Showing papers on "Arsenic published in 1979"
TL;DR: In this paper, four species of arsenic were found in samples of seawater and interstitial water from the northeast Pacific and the continental borderland off southern California: arsenate, arsenite, methylarsonate, and dimethylarsinate.
Abstract: Four species of arsenic were found in samples of seawater and interstitial water from the northeast Pacific and the continental borderland off southern California: arsenate, arsenite, methylarsonate and dimethylarsinate. All were present in the photic zone, with a good correlation between photosynthetic activity and the concentration of the methylated arsenicals. There is less arsenite in the surface waters than in the deep waters, suggesting biological uptake and transport. A sharp increase of arsenate at the base of the photic zone indicates rapid regeneration of this species. In the deep waters arsenate is dominant, but arsenite is still present in excess of equilibrium concentrations. No arsenic biomethylation was found in the interstitial waters of oxic and anoxic sediments, but arsenite was present there. In Santa Barbara Basin arsenite accounts for 20% of the arsenic in the interstitial water, the highest proportion found. Total arsenic is lower in the interstitial than in the overlying waters, suggesting removal of arsenic into the solid phases by adsorption of coprecipitation. Biological-chemical interactions and the kinetics of redox reactions are important in influencing the speciation of arsenic.
349 citations
TL;DR: Arsenate uptake consists of a rapid, apparently irreversible, initial phase followed by a less rapid 'steady state' phase, both of which are temperature sensitive and strongly inhibited by phosphate.
Abstract: Arsenate uptake consists of a rapid, apparently irreversible, initial phase followed by a less rapid 'steady state' phase, both of which are temperature sensitive and strongly inhibited by phosphate. By comparison, 'steady state' uptake of phosphate was only weakly inhibited by arsenate. The initial and 'steady state' phases of arsenate uptake were highly correlated (R = 0.958, P < 0.001). Arsenite also appeared to exhibit initial and 'steady state' uptake phases but uptake was slower by a factor of 3-4 than for arsenate at the same concentration. The results are discussed in relation to recent work on a DNP-sensitive initial binding step in the uptake of other elements.
228 citations
TL;DR: Oral doses of carrier-free 74 As as arsenic acid were administered to six adult males and the proportion of chemical species of arsenic in the urine was as follows: 51% dimethylarsinic acid, 21% monomethylarsenic compound, and 27% inorganic arsenic.
217 citations
19 Mar 1979
127 citations
TL;DR: It was concluded that reduction to arsine, not methylation to trimethylarsine, was the primary mechanism for gaseous loss of arsenicals from soil.
Abstract: Arsenate, arsenite, monomethylarsonate, and dimethylarsinate were added to different soils, and evolution of gaseous arsenical products was determined over 3 weeks. Arsine was produced in all three soils from all substrates, whereas methylarsine and dimethylarsine were produced only from methylarsonate and dimethylarsinate, respectively. At least three times more arsine than dimethylarsine was produced in soil incubated with dimethylarsinate. Resting cell suspensions of Pseudomonas and Alcaligenes produced arsine as the sole product when incubated anaerobically in the presence of arsenate or arsenite. In all instances, no trimethylarsine was observed, nor could any evidence be shown for the methylation of any arsenical substrate in soil or in culture. It was concluded that reduction to arsine, not methylation to trimethylarsine, was the primary mechanism for gaseous loss of arsenicals from soil.
110 citations
TL;DR: The reduction and methylation of arsenate to dimethylarsinic acid by the cell produces a stable, non‐toxic compound.
Abstract: Arsenate is taken up readily by Skeletonema costatum (Greville) Cleve due to its chemical similarity to phosphate, and it inhibits primary productivity at concentrations as low as 67 nM when the phosphate concentration is low. A phosphate enrichment of greater than 0.3 ..mu..M alleviates this inhibition; however, the arsenate stress causes an increase in the cell's requirement for phosphorus. Arsenite is also toxic to Skeletonema at similar concentrations. Methylated species, such as dimethylarsinic acid, did not affect cell productivity at the levels examined. Thus, the reduction and methylation of arsenate to dimithylarsinic acid by the cell produces a stable, non-toxic compound.
103 citations
TL;DR: Sulfide precipitation with Na2S is found to be highly effective to obtain a high degree of separation of heavy metal cations (Cd, Zn, Cu, and Pb) and oxyanions of arsenic and selenium from complex wastewaters as mentioned in this paper.
Abstract: Sulfide precipitation with Na2S is found to be highly effective to obtain a high degree of separation of heavy metal cations (Cd, Zn, Cu, and Pb) and of the oxyanions of arsenic and selenium from complex wastewaters. The metal separation characteristics are evaluated with a dilute synthetic mixture and with an actual copper smelting plant wastewater. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at sulfide dosages about 60% of the theoretical values and at a final pH greater than 8.0. The removals of Cd, Zn, and Cu from the actual wastewaters are greater than 99%, and As and Se removals are 98 and >92%, respectively. Cd, Cu, and Zn concentrations in the range of 0.05 to 0.1 mg/1 can be achieved with sulfide precipitation. The metal separations and settling rates obtained with conventional hydroxide precipitation (lime) are considerably lower than those obtained with sulfide precipitation.
