The effect of Razdol’naya River on the environmental state of Amur Bay (the Sea of Japan)

Seasonal variations in biogenic substances (nitrates, nitrites, ammonium, phosphates, and silicates), dissolved oxygen, dissolved organic matter, chlorophyll, humus, and suspended matter at seven stations on the Razdol’naya River are examined. Based on seasonal variations, the local sources of river water pollution by biogenic substances were identified. The annual and daily fluxes of biogenic substances through the Razdol’naya River into Amur Bay are calculated. A diffuse pollution source—agricultural fields in river valley—are shown to be the main source of biogenic substance fluxes. The vast hypoxia in the bottom water of Amur Bay, detected by the authors in 2007 and 2008, is supposed to be mostly caused by floods on the Razdol’naya R., which create favorable conditions of water blooming in Amur Bay in summer. The biomass of dead phytoplankton, experiencing microbiological decomposition and oxidation, causes hypoxia of bottom waters in the bay.     

Dynamics of microelement concentrations in bottom sediments of the marginal filter (Razdol’naya R.–Amur Bay)—Result of biogeochemical processes

Atomic-emission spectroscopy was used to determine the concentrations of Be, Ga, Nb, Ta, Y, Zr, Hf, Sc, Mo, U, and Th in subcolloidal, medium-pelite, coarse-pelite, fine-aleurite, and coarse-aleurite fractions of bottom sediments of Razdol’naya R. marginal filter. The concentrations of examined elements are maximal for the subcolloidal sediment fraction. The average concentration (n = 10) of elements in the soil and fluvial sediments (upstream of the mixing zone) were calculated and taken as background concentrations. The highest concentrations of Y, Be, U was shown to correspond to sediments in the zone of fresh and sea water mixing, which is accompanied by flocculation and sorption on Fe and Mn hydroxides and clay minerals (hydromica in fluvial sediments, and smectite in marine sediments).     

Hydrological-morphological processes in the estuary of the Bol’shoi Vilyui River (Eastern Kamchatka Coast)

The results of many-year field studies are used to discuss the issues of formation of the hydrological regime and the morphological pattern of the estuary of the Bol’shoi Vilyui R., belonging to the subtype of lagoon-lacustrine estuaries. A vast body of factual data, which characterize the estuary and the processes taking place in it, as well as the natural conditions under which it exists.     

Potential effect of sedimentary iron-phosphorus accumulation on frequent algal bloom in the Pearl River Estuary

Based on laboratory culture of harmful alga on iron and phosphorus uptake, and the study of accu-mulation of iron-phosphorus in cores and release of iron and phosphorus from surficial sediments collected in the Pearl River Estuary, the reasons of the high frequency of phytoplankton bloom therein are discussed. The results show that Fe starvation can make algal growth rate slow down and the peak of cell number decrease. Fe and P contents in algal cell bear a significant correlation and the molar ratio of P:Fe is ~356:1, suggesting that algal uptake of Fe and P is synergistic. Total Fe and total P in sediments are positively correlated and Fe-P is the main species of inorganic sedimentary P. Through continuous leaching with agitation, 34.26%―80.21% of exchangeable P and 4.04%―22.52% of ex-changeable Fe are released from surficial sediments, implying that the accumulation of Fe-P in sedi-ments is available for providing nutrients (P and essential Fe) for the demand of phytoplankton bloom. These factors might be responsible for a higher frequency of red tides than other marine regions.     

Spatiotemporal distributions of earthquakes in the northeastern segment of the Amur plate in two phases of variations in the modulus of the Earth’s rotation rate

The modeling results are presented on the annual dynamics of seismicity in the northeastern segment of the Amur plate, which are obtained from statistical studies of the number of earthquakes with magnitudes 2 ≤ М ≤ 6 in different phases of variations in the Earth’s rotation rate. We have calculated a degree of relationship between the observed seismicity variations and phases of decrease and increase in the Earth’s rotation rate for the magnitude ranges between 2 ≤ М < 4 and 4 ≤ М < 5 using rank correlation methods. It has been established that epicenters of earthquakes with magnitudes 5 ≤ М ≤ 6 are spatially grouped into a sequence of homogeneous equally spaced, 3.5°–4°, on average, east-westerly oriented clusters.     

Ecological–Geochemical Conditions of Surface Water and Groundwater and Estimation of the Anthropogenic Effect in the Basin of the Ganjiang River

Water Resources - Data of studies of 2013–2019 were used to assess the current environmental-geochemical conditions of surface water and groundwater in the basin of the Ganjiang River, the...     

