The influence of geochemical processes in the near-bottom layer on the hydrochemical characteristics of the waters of the Sea of Japan

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 μM/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 × 10¹² 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.     

Statistical forecast of temperature dynamics within month on the basis of hydrodynamic model outputs

A method of a long-term forecast of smoothed temperature dynamics within month with a zero lead time for some Russian sites is considered. A procedure of a search for optimum predictors and a regression-analog prediction scheme are described. Hydrodynamic forecasts for the first ten days of the prognostic month are used as a predictor. Results of the prediction scheme verification on independent data with the use of hydrodynamic model outputs are discussed. Ways to improve the prediction scheme are suggested.     

Algorithm for Calculating the Mineralization of Riverine Waters and Salinity of Estuarine Waters from Conductivity Data

Oceanology - The empirical relationship between the mineralization of riverine waters and specific conductivity normalized to 15°C was obtained in testing Razdolnaya River water from March...     

Estimation of Primary Production in the Northwestern Part of the Sea of Japan by Ship- and Satellite-Based Observations

Oceanology - The study analyzes data of ship-based observations on 45 stations performed aboard the R/V Akademik M.A. Lavrentyev on cruise 33 May 7–18, 2004, in the northwestern part...     

Multimodel approach to seasonal prediction

Multimodel forecast fields of temperature at 850 hPa and seasonal precipitation are combined using a procedure of two-step averaging. It is shown that the resulting forecasts averaged over the multimodel ensemble outperform the forecasts of individual models. The verification of forecast production has been carried out on cross-validated hindcasts according to WMO requirements. The simulation of spatiotemporal variability of atmospheric variables is assessed. The results indicate that the combined models are rather skillful in the tropical oceans, while the accuracy in the extratropics is poor.     

The carbonate system of Amur Bay (sea of Japan) under conditions of hypoxia

In the course of the expedition of the Pacific Oceanological Institute in August 2007, extensive hypoxia was found in the near-bottom layer of the Amur Bay water mass. The hypoxia’s formation was immediately reflected in the values and distribution of the carbonate parameters in the near-bottom waters of the bay. The maximum values of the carbon dioxide partial pressure, the dissolved inorganic carbon, and the total alkalinity were associated with the areas of the minimum oxygen content. The microbial destruction of the dead phytoplankton greatly increased the partial pressure of carbon dioxide, which was over 2000 μatm in the hypoxia centers at a depth of about 20 m. At the same time, the carbon dioxide partial pressure in the surface waters of Amur Bay was considerably lower than that in the atmosphere. Hence, the bay’s aquatic area was a sink for the atmospheric CO₂ despite its high content in the near-bottom waters. It was shown that the excess alkalinity associated with the hypoxia sites in the near-bottom layer of water was caused by the sulfate reduction proceeding in the upper layer of the sediment.     

Radium Isotopes and Nutrients in Razdolnaya River Estuary (Amur Bay,the Sea of Japan) in the Period of Summer Flood

Water Resources - The activity of dissolved radium isotopes 223Ra, 224Ra, 228Ra, the concentrations of nutrients: ammonium, nitrates, nitrites, phosphates, silicates, total nitrogen, and total...     

Major ion composition and carbonate equilibrium in the sediment pore water of the Razdol’naya River estuary of Amur Bay,the Sea of Japan

The complex study of the river water and pore solutions from the bottom sediments in the lower reaches of the Razdol’naya River was conducted in February 2010. The major ion composition of the waters indicates the submarine origin of the near-bottom and pore waters in the lower reaches of the Razdol’naya River in the winter. The river estuary extends upstream for more than 20 km. It was established that the studied sediments are reduced oozes containing pyrite, hydrotroilite, and iron monosulfide, which is direct evidence for sulfate-reduction in the sediments. The diagenesis of organic matter is the main reason for the considerable decrease in the amount of sulfates and the increase in the alkalinity of the sediment pore water. The sedimentary pore water sampled from the deep river pits is characterized by excess alkalinity that cannot be explained by sulfate-reduction and methane genesis. It was suggested that the chemical weathering of silicate minerals and the bacterial mineralization of salts of organic acids could result in the excess alkalinity of the sediment pore water.     

Estimation of Bivalve Mollusk Plantation Productivity Based on Simulation Results

Oceanology - The potential productivity of oysters and mussels was estimated for Voevoda Bay (Russky Island, Primorskii krai) using the FARM model. The main sources of primary production in the...