Acid-soluble Metals Research Articles

Chemical characteristics of aerosols in the Kuroshio area

Aerosol samples were collected with a Sierrer Model 235 cascade impactor in the marine atmosphere over the Kuroshio area in consecutive four seasons from 1987 to 1988. Na, Cl, Al, V, and water soluble and acid soluble Mn, Fe, Pb, Cu, V, Cd were determined by neutron activation analysis and atomic absorption spectrophotometry, respectively. Seawater source chemical species in the aerosols appeared in high content in large over 3.6 μm diameter particles, and crustal source vanadium appeared in 3.6 μm diameter particles, but pollution source vanadium appeared in less than 0.52 μm diameter particles. Trace metals in the aerosols mostly had the highest concentration of water soluble metals on fine particles, and acid soluble metals on large particles. The concentrations of trace metals in the aerosols were higher in autumn and winter, lower in spring and summer.

Dry deposition measurements using water as a receptor: A chemical approach

The field measurement of dry deposition still represents a difficult task. In our approach, a 1 to 2 cm thick layer of water in a petri dish with a diameter of 22 cm, serves as a surrogate surface. The atmospheric constituents taken up by the water can be analyzed chemically by the same procedure as for the wet deposition samples. In contrast to solid surrogate surfaces, water exhibits the following advantageous properties: low and constant surface resistance, high sticking coefficient for aerosols, and predictable Sorption behavior for gases. Consequently, the deposition rates measured to the wet surface are generally higher, by up to a factor of 4 for NH4 +, Cl−, NO3 − and SO4 2−, than those to a dry surface, but still smaller than the concurrent wet deposition rates. We observed the following average dry deposition rates in μmol m−2 d−1∶ NH4 + 48.3, Ca2+ 40.7, Na+ 15.8, Mg2+ 8.4, K+ 4.2, H-Aci 36.4; SO4 2− 57.2, Cl− 39.2, NO3 − 34.5, HSO3 − 5.7, formate 4.0; acid soluble metals: Fe 2.8, Zn 0.60, Cu 0.11, Pb 0.073, Cd 0.0022. The soluble fraction of Zn, Cd, Cu, Pb and Fe in the dry deposition varied with the pH of the water phase corresponding to the adsorption tendency of these metals to oxide surfaces. The sampling method also allows tracing of regionally and locally emitted atmospheric pollutants. In our study the local pollution sources included road salting, construction work and a refuse incinerator. Finally, chemical reactions occurring in the atmosphere, such as the conversion of Cl− to HCl by HNO3 or the oxidation of SO2, can be identified by evaluating the data. The method proposed is relevant to measure reproducibly the dry deposition of a variety of compounds to water bodies and moist vegetation.

Regional variation in the distribution of trace metals in modern intertidal sediments of northern Spencer Gulf, South Australia

Spencer Gulf, a sheltered marine inlet extending 270 km inland from the Southern Ocean is important to the maintenance of South Australia's commercial fishery. At the northern end of the Gulf, the tidal range of 3 m exposes 40% of the marine sediments at low water. These intertidal flats vary from wide expanses of coarse sand to finer sediments colonized by blue-green algal mats or mangroves. Dissecting channels are tidal, with virtually no terrestrial runoff. Intertidal sediments from industrial and undeveloped shorelines have been analysed to determine the concentration of trace metals in the surface layer, and factors influencing their local distribution. Physical and chemical characteristics of the depositional environment at sampling sites are defined by field measurements of temperature, salinity, pH, and dissolved H 2S in overlying water, and by laboratory determination of the grain size, organic matter and total carbonate content of the sediment samples. Nitric acid soluble metal content of surface sediments is highly variable, with ranges of <0.2–23 ppm Cd, <0.2–50 ppm Cu, 0.1–17% Fe, 20–3000 ppm Mn, <1–600 ppm Pb, and 4–3200 ppm Zn. Generally, high metal concentrations have been found near existing industries, and in sheltered, organic rich muds. The lowest metal concentrations were found in sandy sediments from exposed beaches. The measured ranges of 12–36°C temperature, 19–59‰ salinity, pH 7–9.5, and <0.1–>5 mg 1 −1 dissolved H 2S indicate the highly variable chemical environment in shallow water overlying the sediments. Proximity to a point source, the established pattern of littoral transport, and the physical and chemical features of the depositional environment apparently control the distribution of trace metals in sediments.