Quantifying the sources of dissolved inorganic carbon within the sulfate-methane transition zone in nearshore sediments of Qi’ao Island,Pearl River Estuary,Southern China

The significance of the various biogeochemical pathways that drive carbon cycling and the relative fractions of dissolved inorganic carbon(DIC) produced by these reactions within the sulfate-methane transition zone(SMTZ) are still being debated. Unraveling these processes is important to our understanding of the benthic DIC sources and their contributions to the global carbon cycle. Here, we measure pore water geochemistry(chlorine, sulfate, methane, Ca~(2+), Mg~(2+), DIC and δ~(13)C-DIC) as well as solid geochemistry(sedimentary organic carbon(SOC) and δ~(13)C of SOC) in nearshore sediments from Qi'ao Island in the Pearl River Estuary of the Southern China Sea. Our analysis indicates that SOC originates from the mixing of carbon from terrestrial and marine sources, and that terrestrial materials dominate the net loss of SOC during the degradation of organic matter, especially at sites located near the river outlets. Sulfate reduction via SOC degradation is not appreciable in the upper sediment layer due to conservative mixing-dilution by freshwater. However, below this layer, the anaerobic oxidation of methane(AOM) and methanogenesis occur. Within the SMTZ, the δ~(13)C mass balance shows that the proportions of DIC derived from organoclastic SO_4~(2-) reduction(OSR) and AOM are 50.3% to 66.7% and 0.1% to 17.9%, respectively, whereas methanogenesis contributes 17.0% to 43.9%. This study reveals that the upward diffusion of DIC from ongoing methanogenesis significantly influences carbon cycling within the SMTZ in these estuarine sediments. As a result, we suggest that the plots of the ratio of change in sulfate to change in DIC in pore water should be used with caution when discriminating between sulfate reduction pathways in methane-rich sediments.     

Lateral Inhomogeneity of Basement Layer in Three Gorges Region of Changjiang River (Yangtze River)

Seismic tomography from the Pg wave data along the non-longitudinal profile in the Three Gorges Region is presented in this paper.The seismic tomography method,and the acquisition and analysis of seismic travel time are broadly outlined.The tomography of basement reveals a great amount of significant information and shows that the low-velocity zone is due to the lithologic difference and the fault fracture zone.It also demonstrates that there exist three high-velocity zones with v>6.4 km/s at the basement; the largest of zones which strikes north-south is located at the southwestern side of Huangling Anticlinorium and extends into the anticlinorium northward.The other two high-velocity zones are,respectively,situated at the eastern side of the anticlinorium and the western side of the profile.The high-velocity zones are inferred to originate from the upwelling of material with high-velocity from deep crust.     

Characteristics of vertical ozone distribution in the lower troposphere in the Yangtze River Delta at Lin’an in the spring of 2001

Deterioration of air quality as a result of rapid eco- nomic development in the Yangtze River Delta (YRD) has attracted much scientific and public attention[1―7]. To explore the air quality of a region, measurement of pollutants in locations reflecting the “background” atmospheric conditions of the region is essential. The Regional Baseline Air Quality Monitoring Station of the Chinese Academy of Meteorological Sciences (CAMS) at Lin’an is located in such an area in Zhe- jiang Pro…     

Source characterization and spatio–temporal evolution of the metal pollution in the sediments of the Basque estuaries (Bay of Biscay)

According to Water Framework Directive requirements, Member States must identify and analyze effects derived from human pressures in aquatic systems. As different kind of pressures can impact water bodies at different scales, analyses of spatio-temporal evolution of water bodies becomes essential in order to understand ecosystem responses. In this investigation, an analysis of spatio-temporal evolution of sedimentary metal pollution (Cd, Cr, Cu, Hg, Ni, Pb, Zn) in 12 Basque estuaries (Bay of Biscay) is presented. Data collected in extensive sampling surveys is the basis for the GIS-based statistical approach used. The implementation of pollution abatement measures is reflected in a long-term decontamination process, mostly evident in estuaries with highest historical sediment pollution levels. Spatial evolution is determined by either naturally occurring or human driven processes. Such spatial processes are more obviously being reflected in estuaries with lower historical sediment pollution levels.     

Features and Factors of Hydrological and Morphological Changes in the Agrakhan Bay at the Mouth of the Terek River in the 20th–Early 21st Centuries

Water Resources - The Agrakhan Bay of the Caspian Sea is a unique hydrographic and environmentally valuable object at the mouth of the Terek River. At the beginning of the 20th century, it was a...     

