Nutrient Transport into the White Sea with River Runoff

Averaged data from long-term observations of concentrations of mineral-nutrient fractions along with fragmentary data and indirect estimates of organic-component concentrations in the tributaries of the sea (the Niva, the Onega, the Northern Dvina, the Mezen, and the Kem rivers) are analyzed. Monthly variations in the concentrations of the major nutrients in the river water flowing into the sea are characterized, and relationships between them in different seasons are determined. Annual nutrient transport into the White Sea by river water is assessed based on characteristics of river runoff and nutrient concentrations using a mathematical model. Wide variations are established in the ratios of organic and mineral fractions of nutrients delivered into the sea. The shares of mineral components in the total runoff of N_tot and P_tot into the sea are found to be equal to 18.1 and 18.8%, respectively.     

Space and time variations in concentrations of biogenic and organic matter and phytoplankton in the water of the Selenga River and its delta branches

Specific features of the concentration dynamics of biogenic substances, organic C, and phytoplankton in the lower reaches of the Selenga and its delta branch are identified. The quantitative and qualitative changes in these components are demonstrated for the conditions of extremely low water abundance. High correlation was shown to exist between variations of the concentrations of nitrate N, mineral P, and phytoplankton biomass.     

Seasonal and Long-Term Variations in the Concentrations and Discharges of Biogenic Substances in the Razdolnaya River (Primorskii Krai)

Seasonal and long-term variations in the concentrations and discharge of dissolved nitrogen compounds and other biogenic substances by the Razdol'naya River runoff in the last 20 years are considered. The Razdol'naya River is one of the major rivers in the region, and its basin is subject to intense economic development. The natural and anthropogenic factors that affect variations in the concentrations of biogenic substances are characterized. The seasonal variations in the discharge of biogenic substances is shown to be controlled mostly by variations in water discharge.     

Concentration dynamics of biogenic elements and phytoplankton at Selenga R. Mouth and in Selenga shallows (Lake Baikal)

The seasonal and year-to-year dynamics of the concentrations of biogenic elements and organic matter, as well as quantitative composition of phytoplankton in water of Selenga delta branches is studied. The distribution of those components from the mouth of the Kharauz branch (the main branch) to the water area of the Selenga shallows in different hydrological seasons is shown. The concentrations of nitrate nitrogen and phosphate phosphorus in the zone of mixing of river and lake waters have been found to drop by 30 and 50%, respectively, because of the consumption of those substances by phytoplankton.     

Long-term variations of water quality of the Selenga and Kiran rivers at the Russian-Mongolian boundary

Principal-Component Method is used to identify the major factors governing the long-term variations of water chemistry in the transboundary rivers of Selenga and Kiran. Their preliminary interpretation was made. Water chemistry formation in both large (Selenga) and small (Kiran) rivers is shown to be mostly governed by natural-climatic factors. Thus, an increase in water abundance has a dual effect on water chemistry: on the one hand, water is enriched with substances increasingly entering it because of the more intense erosion and dissolution of solid rocks, and, on the other hand, the concentrations of chemicals of anthropogenic origin decrease because of their greater dilution. A conclusion was made regarding a relationship between a positive trend in water temperature and an increase in the concentration of chlorine ion in water. A preliminary estimate is given to the effect of municipal and industrial wastes, as well as surface and subsurface waters of various genesis on long-term variations of river water chemistry. Trends in changes in water chemistry were studied by using approximations of long-term series of the variables that determine the interpretation of principal factors with the help of a slow trend by “caterpillar” method.     

Suspended and Dissolved Forms of Nutrients: Their Relationships and Interaction in the Major Tributaries of the Caspian Sea

Normal annual data are used to evaluate the within-year variations in the concentrations of biogenic substances (organic and mineral components of N and P, dissolved organic carbon, inorganic Si) in the major tributaries of the Caspian Sea. Variations in the concentrations of biogenic substances are analyzed, the relationships between their mass concentrations in individual months are evaluated, and correlation between the organic and mineral components of N and P and their aggregated fractions are established. The obtained high-significance correlation between the concentrations of N and P components suggests that the rates of biochemical processes of biogenic substance transformation taking place in the water of tributaries are commensurable.     

