(Table S1) Trace element and isotopic compositions of anhydrites sampled in the Manus Basin, Papua New Guinea

Microchemical analyses of rare earth element (REE) concentrations and Sr and S isotope ratios of anhydrite are used to identify sub-seafloor processes governing the formation of hydrothermal fluids in the convergent margin Manus Basin, Papua New Guinea. Samples comprise drill-core vein anhydrite and seafloor massive anhydrite from the PACMANUS (Roman Ruins, Snowcap and Fenway) and SuSu Knolls (North Su) active hydrothermal fields. Chondrite-normalized REE patterns in anhydrite show remarkable heterogeneity on the scale of individual grains, different from the near uniform REEN patterns measured in anhydrite from mid-ocean ridge deposits. The REEN patterns in anhydrite are correlated with REE distributions measured in hydrothermal fluids venting at the seafloor at these vent fields and are interpreted to record episodes of hydrothermal fluid formation affected by magmatic volatile degassing. 87Sr/86Sr ratios vary dramatically within individual grains between that of contemporary seawater and that of endmember hydrothermal fluid. Anhydrite was precipitated from a highly variable mixture of the two. The intra-grain heterogeneity implies that anhydrite preserves periods of contrasting hydrothermal versus seawater dominant near-seafloor fluid circulation. Most sulfate d34S values of anhydrite cluster around that of contemporary seawater, consistent with anhydrite precipitating from hydrothermal fluid mixed with locally entrained seawater. Sulfate d34S isotope ratios in some anhydrites are, however, lighter than that of seawater, which are interpreted as recording a source of sulfate derived from magmatic SO2 degassed from underlying felsic magmas in the Manus Basin. The range of elemental and isotopic signatures observed in anhydrite records a range of sub-seafloor processes including high-temperature hydrothermal fluid circulation, varying extents of magmatic volatile degassing, seawater entrainment and fluid mixing. The chemical and isotopic heterogeneity recorded in anhydrite at the inter- and intra-grain scale captures the dynamics of hydrothermal fluid formation and sub-seafloor circulation that is highly variable both spatially and temporally on timescales over which hydrothermal deposits are formed. Microchemical analysis of hydrothermal minerals can provide information about the temporal history of submarine hydrothermal systems that are variable over time and cannot necessarily be inferred only from the study of vent fluids.

Feldspar Pb-isotope ratios for earliest Pleistocene sediments of the sub-polar North Atlantic Ocean

Relatively little is known in detail about the locations of the early Pleistocene ice-sheets responsible for ice-rafted debris (IRD) inputs to the sub-polar North Atlantic Ocean during intensification of northern hemisphere glaciation (iNHG). To shed new light on this problem, we present the first combined in-depth analysis of IRD flux and geochemical provenance of individual sand-sized IRD deposited in the sub-polar North Atlantic Ocean during the earliest large amplitude Pleistocene glacial, marine isotope stage (MIS) 100 (~2.52 Ma), arguably the key glacial during iNHG. IRD provenance is assessed using laser ablation lead (Pb) isotope analyses of single feldspar grains. We find that the Pb-isotope composition (206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) of individual ice-rafted (>150 µm) feldspars deposited at DSDP Site 611A, ODP Site 981 and IODP Site U1308 during MIS 100 records a shift from predominantly Archaean-aged circum-North Atlantic Ocean continental sources during early glacial ice-rafting events to dominantly Palaeozoic and Proterozoic-aged sources during full glacial conditions. The distribution of feldspars in Pb-Pb space for full glacial MIS 100 more closely resembles that documented for feldspars deposited at the centre of the last glacial IRD belt (at IODP/DSDP Site U1308/609) during ambient (non-Heinrich-event) ice-rafting episodes of MIS 2 (~23.8 ka) than that documented for MIS 5d (~106 ka). Comparison of our early Pleistocene and last glacial cycle datasets suggests that MIS 100 was characterised by abundant iceberg calving from large ice-sheets on multiple continents in the high northern latitudes (not just on Greenland).

