Description:    Between 1990 and 2007, twenty-nine box cores were recovered within the Arctic Ocean spanning shelf, slope and basin locations, and analyzed for aluminum (Al), manganese (Mn), other inorganic components and organic carbon (C Org ). Using these core data together with literature values, we have constructed budgets for Al and Mn in the Arctic Ocean. Most of the Al and Mn entering the Arctic comes from rivers or coastal erosion, and almost all of these two elements is trapped within the Arctic. Total Mn distributions in sediments reflect the recycling and loss of much of the Mn from shelf sediments with ultimate burial over the slopes and in basins. Mn enrichments observed as bands in long cores from the basins appear to co-occur with inter-glacial periods. Our Mn budget suggests that change in sea level associated with the accumulation and melting of glaciers is a likely cause for the banding. The Arctic Ocean, which presently contains as much as 50% shelf area, loses most of that when global sea level falls by ~120 m during glacial maxima. With lower sea level, Mn input from rivers and coastal erosion declines, and inputs become stored in permafrost on the sub-aerial shelves or at the shelf margin. Sea-level rise re-establishes coastal erosion and large riverine inputs at the margin and initiates the remobilization of Mn stored on shelves by turning on algal productivity, which provides the C Org required to reduce sedimentary Mn oxyhydroxides. Content Type Journal Article Category Original Paper Pages 1-27 DOI 10.1007/s10498-011-9149-9 Authors Robie W. Macdonald, Department of Fisheries and Oceans, Institute of Ocean Sciences, PO Box 6000, Sidney, BC V8L 4B2, Canada Charles Gobeil, INRS-ETE, Université du Québec, 490 de la Couronne, Quebec, QC G1K 9A9, Canada Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    The colloidal distribution and size fractionation of organic carbon and trace elements were studied in a seasonally stratified, organic-rich boreal lake, Lake Maselga, located in the European subarctic zone (NW Russia, Arkhangelsk region). This study took place over the course of 5 years in winter (glacial) and summer periods and during the spring and autumn overturn. A newly developed in situ dialysis technique (1, 10, and 50 kDa) and traditional frontal filtration and ultrafiltration (20, 10, 5, 0.22, and 0.025 μm) were used to assess element concentrations at different depths. No significant changes in element concentrations occurred during filtration through sub-colloidal pore-size membranes (20–0.22 μm), suggesting a negligible amount of particulate Fe, OC, and associated trace metals. Large colloids (0.025–0.22 μm) were found to be the main carriers of poorly soluble elements (Fe, Al, Ti, Zr, REEs, Th, and U) during the summer and winter stratification. There was also a clear change in the vertical pattern of the percentage of colloidal Al, Ti, V, Cr, Fe, and Ni during different seasons, and the greatest proportion of colloidal forms was observed during the spring and autumn overturn. This pattern is most likely linked to the dominance of soil (allochthonous) organic carbon, which complexes with trace metals during these periods. During the summer seasons, autochthonous production of small exometabolites or photodegradation increases the concentration of the low-molecular weight fractions (〈1 kDa) that dominate the speciation of divalent heavy metals in surface horizons. The colloidal status of As (30–60%), which was documented in different seasons along the full depth of the water column, is most likely linked to the presence of organic complexes. The overall results of this study suggest that changes in the colloidal speciation of trace elements with depth in different seasons depend on changes in the redox conditions, the input of soil OM, the biodegradation of plankton biomass releasing dissolved organic matter in the bottom horizons, and in upward diffusion from the sediments. Content Type Journal Article Category Original Paper Pages 1-25 DOI 10.1007/s10498-011-9154-z Authors O. S. Pokrovsky, GET (ex. LMTG) UMR 5563 CNRS, Université de Toulouse, Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France L. S. Shirokova, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia S. A. Zabelina, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia T. Ya. Vorobieva, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia O. Yu. Moreva, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia