The bioavailability of sediment-bound Cd, Co, and Ag to the mussel Mytilus edulis

1997 ◽  
Vol 54 (1) ◽  
pp. 147-156 ◽  
Author(s):  
C Gagnon ◽  
N S Fisher
Keyword(s):  
Mytilus Edulis ◽  
Manganese Oxides ◽  
Assimilation Efficiency ◽  
Chemical Properties ◽  
Fulvic Acids ◽  
Organic Coating ◽  
Natural Sediment ◽  
Coated Particles ◽  
Sediment Particles ◽  
Physical And Chemical

Marine sediments, long thought to be a final repository of toxic contaminants in marine ecosystems, may also serve as a source of toxic contaminants for marine food chains. The influence of physical and chemical properties of oxidized sediments on the bioavailability of metals from sediments to marine filter-feeding invertebrates is largely unknown. We examined the relative importance of specific sedimentary components that may affect the uptake of Cd, Co, and Ag by the mussel Mytilus edulis. Iron and manganese oxides, montmorillonite clay, silica, and natural sediment particles were radiolabeled with 109Cd,57Co, and 110mAg; some particles were also coated with marine fulvic acids to simulate the influence of organic coating on metal bioavailability. Mussels were fed radiolabeled particles and then allowed to depurate by feeding on nonradioactive particles, following a pulse-chase protocol developed to determine assimilation efficiencies of ingested metals. Metals were absorbed by mussels from all sediment particles, but metals associated with organic-coated particles were generally absorbed to a greater extent than metals associated with uncoated particles; absorption efficiencies were as high as 34% (for Co from organic-coated silica particles). Desorption experiments with radiolabeled particles at pH 5 were performed in parallel to simulate the behavior of food-bound metals in the acidic gut of bivalves. High correlations (r > 0.97) between the amount of metal desorbed under these conditions and the assimilation efficiency for metal bound to particles were noted among organic-coated particles but not uncoated particles (r < 0.6). Differences between coated and uncoated particles were principally due to differences in gut transit times of the ingested particles. These results suggest that suspended sediment particles may be a source of metals for suspension-feeding animals, but the relationship between metal partitioning to sediments and biological availability is not obvious, because organic coatings and the acidic gut environment influence metal absorption in mussels.

scholarly journals Humus is a guarantor of the stability of agroecosystems

2021 ◽  
Vol 36 ◽  
pp. 03020
Author(s):  
E.S. Gasanova ◽  
A.N. Kozhokina ◽  
N.G. Myazin ◽  
K.E. Stekolnikov
Keyword(s):  
Complex Structure ◽  
Chemical Properties ◽  
Fulvic Acids ◽  
Mineral Fertilizers ◽  
Joint Application ◽  
Nuclear Structures ◽  
The Stability ◽  
Physical And Chemical ◽  
Properties Of Soil ◽  
And Chemical Properties

The paper studies the processes of transformation of the molecular structure of humic (HA) and fulvic acids (FA) of leached chernozem under the influence of fertilizers and meliorant. The research was carried out under the conditions of many years of stationary experiment of the Department of Agrochemistry, Soil Science and Agroecology of the FSBEI HE Voronezh SAU. Samples of leached low-humus thin heavy-loamy chernozem were analyzed. The isolated and purified preparations of HA and FA were studied on a SM2203 spectrofluorimeter in the ultraviolet and visible ranges. The paper also presents the results of determining the most important physical and chemical properties of soil variants using various fertilizer and meliorant systems. Limed variants have optimal indicators. Based on the analysis, it can be assumed that the FA molecules of the variant with a double dose of mineral fertilizers on the background of manure differ in a developed aliphatic part, have many auxochromic substituents. HA of the same variant are characterized by a high condensation of nuclear structures. The HA and FA molecules of the variant with the joint application of fertilizers and meliorant have a more complex structure of the nuclear and peripheral parts. According to the results of calculations of extinction coefficients, it was found that liming contributes to the accumulation of more mature forms of humic acids.

scholarly journals Preparation of nano manganese oxides by H2O2 in-situ oxidation: effect of regulation mechanism on physical and chemical properties