Water and acid soluble trace metals in atmospheric particles

Continental aerosols were collected above a deciduous forest in eastern Tennessee and subjected to selective extractions to determine the water soluble and acid leachable concentrations of Cd, Mn, Pb, and Zn. The combined contribution of these metals to the total aerosol mass is 0.5%, ∼70% of which is attributable to Pb alone. A substantial fraction ( ∼ 50% or greater) of the acid leachable metals are soluble in distilled water. This water soluble fraction generally increased with decreasing particle size and with increasing frequency of atmospheric water vapor saturation during a sampling period. The pattern of relative solubilities (Zn &gt; Mn ≃ Cd &gt; Pb) is similar to the general order of the thermodynamic solubilities of the most probable salts of these elements in continental aerosols with mixed fossil fuel and soil sources.

Adsorption and desorption of heavy metals in bottom mud of urban rivers

An adsorption experiment has been carried out to determine the factors affecting the uptake of heavy metals by bottom mud in urban rivers. The adsorption of Cu, Zn, Cd, and Pb was described using the Freundlich adsorption equation. The Freundlich constant ( K) was related to the grain size and organic matter content of bottom mud. It was found that the main factor controlling the adsorption of metal was organic matter, since the adsorbed metals decreased remarkably due to the destruction of organic matter from the fine bottom mud. The desorption experiment proved that the metals adsorbed by mud were extracted approx. 100% with dilute HCI. Therefore, the amount of heavy metal adsorbed per 1 g of TOC can be calculated from the acid soluble metal content of bottom mud. Moreover, the method of extraction by 2 N CH 3COONH 4 can be used to distinguish between an ion exchangeable form by minerals and a chemical form by organic matter. The adsorption and desorption experiments indicated that fine bottom mud with a high organic matter content contributes to the uptake of metals in urban rivers and that such metals can be extracted with 0.5 N HCI.

Effect of diagenetically remobilized metals on regional difference in manganese nodules.

Pelagic manganese nodules were sampled at two sites. One was in the subtropical Pacific where the biological productivity in the surface water was low and Mn did not migrate in the surface sediment. The other was in the equatorial Pacific where manganese oxide in the sediment was reduced by organic material and dissolved Mn was lost from the sediment to the bottom water. It has been demonstrated that the difference in the sedimentary environment is reflected in manganese nodules. The bottom surface of the equatorial nodules contained larger amounts of transition metals soluble in weak acids than other sides in contact with sea water and the acid soluble metals decreased with depth from the bottom surface. On the bottom side of the equatorial nodule the oxide fractions of Cu and Ni increased with depth, indicating the trapping of metals which diffused through the pore waters of sediments and nodules. The bottom surface of the larger subtropical noudles contained much smaller amounts of 230Th than other surfaces, but the growth rate obtained from the depth profile of 230Th was similar to those of the other surfaces. The smaller subtropical nodules contained a normal amount of 230Th at the bottom surface. The concentration of 232Th decreased with depth at each surface, that is, with time, except for the bottom surface of the larger subtropical nodules, in which 232Th concentration is similar to that in the interior of nodules. These observations apparently lead to the conclusion that the bottom surface of the larger subtropical nodules are not growing at present, but the following possibility can not be excluded. The bottom surface is now growing with Th supplied chiefly from weathering debris rather than authigenic particles in sea water.

汚濁感潮河川における底泥の巻き上げと懸濁態リン・重金属元素の挙動

Concentrations of phosphorus and heavy metals in water and suspended matter (SM) were examined in a polluted tidal river during tidal sediment transportation.The increases in concentrations of phosphorus and heavy metals in the Shonai River water following sediment transportation were attributed mainly to increases of phosphorus and metals in particulate form. Among various forms of phosphorus and heavy metals in SM, hydroxylamine-acetic acid (HA) soluble phosphorus and metals and hydrogen peroxide (HO) soluble phosphorus, whose concentrations in SM varied with the organic contents, were thought to be easily movable. Relationships among parameters suggested that the phosphorus and metals were mainly attached or adsorbed onto organic matter (HO soluble phosphorus, HA soluble zinc, copper, and lead), or adsorbed on iron hydroxide (HA soluble phosphorus). Their concentrations in SM decreased when sediment transportation was frequent, and were higher after the long meteorologically stable days compared to just after a storm. Thus, it was suggested that the movable phosphorus and heavy metals were lost partially from SM during the stage in which they scaled onto the bottom, but during meteorologically stable days, were more liable to be accumulated in bottom sediments owing to the fact that supply was greater than loss. Because of the considerable reduction to soluble form, manganese did not accumulate in SM or bottom sediments in the semireductive environment under study.