S. I. Klimov, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia A. V. Chupakov, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia N. V. Shorina, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia N. M. Kokryatskaya, Institute of Ecological Problems of the North, 163061, Naberezhnaya Severnoi Dviny, 23, 163000 Arkhangelsk, Russia S. Audry, GET (ex. LMTG) UMR 5563 CNRS, Université de Toulouse, Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France J. Viers, GET (ex. LMTG) UMR 5563 CNRS, Université de Toulouse, Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France C. Zoutien, GET (ex. LMTG) UMR 5563 CNRS, Université de Toulouse, Observatoire Midi-Pyrénées, 14 Avenue Edouard Belin, 31400 Toulouse, France R. Freydier, HydroSciences Montpellier, Case MSE, Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    The Kaoping (Taiwan) and Kapuas (Indonesia) Rivers differ in hydrological cycle, topography and landscape. These differences strengthen the use of 14 C dating, lignin-derived phenols, δ 13 C values and C/N ratios to determine the sources and diagenesis of surface sedimentary organic carbon (OC) in both rivers. The Kapuas River is surrounded by forest, resulting in sedimentary OC with a 14 C age between 600 and 740 years, Λ (total lignin expressed as mg/100 mg OC) values from 0.94 to 3.70, δ 13 C values from −27.87 to −30.00‰, C/N ratios from 6.7 to 30.8, %OC from 0.63 to 9.24% and vanillic acid to vanillin ratio, (Ad/Al)v, values from 0.73 to 2.09, all of which indicate the presence of recent plant-derived organic matter. The tributaries and three locations upstream of the Kaoping River are also surrounded by forests, resulting in Λ values (0.51–4.80), δ 13 C values (−23.85 to −27.08‰), C/N ratios (14.1–28.7), %OC (1.01–7.86%) and (Ad/Al)v values (0.86–1.88), which are indicative of a terrestrial signal. No lignin oxidation products were detected in the mainstream of the Kaoping River or its coastal zone, hence the surface sediments OC with a 14 C age between 4,915 and 15,870 years, enriched δ 13 C values (−23.30 and −26.54‰), lower C/N ratios (6.0–17.5) and lower %OC (0.15–2.24%) likely represent old rock and soil material. Massive floods during typhoons most probably cause plant materials from the Kaoping River and its coastal zone to be transported into the deep sea. Content Type Journal Article Category Original Paper Pages 1-18 DOI 10.1007/s10498-011-9153-0 Authors Pei Sun Loh, Institute of Marine Geology and Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan Chen-Tung Arthur Chen, Institute of Marine Geology and Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan Jiann-Yuh Lou, Department of Marine Science, Chinese Naval Academy, Kaohsiung, Taiwan Gusti Z. Anshari, Centre for Wetlands People and Biodiversity, Universitas Tanjungpura, Pontianak, Indonesia Houng-Yung Chen, Institute of Marine Biology, National Sun Yat-sen University, Kaohsiung, Taiwan Jough-Tai Wang, Department of Atmospheric Sciences and Graduate Institute of Atmospheric Physics, National Central University, Zhongli, Taiwan Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    Benthic fluxes of soluble reactive phosphorus (SRP) and dissolved inorganic carbon (DIC) were measured in situ using autonomous landers in the Gulf of Finland in the Baltic Sea, on four expeditions between 2002 and 2005. These measurements together with model estimates of bottom water oxygen conditions were used to compute the magnitude of the yearly integrated benthic SRP flux (also called internal phosphorus load). The yearly integrated benthic SRP flux was found to be almost 10 times larger than the external (river and land sources) phosphorus load. The average SRP flux was 1.25 ± 0.56 mmol m −2  d −1 on anoxic bottoms, and −0.01 ± 0.08 mmol m −2  d −1 on oxic bottoms. The bottom water oxygen conditions determined whether the SRP flux was in a high or low regime, and degradation of organic matter (as estimated from benthic DIC fluxes) correlated positively with SRP fluxes on anoxic bottoms. From this correlation, we estimated a potential increase in phosphorus flux of 0.69 ± 0.26 mmol m −2  d −1 from presently oxic bottoms, if they would turn anoxic. An almost full annual data set of in situ bottom water oxygen measurements showed high variability of oxygen concentration. Because of this, an estimate of the time which the sediments were exposed to oxygenated overlying bottom water was computed using a coupled thermohydrodynamic ocean–sea and ecosystem model. Total phosphorus burial