Bottom sediments and their role in surface water pollution with mercury (with a special reference to the Northern Dvina River Mouth and the Dvina Bay of the White Sea)

2010 ◽  
Vol 35 (9) ◽  
pp. 611-618 ◽  
Author(s):  
Yu. A. Fedorov ◽  
A. E. Ovsepyan ◽  
V. B. Korobov ◽  
I. V. Dotsenko
Keyword(s):  
Water Pollution ◽  
Surface Water ◽  
Special Reference ◽  
Bottom Sediments ◽  
White Sea ◽  
River Mouth ◽  
The White Sea ◽  
Surface Water Pollution

scholarly journals Biogeochemistry of the Kem' River estuary, White Sea (Russia)

2005 ◽  
Vol 9 (1/2) ◽  
pp. 57-66 ◽  
Author(s):  
V. R. Shevchenko ◽  
Y. S. Dolotov ◽  
N. N. Filatov ◽  
T. N. Alexeeva ◽  
A. S. Filippov ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Bottom Sediments ◽  
Suspended Matter ◽  
White Sea ◽  
Outer Part ◽  
River Mouth ◽  
Adjacent Area ◽  
The White Sea

Abstract. The biogeochemistry of the river-sea interface was studied in the Kem' River (the largest river flowing to the White Sea from Karelian coast) estuary and adjacent area of the White Sea onboard the RV "Ekolog" in summer 2001, 2002 and 2003. The study area can be divided into 3 zones: I - the estuary itself, with water depth from 1 to 5m and low salinity in the surface layer (salinity is lower than 0.2psu in the Kem' River and varies from 15 to 20psu in outer part of this zone); II - the intermediate zone with depths from 5 to 10m and salinity at the surface from 16 to 22psu; III - the marine zone with depths from 10 to 29 m and salinity 21-24.5psu. Highest concentrations of the suspended particulate matter (SPM) were registered in the Kem' mouth (5-7mg/l). They sharply decreased to values <1mg/l towards the sea. At beginning of July 2001, particulate organic carbon (POC) concentration in the river mouth was 404µg/l and POC content in total SPM was 5.64%. In the marine part of the studied area the POC concentration varied from 132 to 274µg/l and the POC contents in suspended matter increased to 19-52.6%. These studies show, that the majority of riverborne suspended matter in the Kem' estuary deposits near the river mouth within the 20psu isohaline, where sedimentation of the suspended matter takes place. The role of fresh-water phytoplankton species decreases and the role of marine species increases from the river to sea and the percentage of green algae decreases and the role of diatoms increases. The organic carbon (Corg) to nitrogen (N) ratio (Corg/N) in both suspended matter and bottom sediments decreases from the river to the marine part of the mixing zone (from 8.5 to 6.1 in the suspended matter and from 14.6 to 7.5 in the bottom sediments), demonstrating that content of terrestrial-derived organic matter decreases and content of marine organic matter increases from the river mouth to the sea. The Kem' estuary exhibits a similar character of biogeochemial processes as in the large Arctic estuaries, but the scale of these processes (amount of river input of SPM, POC, area of estuaries) is different.

scholarly journals The Study of Uranium Accumulation in Marine Bottom Sediments: Effect of Redox Conditions at the Time of Sedimentation

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 332
Author(s):  
Nadezhda Khaustova ◽  
Yulia Tikhomirova ◽  
Svetlana Korost ◽  
Elena Poludetkina ◽  
Andrey Voropaev ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
White Sea ◽  
Uranium Content ◽  
Black Shales ◽  
Redox Conditions ◽  
Source Rocks ◽  
Shelf Zone ◽  
The Black Sea ◽  
The White Sea ◽  
Run Off

To evaluate the effect of redox conditions at the sedimentation stage on uranium content and U/TOC ratio in marine source rocks, we analyzed the accumulation of uranium in modern marine bottom sediments formed in different redox conditions. The behavior of uranium from bottom sediments formed in oxidizing and sub-oxidizing settings has been studied on the sediments of the Upper Pleistocene–Holocene age accumulated in the coastal area of the White Sea (Kandalaksha Gulf). We studied the content of uranium, Eh, pH, TOC, C, H, N, and S element and isotope compositions and other parameters in two sampled columns of bottom sediments at a depth of 0–2.5 m. The composition of sediments was typical for the shelf zone where marine genesis mixes with the continental run-off. The upper layer of sediments (0–50 cm) were characterized by oxidizing conditions (Eh ~ 400 mV); with the increase in depth, redox conditions changed from oxidizing to reducing (0 ÷ 200 mV). The uranium concentration in the upper layer was 1–1.5 ppm, U/TOC ratio varied in the range of 0.8–1.1 ppmU/%TOC. The uranium content and U/TOC ratio increased up to the values of 2.6 ppm and 1.4 ppmU/%TOC at a depth of 0.5−2.5 m, respectively, but the general content of uranium in the studied environment was close to the values characterizing continental run-off. The results obtained for the White Sea sediments were compared with the sediment of the Black Sea, formed in the anoxic conditions of hydrogen sulfide contamination. In these conditions, the uranium content varied from 10 to 20 ppm. The obtained data were interpreted using thermodynamic modeling of the uranium forms in the seawater at different pH and Eh. This study demonstrated that the change of redox conditions from oxidizing to reducing leads to increased uranium content due to a decrease in uranium’s solubility in water. These results show that oxidation–reduction potential could be one of the most important factors controlling uranium content in black shales formed in the marine environment.

Evaluarea impactului ecositemelor urbane asupra mediului în regiunea de dezvoltare economica Centru

2019 ◽  
Author(s):  
Constantin Bulimaga ◽  
◽  
Corina Certan ◽  
Keyword(s):  
Water Pollution ◽  
Surface Water ◽  
Anthropogenic Impact ◽  
Ph Value ◽  
Urban Ecosystems ◽  
Soil Extract ◽  
Specific Character ◽  
Surface Water Pollution

Regardless of the fact that both urban ecosystems studied – Orhei and Telenești – have purification stations, they are still an essential source of surface water pollution. The aqueous soil extract (Telenești) has a pH value of 8 up to 9.8 due to the high content of calcium and potassium in the soil, due to the fact that the area under investigation has a specific character caused by the spread of solonetz-type soils, solonized chernozems, and salinated soils. The anthropogenic impact in urban ecosystems produces an imbalance in the ratio of spontaneous species and ruderal and ruderal-segetal species. The number of spontaneous species is the indicator of the degree of anthropization in urban ecosystems. Urban ecosystems have a major impact on the environment.

Sign in / Sign up

Export Citation Format

Share Document