Soil, snow, weather, and sub-surface storage data from a mountain catchment in the rain-snow transition zone

A comprehensive hydroclimatic data set is presented for the 2011 water year to improve understanding of hydrologic processes in the rain-snow transition zone. This type of dataset is extremely rare in scientific literature because of the quality and quantity of soil depth, soil texture, soil moisture, and soil temperature data. Standard meteorological and snow cover data for the entire 2011 water year are included, which include several rain-on-snow events. Surface soil textures and soil depths from 57 points are presented as well as soil texture profiles from 14 points. Meteorological data include continuous hourly shielded, unshielded, and wind corrected precipitation, wind speed, air temperature, relative humidity, dew point temperature, and incoming solar and thermal radiation data. Sub-surface data included are hourly soil moisture data from multiple depths from 7 soil profiles within the catchment, and soil temperatures from multiple depths from 2 soil profiles. Hydrologic response data include hourly stream discharge from the catchment outlet weir, continuous snow depths from one location, intermittent snow depths from 5 locations, and snow depth and density data from ten weekly snow surveys. Though it represents only a single water year, the presentation of both above and below ground hydrologic condition makes it one of the most detailed and complete hydro-climatic datasets from the climatically sensitive rain-snow transition zone for a wide range of modeling and descriptive studies.

Chemistry of interstitial waters and sediments at DSDP Leg 64 Holes

Studies of interstitial waters obtained from DSDP Leg 64 drill sites in the Gulf of California have revealed information both on early diagenetic processes in the sediments resulting from the breakdown of organic matter and on hydrothermal interactions between sediments and hot doleritic sill intrusions into the sediments. In all the sites drilled sulfate reduction occurred as a result of rapid sediment accumulation rates and of relatively high organic carbon contents; in most sites methane production occurred after sulfate depletion. Associated with this methane production are high values of alkalinity and high concentrations of dissolved ammonia, which causes ion exchange processes with the solid phases leading to intermediate maxima in Mg++, K+, Rb+, and Sr++(?). Though this phenomenon is common in Leg 64 drill sites, these concentration reversals had been noticed previously only in Site 262 (Timor Trough) and Site 440 (Japan Trench). Penetrating, hot dolerite sills have led to substantial hydrothermal alteration in sediments at sites drilled in the Guaymas Basin. Site 477 is an active hydrothermal system in which the pore-water chemistry typically shows depletions in sulfate and magnesium and large increases in lithium, potassium, rubidium, calcium, strontium, and chloride. Strontium isotope data also indicate large contributions of volcanic matter and basalt to the pore-water strontium concentrations. At Sites 478 and 481 dolerite sill intrusions have cooled to ambient temperatures but interstitial water concentrations of Li+, Rb+, Sr++ , and Cl- show the gradual decay of a hydrothermal signal that must have been similar to the interstitial water chemistry at Site 477 at the time of sill intrusion. Studies of oxygen isotopes of the interstitial waters at Site 481 indicate positive values of d18O (SMOW) as a result of high-temperature alteration reactions occurring in the sills and the surrounding sediments. A minimum in dissolved chloride at about 100-125 meters sub-bottom at Sites 478, 481, and particularly Site 479 records a possible paleosalinity signal, associated with an event that substantially lowered salinities in the inner parts of the Gulf of California during Quaternary time.

Haemolymph inorganic ion composition, physiology and behaviour dependent on temperature and ambient magnesium concentration in early life history stages of Paralomis granulosa (Decapoda, Anomura, Lithodidae)