Spatial distribution of phosphorus forms in sediments in the Gulf of Gdańsk (southern Baltic Sea)

The paper analyses the concentrations of total phosphorus and its forms in sediments from the Gulf of Gdańsk on the basis of studies conducted at 25 sampling sites in 2001–05. The phosphorus speciation analysis was performed by sequential extraction. The extensive spatial variability of P_tot concentrations and speciation was found to be dependent on the physicochemical properties of the sediments, the oxygen conditions in the water and sediments, and the depth of the water column above the sediment surface. In the coastal zone, the sedimentation of riverine suspended matter and the sorption and chemisorption processes exert a considerable influence on P speciation. Over 70% of variation of total phosphorus concentration in sediments in the Gulf of Gdańsk could be explained by changes of proportion of fine fraction of sediments (grain size <0.0625 mm). Maximum P_tot concentrations were recorded in clays and silts in the deep water, stratified part of the Gulf of Gdańsk. In the coastal zone, where sandy sediments are dominant, phosphorus concentrations were much lower; this was due to the considerable dynamics of the bottom water and intensive sea floor transport. P_tot concentrations in the Gulf of Gdańsk sediments ranged from 1.75 to 957.17 μmol g⁻¹ d.w. Of all the forms of phosphorus, the highest concentrations were found for organic phosphorus (Org-P). Of its inorganic forms, the highest concentrations were of phosphorus bound to clay minerals and aluminium oxides (NaOH-P), the lowest ones were of loosely bound phosphorus (NaCl-P). On the basis of determinations of total phosphorus concentrations in sediments of a given type and the available data on the seabed areas covered by particular sediment types in the Gulf of Gdańsk, the mass of total phosphorus in the surficial sediment layer (0–2 cm) was estimated at ca. 15.6×10³ tonnes.     

The regime of dissolved gases and organic matter in Selenga basin rivers

The gas regime and active reaction of water in Selenga basin rivers are analyzed. It is shown that, in the lower reaches of the Selenga and Uda rivers, which experience the highest anthropogenic impact, the minimal values of hydrogen index were recorded in under-ice period, while in the rivers of Chikoi, Khilok, Dzhida, and Temnik, during spring flood and summer freshets. The concentrations of organic substances are heterogeneous and vary widely under the effect of matter input with major tributaries and wastewater discharge from GOS. It has been established that the concentrations of readily oxidizable organic substances in 28–33% of the taken samples are above the established standards on maximal allowable concentrations in the period of open river channels. In spring and autumn, the organic matter in the rivers of the basin is mostly represented by soil terrigenous material.     

The role of zooplankton in phytoplankton biomass decline and water transparency regulation in a water body subject to high organic and mineral load

Under biogenic load and at high abundance of ichthyofauna (the concentration of total phosphorus P_tot = 0.20 mg P/l, mineral phosphorus P_min = 0.13 mg P/l, and at the ratio N: P = 4: 1 in early summer), zooplankton reduced phytoplankton biomass during summer and autumn and determined high water transparency, reaching >50% of the depth of the water body. It was found that, with a passage of ichthyofauna to artificial food, the trophic press of plankton-eating fish on zooplankton decreases. Under such conditions, with the biomass ratio of plant-eating zooplankton to edible phytoplankton between 0.4 and 7.9, zooplankton can reduce phytoplankton biomass within a day. The major portion (up to 100%) in phytoplankton biomass reduction was due to large-size filterers-phytophages Daphnia longispina and verticators Asplanchna priodonta helvetica.     

