Dissolved Inorganic Carbon

essentially induced by local modifications of the electronic properties of a surface near chemisorbed particles and hence, we believe, are of general importance for chemical processes at surfaces whenever the diffusion lengths of adsorbing species reach critical values compared with their lateral distribution. Ⅺ

Evidence of increasing concentrations of dissolved carbon dioxide, especially in the surface ocean and its associated impacts on calcifying organisms, is accumulating. Among these organisms, benthic and planktonic foraminifera are responsible for a large amount of the globally precipitated calcium carbonate. Hence, their response to an acidifying ocean may have important consequences for future inorganic carbon cycling. To assess the sensitivity of benthic foraminifera to changing carbon dioxide levels and subsequent alteration in seawater carbonate chemistry, we cultured specimens of the shallow water species Ammonia tepida at two concentrations of atmospheric CO 2 (230 and 1900 ppmv) and two temperatures (10 • C and 15 • C). Shell weights and elemental compositions were determined. Impact of high and low pCO 2 on elemental composition are compared with results of a previous experiment were specimens were grown under ambient conditions (380 ppvm, no shell weight measurements of specimen grown under ambient conditions are, however, available). Results indicate that shell weights decrease with decreasing [CO 2- 3 ], although calcification was observed even in the presence of calcium carbonate under-saturation, and also decrease with increasing temperature. Thus both warming and ocean acidification may act to decrease shell weights in the future. Changes in [CO 2- 3 ] or total dissolved inorganic carbon do not affect the Mg distribution coefficient. On the contrary, Sr incorporation is enhanced under increasing [CO 2- 3 ]. Implications of these results for the paleoceanographic application of foraminifera are discussed.

Since 1951, when the first official measurements of Prespa Lake water level were made up to nowadays, big fluctuations of this parameter have been observed. So far, many publications have been devoted to finding the reason for these fluctuations, but it seems that the real reason is still unclear. Using isotopic natural tracers (50 and §H) distribution into the local precipitation, surface and ground water flows and accumulation, Anovski et all. confirmed the old theory for underground connection between Big Prespa and Ohrid Lake for the first time in 1988. Taking into account that the Prespa watershed is very complex, as it includes underground water outflows, the main problem for calculating the water stock is the non existence of reliable hydrological and meteorological data. Sometimes the data presented from Macedonian, Albanian and Greek side differs significantly as a result of low number of hydro-meteorological stations, low number of established measurement points, utilizing equipments sull not sophisticated enough and the non existence of a unique standardization. This work will evaluate the measured, estimated and calculated data and parameters from Prespa Lake basin archived or published in various Symposiums proceedings and Journals as: delineation of catchment area, precipitation over the catchment area, precipitation over the lake surface, condensation over the catchment area, condensation over the lake surface, surface water inflow in the lake (run off), underground water inflow and artificial water inflow in the lake, evapo-transpiration from the catchment area, evaporation from the lake surface, surface water outflow from the lake, underground Waters outflow through porous media and karst, artificial water outflow from the lake and irreversibly consumed water (irrigation mainly). All the mentioned parameters are of high importance as they influence the water level of Prespa Lake.

We have employed a Multi-parameter Linear Regression (MLR) analysis procedure to determine the uptake of anthropogenic CO 2 between two east-west hydrographic surveys of the North Pacific that occurred in 1994 and 2004. The results revealed water column integrated uptake rates of anthropogenic CO 2 that ranged from 1.1 to 1.3 mol m -2 yr -1 depending on location. The combined effect of the tilted density surfaces and the younger waters with higher anthropogenic CO 2 concentrations leads to higher total column inventories in the western North Pacific.