Distribution of Heavy Metals in Bottom Mud of River. V. Distribution of Heavy Metals in Bottom of Tsurumi River

To examine the distribution and status of Cu, Cr, Pb, Zn, Cd, and Ni in the mud of Tsurumi River, surface mud samples were collected at 8 stations from the mouth to up the river. Total heavy metals of mud in the upper and middle part of the river showed values near the mean of heavy metals in Japanese rivers of the first category. Ethylenediaminetetraacetic acid (EDTA)-soluble Cu represented 30% of the total Cu, while Cd, Pb, and Zn 10 to 20% and Cr, Ni about 5%. Acid-soluble heavy metals were 10% higher than EDTA-soluble heavy metals. In the mouth of the river, near the Tsurumi industrial area, the total heavy metals were 2 to 6 times more than that in the upper and middle of the river. EDTA-soluble Cu and Cd showed about 60% of the total Cu and Cd, Zn and Pb about 70% and Cr and Ni 10 to 20%. Acid-soluble heavy metals were 10 to 20% more than that of EDTA-soluble metals. Therefore 1/2 to 2/3 of total heavy metals were extracted with 0.5 N HCl. These data indicated that a large portion of heavy metals in the mouth of the river came from industrial wastes and that such heavy metals can be extracted with 0.5 N HCl or EDTA.

Liming effects on the toxicity to perennial ryegrass of a sewage sludge contaminated with zinc, nickel, copper and chromium

Up to 12% of the dry matter of a sewage sludge containing 0·65% Zn, 0·20% Ni, 0·50% Cu and 0·42% Cr was mixed with an acid soil limed to give a pH range from 4·3 to 6·8 and cropped with ryegrass in pots. Yields of two cuts of grass were reduced by the largest amount of sludge at soil pHs less than 6. Concentrations of more than 350 μg/g Zn, 160 μg/g Ni and 40 μg/g Cu in the grass dry matter were associated with lowered yields. The treatments had no effect on Cr and Pb concentrations in the grass. 0·5MM acetic acid-soluble metals in the cropped air-dried soils were increased by the maximum sludge additions to 350 mg/kg Zn, 70 mg/kg Ni and 100 mg/kg Cu, equivalent to 48% of the total applied Zn, 25% of the Ni and 18% of the Cu. At these high rates, the pH of the sludge (5·3) significantly affected soil pH. Sludges used on agricultural land should be adjusted to pH 7 before spreading so as to minimise any possible heavy metal toxicities to crops.

Metal distribution along a profile of an inter-tidal area

The sediment from an intertidal area has been investigated with regard to the vertical and areal distribution of the following acid-soluble metals: Na, K, Mg, Ca, Fe, Co, Ni, Cu, Ag and Pb. In addition to the metals, granulometric properties, content of organic matter, carbonate concentrations and E h are measured. The metals are accumulated along the margins of the area and show a high correlation with organic matter and the finest sediment fraction. The interstitial water is diluted with infiltrated rain water. The higher level of this water, of the marsh area compared with that of the tidal flat area, gives rise to an upward percolation in the sediment of the tidal flat area. The metal interrelationships and concentrations are determined by processes in the uppermost oxidized layer and only to a minor extent by reducing processes in the lower hydrogen sulphide-rich layers.

The spectrophotometric determination of sulphur in iron alloys: Methylene blue method

Sulphur is determined in iron alloys by evolution as hydrogen sulphide, followed by reaction with N,N-disaethyl- p-phenylenediamine and iron III to form methylene blue, which is measured spectrophotometricalty. Replicate results are reported for acid soluble metal samples containing 0.3–230 ppm of sulphur. An evaluation of the accuracy of the methylene blue procedure was made using radiotracer techniques.