The Carbonate System of the Estuaries of the Syran and Ul’ban Rivers (Ul’banskii Bay,the Sea of Okhotsk) during Spring Flood

Water Resources - In the period of summer flood 2016, a number of chemical characteristics associated with carbon cycle were studied in the estuaries of the Syran and Ul’ban rivers in the...     

Hydrochemical Regime in Riverine Aqual Complexes: Case Study of the Small Il’d River (Rybinsk Reservoir Basin)

Water Resources - The results of studying the space and time dynamics of the hydrochemical regime in discrete aquatic areas of a riverine aquatic–territorial complex of a small river over...     

Magnetic Field Variations and Dynamics of the Outer Electron Radiation Belt of the Earth’s Magnetosphere in February 2014

Geomagnetism and Aeronomy - The paper presents the results of a comparative analysis of the dynamics of relativistic electron fluxes of the Earth’s outer radiation belt and correspondent ring...     

Assessment of water and bottom sediment conditions in the bights of Koz’mina and Lake Vtoroe (Nakhodka Gulf,Peter the Great Bay,the Sea of Japan)

The state of the water area in the Bays of Koz’mina and Lake Vtoroe (Nakhodka Gulf is evaluated. The data given include water temperature and salinity, biochemical oxygen demand, pH, alkalinity, chlorophyll a, organic matter, biogenic elements, oil products, detergents, polycyclic aromatic hydrocarbons, phenols, and organochlorine pesticides in water and bottom sediments. Pollutants may enter the system of bights from both onshore sources and the open part of the bay. The water and bottom sediments in this part of the bay show higher values of BOD5 and the concentrations of oil products, polycyclic aromatic hydrocarbons, phenols, and organochlorine pesticides. The anthropogenic load on the water body is shown to increase because of the new industrial construction on its shore.     

Temporal trend of the suspended sediment transport of the Amazon River (1984–2016)

ABSTRACT

We discuss the claim that the Amazon River has been subjected to a noticeable increase in suspended sediment transport (SST) in response to both climate and land-use changes. To study this, both satellite imagery and in situ data were compiled to produce a 32-year time series (1984–2016) of suspended sediment concentration. Both parametric and nonparametric statistics were applied to examine the SST time trend. The results indicate that there has been no statistically significant increase in SST in the last 32 years, independent of the statistical approach. The results indicate that, over the last 32 years at the Óbidos station, in Brazil, a recurring pattern of increase and decrease in SST has occurred, rather than a unidirectional systematic trend. This further explains the increasing trend reported in the literature and indicates that short time series are not recommended for time trend analyses due to the large inter-annual variability.     

Geochemical types of natural waters in the interfluve of the Enzor’yakhi and the Yun’yakhi (eastern slope of the Polar Urals)

Natural-water chemistry in the interfluve of the Enzor’yakhi and the Yun’yakhi rivers (the eastern slope of the Polar Urals) is characterized in terms of the ratios of major ions belonging to hydrocarbonate calcium-magnesium and magnesium-calcium chemical types. From the viewpoint of evolution of the water-rock system in the region, five geochemical types of water were identified by the degree of their equilibrium with secondary minerals, reflecting different formation conditions of their chemistry. A specific feature of the region is the formation of waters of organogenic geochemical type, which are considerably enriched by organic matter, determining the specifics of migration of some chemical elements in such waters.     

Hydrological Processes in a Lagoon–Channel Estuary in the Warm Season: Case Study of the Mouth of the Bol’shaya R., Western Kamchatka

Water Resources - The results of long-term field studies are used to consider in detail the issues of hydrological regime formation in a lagoon–channel estuary of the Bol’shaya R. in...     

Annual variation in neustonic micro- and meso-plastic particles and zooplankton in the Bay of Calvi (Mediterranean–Corsica)

The annual variation in neustonic plastic particles and zooplankton was studied in the Bay of Calvi (Corsica) between 30 August 2011 and 7 August 2012. Plastic particles were classified into three size classes, small microplastics (0.2–2 mm), large microplastics (2–5 mm) and mesoplastics (5–10 mm).74% of the 38 samples contained plastic particles of varying composition: e.g. filaments, polystyrene, thin plastic films. An average concentration of 6.2 particles/100 m² was observed. The highest abundance values (69 particles/100 m²) observed occurred during periods of low offshore wind conditions. These values rose in the same order of magnitude as in previous studies in the North Western Mediterranean.The relationships between the abundance values of the size classes between zooplankton and plastic particles were then examined. The ratio for the intermediate size class (2–5 mm) reached 2.73. This would suggest a potential confusion for predators regarding planktonic prey of this size class.