Transformations of Organogenic Substances in the White Sea Ecosystem: Assessment Based on the Results of Mathematical Modeling

Methods of systems analysis and mathematical modeling are used to generalize hydrological, hydrochemical, and hydrobiological observational data with the aim to study the biohydrochemical conditions of organic and biogenic substance transformations in eight water areas in the White Sea. A hydroecological model describing transformations of N, P, and Si compounds and dissolved organic C, as well as the regime of O₂ was used as a means of the study. Water exchange between water areas was evaluated using a hydrodynamic model. Averaged data on annual variations in water temperature, illumination, and transparency, as well as run-off characteristics (water flow in river mouths and organic and biogenic matter concentrations in the river water entering the sea) were used to calculate the dynamics of organic and mineral compounds of nutrients in different areas of the sea. The principal attention is paid to the verification of the model against field observational data, assessment of the biomass development conditions of aquatic animals, analysis of model results regarding the turnover time of organic and mineral components, and the evaluation of balances of organic dissolved and particulate N and P forms.__________Translated from Vodnye Resursy, Vol. 32, No. 4, 2005, pp. 435–451.Original Russian Text Copyright © 2005 by Leonov, Filatov, Chicherina.     

喀斯特筑坝河流中生物碳泵效应的碳施肥及对水化学时空变化的影响——以贵州平寨水库及红枫湖为例

耦联水生光合作用的碳酸盐风化碳汇是全球碳循环的重要组成部分,而生物碳泵效应是稳定碳酸盐风化碳汇的关键机制.河流筑坝后,生物碳泵效应的变化、控制因素及对水化学影响的研究甚少.本研究对2个喀斯特筑坝河流平寨水库和红枫湖进行系统采样,以研究河流筑坝后生物碳泵效应的变化、控制因素及对水化学的影响.研究结果表明,入库河流的水化学变化不明显,而2个水库的水化学则表现出显著的季节变化特征,具体表现为水库的水温和pH均呈现出夏季高、冬季低的变化特征,而电导率（EC）、HCO₃^-浓度和pCO₂则表现出夏季低、冬季高的季节变化特征.以叶绿素a（Chl.a）浓度和溶解氧（DO）饱和度指代的生物碳泵效应则是在夏季最强、冬季最弱.生物碳泵效应利用溶解性无机碳（DIC）,形成有机质并释放出氧气,是造成夏季水库pH值和DO饱和度升高,电导率（EC）、HCO₃^-浓度和pCO₂降低的主要因素.空间上,水库的Chl.a浓度及DO饱和度均大于河水,EC、HCO₃^-浓度和pCO₂均小于河水,这表明河流筑坝后,由于水库的“湖泊化”导致水库的生物碳泵效应显著提高.通过对Chl.a与碳、氮和磷浓度及化学计量比的相关性分析发现,平寨水库和红枫湖的生物碳泵效应受到碳施肥的影响.平寨水库和红枫湖水库生物碳泵效应碳施肥机制的发现,表明在喀斯特地区,生物碳泵效应不仅受到氮磷元素的控制,也受到碳元素的控制,因此在富营养化湖泊治理时,也应考虑碳的影响.     

Hydrochemical and Microbiological Features of Lake Mogil'noe

A comprehensive hydrochemical and microbiological study was conducted in Lake Mogil'noe. The vertical hysrochemical structure of the lake was analyzed. Large amounts of mineral compounds containing biogenic elements and their organic forms are shown to accumulate in the anaerobic zone of the lake. An abrupt increase in the concentration of C_org is recorded in the near-bottom layer, where it is almost an order of magnitude higher than that in the anaerobic zone of the Black Sea at a depth of 2000 m. All the processes are found to be most rapid in the boundary layer between the aerobic and anaerobic zones (8.25–9.25 m), where the primary production attains its maximum, the concentration of sulfates abruptly increases relative to the aerobic and anaerobic zones, microorganism population is maximum, as are the rates of sulfate reduction and glucose consumption by heterotrophic organisms.     

Constraints of authigenic carbonates on trace elements (Sr, Mg) of lacustrine ostracod shells in paleoenvironment reconstruction and its mechanism

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15-55 m) of the Heqing Basin in Yunnan Province, southwest China. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo re- flected the changes in its ambient water composition and ecology; (2) the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly con- trolled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in fu- ture in vitro experiments.     

Long-term trends in total and anthropogenic discharge of organic and biogenic substances by Russian rivers into the Arctic and Pacific seas

The discharge of organic and biogenic substances by Russian rivers into the Arctic and Pacific seas, their anthropogenic component, and the trends in variations in the runoff of some components in individual periods of 1981–2000 are estimated.     