This paper presents a comprehensive analysis of the basin-wide inventory of anthropogenic CO 2 in the Atlantic Ocean based on high-quality inorganic carbon, alkalinity, chlorofluorocarbon, and nutrient data collected during the World Ocean Circulation Experiment (WOCE) Hydrographic Program, the Joint Global Ocean Flux Study (JGOFS), and the Ocean-Atmosphere Carbon Exchange Study (OACES) surveys of the Atlantic Ocean between 1990 and 1998. Anthropogenic CO 2 was separated from the large pool of dissolved inorganic carbon using an extended version of the DC* method originally developed by Gruber et al. [1996]. The extension of the method includes the use of an optimum multiparameter analysis to determine the relative contributions from various source water types to the sample on an isopycnal surface. Total inventories of anthropogenic CO 2 in the Atlantic Ocean are highest in the subtropical regions at 20°-40°, whereas anthropogenic CO 2 penetrates the deepest in high-latitude regions (>40°N). The deeper penetration at high northern latitudes is largely due to the formation of deep water that feeds the Deep Western Boundary Current, which transports anthropogenic CO 2 into the interior. In contrast, waters south of 50°S in the Southern Ocean contain little anthropogenic CO 2 . Analysis of the data collected during the 1990-1998 period yielded a total anthropogenic CO 2 inventory of 28.4 ± 4.7 Pg C in the North Atlantic (equator-70°N) and of 18.5 ± 3.9 Pg C in the South Atlantic (equator-70°S). These estimated basin-wide inventories of anthropogenic CO 2 are in good agreement with previous estimates obtained by , after accounting for the difference in observational periods. Our calculation of the anthropogenic CO 2 inventory in the Atlantic Ocean, in conjunction with the inventories calculated previously for the Indian Ocean and for the Pacific Ocean , yields a global anthropogenic CO 2 inventory of 112 ± 17 Pg C that has accumulated in the world oceans during the industrial era. This global oceanic uptake accounts for approximately 29% of the total CO 2 emissions from the burning of fossil fuels, land-use changes, and cement production during the past 250 years.

The exchange of CO2 across the air‐sea interface is a main determinant of the distribution of atmospheric CO2 from which major conclusions about the carbon cycle are drawn, yet our knowledge of atmosphere‐ocean fluxes still has major gaps. A new analysis based on recent ocean dissolved inorganic carbon data and on models permits us to separately estimate the preindustrial and present air‐sea CO2 flux distributions without requiring knowledge of the gas exchange coefficient. We find a smaller carbon sink at mid to high latitudes of the southern hemisphere than previous data based estimates and a shift of ocean uptake to lower latitude regions compared to estimates and simulations. The total uptake of anthropogenic CO2 for 1990 is 1.8 (±0.4) Pg C yr−1. Our ocean based results support the interpretation of the latitudinal distribution of atmospheric CO2 data as evidence for a large northern hemisphere land carbon sink.

Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C. Sampling approaches range in their representation of wetland C from short to long timeframes and local to landscape spatial scales. This review summarizes common and cutting-edge methodological approaches for quantifying wetland C pools and fluxes. We first define each of the major C pools and fluxes and provide rationale for their importance to wetland C dynamics. For each approach, we clarify what component of wetland C is measured and its spatial and temporal representativeness and constraints. We describe practical considerations for each approach, such as where and when an approach is typically used, who can conduct the measurements (expertise, training requirements), and how approaches are conducted, including considerations on equipment complexity and costs. Finally, we review key covariates and ancillary measurements that enhance the interpretation of findings and facilitate model development. The protocols that we describe to measure soil, water, vegetation, and gases are also relevant for related disciplines such as ecology. Improved quality and consistency of data collection and reporting across studies will help reduce global uncertainties and develop management strategies to use wetlands as nature-based climate solutions.