rates were calculated from vertical profiles of total phosphorus in sediment and sediment accumulation rates. Recycling and burial efficiencies for phosphorus of 97 and 3%, respectively, were estimated for anoxic accumulation bottoms from a benthic mass balance, which was based on the measured effluxes and burial rates. Content Type Journal Article Category Original Paper Pages 1-22 DOI 10.1007/s10498-011-9155-y Authors Lena Viktorsson, Department of Earth Sciences, University of Gothenburg, BOX 460, S-405 30 Gothenburg, Sweden Elin Almroth-Rosell, Department of Chemistry, Marine Chemistry, University of Gothenburg, SE-412 96 Gothenburg, Sweden Anders Tengberg, Department of Chemistry, Marine Chemistry, University of Gothenburg, SE-412 96 Gothenburg, Sweden Roman Vankevich, SPb Scientific Research Center for Environmental Safety, Korpusnaya 18, Saint-Petersburg, Russia Ivan Neelov, Russian State Hydrometeorological University, Maloohtinskiy 98, Saint-Petersburg, Russia Alexey Isaev, Russian State Hydrometeorological University, Maloohtinskiy 98, Saint-Petersburg, Russia Victor Kravtsov, Atlantic Branch of P.P Shirshov Institute of Oceanology, Russian Academy of Science (ABIORAS), Prospect Mira 1, Kaliningrad, 236022-RU Russia Per O. J. Hall, Department of Chemistry, Marine Chemistry, University of Gothenburg, SE-412 96 Gothenburg, Sweden Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    The balance between physicochemical processes, influencing vertical and temporal distributions of metal compounds in one relatively isolated anoxic environment, constitutes the objective of the present work. Ion activity product (IAP) was calculated for manganese and iron sulfides, in order to define the metal sulfide forms that control Fe and Mn solubility in the bottom waters of anoxic lagoons. Iron solubility depended on amorphous FeS formation, while manganese sulfides were a minor component in a solid solution lowering its solid-phase activity. A theoretical physicochemical model was developed for the iron speciation, based on experimental pH and redox potential data. A very good match was achieved for the measured and the theoretical total dissolved iron, at all depths. The dominance of oxidant iron species Fe(OH) 3 − in the surface waters and their sequence by FeSH + and FeS aq in the deeper layers brings out the influence of physicochemical parameters (dissolved oxygen, sulfide, pH and E h ) in vertical distribution of dissolved metal species, in anoxic/hypoxic basins. Based on these findings, we can conclude that the distribution of manganese and iron is of special interest, not only because these are the indicators of redox conditions but also for the role of their oxidized/reduced forms in the formation of the biogeochemical structure of redox zone. Content Type Journal Article Category Original Paper Pages 1-19 DOI 10.1007/s10498-012-9179-y Authors Areti Gianni, Department of Environmental and Natural Resources Management, University of Ioannina, 2 Seferi Str., 30100 Agrinio, Greece Miltiadis Zamparas, Department of Environmental and Natural Resources Management, University of Ioannina, 2 Seferi Str., 30100 Agrinio, Greece Ioannis T. Papadas, Department of Environmental and Natural Resources Management, University of Ioannina, 2 Seferi Str., 30100 Agrinio, Greece George Kehayias, Department of Environmental and Natural Resources Management, University of Ioannina, 2 Seferi Str., 30100 Agrinio, Greece Yiannis Deligiannakis, Department of Environmental and Natural Resources Management, University of Ioannina, 2 Seferi Str., 30100 Agrinio, Greece Ierotheos Zacharias, Department of Environmental and Natural Resources Management, University of Ioannina, 2 Seferi Str., 30100 Agrinio, Greece Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    Hypoxic conditions in the coastal waters off Texas (USA) were observed since the late 1970s, but little is known about the causes of stratification that contribute to hypoxia formation. Typically, this hypoxia is attributed to downcoast (southwestward) advection of waters from the Mississippi–Atchafalaya River system. Here, we present evidence for a hypoxic event on the inner shelf of Texas coincident with the presence of freshwater linked to high flow of the Brazos River in Texas. These conclusions are based on hydrographic observations and isotopic measurements of waters on the inner shelf near the Brazos River mouth. These data characterize the development, breakdown, and dispersal of a hypoxic event lasting