Distribution Of Biogenic Elements Research Articles

Estimation of 226Ra and 228Ra Content Using Various Types of Sorbents and Their Distribution in the Surface Layer of the Black Sea

Radium isotopes have traditionally been used as tracers of surface and underground fresh waters in land-ocean interactions. The concentration of these isotopes is most effective on sorbents containing mixed oxides of manganese. During the 116 RV Professor Vodyanitsky cruise (22 April-17 May 2021), a study about the possibility and efficiency of 226Ra and 228Ra recovery from seawater using various types of sorbents was conducted. The influence of seawater flow rate on the sorption of 226Ra and 228Ra isotopes was estimated. It was indicated that the Modix, DMM, PAN-MnO2, and CRM-Sr sorbents show the best sorption efficiency at a flow rate of 4-8 column volumes per minute. Additionally, the distribution of biogenic elements (dissolved inorganic phosphorus (DIP), silicic acid, and the sum of nitrates and nitrites), salinity, and 226Ra and 228Ra isotopes was studied in the surface layer of the Black Sea in April-May 2021. Correlation dependencies between the concentration of long-lived radium isotopes and salinity are defined for various areas of the Black Sea. Two processes control the dependence of radium isotope concentration on salinity: conservative mixing of riverine and marine end members and desorption of long-lived radium isotopes when river particulate matter meets saline seawater. Despite the high long-lived radium isotope concentration in freshwater in comparison with that in seawater, their content near the Caucasus shore is lower mainly because riverine waters meet with a great open seawater body with a low content of these radionuclides, and radium desorption processes take place in an offshore area. The 228Ra/226Ra ratio derived from our data displays freshwater inflow spreading over not only the coastal region, but also the deep-sea region. The lowered concentration of the main biogenic elements corresponds to high-temperature fields because of their intensive uptake by phytoplankton. Therefore, nutrients coupled with long-lived radium isotopes trace the hydrological and biogeochemical peculiarities of the studied region.

Effect of dam removal of small hydropower station on migration and distribution of biogenic elements: Progress and prospects

The small hydropower stations have reached a new balance after years of operation. The ecological balance of the river would been broken by the dam removal and the reservoir area above the dam would disappear. Consequently, a series of changes occurred in water depth, velocity of flow, the concentration of organic and inorganic nutrients, distribution and form of organic matter, aquatic organism, etc. It is unclear what would happen for the hydrodynamic conditions, sediment characteristics and aquatic organism community structure of the reservoir area and the lower reaches after the dam removal. Therefore, it is urgent to study the impact of dam removal on the transportation and redistribution of organic debris and the potential ecological effects with benthos as indicators in the river where the small hydropower station is located.

Phytomass Reserves and Distribution of Biogenic Elements in Gmelin Larch Stands in Central Evenkia (Using the Example of a Small Drainage Basin)

For the first time, for a small watershed in Central Evenkia, using the method of model trees, a change in the composition and structure, as well as in the phytomass and biogenic elements reserves in larch forests, depending on the age of the stands, was revealed. It was found that the main mass-forming components in the phytomass of all stands are the trunk and root fractions. The proportion of the trunk phytomass increases and the proportion of branches and needles decreases with age. It was found that the composition of the roots changes little with the age of the stand, which confirms the hypothesis of the annual primary carbon investment into larch roots in the permafrost zone. It is shown that the largest carbon reserves are accumulated in overmature stands, while nitrogen reserves accumulates in the needles of young stands.

Periodic dependences in the distribution of chemical elements in the human hair ash residue

150 years ago D. I. Mendeleev revealed the Periodic law to the world and since that time periodic dependencies have been increasingly used in various fields of basic and applied sciences. For the first time we consider the regularities of periodic dependences of the concentration of chemical elements in the ash residue of human hair on the number of the element. Such dependencies for various regions of Russia reveal strictly individual character. It is shown that distributions of the chemical elements for men and women also differ, as well as the distributions determined for the same groups in inhabitants of different regions of residence and depend to a significant extent on the genetic and physiological characteristics of human organism, variability of environmental conditions, earlier diseases and other impacts. This means that population of different urban regions (e.g., Siberian region) is characterized by a strictly individual distribution of biogenic elements. A hypothesis has been put forward that extrema observed on the studied dependences can be a kind of code for a given locality, reflecting correlation with various factors of genetic and ecological nature.