We studied the seawater carbon dioxide (CO 2 ) system in the Palau coral reef by measuring total alkalinity (TA) and total dissolved inorganic carbon (DIC). Variation in the CO 2 system on the reef flat and in the lagoon was analyzed by TA-DIC diagrams, taking into accounts the differing residence times of seawater. CO 2 in the offshore water was relatively stable in space and time, but on the reef flat it was subject to rapid (about 3 h) and substantial changes due to photosynthesis and calcification during the day and due to respiration and calcification at night. Water flowed into the lagoon where decomposition of organic matter and continuing calcification occurred over relatively long residence times (,30 d). Despite the spatial and temporal variations, the center of the lagoon had relatively constant TA and DIC values similar to the mean values for the entire lagoon. A long-term 30-40% decrease in reef productivity and calcification has occurred over the last decade, primarily a result of degradation of the reef environment following a major coral reef bleaching event in 1998. This is reflected in decreases in the differences in TA and DIC between offshore lagoon waters and those in center of the lagoon.

Weekly water samples were taken to measure stable isotope composition (δ13C and δ15N) of particulate organic matter (POM) in Lake Wauberg, Florida, from June 1994 to May 1995. The average δ13C of POM was ‐19.3%, consistent with an autochthonous origin from phytoplankton production, and exhibited a seasonal pattern that coincided with changes in water temperature, pH, CO2 concentration, and phytoplankton biomass in the surface water. The 13C enrichment in POM was attributed to reduced isotope fractionation due to carbon (C) limitation and the use of an isotopically heavy dissolved inorganic carbon pool supported mainly by atmospheric invasion and anaerobic respiration. Intermittent declines in δ13C of POM were related to the frequent collapses of phytoplankton blooms and increases in CO2 concentration resulting from both increased community respiration and terrestrial loading. Average δ15N of POM was 1.3% and varied within a narrow range (20.1% to 2.5%). No significant correlation be...

The Hooghly-Matla estuarine complex in the Gangetic Delta system is one of the most genetically rich ecosystems of the Indian sub-continent. The present paper is an approach to prepare a baseline data integrating both western (Hooghly) and central (Matla) sectors of Indian Sundarbans. Since phytoplankton forms the foundation of aquatic food chain, therefore its seasonal variation through phytopigment level has also been assessed in the present study. A unique seasonal variation was observed for parameters like salinity, pH, nutrient load and suspended solid, and the phytopigment level oscillated significantly with this parameters confirming the regulatory role of hydrological parameters on the food chain of the system.

A positive carbon isotope excursion is reported for the global Hangenberg Event near the Devonian-Carboniferous boundary, one of the most significant Phanerozoic mass extinction events. The δ 13 C excursion occurs both in micritic limestones and in sedimentary organic matter of black shales and limestones from different palaeogeographical regions, which were precisely correlated by conodont biostratigraphy. The excursion indicates global change in the isotopic composition of marine dissolved inorganic carbon and atmospheric CO 2 . This resulted from the increased burial of organic matter by globally widespread deposition of black shales. The δ 18 O values of conodont apatite indicate that globally widespread black shale deposition was preceded by increasing temperature, probably with a thermal gradient between equatorial and higher latitudes (∼ 20 °S). The main regressive interval of the event, correlated previously with a short-lived glacial episode in Gondwana, yielded no material for geochemical analyses, but low temperatures are recorded in overlying beds and increase again during the terminal Devonian. Early Carboniferous sea-surface temperatures were similar to those of the Late Devonian. This pattern of increased organic carbon burial, and changes in climate and sea level, is similar to that of several other extinction events of the Phanerozoic. It supports the hypothesis that increased organic carbon burial and oceanic anoxia can trigger mass extinctions, glaciations and eustatic sea-level change.

