in thermokarst lakes.
PubDate: 2017-11-07
DOI: 10.1007/s10498-017-9325-7

• The Iodide and Iodate Distribution in the Seto Inland Sea, Japan
• Authors: Kazuhiko Takeda; Kengo Yamane; Yuuta Horioka; Kazuaki Ito
Abstract: We report the vertical and horizontal distributions of inorganic iodine (iodide and iodate) and their related species (bromide nitrate and nitrite) in the Seto Inland Sea, which is a semi-enclosed coastal sea area of western Japan. In this study, ion chromatography with ultraviolet detection was employed to determine the iodide, iodate, bromide nitrate, and nitrite levels simultaneously in a single run. Iodide was higher at inshore sites than at offshore sites. Vertical profiles showed that iodide increased in the bottom layer of inshore sites of Osaka Bay and Hiroshima Bay, but were low in the bottom layer of the Kii Channel, the main channel connecting Osaka Bay with the Pacific Ocean. Iodates were low in the low-salinity inshore surface, but were high in the bottom layer of the Kii Channel. The riverine flux of iodine to the coastal marine environment was negligible. The vertical profiles of total inorganic iodine (iodide + iodate) looked uniform; however, plots of total inorganic iodine versus salinity demonstrated a net loss of total inorganic iodine in the low-salinity inshore surface. The iodine distributions in the Seto Inland Sea could be explained by three-end-member mixing, with one member being non-iodine river water, another high-salinity and high-iodate water of the open ocean, and the final high-iodide and low-iodate inland water with a salinity of around 32–33.
PubDate: 2017-10-19
DOI: 10.1007/s10498-017-9324-8

• Oxygen, Hydrogen, Boron and Lithium Isotope Data of a Natural Spring Water
with an Extreme Composition: A Fluid from the Dehydrating Slab'
• Authors: Tiziano Boschetti; Lorenzo Toscani; Paola Iacumin; Enricomaria Selmo
Abstract: The chemical and isotope compositions of slab dehydration fluids from convergent margins have been theorized by many authors who have adopted several approaches. A direct collection of natural water is possible only in an oceanic environment, despite several difficulties in estimating the deepest component due to the mixing with seawater or hydrothermal fluids from the ridge. Accordingly, the study of melt inclusions is a valuable alternative. However, the latter mainly represents high temperature/pressure conditions in deep magmatic or metamorphic settings. Here, we present new H, O, Li and B isotope along with a revision of previously published chemical data from a potential natural example of slab dehydration water, sampled in a forearc region and affected by low-temperature metamorphism and serpentinization processes (Aqua de Ney, Northern California). Its extreme composition challenges the understanding of its origin and deep temperature, but this work is a further step on a topic of increasing interest for several scientists from different academic disciplines.
PubDate: 2017-10-09
DOI: 10.1007/s10498-017-9323-9

• Characterization and Assessment of Groundwater Resources in a Complex
Hydrological Basin of Central Greece (Kopaida basin) with the Joint Use of
Hydrogeochemical Analysis, Multivariate Statistics and Stable Isotopes
• Authors: Evangelos P. Tziritis; Partha S. Datta; Rahim Barzegar
Abstract: Combined assessments from different methodologies, including hydrogeochemical analysis, multivariate statistics and stable isotopes, were used in order to characterize the groundwater resources of a heterogeneous aquifer system in central Greece and to evaluate the overall environmental regime. Results outlined the driving factors that chiefly control groundwater chemistry and delineated the major pathways of groundwater flow. Following the results of the combined assessments, hydrogeochemistry is influenced both by geogenic and anthropogenic factors including the geological substrate, intense agricultural activities and ongoing geochemical processes which impact the concentrations of redox sensitive agents like NO3, Fe, Mn and SO4. Stable isotope evaluations supplemented the above assessments by providing critical information for the hydrodynamics of the heterogeneous aquifer system. Evaporation is the main factor influencing the isotopic composition of water resources, in addition to the slow percolation rates of the thick unsaturated zone. Comparisons between δ 18Ο and δD values for surface and groundwater samples revealed an interaction among water systems through the developed karstic network and/or the riverbeds of higher permeabilities. Eventually, the integrated conceptual approach of diverse methodologies was applied successfully for the identification of hydrogeological and hydrogeochemical assessments in the case of Kopaida basin; evaluations were cross-confirmed and supplemented when needed, hence providing essential information for strategic planning and water resources management.
PubDate: 2017-09-09
DOI: 10.1007/s10498-017-9322-x