2021 ◽  
Author(s):  
Mingdong Li ◽  
Jiawei Wang ◽  
Dejin Fu ◽  
Bibo Gou ◽  
Xiaoliang Chen ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Manganese Oxides ◽  
Ph Value ◽  
Chemical Properties ◽  
Manganese Sulfate ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Manganese oxides showed many special physicochemical properties in many fields such as electrochemistry, adsorption and catalysis. They were widely used in cathode materials for lithium batteries, molecular sieves, catalytic materials and adsorbents. In this paper, in situ oxidation of manganese sulfate solution was conducted with H2O2 as oxidant, and the characterization means of XRD, SEM and BET were used. The purpose was to study the effects of different regulation mechanisms on the physical and chemical properties of manganese oxides such as morphology, phase composition, surface properties and specific surface area. The adsorption properties of γ-MnO2 for Co and Ni in manganese ore leaching solution were tested. The results showed as follows. Under alkaline conditions, the main product of manganese sulfate solution oxidized by H2O2 was Mn3O4 spherical particles with a radius of about 50 nm, these particles had micropores or mesopores, the oxidation reaction rate was rapid, and the specific surface area and N2 adsorption capacity changed with the change of reaction conditions.The temperature had a great influence on the micro morphology of the product.The micro morphology was slender nanorod when the temperature was 20℃. With the increase of temperature, the length of nanorod became shorter. When the temperature rises to 50℃, the rod became spherical. When the pH value decreased from 9 to 7, the diffraction peak of each crystal plane in the product Mn3O4 decreased gradually. The diffraction peak of γ-MnO2 appeared when the pH value decreased to 5. All the products were γ-MnO2 when the pH value decreased to 3. With the increase of Mn2+ concentration, the grain size decreased and agglomeration was easy to occur. The optimum conditions were obtained as follows: the temperature was 30℃, pH was 3, reaction time was 90 min, the mole ration of H2O2 to Mn2+ was 1:1, and Mn2+ concentration was 10g/L. Under the optimum conditions, γ-MnO2 with high specific surface area (172.41 m2/g) was prepared. This γ-MnO2 has a good adsorption effect on Co and Ni in manganese ore leaching solution, and the adsorption efficiency could be reached 94.75 % and 95.67 %. This study would provide a reference for the preparation of manganese oxides with different physical and chemical properties.

Statistical criteria of stellar population types

1966 ◽  
Vol 24 ◽  
pp. 101-110
Author(s):  
W. Iwanowska
Keyword(s):  
Stellar Population ◽  
Chemical Properties ◽  
Spectrophotometric Study ◽  
Physical And Chemical Properties ◽  
Population Type ◽  
The Galaxy ◽  
Distribution Parameters ◽  
Physical And Chemical ◽  
Statistical Criteria ◽  
And Chemical Properties

In connection with the spectrophotometric study of population-type characteristics of various kinds of stars, a statistical analysis of kinematical and distribution parameters of the same stars is performed at the Toruń Observatory. This has a twofold purpose: first, to provide a practical guide in selecting stars for observing programmes, second, to contribute to the understanding of relations existing between the physical and chemical properties of stars and their kinematics and distribution in the Galaxy.

Biophysical Measurement of Molecular Weight of Foot-and-Mouth Disease RNA Fragments

1974 ◽  
Vol 32 ◽  
pp. 262-263
Author(s):  
Sydney S. Breese ◽  
Howard L. Bachrach
Keyword(s):  
Chemical Properties ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Distilled Water ◽  
Bovine Plasma ◽  
Mouth Disease Virus ◽  
Foot And Mouth ◽  
Carbon Coated ◽  
Rna Fragments ◽  
Physical And Chemical

Continuing studies on the physical and chemical properties of foot-and-mouth disease virus (FMDV) have included electron microscopy of RNA strands released when highly purified virus (1) was dialyzed against demlneralized distilled water. The RNA strands were dried on formvar-carbon coated electron microscope screens pretreated with 0.1% bovine plasma albumin in distilled water. At this low salt concentration the RNA strands were extended and were stained with 1% phosphotungstic acid. Random dispersions of strands were recorded on electron micrographs, enlarged to 30,000 or 40,000 X and the lengths measured with a map-measuring wheel. Figure 1 is a typical micrograph and Fig. 2 shows the distributions of strand lengths for the three major types of FMDV (A119 of 6/9/72; C3-Rezende of 1/5/73; and O1-Brugge of 8/24/73.