100 citations
TL;DR: In this paper, the state of an arsenic layer electrodeposited at various potentials on platinum electrodes has been examined electrochemically and the relation between the state and the electrocatalytic activity for hydrogen evolution has been investigated.
93 citations
TL;DR: The results seem to indicate that arsenic is associated with the lipid phase, manganese with the dry matter and selenium with the aqueous phase of brain tissue.
90 citations
TL;DR: Arsenic, cadmium, copper and zinc occur at elevated levels in the waters of Carnon River and the upper reaches of Restronguet Creek, these concentrations decreasing progressively towards the estuary of Carrick Roads as discussed by the authors.
84 citations
TL;DR: The tropospheric burden of arsenic has been estimated from representative global surface concentrations and an estimated small particle troposphere scale height of 3.9 km to be ∼8×108 g As as mentioned in this paper.
Abstract: The tropospheric burden of arsenic has been estimated from representative global surface concentrations and an estimated small particle tropospheric scale height of 3.9 km to be ∼8×108 g As. Total atmospheric arsenic emissions from both natural and anthropogenic sources have been estimated to be 31×109 g As/yr. On a global basis the major source of atmospheric arsenic appears to be from anthropogenic volatilization processes, and the major natural sources of arsenic appear to be volcanoes and the terrestrial biosphere. Total atmospheric arsenic removal is estimated to be 30–50×109 g As/yr. The global tropospheric residence time of arsenic appears to be about 9 days.
TL;DR: Differential extraction procedures carried out on tissues from organisms suggest that organic forms of arsenic in marine food webs are derived from an in vivo synthesis by primary producers and are efficiently transferred along a marine food chain.
TL;DR: Under restricted ingestion of seafoods, if the ratios of arsenite to total arsenic increase in the urine of arsenic workers, it is of importance as suggesting an increased absorption of toxic arsenite.
Abstract: The outputs of inorganic arsenic compound (As+3, As+5), monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) in the urine were observed with passage of time after oral intake of arsenic trioxide. The subject was completely restricted from the ingestion of seafoods for two days before the experiment and during the urine sampling period, because of high arsenic content of these foods. As+3 was excreted in large amounts during the first 12 hours, the outputs corres-ponding to about 12% of the ingested amount, and the outputs of As+3 also were greater than those of MMAA and DMAA during the same period. The urinary outputs of arsenic compounds as total arsenic following the ingestion of arsenic trioxide amounted to 40% of the ingested amount during the first 12 hours, and 70% by 72 hours. Under restricted ingestion of seafoods, if the ratios of arsenite to total arsenic increase in the urine of arsenic workers, it is of importance as suggesting an increased absorption of toxic arsenite.
TL;DR: Study of arsenic accumulation and elimination processes in the Mediterranean mussel Mytilus galloprovincialis revealed that arsenic turnover was significantly more rapid in actively growing individuals living under natural conditions.
Abstract: Radiotracer experiments were designed to study the effects of certain environmental and biological factors on arsenic accumulation and elimination processes in the Mediterranean mussel Mytilus galloprovincialis. Arsenic (as arsenate) uptake increased with increasing arsenic concentration in the water; however, the response was not proportional, indicating that accumulation was partially suppressed at higher external arsenic concentrations. In general, approximately 80% of the 74As taken up was associated with the soft parts, with small mussels concentrating 74As to a greater degree than larger individuals. The highest 74As concentrations were recorded in the byssus and the digestive gland. Increased temperature enhanced both arsenic uptake and loss. Mussels in sea water at 19‰ S accumulated approximately three times more 74As than those held at 38‰ S. Arsenic loss was much less affected by salinity, with only a tendency for greater arsenic retention noted at lower salinities. Studies carried out in the laboratory and in situ revealed that arsenic turnover was significantly more rapid in actively growing individuals living under natural conditions. Arsenic-74 loss from the in situ group was essentially biphasic, with biological half-times of approximately 3 and 32 days for the fast and slow compartments, respectively. The active secretion of arsenic in the byssal threads contributed to the total elimination of the element from the mussels.
01 Jan 1979
TL;DR: In this article, the initial and steady state phases of arsenate uptake were investigated and it was shown that the latter phase is temperature sensitive and strongly inhibited by phosphate, whereas the former phase is not temperature sensitive.
Abstract: Arsenate uptake consists of a rapid, apparently irreversible, initial phase followed by a less rapid 'steady state' phase, both of which are temperature sensitive and strongly inhibited by phosphate. By comparison, 'steady state' uptake of phosphate was only weakly inhibited by arsenate. The initial and 'steady state' phases of arsenate uptake were highly correlated (R = 0.958, P < 0.001). Arsenite also appeared to exhibit initial and 'steady state' uptake phases but uptake was slower by a factor of 3-4 than for arsenate at the same concentration. The results are discussed in relation to recent work on a DNP-sensitive initial binding step in the uptake of other elements.