Coastal plantation ecosystems play a crucial role in combating global warming by serving as effective carbon sinks. Sonneratia apetala (Keora) is a fast-growing tree species that significantly influences local carbon sequestration rates, but still there is lack of knowledge about how this carbon sequestration rate changes with stand age and structure. So, we investigated how carbon stock changes across four different aged of S. apetala plantation forests (8, 16, 24, and 32 years) in the Chakaria Sundarbans. Twenty representative plots (20 m × 20 m) were selected from 4 different stand ages (8, 16, 24, and 32 years) using stratified random sampling design (SRSD) method. Soil organic carbon (SOC) content from 0 to 30 cm soil layers, aboveground biomass (AGB) and belowground biomass (BGB) were studied to calculate the total carbon stock (TCS). A positive correlation was observed between TCS and stand age. The TCS at the 8, 16, 24, and 32 years old plantation sites was 60.85, 109.73, 136.29, and 183.48 t ha-1 , respectively. The mean annual carbon accumulation rate (CAR) were 7.60, 6.86, 5.68, and 5.73 t ha-1 year-1 in these respective sites, indicated that the CAR significantly decreased with stand age. At the stand ages of 8, 16, and 24 years, soil organic carbon storage (SOCS) significantly outweighed total biomass carbon stock (TBCS), with percentages of 85.02 %, 60.68 %, and 55.65 % of TCS, respectively. However, at 32 years old stand, TBCS (54.77 %) exceeded SOCS (45.23 %). The TCS values were equivalent to 223.32, 402.71, 500.18, and 637.37 t ha-1 CO 2 at 8, 16, 24, and 32 years old stands, respectively, revealed a significant potential for CO 2 sequestration. These findings can be used in the development of effective forest management strategies with restoring mangrove to maximize carbon storage potential in the southeastern coasts of Bangladesh, ultimately helping to reduce CO 2 gas emissions to combat adverse effect of climate change.

The seasonal variability of specific growth rate and the carbon stable isotope ratio (δ 13 C) 2 of leaf blades (δ 13 C leaf ) of a temperate seagrass, Zostera marina (within 10 days old) were 3 measured simultaneously, together with the δ 13 C of dissolved inorganic carbon (δ 13 C DIC ) 4

Carbon dioxide is the most abundant anthropogenic greenhouse gas released in the environment and is considered as one of the main drivers of global warming and ensuing climate change. Mangals, recognised as key 'blue carbon' ecosystems, are amongst the world's most carbon-dense ecosystems and can sequester a considerable amount of carbon through biological carbon sequestration in their biomass and soils. In this work, five Rhizophora mucronata natural and planted forests in Mauritius were studied with the aims at evaluating the carbon storage potential and the effect of tidal inundation, forest age, and mineral availability on biomass productivity and sediment carbon storage. Using 25m x 25m quadrats and a simple random sampling technique, plant height and diameter at breast height (DBH) were measured in situ with the GLOBE Observer application (The Globe Program, NASAsponsored) and a measuring tape, respectively. The rate of canopy coverage over the past twenty years was assessed using historical Landsat 7 and 8 images available on Google Earth Pro. Rhizophora allometric equations were used to estimate the above-ground biomass (AGB), below-ground biomass (BGB), and total biomass (TB). Total organic carbon (TOC), sediment carbon storage, and all essential nutrients for plant growth were analysed using standard methods. Soil texture was determined using granulometric analysis. Our findings show that in both natural and planted forests, the zones that were more inundated were first established. However, tree and sapling density, as well as biomass, were negatively correlated with sodium (density: r = -0.830; AGB: r = -0.880). Positive correlations between AGB and nitrate nitrogen (NO 3 -N) (r = 0.686), ammonium nitrogen (NH 4 -N) (r = 0.706), phosphate (r = 0.618), and manganese (r = 0.776) suggest that these minerals were limiting factors. Nevertheless, the combination of forest age and salinity was found to play key roles on the AGB and therefore on total organic carbon (TOC), which is linked to materials originating from the mangroves. High correlations of TOC with NH 4 -N (r = 0.822) and magnesium (r = 0.831) indicate the greater availability of these essential nutrients in older forests. It is noteworthy that the Ferney forest with a relatively lower salinity (5-15 ppt) and the only forest that had already reached a steady state in 2010, had a relatively much higher AGB (326.2 ± 26.3 t ha -1 ) than the global average for Rhizophora mucronata (94.8 t ha -1 ), let alone Rhizophora spp. (281 t ha -1 ). The TOC registered at Ferney (47.34%) was also higher than the global values reported (2.00 ± 2.20% to 40.00 ± 2.20%). Above ground biomass, tonnes per hectare (t ha -1 ) b rate at which canopy coverage is increasing