• Potential Influence of Ocean Acidification on Deep-Sea Fe–Mn Nodules:
Results from Leaching Experiments
• Authors: Quan Wang; Hodaka Kawahata; Takuya Manaka; Kyoko Yamaoka; Atsushi Suzuki
Abstract: With the continuous rise in CO2 emissions, the pH of seawater may decrease extensively in the coming centuries. Deep-sea environments are more vulnerable to decreasing pH since sediments in deep oceans below the carbonate compensation depth (CCD) are often completely devoid of carbonate particles. In order to assess the potential risk of heavy metal release from deep-sea deposits, the mobility of elements from ferromanganese (Fe–Mn) nodules and pelagic clays was examined by means of leaching experiments using phosphate buffer solutions ranging in pH from 7.1 to 8.6 (NBS scale). With decreasing pH, the results showed an enhanced leaching of elements such as Li, B, Mg, Si, Sc, Sr, Ba, Tl, and U, but a reduced leaching of V, Cu, Mo, Cd, and W. Elements in leachates originate mainly from exchangeable fractions, and tend to be affected by sorption–desorption processes. Concentrations of most elements did not exceed widely used international water quality criteria, indicating that changes in pH caused by future ocean acidification may not increase the risk of heavy metal release during deep-sea nodule mining operations.
PubDate: 2017-08-11
DOI: 10.1007/s10498-017-9320-z

• Origin and Geochemistry of Mine Water and its Impact on the Groundwater
and Surface Running Water in Post-mining Environments: Zlatna Gold Mining
Area (Romania)
• Authors: Delia Cristina Papp; Ioan Cociuba; Călin Baciu; Alexandra Cozma
Abstract: In application at the Zlatna gold mining area (Apuseni Mountains, Romania), the correlation of water isotopes and geochemical data were successfully used to assess the genetic relationships between surface running water, groundwater and mine water, as well as to evaluate the mining effects on the surrounding environment after the cessation of mining operations. The majority of mine water sources display pH values between 4 and 5, i.e. acid mine water. The mine water characterized by slightly higher pH values (~6) interacts with ophiolitic rocks which have high pH buffering capacity. The neutral mine water (pH ~ 7) does not come into direct contact with reactive minerals, either because it is discharged from an exploration adit or because of the complete leaching of pyrite and other sulphides in old abandoned mining works. The later also shows low levels of heavy metals concentrations. Calcium is the dominant cation in mine water and in the majority of surface running water and groundwater sources, indicating the same mechanisms of mineralization. All mine water sources are $$\text{SO}_{4}^{2 - }$$ type and show very high $$\text{SO}_{4}^{2 - }$$ concentrations (6539 mg/l mean value). Surface and groundwater sources are classified either as $$\text{SO}_{4}^{2 - }$$ or as $$\text{HCO}_{3}^{ - }$$ type water. Linear correlation between δD and δ18O values indicates that all water sources belong to the meteoric cycle. Low δD and δ18O values of mine water (δD < −70‰; δ18O < −10‰) suggest snow melt and high-altitude precipitations as the main source of recharge. The mine water is less affected by the seasonal variation of temperature. In most cases, the variations in isotopic composition are within narrow limits (less than 1‰ for both δD and δ18O), and this result suggests well-mixed underground systems. Elevated concentration of sulphates, Zn and Fe in mine waters are the main issues of concern. For the study area, no relevant contamination of springs or phreatic water by mine water was revealed. On the contrary, surface running water is contaminated by mine water, and the negative effects of acid mine drainage occur mainly in the summer months when the flow of the surface running water decreases.
PubDate: 2017-08-09
DOI: 10.1007/s10498-017-9321-y

• A Preliminary Assessment of Fossil Fuel and Terrigenous Influences to
Rainwater Organic Matter in Summertime in the Northern Gulf of Mexico
• Authors: Siddhartha Mitra; Christopher L. Osburn; Andrew S. Wozniak
Abstract: We report here for the first time rainwater organic carbon (OC) concentration and composition collected from open waters over the Gulf of Mexico. Rainwater OC concentrations ranged from 3.7 to 17.3 mg L−1. The δ13C of these rainwater samples ranged from −26.7 to −24.2‰ pointing toward terrestrial and/or fossil fuel OC sources (64–100%) combined with marine OC sources. Colored dissolved OM absorbance and EEM fluorescence spectra were indicative of secondary organic aerosol from terrestrial sources as well as aromatic fossil fuel compounds. Air mass back trajectory analyses along with these results indicate that rainwater OC in the Gulf of Mexico may be influenced by oil and gas infrastructure and emissions from known lanes of shipping traffic within the Gulf. These results also suggest that anthropogenic and biogenic emissions from the southeastern continental USA impact rainwater OC in the Gulf of Mexico.
PubDate: 2017-07-29
DOI: 10.1007/s10498-017-9319-5