TL;DR: In this paper, mixed bacterial cultures isolated from an estuarine system are able to demethylate and oxidize dime thy larsinic acid to arsenate, which is similar to the rate of DMA production due to algal reduction and methylation in marine systems.
TL;DR: In this article, high resolution X-ray and neutron correlation functions have been obtained for arsenic sulphide bulk glass and vapour-deposited films by making measurements to high momentum transfers.
Abstract: High resolution X-ray and neutron correlation functions have been obtained for arsenic sulphide bulk glass and vapour-deposited films by making measurements to high momentum transfers. These data are compared with a vatiety of models and it is concluded that the structure of the films is dominated by the presence of As4S4 molecules in the vapour phase, which results in more As-As bonds than the minimum required by stoichoimetry. The extent to which these As4S4 molecules polymerise in the as-deposited film is unclear, but depends strongly on preparation conditions.
TL;DR: The variations in arsenic concentration are probably due to metabolic differences between classes, and not to differences in the amount of total available arsenic in the surrounding water, and may represent maximum tolerable levels for macro- algae.
TL;DR: In this article, the authors studied the interface between anodically grown oxide films and gallium arsenide substrates using Raman backscattering and found that the thermally induced solid-state interfacial reaction, As2O3+2GaAs→Ga2O 3+4As, is responsible for the presence of arsenic at the oxide-semiconductor interface following annealing.
Abstract: The nature of the interface between anodically grown oxide films and gallium arsenide substrates was studied using Raman backscattering. Room‐temperature spectra of GaAs covered with as‐grown anodic films as well as anodized samples dried under nitrogen at 250°C showed only the first‐order longitudinal (LO) and transverse (TO) optical modes and the less‐intense two‐phonon features of the GaAs substrate. Heating the films at 450°C and above results in the appearance of intense LO (257 cm−1) and TO (198 cm−1) bands due to crystalline arsenic and the structureless Raman scattering near 200–250 cm−1 due to amorphous arsenic. Polarized Raman spectra indicate that elemental arsenic is not an intrinsic oxidation product of the room‐temperature anodization. We suggest that the thermally induced solid‐state interfacial reaction, As2O3+2GaAs→Ga2O3+4As, is responsible for the presence of arsenic at the oxide‐semiconductor interface following annealing.
TL;DR: Dimethylarsinic acid (DMAA), the major metabolite was detected in the plasma and red blood cells within 50 min after dosing and was present as DMAA in blood and urine samples analysed for arsenic metabolites.
TL;DR: A method is described for the determination of antimony, arsenic and tin in foodstuffs in which organic matter is destroyed using a wet-oxidation procedure, except for arsenic in samples of marine origin in which Organic Matter is destroyed by the dry-ashing technique.
Abstract: A method is described for the determination of antimony, arsenic and tin in foodstuffs in which organic matter is destroyed using a wet-oxidation procedure, except for arsenic in samples of marine origin in which organic matter is destroyed by the dry-ashing technique. Each element is obtained in the highest valency state and converted into the respective normal hydride with sodium tetrahydroborate(III), prior to atomisation in a flame-heated silica tube and atomic-absorption spectrophotometric measurement. The optimum conditions for this procedure are discussed and direct and indirect interference effects are described. The accuracy of the procedure is assessed for each element, and where possible the accuracy of the method in application is considered. Standard deviations of the results for levels normally found in foodstuffs have been calculated and derived limits of detection and confidence intervals are given.
TL;DR: In this paper, a semi-automatic hydride generation device coupled with a microwave-induced argonhelium plasma was used with a 0.5m monochromator for the analysis of germanium, arsenic, selenium, tin and antimony in several complex samples.
Abstract: This paper describes the utilisation of a semi-automatic hydride generation device coupled to a microwave-induced argon-helium plasma that is used with a 0.5-m monochromator for the analysis of germanium, arsenic, selenium, tin and antimony in several complex samples. Incorporated in the system are a condensation tube and a Chromosorb 102 column that are used to separate the analyte species from hydrogen evolved during the course of the generation reaction, and to separate the analytes from condensed contaminants that cause spectral background interferences.Results reported are standard recoveries and relative precision for germanium, arsenic, selenium, tin and antimony in whole blood and in enriched flour. Also reported are arsenic and antimony values for NBS orchard leaves. Results obtained on complex samples are compared with the precision obtained for aqueous standards.
TL;DR: Changes in hematology, blood biochemistry and pathology of major organs and skin were essentially negative in all groups, and the maximum no-effect level observed in the present study was compared with the possible amount of arsenic taken via seaweed in mankind.
TL;DR: In this paper, a simple procedure for the determination of selenium and tellurium in electrolytic copper is described, where two elements are first separated from copper by passing an ammoniacal solution of the sample through Chelex-100 resin.