Tailoring microstructures of materials through biomimetics

1993 ◽  
Vol 51 ◽  
pp. 500-501
Author(s):  
Mehmet Sarikaya ◽  
Ilhan A. Aksay
Keyword(s):  
Chemical Properties ◽  
Design And Synthesis ◽  
Structure Sensitive ◽  
Macro Scale ◽  
Methods Of Synthesis ◽  
Successive Level ◽  
Engineering Materials ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Synthesis Of Materials

Biomimetics involves investigation of structure, function, and methods of synthesis of biological composite materials. The goal is to apply this information to the design and synthesis of materials for engineering applications.Properties of engineering materials are structure sensitive through the whole spectrum of dimensions from nanometer to macro scale. The goal in designing and processing of technological materials, therefore, is to control microstructural evolution at each of these dimensions so as to achieve predictable physical and chemical properties. Control at each successive level of dimension, however, is a major challenge as is the retention of integrity between successive levels. Engineering materials are rarely fabricated to achieve more than a few of the desired properties and the synthesis techniques usually involve high temperature or low pressure conditions that are energy inefficient and environmentally damaging.In contrast to human-made materials, organisms synthesize composites whose intricate structures are more controlled at each scale and hierarchical order.

Response of corn (Zea mays L.) to various organic-based fertilizers in marginal upland of Sta. Rita, Samar

2017 ◽  
pp. 31-43
Author(s):  
Berta Ratilla ◽  
Loreme Cagande ◽  
Othello Capuno
Keyword(s):  
Block Design ◽  
Management Strategies ◽  
Chemical Properties ◽  
Organic Fertilizers ◽  
Growth And Yield ◽  
Physical And Chemical Properties ◽  
Total N ◽  
Randomized Complete Block Design ◽  
Physical And Chemical ◽  
And Chemical Properties

Organic farming is one of the management strategies that improve productivity of marginal uplands. The study aimed to: (1) evaluate effects of various organic-based fertilizers on the growth and yield of corn; (2) determine the appropriate combination for optimum yield; and (3) assess changes on the soil physical and chemical properties. Experiment was laid out in Randomized Complete Block Design, with 3 replications and 7 treatments, namely; T0=(0-0-0); T1=1t ha-1 Evans + 45-30-30kg N, P2O5, K2O ha-1; T2=t ha-1 Wellgrow + 45-30-30kg N, P2O5, K2O ha-1; T3=15t ha-1 chicken dung; T4=10t ha-1 chicken dung + 45-30-30kg N, P2O5, K2O ha-1; T5=15t ha-1 Vermicast; and T6=10t ha-1 Vermicast + 45-30-30kg N, P2O5, K2O ha-1. Application of organic-based fertilizers with or without inorganic fertilizers promoted growth of corn than the control. But due to high infestation of corn silk beetle(Monolepta bifasciata Horns), its grain yield was greatly affected. In the second cropping, except for Evans, any of these fertilizers applied alone or combined with 45-30-30kg N, P2O5, K2O ha-1 appeared appropriate in increasing corn earyield. Soil physical and chemical properties changed with addition of organic fertilizers. While bulk density decreased irrespective of treatments, pH, total N, available P and exchangeable K generally increased more with chicken dung application.

THE IMPORTANCE OF THE RED BOOK OF SOILS FOR MONITORING AND JUSTIFICATION OF CONSERVATION MEASURES

2020 ◽  
Author(s):  
O.S. Bezuglova ◽  
Keyword(s):  
Chemical Properties ◽  
Natural State ◽  
Soil Maps ◽  
Rostov Region ◽  
Conservation Measures ◽  
Background Data ◽  
The Russian Federation ◽  
Physical And Chemical ◽  
And Chemical Properties

Rostov Region belongs to the highly protected natural territories characterized by the continuous plowing. There territories are the only reserves with the soils preserved in their natural state. However, these areas often lack detailed information about the soils quality and composition. Surveying soils on these territories is crucial for determination of their basic physical and chemical properties. The resulted compilation of soil maps could lay a foundation for creating the Red Book of Soils and the formation of a section in the soil-geographical database of the Russian Federation. Subsequently, such information can be used as a background data for the main types of soils in the region. It will be also valuable during monitoring and justification of conservation measures.

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