• Inputs and Internal Cycling of Nitrogen to a Causeway Influenced,
Hypersaline Lake, Great Salt Lake, Utah, USA
• Authors: D. Naftz
Abstract: Nitrogen inputs to Great Salt Lake (GSL), located in the western USA, were quantified relative to the resident nitrogen mass in order to better determine numeric nutrient criteria that may be considered at some point in the future. Total dissolved nitrogen inputs from four surface-water sources entering GSL were modeled during the 5-year study period (2010–2014) and ranged from 1.90 × 106 to 5.56 × 106 kg/year. The railroad causeway breach was a significant conduit for the export of dissolved nitrogen from Gilbert to Gunnison Bay, and in 2011 and 2012, net losses of total nitrogen mass from Gilbert Bay via the Causeway breach were 9.59 × 105 and 1.51 × 106 kg. Atmospheric deposition (wet + dry) was a significant source of nitrogen to Gilbert Bay, exceeding the dissolved nitrogen load contributed via the Farmington Bay causeway surface-water input by >100,000 kg during 2 years of the study. Closure of two railroad causeway culverts in 2012 and 2013 likely initiated a decreasing trend in the volume of the higher density Deep Brine Layer and associated declines in total dissolved nitrogen mass contained in this layer. The large dissolved nitrogen pool in Gilbert Bay relative to the amount of nitrogen contributed by surface-water inflow sources is consistent with the terminal nature of GSL and the predominance of internal nutrient cycling. The opening of the new railroad causeway breach in 2016 will likely facilitate more efficient bidirectional flow between Gilbert and Gunnison Bays, resulting in potentially substantial changes in nutrient pools within GSL.
PubDate: 2017-06-09
DOI: 10.1007/s10498-017-9318-6

• 2α-Methylhopane: Indicator for Oil–Source Correlation in the Pearl
River Mouth Basin, China
• Authors: Wanfeng Zhang; Xiangtao Jiang; Liling Pang; Xuanbo Gao; Shukui Zhu
Abstract: Oil samples collected from the Pearl River Mouth Basin (PRMB) were analyzed using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS). High abundances of compounds in the 2α-methylhopane series were observed and accurately quantified. Although the 2α-methylhopane series can be a prominent biomarker in the oil and source rock samples, it has generally been used less than non-methylated hopanes. In this study, the 2α-MHI [C312α-methylhopane × 100/(C312α-methylhopane + C30-αβ-hopane) (%)] ranges from 0.81 to 5.77% and 9.06 to 23.93% in Enping Formation- and Wenchang Formation-derived oils, respectively. The high abundance of the 2α-methylhopane series in Wenchang Formation-derived oils is attributed to anoxygenic phototrophs. The relevant 2α-methylhopane parameters showed correlations with C30-4-methyl steranes/∑C29 steranes, Pr/Ph and bicadinane-T/C30-αβ-hopane. Furthermore, the 2α-methylhopane series are rich in middle-deep lacustrine environments as well as marine sedimentary environment. The results indicated that the 2α-methylhopane series could be used as effective biomarkers to distinguish oils derived from different source rocks, as well as to enlarge the PRMB biomarker assemblages, which is beneficial to the evaluation of petroleum resources.
PubDate: 2017-05-16
DOI: 10.1007/s10498-017-9317-7