Marine brachyuran and anomuran crustaceans are completely absent from the extremely cold (-1.8 °C) Antarctic continental shelf, but caridean shrimps are abundant. This has at least partly been attributed to low capacities for magnesium excretion in brachyuran and anomuran lithodid crabs ([Mg2+]HL = 20-50 mmol/L) compared to caridean shrimp species ([Mg2+]HL = 5-12 mmol/L). Magnesium has an anaesthetizing effect and reduces cold tolerance and activity of adult brachyuran crabs. We investigated whether the capacity for magnesium regulation is a factor that influences temperature-dependent activity of early ontogenetic stages of the Sub-Antarctic lithodid crab Paralomis granulosa. Ion composition (Na+, Mg2+, Ca2+, Cl-, [SO4]2-) was measured in haemolymph withdrawn from larval stages, the first and second juvenile instars (crabs I and II) and adult males and females. Magnesium excretion improved during ontogeny, but haemolymph sulphate concentration was lowest in the zoeal stages. Neither haemolymph magnesium concentrations nor Ca2+:Mg2+ ratios paralleled activity levels of the life stages. Long-term (3 week) cold exposure of crab I to 1 °C caused a significant rise of haemolymph sulphate concentration and a decrease in magnesium and calcium concentrations compared to control temperature (9 °C). Spontaneous swimming activity of the zoeal stages was determined at 1, 4 and 9 °C in natural sea water (NSW, [Mg2+] = 51 mmol/L) and in sea water enriched with magnesium (NSW + Mg2+, [Mg2+] = 97 mmol/L). It declined significantly with temperature but only insignificantly with increased magnesium concentration. Spontaneous velocities were low, reflecting the demersal life style of the zoeae. Heart rate, scaphognathite beat rate and forced swimming activity (maxilliped beat rate, zoea I) or antennule beat rate (crab I) were investigated in response to acute temperature change (9, 6, 3, 1, -1 °C) in NSW or NSW + Mg2+. High magnesium concentration reduced heart rates in both stages. The temperature-frequency curve of the maxilliped beat (maximum: 9.6 beats/s at 6.6 °C in NSW) of zoea I was depressed and shifted towards warmer temperatures by 2 °C in NSW + Mg2+, but antennule beat rate of crab I was not affected. Magnesium may therefore influence cold tolerance of highly active larvae, but it remains questionable whether the slow-moving lithodid crabs with demersal larvae would benefit from an enhanced magnesium excretion in nature.

(Table 1) Effects of desiccation on photochemical processes and nitrogenase activity in Nostoc commune s.l. colonies

The effects of desiccation on photochemical processes and nitrogenase activity were evaluated in Nostoc commune s.l. colonies in situ from a wet thufur meadow at Petuniabukta, Billefjorden, Central Svalbard, during the 2009 arctic summer. The colonies were collected in the fully hydrated state, and were subjected to slow desiccation at ambient temperatures (5 - 8°C) and low light (30 - 80 µmol/m**2/s). For each colony the weight, area, photochemical performance, and nitrogenase activity were determined at the beginning, as well as on every day during the first four days of the experiment; thereafter, on every second day until desiccation was complete. The photochemical performance was evaluated from variable chlorophyll fluorescence parameters (FV/FM, Phi(PSII) , qP, and NPQ), and the nitrogenase activity was estimated by an acetylene-ethylene reduction assay. A significant decrease in the photochemically active area was recorded from the third day, when the colony had lost approximately 40% of its original weight indicating some changes in the extracellular matrix, and stopped on the 14th to 18th day. No effects of the desiccation on the main photochemical parameters (FV/FM, Phi(PSII), qP) were observed up to the sixth to eighth days of desiccation. Slightly lower values of FV/FM and Phi(PSII) recorded in fully-hydrated colonies could be caused by impaired diffusion of CO2 into cells. The steep reduction of photochemical activity occurred between the eighth and tenth day of the experiment, when the colony had lost approximately 80% of its fully-hydrated weight. The nitrogenase activity was highest on the first day, probably due to improved diffusion of N2 into cells, then declined, but was detectable until the sixth day of the experiment. Since Nostoc commune s.l. colonies were capable of photosynthesis and nitrogen fixation to the level of ca. 60% of its fully-hydrated weight, even partly-hydrated colonies contribute substantially to carbon and nitrogen cycling in the High Arctic wet meadow tundra ecosystem.

AMS 14C ages and isotopic compositions of samples from the Derugin Basin, Sea of Okhotsk