Disturbed coral reefs are often dominated by dense mat-or canopy-forming assemblages of macroalgae. This study investigated how such dense macroalgal assemblages change the chemical and physical microenvironment for understorey corals, and how the altered environmental conditions affect the physiological performance of corals. Field measurements were conducted on macroalgal-dominated inshore reefs in the Great Barrier Reef in quadrats with macroalgal biomass ranging from 235 to 1029 g DW m 22 dry weight. Underneath mat-forming assemblages, the mean concentration of dissolved oxygen was reduced by 26% and irradiance by 96% compared with conditions above the mat, while concentrations of dissolved organic carbon and soluble reactive phosphorous increased by 26% and 267%, respectively. The difference was significant but less pronounced under canopy-forming assemblages. Dissolved oxygen declined and dissolved inorganic carbon and alkalinity increased with increasing algal biomass underneath mat-forming but not under canopy-forming assemblages. The responses of corals to conditions similar to those found underneath algal assemblages were investigated in an aquarium experiment. Coral nubbins of the species Acropora millepora showed reduced photosynthetic yields and increased RNA/DNA ratios when exposed to conditions simulating those underneath assemblages (pre-incubating seawater with macroalgae, and shading). The magnitude of these stress responses increased with increasing proportion of pre-incubated algal water. Our study shows that mat-forming and, to a lesser extent, canopyforming macroalgal assemblages alter the physical and chemical microenvironment sufficiently to directly and detrimentally affect the metabolism of corals, potentially impeding reef recovery from algal to coral-dominated states after disturbance. Macroalgal dominance on coral reefs therefore simultaneously represents a consequence and cause of coral reef degradation.

Chemical weathering of silicate and carbonate rocks by carbonic acid is important in the context of atmospheric CO 2 sequestration and its delivery to the oceans via rivers as dissolved inorganic carbon (DIC). In this work, silicate weathering contribution to DIC in the Krishna river system, draining the Deccan basalts in south-western India has been determined using a new approach based on d 13 C-Si / HCO 3 systematics of the waters. d 13 C in the samples ranges from À 8.5x to À 20.7x and shows a strong linear inverse trend with Si / HCO 3 (r 2 = 0.80). The Si / HCO 3 ratios in rivers vary from ~0.55 to ~0.10, the higher value matches the expected ratio for chemical weathering of Deccan basalts based on their composition. The d 13 C-Si / HCO 3 trend suggests the mixing of two end members, a carbonate derived endmember with low Si / HCO 3 and enriched in 13 C and a silicate derived endmember with higher Si / HCO 3 and depleted in 13 C. Small rivers of the western ghats are depleted in 13 C (d 13 C: À 18.7 F 2x) and have high Si / HCO 3 . These properties are interpreted as signatures of basalt (silicate) weathering with CO 2 from C 3 vegetation. Three samples from the Krishna mainstream and two of its larger tributaries, the Bhima and the Ghod, are enriched in 13 C (d 13 C: À 8.5x to À 15x) with higher HCO 3 and lower Si / HCO 3 ratios, indicating that a significant fraction of DIC in these samples is derived from carbonate weathering. Carbonate dispersed in river sediments can be a likely source of DIC.