• Dissolution Rates of Actinolite in Water and Its Modified Mineral Surface
Across the Critical State
• Authors: Ronghua Zhang; Xuetong Zhang; Shumin Hu
Abstract: Dissolution kinetic experiments of actinolite in water were performed using a flow-through reactor at temperatures from 20 to 400 °C and 23.5±0.5 MPa. The results indicate that the steady-state release rates of the different elements of actinolite vary with temperature. Generally, Ca, Mg, Fe, and Al dissolve more quickly than Si at temperatures from 20 °C to near 300 °C, but slower from 300 to 400 °C. The Si release rate increases with temperatures from 20 to 300 °C and then decreases from 300 to 400 °C. Si release rate reaches the maximum at 300 °C. Amorphous Si-rich surface layers occur at temperature <300 °C. Hydrations of actinolite are relatively faster, and proton–metal exchange reactions are weakening across the critical point. Mi-rich (Fe, Ca, Mg) and Si-deficient surface layers form at temperatures ≥300 °C. XPS, TEM, and SEM observations indicate that the hydrated silicate occurred at surface as temperature >300 °C. Water property variations within the critical region strongly affect the dissolution rates and the modification of surface.
PubDate: 2017-04-28
DOI: 10.1007/s10498-017-9316-8

• Sediment Biogeochemistry of Mesophotic Meadows of Calcifying Macroalgae
• Authors: Francis J. Sansone; Heather L. Spalding; Celia M. Smith
Abstract: Mesophotic (low light) sands were studied in Hawaiian coastal waters (39–204 m water depth) from O‘ahu to Kaho‘olawe by sampling inside and outside of extensive macroalgal meadows of chlorophytes Halimeda kanaloana and Udotea sp. during September 2004, December 2004, and November 2006. Porewater nutrient concentrations in these permeable sediments were comparable to those in nearshore sands and were highly elevated at sediment depths available to holdfasts of some algae (5–10 cm); maximum levels were 3.0 µM reactive phosphorus, 33 µM nitrate, 0.70 µM nitrite, 38 µM ammonium, and 130 µM silicic acid. Benthic material is calculated to be the major source of organic matter driving diagenesis in these sediments. Vegetated sediments appeared more oxidizing than unvegetated sediments, and the presence of macroalgae, particularly Halimeda, was generally associated with higher sediment dissolved inorganic carbon levels. Halimeda-vegetated sediments generally had low dissolved inorganic nitrogen (DIN) levels compared to the Udotea-vegetated and non-vegetated sediments, consistent with the net N loss indicated by sediment stoichiometric relationships. In contrast, Udotea-vegetated sediments showed minimal apparent algal DIN uptake.
PubDate: 2017-03-30
DOI: 10.1007/s10498-017-9315-9

• Chemical Analysis of Gaet’ale, a Hypersaline Pond in Danakil Depression
(Ethiopia): New Record for the Most Saline Water Body on Earth
• Authors: Eduardo Pérez; Yonas Chebude
Abstract: The chemical analysis of the water of Gaet’ale Pond, a small water body located in Danakil Depression, Ethiopia, resulted to be the most saline water body on earth with total dissolved solids (TDS) of 433 g kg−1. The composition of the water indicates the predominance of two main salts: CaCl2 and MgCl2 at a proportion of Ca:Mg = 3.1 (w/w). Traces of K+, Na+ and NO3 − are also detected, as well as Fe(III) complexes that give the water a characteristic yellow color. Density measurements, elemental analysis, thermogravimetrical analysis (TGA) and powder X-ray diffraction data are consistent with the composition and salinity determined. The water of this pond has a similar composition to Don Juan Pond, Antarctica, but a higher salinity, which can be explained in terms of temperature and solubility of the main components.
PubDate: 2017-03-23
DOI: 10.1007/s10498-017-9312-z

• Evolution of Mg/Ca Ratios During Limestone Dissolution Under Epikarstic
Conditions
• Authors: Pavel Pracný; Jiří Faimon; Dalibor Všianský; Ludvík Kabelka
Abstract: The Mg/Ca ratios in karst water are generally believed to comprise information on climate, and, being encoded in speleothems, they are utilized as paleoenvironmental proxy. However, the mechanism and dynamic of Mg release from limestone during dissolution is not well understood. A theoretical evolution of the Mg/Ca ratios during limestone dissolution under epikarstic conditions (T = 10 °C, $$\log P_{{{\text{CO}}_{2} }}$$  = −1.5) was studied via a dynamic model. The results were compared with (1) the dripwater data set collected in Punkva Caves (Moravian Karst, Czech Republic) during one-year period and (2) the published data from various locations worldwide. The modeling showed that the Mg/Ca ratios are governed by composition of Mg-calcite present in limestone. Two distinct stages in the dissolution dynamics were recognized: (1) an initial congruent dissolution with stoichiometric release of Ca and Mg and, subsequently, (2) an incongruent dissolution demonstrated by the gradual release of Mg with simultaneous Ca decrease via calcite precipitation. Additional identified factors influencing the reaction path and Mg/Ca ratio evolution were the dolomitic component of limestone and the ratio of limestone/solution boundary area to water volume. Finally, the water–rock interaction time controls the resulting Mg/Ca ratio in dripwater determining how far the dissolution proceeds along the reaction path. Thus, the study results indicate that Mg/Ca ratio depends on many factors in addition to climatic variables.
PubDate: 2017-03-04
DOI: 10.1007/s10498-017-9313-y