An area of massive barite precipitations was studied at a tectonic horst in 1500 m water depth in the Derugin Basin, Sea of Okhotsk. Seafloor observations and dredge samples showed irregular, block- to column-shaped barite build-ups up to 10 m high which were scattered over the seafloor along an observation track 3.5 km long. High methane concentrations in the water column show that methane expulsion and probably carbonate precipitation is a recently active process. Small fields of chemoautotrophic clams (Calyptogena sp., Acharax sp.) at the seafloor provide additional evidence for active fluid venting. The white to yellow barites show a very porous and often layered internal fabric, and are typically covered by dark-brown Mn-rich sediment; electron microprobe spectroscopy measurements of barite sub-samples show a Ba substitution of up to 10.5 mol% of Sr. Rare idiomorphic pyrite crystals (~1%) in the barite fabric imply the presence of H2S. This was confirmed by clusters of living chemoautotrophic tube worms (1 mm in diameter) found in pores and channels within the barite. Microscopic examination showed that micritic aragonite and Mg-calcite aggregates or crusts are common authigenic precipitations within the barite fabric. Equivalent micritic carbonates and barite carbonate cemented worm tubes were recovered from sediment cores taken in the vicinity of the barite build-up area. Negative d13C values of these carbonates (>-43.5 per mill PDB) indicate methane as major carbon source; d18O values between 4.04 and 5.88 per mill PDB correspond to formation temperatures, which are certainly below 5°C. One core also contained shells of Calyptogena sp. at different core depths with 14C-ages ranging from 20 680 to >49 080 yr. Pore water analyses revealed that fluids also contain high amounts of Ba; they also show decreasing SO4**2- concentrations and a parallel increase of H2S with depth. Additionally, S and O isotope data of barite sulfate (d34S: 21.0-38.6 per mill CDT; d18O: 9.0-17.6 per mill SMOW) strongly point to biological sulfate reduction processes. The isotope ranges of both S and O can be exclusively explained as the result of a mixture of residual sulfate after a biological sulfate reduction and isotopic fractionation with 'normal' seawater sulfate. While massive barite deposits are commonly assumed to be of hydrothermal origin, the assemblage of cheomautotrophic clams, methane-derived carbonates, and non-thermally equilibrated barite sulfate strongly implies that these barites have formed at ambient bottom water temperatures and form the features of a Giant Cold Seep setting that has been active for at least 49 000 yr.

Seawater carbonate chemistry and biological processes of Limacina helicina during experiments, 2011

Due to their aragonitic shell, thecosome pteropods may be particularly vulnerable to ocean acidification driven by anthropogenic CO2 emissions. This applies specifically to species inhabiting Arctic surface waters that are projected to become temporarily and locally undersaturated with respect to aragonite as early as 2016. This study investigated the effects of rising partial pressure of CO2 (pCO2) and elevated temperature on pre-winter juveniles of the polar pteropod Limacina helicina. After a 29 day experiment in September/October 2009 at three different temperatures and under pCO2 scenarios projected for this century, mortality, shell degradation, shell diameter and shell increment were investigated. Temperature and pCO2 had a significant effect on mortality, but temperature was the overriding factor. Shell diameter, shell increment and shell degradation were significantly impacted by pCO2 but not by temperature. Mortality was 46% higher at 8 °C than at in situ temperature (3 °C), and 14% higher at 1100 ?atm than at 230 ?atm. Shell diameter and increment were reduced by 10 and 12% at 1100 ?atm and 230 ?atm, respectively, and shell degradation was 41% higher at elevated compared to ambient pCO2. We conclude that pre-winter juveniles will be negatively affected by both rising temperature and pCO2 which may result in a possible decline in abundance of the overwintering population, the basis for next year's reproduction.

Chemical characterization of marine sub-micrometer aerosol particles during the MERIAN cruise MSM18/3 from the Cape Verde island Sao Vicente to Gabun (Atlantic Ocean)