In August 2003, the McLure Fire burned through several watersheds north of Kamloops, including Fishtrap Creek. The burn was extensive, killing almost all the trees in the riparian area. Given our current knowledge, it is not possible to accurately predict channel response to wildfire, the rate of change, or the time scale at which response and recovery may be expected to occur. The purpose of this study is to document the timing and magnitude of initial changes in channel morphology, peak flows, sediment supply, and sediment mobility in Fishtrap Creek in the aftermath of the McLure Fire. We take an empirical approach that combines stream channel

The isotopic composition of total organic carbon (TOC) in lakes has been widely used to interpret paleoclimatic changes and the depositional environments of lake sediments. However, the main factors that affect the carbon isotopes of TOC may vary in different lake sediment records, limiting the ability of organic carbon isotopes to explain biogeochemical and environmental changes, especially in lakes with a large number of aquatic plants. In this study, the δ 13 C values of macrophyte remains and bulk carbonate in a sedimentary core from Lake Koucha were investigated to evaluate their paleoenvironmental implications. We found that the bulk carbonate was dominated by authigenic carbonates formed in the lake and that their δ 18 O and δ 13 C values can be used to reconstruct environmental changes in the Lake Koucha area. The macrophyte productivity derived from the carbon isotopic offset between the macrophyte remains and the bulk carbonate (ε remains -BC ) in the Lake Koucha area agree well with total solar irradiance (TSI) records inferred from Δ 10 Be and temperature records based on tree rings from the Qinghai-Tibetan Plateau. Although

We present radiocarbon ( 14 C) measurements of dissolved inorganic carbon (DIC) from surface waters of 11 lakes, widely distributed in China. Surface lake water DIC F 14 C values show distinct differences, and we relate these to the physical exchange character ("open" or "closed") of each lake. Open lakes studied here generally have lower DIC F 14 C values than closed lakes. We present a simple model of a lake water cycle to calculate an average residence time for each lake. Comparisons between lake DIC F 14 C and average residence time shows that the DIC F 14 C increases with the average residence time and reflects a steady-state.

Present study focussed on the water quality status in relation to various anthropogenic activities in the Kodungallur-Azhikode Estuary (KAE). Average depth of the estuary was 3.6 ± 0.2 m with maximum of 4.3 ± 0.4 m in the estuarine mouth. Dissolved oxygen showed an average of 5.1±1 mg/l in the water column, whereas the highest BOD value was noticed during monsoon period (3.1 ± 0.8 mg/l) which could be due to high organic enrichment in the water column. pH displayed slightly alkaline condition in most of the stations and it varied from 7.2 ± 0.5 in Station 7 to 7.5 ± 0.5 in Station 1. Salinity in the estuary displayed mixo-mesohaline nature with clear vertical stratification. High river discharge could have resulted in nutrients and silt loading into the estuary, which makes a highly turbid water column particularly during the monsoon period, which limits light penetration and subsequent primary productivity. Turbidity in the water column showed an average of 20.2 ± 15.8 NTU. Estuary was nitrogen limited during post and pre monsoon periods. Nitrate-nitrogen content in the estuarine water gave negative correlation with ammonia.

The Baltic-C project aims at building predictive capability regarding the Baltic Sea organic/inorganic carbon and oxygen systems during present and future climate conditions. This modeling framework will be used for the predictive analysis of the functioning and dynamics of the Baltic Sea organic/inorganic carbon and oxygen systems. Significant components of the Baltic Sea carbon and oxygen systems relates to the uptake/release to the atmosphere. Air-sea exchange is controlled by the difference in concentration between the water surface and the atmosphere, but also by the efficiency of the transfer. Combination of surface water cooling and a deep ocean mixed layer generates convective eddies scaling with the depth of a mixed layer that enhances the efficiency of the air-sea transfer of CO2 (and possibly other gases). This enhancement is explained by the convective eddies disturbing the molecular diffusion layer and inducing increased turbulent mixing in the water (Rutgersson and Sme...

We estimated the net annual air-sea exchange of CO2 using high-quality monitoring data from the Gotland Sea, Bornholm Sea, and Kattegat for the 1993-2007 period. Sea surface partial pressure of CO2 (pCO2w), was calculated from pH, total alkalinity, temperature, and salinity. The pCO2w, daily wind speed, and three parameterizations of the gas transfer velocity (k) were used for the flux calculations. Direct pCO2 measurements from research cruises and data collected with an automated pCO2 measurement system deployed on a cargo ship were used to validate the calculated pCO2 data. The uptake and release of CO2 over the southern Baltic Sea and the Kattegat display large seasonal and inter-annual variations as well as regional differences. We demonstrate that regions in the southern Baltic Sea and the Kattegat alternate between being sinks (-) and sources (+) of CO2 within the +4.5 to -5 mol m-2 y-1 range. The average air-sea exchange over the period was -0.07 mol m-2 y-1 in the Gotland S...