from June through September 2007 off the Texas coast. Oxygen isotope compositions of shelf water indicate that (1) discharge from the Brazos River was the principal source of freshwater and water column stratification during the 2007 event, and (2) during low Brazos River discharge in 2008, freshwater on the Texas shelf was derived mainly from the Mississippi–Atchafalaya River System. Based on these findings, we conclude that the Mississippi–Atchafalaya River System is not the sole cause of hypoxia in the northern Gulf of Mexico; however, more data are needed to determine the relative influence of the Texas versus Mississippi rivers during normal and low flow conditions of Texas rivers. Content Type Journal Article Category Original Paper Pages 1-23 DOI 10.1007/s10498-011-9156-x Authors Steven F. DiMarco, Department of Oceanography, Texas A&M University, 3146 TAMU, College Station, TX 77843-3146, USA Josiah Strauss, Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia Nelson May, Southeast Fisheries Science Center, National Marine Fisheries Service, NOAA, Stennis Space Center, MS 39529-0001, USA Ruth L. Mullins-Perry, Department of Oceanography, Texas A&M University, 3146 TAMU, College Station, TX 77843-3146, USA Ethan L. Grossman, Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843-3115, USA David Shormann, DIVE, LLC, P.O. Box 1324, Magnolia, TX 77353, USA Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    This paper explores the influence of a fluorine-rich granite on fluoride concentration in a small boreal catchment in northern Europe. The materials include stream water and shallow groundwater sampled in spatial and temporal dimensions, and analytical data on fluoride and a number of ancillary variables. Fluoride increased strongly towards the lower reaches of the catchment—at the stream outlet the concentrations were up to 4.2 mg L −1 and 1.6–4.7 times higher than upstream. Additionally, fluoride concentrations were particularly high in groundwater and small surface-water bodies (including quarries) above or in direct contact with the granite and showed a strong inverse correlation with water discharge in the stream. Taken together, these data and patterns pin-point the granite intrusion as the ultimate source, explaining the abundance and distribution of dissolved fluoride within the catchment. The granite most likely deliver fluoride to the stream by three mechanisms: (1) weathering of the fine fraction of glacial deposits, derived from the granite and associated fluorine-rich greisen alterations, (2) large relative input of baseflow, partially originating in the granite and greisen, into the lower reaches during low flow in particular, and (3) water-conducting fractures or fracture zones running through the fluorine-rich granite and greisen. Content Type Journal Article Category Original Paper Pages 1-18 DOI 10.1007/s10498-011-9151-2 Authors T. Berger, School of Natural Sciences, Linnaeus University, 39182 Kalmar, Sweden P. Peltola, School of Natural Sciences, Linnaeus University, 39182 Kalmar, Sweden H. Drake, School of Natural Sciences, Linnaeus University, 39182 Kalmar, Sweden M. Åström, School of Natural Sciences, Linnaeus University, 39182 Kalmar, Sweden Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    The behaviour of dissolved Al in the Great Ouse estuary, in particular with respect to salinity, is complex. There is, however, evidence from field data as well as laboratory mixing experiments to suggest that flocculation and sorption mechanisms play important roles affecting the concentrations of dissolved Al during the early stages of estuarine mixing. In contrast, a near-buffering of dissolved Al occurs in the entire stretch of the estuary (salinity 〉0.2) with concentrations varying around 1.4 μg l −1 . This distribution and lack of variation with salinity is attributable to sorption processes which might dominate over other processes in these turbid estuarine waters (suspended particulate load 48–888 mg l −1 ) impacting dissolved Al levels. Sorption models have been developed for both dissolved and leachable particulate Al concentrations in these waters. These observations provide compelling evidence of sorption processes that might be important in the geochemistry of Al in estuarine waters. Content Type Journal Article Category Original Paper Pages 1-20 DOI 10.1007/s10498-012-9159-2 Authors S. Upadhyay, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ UK Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description:    