Sub-micron marine aerosol particles (PM1) were collected during the MERIAN cruise MSM 18/3 between 22 June 2011 and 21 July 2011 from the Cape Verde island Sao Vicente to Gabun crossing the tropical Atlantic Ocean and passing equatorial upwelling areas. According to air mass origin and chemical composition of the aerosol particles, three main regimes could be established. Aerosol particles in the first part of the cruise were mainly of marine origin, in the second part was marine and slightly biomass burning influenced (increasing tendency) and in the in last part of the cruise, approaching the African mainland, biomass burning influences became dominant. Generally aerosols were dominated by sulfate (caverage = 1.99 µg/m**3) and ammonium ions (caverage = 0.72 µg/m**3) that are well correlated and slightly increasing along the cruise. High concentrations of water insoluble organic carbon (WISOC) averaging 0.51 µg/m**3 were found probably attributed to the high oceanic productivity in this region. Water soluble organic carbon (WSOC) was strongly increasing along the cruise from concentrations of 0.26 µg/m**3 in the mainly marine influenced part to concentrations up to 3.3 µg/m**3 that are probably caused by biomass burning influences. Major organic constituents were oxalic acid, methansulfonic acid (MSA) and aliphatic amines. MSA concentrations were quite constant along the cruise (caverage = 43 ng/m**3). While aliphatic amines were more abundant in the first mainly marine influenced part with concentrations of about 20 ng/m**3, oxalic acid showed the opposite pattern with average concentrations of 12 ng/m**3 in the marine and 158 ng/m**3 in the biomass burning influenced part. The alpha dicarbonyl compounds glyoxal and methylglyoxal were detected in the aerosol particles in the low ng/m**3 range and followed oxalic acid closely. MSA and aliphatic amines accounted for biogenic marine (secondary) aerosol constituents whereas oxalic acid and the alpha dicarbonyl compounds were believed to result mainly from biomass burning. N-alkane concentrations increased along the cruise from 0.81 to 4.66 ng/m**3, PAHs and hopanes were abundant in the last part of the cruise (caverage of PAHs = 0.13 ng/m**3, caverage of hopanes = 0.19 ng/m**3). Levoglucosan was identified in several samples of the last part of the cruise in concentrations around 2 ng/m**3, pointing to (aged) biomass burning influences. The investigated organic compounds could explain 9.5% of WSOC in the mainly marine influenced part (dominating compounds: aliphatic amines and MSA) and 2.7% of WSOC in the biomass burning influenced part (dominating compound: oxalic acid) of the cruise.

(Table 3) Carbon and oxygen isotopic data of carbonates from Core SLR 37-1, HYC 25-1 and an aragonite crust from station DR 35-1

An area of massive barite precipitations was studied at a tectonic horst in 1500 m water depth in the Derugin Basin, Sea of Okhotsk. Seafloor observations and dredge samples showed irregular, block- to column-shaped barite build-ups up to 10 m high which were scattered over the seafloor along an observation track 3.5 km long. High methane concentrations in the water column show that methane expulsion and probably carbonate precipitation is a recently active process. Small fields of chemoautotrophic clams (Calyptogena sp., Acharax sp.) at the seafloor provide additional evidence for active fluid venting. The white to yellow barites show a very porous and often layered internal fabric, and are typically covered by dark-brown Mn-rich sediment; electron microprobe spectroscopy measurements of barite sub-samples show a Ba substitution of up to 10.5 mol% of Sr. Rare idiomorphic pyrite crystals (1%) in the barite fabric imply the presence of H2S. This was confirmed by clusters of living chemoautotrophic tube worms (1 mm in diameter) found in pores and channels within the barite. Microscopic examination showed that micritic aragonite and Mg-calcite aggregates or crusts are common authigenic precipitations within the barite fabric. Equivalent micritic carbonates and barite carbonate cemented worm tubes were recovered from sediment cores taken in the vicinity of the barite build-up area. Negative ?13C values of these carbonates (>?43.5? PDB) indicate methane as major carbon source; ?18O values between 4.04 and 5.88? PDB correspond to formation temperatures, which are certainly below 5°C. One core also contained shells of Calyptogena sp. at different core depths with 14C-ages ranging from 20 680 to >49 080 yr. Pore water analyses revealed that fluids also contain high amounts of Ba; they also show decreasing SO42- concentrations and a parallel increase of H2S with depth. Additionally, S and O isotope data of barite sulfate (?34S: 21.0-38.6? CDT; ?18O: 9.0-17.6? SMOW) strongly point to biological sulfate reduction processes. The isotope ranges of both S and O can be exclusively explained as the result of a mixture of residual sulfate after a biological sulfate reduction and isotopic fractionation with 'normal' seawater sulfate. While massive barite deposits are commonly assumed to be of hydrothermal origin, the assemblage of cheomautotrophic clams, methane-derived carbonates, and non-thermally equilibrated barite sulfate strongly implies that these barites have formed at ambient bottom water temperatures and form the features of a Giant Cold Seep setting that has been active for at least 49 000 yr.