This paper presents a refined four-box carbon reservoir model for the recovery of atmospheric 14 C concentration following the Genesis Flood (2463 BC). Using 421 independently calibrated anchor points spanning the entire post-Flood period, we demonstrate that transfer boundaries between carbon reservoirs exhibit elastic rebound behaviour rather than monotonic equilibration. This framework explains the Suess wiggles as predicted oscillatory features and is independently validated by the 1963 nuclear bomb peak.

Data from the R/V Mirai cruise (May–June 2000) have been examined to discover how mesoscale processes associated with eddy dynamics direct affect the water masses, the distributions and the vertical fluxes of the dissolved oxygen, nutrients and dissolved inorganic carbon in the western subarctic Pacific. Using maps of the temperature, salinity, dissolved oxygen, nutrients, chlorophyll and sea-air pCO2 difference we

According to the results of the international expedition aboard the R/Vs Roger Revelle and Professor Khromov in the summer 1999, areas with low oxygen contents (below 210 µ M/kg) and those with increased contents of dissolved inorganic carbon and phosphates were found that roughly coincided with one another. These areas are located near the bottom on the southwestern slope of the Tsushima Basin in the region of the Korea Strait and on the continental slope in the region of the Tatar Strait in the northern part of the sea at about 46° N. The set of hydrochemical data points to a high geochemical activity in the near-bottom layer of the areas noted. This activity is confirmed by direct observations of the composition of the interstitial water in the sediments collected in the northern part of the sea during the expedition of R/V Akademik M.A. Lavrent'ev in 2003. It was supposed that the main cause of the increased geochemical activity is the runoff of suspended and dissolved matter from the Korea and Tatar straits. In the areas mentioned, the near-bottom waters are characterized by low values of the nitrogen-phosphorus ratio (below 10), which is geochemical proof of the denitrification process occurring under the conditions of high oxygen concentrations characteristic of the Sea of Japan. Based on the value of the annual production in the Sea of Japan, a rate of denitrification equal to 3.4 × 10 12 gN/year was calculated. Hence, it is confirmed that the geochemical processes in the near-bottom layer have a direct influence on the spatiotemporal characteristics of the hydrochemical properties of the waters of the Sea of Japan.

Zooxanthellate colonies of the scleractinian coral Astrangia poculata were grown under combinations of ambient and elevated nutrients (5 µM NO 3 -, 0.3 µM PO 4 -3 , and 2 nM Fe +2 ) and CO 2 (~780 ppmv) treatments for a period of 6 months. Coral calcification rates, estimated from buoyant weights, were not significantly affected by moderately elevated nutrients at ambient CO 2 and were negatively affected by elevated CO 2 at ambient nutrient levels. However, calcification by corals reared under elevated nutrients combined with elevated CO 2 was not significantly different from that of corals reared under ambient conditions, suggesting that CO 2 enrichment can lead to nutrient limitation in zooxanthellate corals. A conceptual model is proposed to explain how nutrients and CO 2 interact to control zooxanthellate coral calcification. Nutrient limited corals are unable to utilize an increase in dissolved inorganic carbon (DIC) as nutrients are already limiting growth, thus the effect of elevated CO 2 on saturation state drives the calcification response. Under nutrient replete conditions, corals may have the ability to utilize more DIC, thus the calcification response to CO 2 becomes the product of a negative effect on saturation state and a positive effect on gross carbon fixation, depending upon which dominates, the calcification response can be either positive or negative. This may help explain how the range of coral responses found in different studies of ocean acidification can be obtained.