• Lipid Biomarker Analysis of Suspended Particulate Matter from the Great
Kwa River, SE Nigeria: Origins and Environmental Implications of Biogenic
and Anthropogenic Organic Compounds
• Authors: Bernd R. T. Simoneit; Oliva Pisani; Bassey O. Ekpo; Ebirien P. Fubara; Prince J. Nna; Okon D. Ekpa
Abstract: Biomarkers found in natural waters, sediments, soils, fossils, crude oil, and coal can be unambiguously linked to specific precursors biosynthesized by biota. Petroleum and its refinery products carry their biomarker information into the environment when they are released by pollution. Lipid biomarkers can be used to assess the environmental status of an ecosystem and the degree to which it has been influenced by biogenic and anthropogenic inputs. The marine ecosystem of the southeastern Niger Delta of Nigeria is receiving new attention due to increased human and industrial development and the consequent potential health effects. Suspended particulate matter (SPM) from the Great Kwa River was characterized using biomarkers to assess such pollution. The total organic carbon contents of SPM from the river at low and high tide was 12–50% (avg 34.75%) and 16–28% (avg 24.25%), respectively. The lipid biomarkers identified using gas chromatography–mass spectrometry were mainly n-alkanes, n-alkan-2-ones, triterpenoids and minor amounts of aromatic compounds. The n-alkanes ranged from C 17 to C 35, with an odd/even predominance and C max > 27, indicating a mixed origin from higher plant wax, biodegraded detritus, and petroleum. The n-alkan-2-ones in most samples ranged from C 16 to C 33, with C max = 31, also supporting an input from vascular plants dominating the riparian zone along the river. The triterpenoids, mainly taraxerone, taraxerol, α- and β-amyrins, and friedelin, also derived from higher plants (angiosperms). Minor amounts of aromatic hydrocarbon derivatives from α- and β-amyrins were present and are likely the result of different diagenetic processes. The presence of trace fossil fuel-derived hopanes with an unresolved complex mixture of branched and cyclic hydrocarbons supported a minor petroleum product input to the SPM of the Great Kwa River.
PubDate: 2017-02-04
DOI: 10.1007/s10498-017-9311-0

• Spatiotemporal Assessment of CO 2 –Carbonic Acid System Dynamics in a
Pristine Coral Reef Ecosystem, French Frigate Shoals, Northwestern
Hawaiian Islands
• Authors: Andrea K. Kealoha; Fred T. Mackenzie; Samuel E. Kahng; Randall K. Kosaki; Simone R. Alin; Christopher D. Winn
Abstract: Observations of surface seawater fugacity of carbon dioxide (fCO2) and pH were collected over a period of several days at French Frigate Shoals (FFS) in the Northwestern Hawaiian Islands (NWHI) in order to gain an understanding of the natural spatiotemporal variability of the marine inorganic carbon system in a pristine coral reef ecosystem. These data show clear island-to-open ocean gradients in fCO2 and total alkalinity that can be measured 10–20 km offshore, indicating that metabolic processes influence the CO2–carbonic acid system over large areas of ocean surrounding FFS and by implication the islands and atolls of the NWHI. The magnitude and extent of this spatial gradient may be driven by a combination of physical and biogeochemical processes including reef water residence time, hydrodynamic forcing of currents and tidal flow, and metabolic processes that occur both on the reef and within the lagoon.
PubDate: 2017-01-27
DOI: 10.1007/s10498-017-9310-1