Radiocesium in Ponds in the Near Zone of Fukushima Dai-ichi NPP

The article presents the results of studying radiocesium concentration and distribution between dissolved and particulate forms in ponds in the near zone of Fukushima Dai-ichi NPP NPP after the 2011 accident. The total concentration of ¹³⁷Cs in pond water and its variations are shown to be largely governed by the concentration of particulate matter being as high as 68 Bq/L, compared with 5 Bq/L in solution. The values of the distribution coefficient K_d in the ponds are similar to those in rivers and in large flow-through lakes in the accidentally polluted zone at Fukushima Dai-ichi NPP. The contributions of the main competing ions K⁺ and NH ₄ ⁺ to radiocesium desorption from solid particles into solution were similar for the ponds; however, their relative effect on dissolved radiocesium concentration varied over time because of variations in ammonium concentration.     

Fe/P concentration ratio in Mozhaisk reservoir deposits as an indicator of phosphate sorption

A relationship is established between within-year variations in Fe_tot/P_tot ratio in pore solution and the concentration of organic P compounds in solid phase. The passage of the FeOOH-P system in the silts of the Mozhaisk Reservoir from the aerobic conditions to aerobic is generally accompanied by dissolution of FeOOH and desorption of phosphates. The change from anaerobic conditions to aerobic during the spring and autumn seasons exhibits hysteresis in oxidation of Fe compounds in silts, such that variations in Fe/P ratio in the solid phase of silt do not agree with those in the pore solution.     

Long-term trends in the total and anthropogenic discharge of organic and biogenic substances by Russian rivers into the Baltic,Black, Azov,and Caspian seas and into Lake Baikal

The discharge of organic and biogenic substances by Russian rivers into the Baltic, Black, Azov, and Caspian seas and into Lake Baikal, as well as their anthropogenic component, and trends in variations in the runoff of ingredients are evaluated for individual periods in 1981–2000.     

The role of zooplankton in the regulation of phytoplankton biomass growth and water transparency in water bodies polluted by nutrients

Experimental studies were carried out in a water body near Moscow and in a flow-through system in the territory of fertilized agricultural fields. It is shown that under high biogenic load, at the concentrations P_tot = 0.14 mg P/l, P_min = 0.07 mg P/l, and the ratio N: P = 7.9: 1, in early summer, and in the absence of plankton-eating fish, zooplankton was regulating phytoplankton development and contributed to the preservation of high water transparency. At the biomass ratio of plant-eating zooplankton to eatable phytoplankton from 0.6 to 42.2, zooplankton can reduce the eatable part of phytoplankton within a day. The main consumers of the eatable fraction of phytoplankton biomass were large-size filterers Daphnia longispina.     

Zonal features of the distribution of biogenic elements and organic matter in small lakes

The results of large-scale studies of water chemistry in small lakes in European Russia were used to characterize the distributions and ratios of biogenic elements and organic matter from the viewpoint of the zonal peculiarities of their turnover rate. Latitudinal regularities were identified in the limiting of lake production with respect to major biogenic elements. A classification of lakes is proposed, where the lakes are regarded as a system based on the percent distribution of organic carbon, nitrogen and phosphorus forms, as well as the trophic status and the totality of indices characterizing the origin of OM and the extent of its transformation.     

The Role of Microorganisms in the Transformation of Biogenic Substances in the Caspian Sea Ecosystem: An Assessment Based on Mathematical Modeling

A hydroecological model is used to study the transformations of biogenic-element (N, P, C, and Si) compounds in different parts of the Caspian Sea. The existing notions of the biotransformation processes of these compounds in the marine environment are formalized. The state of the marine environment is characterized based on calculated annual dynamics of biogenic element concentrations, their relationships, and internal fluxes. Relationships between the concentrations of N and P mineral components are used to establish distinctions between different parts of the sea in the conditions of primary production limited by biogenic elements, as well as the development conditions of aquatic lifeforms (nutrient consumption, release of metabolic products, and detritus formation).