The distribution of biogenic substances in waters of the North Atlantic

The article considers the main regularities of distribution of biogenic elements in accordance with the dissolved oxygen and hydrological characteristics of the marine environment. To study the spatial distribution of biogenic elements taken three main forms of substances in the marine environment: phosphates, nitrates, silicates. Because these compounds in ocean are crucial importance for the development of life. Shows the role of hydrodynamic factors that most significantly affect the distribution and redistribution of nutrients in the waters of the North Atlantic. Quantitative evaluation of the nutrient transport system of currents. The calculated weight amount of phosphates transported by the stream per unit time.

Biogeochemistry of bulk organic matter and biogenic elements in surface sediments of the Yangtze River Estuary and adjacent sea

This study investigated the distribution and roles of total organic carbon (TOC), biogenic silicon (BSi), various forms of nitrogen (N) and phosphorus (P), and the stable carbon isotope (δ13C) in surface sediments of the Yangtze River Estuary (YRE) and adjacent sea. Terrestrial input accounted for 12–63% of total organic matter in the study area. The distribution of biogenic elements was affected by the Changjiang Diluted Water, the Jiangsu Coastal Current, human activities, marine biological processes, and the sediment grain size. Potentially bioavailable N and P accounted for an average 79.6% of the total N (TN) and 31.8% of the total P (TP), respectively. The burial fluxes for TOC, BSi, TN and TP were 39.74–2194.32, 17.34–517.48, 5.02–188.85 and 3.10–62.72μmolcm−2yr−1, respectively. The molar ratios of total N/P (1.2–5.0), Si/P (5.0–14.8) and Fe/P (21–61) indicated that much of the P was sequestered in sediments.

Effects of Spartina alterniflora invasion on biogenic elements in a subtropical coastal mangrove wetland.

The invasion by exotic cordgrass (Spartina alterniflora) has become one of the most serious and challenging environmental and ecological problems in coastal China because it can have adverse effects on local native species, thereby changing ecosystem processes, functions, and services. In this study, 300 surface sediments were collected from 15 stations in the Jiulong River Estuary, southeast China, across four different seasons, in order to reveal the spatiotemporal variability of biogenic elements and their influencing factors in the subtropical coastal mangrove wetland. The biogenic elements including carbon, nitrogen, and sulfur (C, N, and S) were determined by an element analyzer, while the phosphorus (P) was determined by a flow injection analyzer. The concentrations of biogenic elements showed no significant differences among four seasons except total phosphorus (TP); however, our ANOVA analyses revealed a distinct spatial pattern which was closely related with the vegetation type and tidal level. Values of total carbon (TC) and total nitrogen (TN) in the surface sediment of mangrove vegetation zones were higher than those in the cordgrass and mudflat zones. The concentrations of TC, TN, TP, and total sulfur (TS) in the high tidal zones were higher than those in the middle and low tidal zones. Redundancy analysis (RDA) revealed that tidal level, vegetation type, and season had some significant influence on the distribution of biogenic elements in the Jiulong River Estuary, by explaining 18.2, 7.7, and 4.9 % of total variation in the four biogenic elements, respectively. In conclusion, S. alterniflora invasion had substantial effects on the distributions of biogenic elements in the subtropical coastal wetland. If regional changes in the Jiulong River Estuary are to persist and much of the mangrove vegetation was to be replaced by cordgrass, there would be significant decreases on the overall storage of C and N in this coastal zone. Therefore, the native mangrove reforestation and exotic cordgrass elimination should be a priority in mangrove sustainable management for coastal ecosystem health.

About the effect of chemical-biological processes on the diurnal variance of hydrochemical parameters (numerical model)

Data on the diurnal variability of phosphate and oxygen concentrations are analysed using a numerical model, which considers chemical-biological processes and vertical turbulent exchange. We consider how the variation of the photosynthetic rate due to the diurnal course of illumination may affect the variability of these elements. Some modelling experiments were conducted to show the feasibility of assessing primary production from data on the vertical distribution of biogenic elements.