Impacts of ocean acidification on sediment processes in shallow waters of the arctic ocean

Despite the important roles of shallow-water sediments in global biogeochemical cycling, the effects of ocean acidification on sedimentary processes have received relatively little attention. As high-latitude cold waters can absorb more CO2 and usually have a lower buffering capacity than warmer waters, acidification rates in these areas are faster than those in sub-tropical regions. The present study investigates the effects of ocean acidification on sediment composition, processes and sediment-water fluxes in an Arctic coastal system. Undisturbed sediment cores, exempt of large dwelling organisms, were collected, incubated for a period of 14 days, and subject to a gradient of pCO2 covering the range of values projected for the end of the century. On five occasions during the experimental period, the sediment cores were isolated for flux measurements (oxygen, alkalinity, dissolved inorganic carbon, ammonium, nitrate, nitrite, phosphate and silicate). At the end of the experimental period, denitrification rates were measured and sediment samples were taken at several depth intervals for solid-phase analyses. Most of the parameters and processes (i.e. mineralization, denitrification) investigated showed no relationship with the overlying seawater pH, suggesting that ocean acidification will have limited impacts on the microbial activity and associated sediment-water fluxes on Arctic shelves, in the absence of active bio-irrigating organisms. Only following a pH decrease of 1 pH unit, not foreseen in the coming 300 years, significant enhancements of calcium carbonate dissolution and anammox rates were observed. Longer-term experiments on different sediment types are still required to confirm the limited impact of ocean acidification on shallow Arctic sediment processes as observed in this study.

Tree line shifts and disturbance events for sites studied in the Torneträsk area of sub-Arctic Sweden for the period 1800-2009

Aim: Models project that climate warming will cause the tree line to move to higher elevations in alpine areas and more northerly latitudes in Arctic environments. We aimed to document changes or stability of the tree line in a sub-Arctic model area at different temporal and spatial scales, and particularly to clarify the ambiguity that currently exists about tree line dynamics and their causes. Location: The study was conducted in the Tornetrask area in northern Sweden where climate warmed by 2.5 °C between 1913 and 2006. Mountain birch (Betula pubescens ssp. czerepanovii) sets the alpine tree line. Methods: We used repeat photography, dendrochronological analysis, field observations along elevational transects and historical documents to study tree line dynamics. Results: Since 1912, only four out of eight tree line sites had advanced: on average the tree line had shifted 24 m upslope (+0.2 m/year assuming linear shifts). Maximum tree line advance was +145 m (+1.5 m/year in elevation and +2.7 m/year in actual distance), whereas maximum retreat was 120 m downslope. Counter-intuitively, tree line advance was most pronounced during the cooler late 1960s and 1970s. Tree establishment and tree line advance were significantly correlated with periods of low reindeer (Rangifer tarandus) population numbers. A decreased anthropozoogenic impact since the early 20th century was found to be the main factor shaping the current tree line ecotone and its dynamics. In addition, episodic disturbances by moth outbreaks and geomorphological processes resulted in descent and long-term stability of the tree line position, respectively. Main conclusions: In contrast to what is generally stated in the literature, this study shows that in a period of climate warming, disturbance may not only determine when tree line advance will occur but if tree line advance will occur at all. In the case of non-climatic climax tree lines, such as those in our study area, both climate-driven model projections of future tree line positions and the use of the tree line position for bioclimatic monitoring should be used with caution.

Seawater carbonate chemistry and diatom Phaeodactylum tricornutum (CCMA 106) biological processes during experiments, 2010

CO2/pH perturbation experiments were carried out under two different pCO2 levels (39.3 and 101.3 Pa) to evaluate effects of CO2-induced ocean acidification on the marine diatom Phaeodactylum tricornutum. After acclimation (>20 generations) to ambient and elevated CO2 conditions (with corresponding pH values of 8.15 and 7.80, respectively), growth and photosynthetic carbon fixation rates of high CO2 grown cells were enhanced by 5% and 12%, respectively, and dark respiration stimulated by 34% compared to cells grown at ambient CO2. The half saturation constant (Km) for carbon fixation (dissolved inorganic carbon, DIC) increased by 20% under the low pH and high CO2 condition, reflecting a decreased affinity for HCO3- or/and CO2 and down-regulated carbon concentrating mechanism (CCM). In the high CO2 grown cells, the electron transport rate from photosystem II (PSII) was photoinhibited to a greater extent at high levels of photosynthetically active radiation, while non-photochemical quenching was reduced compared to low CO2 grown cells. This was probably due to the down-regulation of CCM, which serves as a sink for excessive energy. The balance between these positive and negative effects on diatom productivity will be a key factor in determining the net effect of rising atmospheric CO2 on ocean primary production.