The Zhabei Salt Lake is located in the hinterland of the northern Qinghai-Tibet Plateau, China. The salt lake is of the sodium sulfate subtype and rich in lithium. In order to exploit lithium in the brine of the salt lake, a 273.15 K-isothermal evaporation experiment of the brine from the Zhabei Salt Lake was carried out for the first time. Based on the 273.15 K-isothermal phase diagram of the quaternary system Na + , Mg 2+ //Cl − , SO 4 2− –H 2 O, the evaporation-crystallization path of the brine was drawn and the sequence of salt precipitation was confirmed. The experimental results show that due to the large amount of SO 4 2− precipitated as mirabilite, the concentration of SO 4 2− in the brine was stabilized at about 0.25 mol L −1 , thus avoiding formation of Li 2 SO 4 ·3Na 2 SO 4 ·12H 2 O in the early stages of the low-temperature evaporation process. Lithium was effectively concentrated to 1.09 mol L −1 in residual mother liquor as the evaporation rate reached 96.76 %, and the molar ratio of Mg/Li decreased from 1.25 to 0.23. The enrichment behavior of lithium is described as a power function of Y  =  k (1 −  X ) −1 , where Y  = the concentration of lithium in the residual brine, X  = the extent of evaporation, and k  = the initial value of lithium concentration of the brine. In addition, the experiment suggests that the salts precipitated from the brine of the Zhabai Salt Lake contain not only the mineral assemblage with the characteristics of carbonate-type salt lakes, such as borax and lansfordite, but also the mineral assemblage with the characteristics of sulfate-type salt lakes, such as carnallite and lithium sulfate monohydrate. This finding, the data from the Zhabei Salt Lake’s brine in 1978, and the distribution characteristics of the hydrochemical zones of salt lakes on the Qinghai-Tibet Plateau, indicate that this salt lake is in a special stage of transition from a sulfate-type salt lake to a carbonate-type. Content Type Journal Article Category Original Paper Pages 1-14 DOI 10.1007/s10498-012-9168-1 Authors Feng Gao, MLR Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Baiwanzhuang Road 26, Beijing, 100037 China Mianping Zheng, MLR Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Baiwanzhuang Road 26, Beijing, 100037 China Pengsheng Song, R & D Center for Saline Lakes and Epithermal Deposits, Chinese Academy of Geological Sciences, Baiwanzhuang Road 26, Beijing, 100037 China Lingzhong Bu, MLR Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Baiwanzhuang Road 26, Beijing, 100037 China Yunsheng Wang, MLR Key Laboratory of Saline Lake Resources and Environments, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Baiwanzhuang Road 26, Beijing, 100037 China Journal Aquatic Geochemistry Online ISSN 1573-1421 Print ISSN 1380-6165

Description: The global carbon cycle, one of the important biogeochemical cycles controlling the surface environment of the Earth, has been greatly affected by human activity. Anthropogenic nutrient loading from urban sewage and agricultural runoff has caused eutrophication of aquatic systems. The impact of this eutrophication and consequent photosynthetic activity on CO 2 exchange between freshwater systems and the atmosphere is unclear. In this study, we focused on how nutrient loading to lakes affects their carbonate system. Here, we report results of surveys of lakes in Japan at different stages of eutrophication. Alkalization due to photosynthetic activity and decreases in P CO 2 had occurred in eutrophic lakes (e.g., Lake Kasumigaura), whereas in an acidotrophic lake (Lake Inawashiro) that was impacted by volcanic hot springs, nutrient loading was changing the pH and carbon cycling. When the influence of volcanic activity was stronger in the past in Lake Inawashiro, precipitation of volcanic-derived iron and aluminum had removed nutrients by co-precipitation. During the last three decades, volcanic activity has weakened and the lake water has become alkalized. We inferred that this rapid alkalization did not result just from the reduction in acid inputs but was also strongly affected by increased photosynthetic activity during this period. Human activities affect many lakes in the world. These lakes may play an important part in the global carbon cycle through their influence on CO 2 exchange between freshwater and the atmosphere. Biogeochemical changes and processes in these systems have important implications for future changes in aquatic carbonate systems on land.