Terrigenous pyroclastic matter as a source of dissolved calcium in the ocean

It has been found experimentally that the intensity of the leaching under the interaction of volcanic ash and seawater decreases as Ca > Mg > Si, and the mobilization of calcium and magnesium is more intense compared to silicon by factors of 30?C70 and 20?C50, respectively. Calcium and magnesium supplied to seawater owing to the halmyrolysis of the terrigenous pyroclastic matter may then interact with the products of organic matter oxidation to fix the free carbon dioxide in the form of autochthonous carbonates. It was shown that the halmyrolysis of terrigenous pyroclastic matter could not provide the complete immobilization of the autochthonous CO₂ produced in the ocean by the oxidation of organic matter. Thus, some other sources exist for the reactive silicates of calcium and magnesium, and these might probably be the silicates of the continental runoff of solid substances.     

Comparison of Field and Satellite Data on the Total Cloudiness for the Atlantic Ocean in the Period 2004–2014

Oceanology - The aim of this study is to compare satellite measurements of the total cloudiness with visual observations of clouds. This makes it possible to compare “different...     

Volcanic Ash as a Source of Dissolved Phosphorus in the Ocean

The process of phosphorus migration from volcanic ash and obsidian to seawater was experimentally studied. For obsidian and ash of the Ksudach, Karymskiy, and Eyjafjallajökull volcanoes, the specific mobilization of phosphorus ranges from 0.3 to 5.0 µg P/g with an average value of ～1.5 µg P/g. The maximum dissolved mineral phosphorus input into the ocean as a result of the interaction between pyroclastic material from arc volcanism and seawater is 4500–9000 t/yr, which does not exceed 0.3–0.6% of its input from river runoff.

     

Medium-Term Earthquake Forecast Method Map of Expected Earthquakes: Results and Prospects

Izvestiya, Atmospheric and Oceanic Physics - This paper is the first in a series of studies generalizing the Map of Expected Earthquakes (MEE) medium-term earthquake forecast method and analyzing...     

Electronic atlas of the Russian Arctic coastal zone

A set of digital maps including geology, Quaternary sediments, landscapes, engineering-geological, vegetation, geocryological and the series of regional sources have been selected to characterize the Russian Arctic coast. Based on this data, new maps of engineering geocryological zoning and zoning of the coast with respect to the intensity of exogenous geological processes and risk of technogenic impacts have been generated at the scales of 1:4,000,000–1:8,000,000. These maps are a tool to assess the impact of industry on the Arctic coast of the country.     

Mussels document loss of bioavailable polycyclic aromatic hydrocarbons and the return to baseline conditions for oiled shorelines in Prince William Sound, Alaska

Polycyclic aromatic hydrocarbons (PAH) were measured in mussels (Mytilus trossulus) collected between 1990 and 2002 from 11 sites on the shores of Prince William Sound (PWS), Alaska, that were heavily oiled by the 1989 Exxon Valdez oil spill (EVOS). This study, utilizing the methods of the NOAA Status and Trends Mussel Watch Program, found that concentrations of PAH released from spill remnants have decreased dramatically with time and by 2002 were at or near the range of total PAH (TPAH) of 3-355 ng/g dry weight obtained for mussels from unoiled reference sites in PWS. Time-series TPAH data indicate a mean TPAH half-life in mussel tissues of 2.4 years with a range from 1.4 to 5.3, yielding an annual mean loss of bioaccumulated TPAH of 25%. The petroleum-derived TPAH fraction in mussel tissues has decreased with time, reflecting the decreasing release of EVOS residues in shoreline sediments. These results show that PAH from EVOS residues that remain buried in shoreline sediments after the early 1990s are in a form and at locations that have a low accessibility to mussels living in the intertidal zone.     

Management of a shallow temperate estuary to control eutrophication: The effect of hydrodynamics on the system’s nutrient loading

The Mondego estuary, a shallow warm-temperate intertidal system located on the west coast of Portugal, has for some decades been under severe ecological stress, mainly caused by eutrophication. Water circulation in this system was, until 1998, mainly dependent on tides and on the freshwater input of a small tributary artificially controlled by a sluice. After 1998, the sluice opening was effectively minimised to reduce the nutrient loading, and the system hydrodynamics improved due to engineering work in the upstream areas. The objective of the present study was to evaluate the effect of the mitigation measures implemented in 1998. Changes to the hydrodynamics of the system were assessed using precipitation and salinity data in relation to the concentrations of dissolved inorganic nutrients, as well as the linkage between dissolved N:P ratios and the biological parameters (phytoplankton chlorophyll a concentrations, green macroalgal biomass and seagrass biomass). Two distinctive periods were compared, over a ten year period: from January 1993 to January 1997 and from January 1999 until January 2003. The effective reduction in the dissolved N:P atomic ratio from 37.7 to 13.2 after 1998 is a result of lowered ammonia, but not the oxidised forms of nitrogen (nitrate plus nitrite), or increased concentrations of dissolved inorganic phosphorus. Results suggest that the phytoplankton is not nutrient limited, yet maximum and mean biomass of green macroalgae was reduced by one order of magnitude after the mitigation measures. This suggests that besides lowering the water residence time of the system, macroalgal growth became nitrogen limited. In parallel to these changes the seagrass-covered area and biomass of Zostera noltii showed signs of recovery.