• CO 2 Outgassing from Spring Waters
• Authors: Benjamin J. Maas; Carol M. Wicks
Abstract: CO2 released from lakes, rivers, and estuaries has been included in estimates of the global CO2 budget; however, CO2 released from carbonate springs has not been routinely included in the estimate of the global CO2 budget. The omission of carbonate spring water as a source of CO2 might result in an underestimation of the overall flux of CO2 from surface waters to the atmosphere. In this study, the flux of CO2 from carbonate springs was calculated and compared to the rate of outgassing of CO2 reported in the literature for other surface water bodies. The calculated fluxes of CO2 from carbonate springs ranged 280–380,000 mmol m−2 d−1. A range that is larger than the range of CO2 fluxes reported for estuaries (100–1900 mmol m−2 d−1), headwater streams and rivers (100–1600 mmol m−2 d−1), freshwater lakes (−300 to 3200 mmol m−2 d−1), and saline lakes (−300 to 9900 mmol m−2 d−1). This work demonstrates that the outgassing of CO2 from springs should be included in the global CO2 budget.
PubDate: 2016-11-30
DOI: 10.1007/s10498-016-9302-6

• Dissolution of Al-Substituted Goethite in the Presence of Ferrichrome and
Enterobactin at pH 6.5
• Authors: William E. Dubbin; Florence Bullough
Abstract: Naturally occurring goethites often show Al for Fe substitution approaching 33 mol% Al. This substitution has potential to influence the rate of goethite dissolution and therefore the supply of bioavailable Fe. Siderophores such as ferrichrome and enterobactin have considerable potential to dissolve Fe from Fe3+ rich minerals, including Al-substituted goethites. Here, we show that Al substitution in synthetic goethites (0.021 ≥ x ≥ 0.098) gives rise to a significant increase in both ferrichrome- and enterobactin-mediated dissolution rates. In the presence of ferrichrome, Al-goethite (x = 0.033) yields a dissolution rate of 19.0 × 10−3 µmol m−2 h−1, nearly twice that of pure goethite, whereas dissolution of the most highly substituted Al-goethite (x = 0.098) is 36.9 × 10−3 µmol m−2 h−1, more than threefold greater than the pure mineral. Similarly, in the presence of enterobactin, the dissolution rate of Al-goethite increases with increasing Al substitution. Ferrichrome is a less effective ligand than enterobactin in its dissolution of both pure goethite and the range of Al-goethites, an observation we ascribe to the lower affinity of the hydroxamate functional groups of ferrichrome for both Fe3+ and Al3+. Despite greater affinity of both ferrichrome and enterobactin for Fe3+ over Al3+, we observe a broadly congruent dissolution of all our Al-goethites.
PubDate: 2016-10-12
DOI: 10.1007/s10498-016-9304-4

• The Application of Raman Spectroscopy to Probe the Association of H 4 SiO
4 with Iron Oxides
• Authors: Yohan Ferras; John Robertson; Peter J. Swedlund
Abstract: The aquatic geochemistry of many trace elements is influenced by two important products from the weathering of minerals: iron oxide solid phases and silicic acid (H4SiO4) in the aqueous phase. The chemistry of H4SiO4 on iron oxide surfaces is an interesting mix of sorption and polymerization, and this has been shown to affect the sorption, coprecipitation and transport of many trace elements. Infrared spectroscopy is a valuable probe of H4SiO4 chemistry on iron oxide surfaces, and in this study, we assess the utility of Raman spectroscopy for studying H4SiO4 chemistry on the poorly ordered iron oxide ferrihydrite. This was undertaken because Raman spectroscopy provides complimentary information to IR, in addition to often having narrower bands than IR spectra and less interference from water during in situ measurements. The IR spectra of H4SiO4 adsorbed on ferrihydrite showed the expected strong Si–O stretching feature, termed ν(Si–O), which had a central band and shoulders on either side. As the surface concentration of H4SiO4 increased, there was a clear shift in the position of the central band of the ν(Si–O) feature from ~950 to 1060 cm−1 reflecting the degree of silicate polymerization. The Raman spectra of the same samples had a very broad and weak ν(Si–O) feature which had a poor signal-to-noise ratio even after accumulating spectra over 1 h. The ν(Si–O) in the Raman spectra did not have discernable shoulders, as observed in the IR spectra, and there was only a fairly subtle shift in the position of this feature from 950 to 970 cm−1 as the degree of silicate polymerization increased. Overall, the results indicate that Raman spectroscopy can be used to study H4SiO4 adsorption and polymerization on iron oxides, but its utility is constrained by a weak signal combined with a subtle shift in peak position with H4SiO4 polymerization.
PubDate: 2016-08-17
DOI: 10.1007/s10498-016-9294-2

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