Atmospheric Input Of Trace Metals Research Articles

Solubility of aerosol trace elements: Sources and deposition fluxes in the Canary Region

African dust inputs have important effects on the climate and marine biogeochemistry of the subtropical North Atlantic Ocean. The impact of dust inputs on oceanic carbon uptake and climate is dependent on total dust deposition fluxes as well as the bioavailability of nutrients and metals in the dust. In this work, the solubility of trace metals (Fe, Al, Mn, Co and Cu) and ions (Ca, sulphate, nitrate and phosphate) has been estimated from the analysis of a long-time series of 109 samples collected over a 3-year period in the Canary Islands. Solubility is primarily a function of aerosol origin, with higher solubility values corresponding to aerosols with more anthropogenic influence. Using soluble fractions of trace elements measured in this work, atmospheric deposition fluxes of soluble metals and nutrients have been calculated. Inputs of dissolved nutrients (P, N and Fe) have been estimated for the mixed layer. Considering that P is the limiting factor when ratios of these elements are compared with phytoplankton requirements, an increase of 0.58 nM of P in the mixed layer (∼150 m depth) and in a year can be estimated, which can support an increase of 0.02 μg Chla L−1 y−1. These atmospheric inputs of trace metals and nutrients appear to be significant relative to the concentrations reported in this region, especially during the summer months when the water column is more stratified and deep-water nutrient inputs are reduced.

Atmospheric deposition of trace metals to the western North Pacific Ocean observed at coastal station in Japan

Abstract To understand the atmospheric input of trace metals to surface seawaters, the total deposition samples were collected simultaneously from three coastal stations in Japan. The trace metal concentrations (Al, Sc, Ti, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, and Th) were then determined for particulate and dissolved fractions using a high-resolution ICP-MS. The observed total Fe flux (average, 194 μg/m 2 /day) at the northern station (Kushiro, KU), which is close to HNLC region of western North Pacific, was within the lower limit of the previous estimation for coastal area of Japan based upon a model. Except for Sc and Fe, all the elements showed an increasing tendency toward dissolution with decreasing the pH from 5.7 to 3.4. At the southern station (Cape Hedo, HE), the tendency toward dissolution of Ti, Mn, Zn, Cd, Pb and Th was twice higher than that at the other two stations. A higher dissolved fraction of these metals was observed with higher enrichment factors at the HE station, which implies an anthropogenic effect on the dissolution of trace metals. In order to elucidate the relationship between anthropogenic sources and this dissolution tendency of Al and Fe, we calculated the Sc-normalized enrichment factors ( Sc EF). The relationship between the Sc EF and the dissolution tendency indicated a higher dissolution tendency of Al or Fe in the sample having a higher Sc EF. These results indicated that in addition to low pH condition the variation of the source control the tendency toward dissolution of metals in the deposition samples.

Cadmium and phosphate in coastal Antarctic seawater: Implications for Southern Ocean nutrient cycling

Cadmium is a biologically important trace metal that co-varies with phosphate (PO 4 3− or Dissolved Inorganic Phosphate, DIP) in seawater. However, the exact nature of Cd uptake mechanisms and the relationship with phosphate and other nutrients in global oceans remain elusive. Here, we present a time series study of Cd and PO 4 3− from coastal Antarctic seawater, showing that Cd co-varies with macronutrients during times of high biological activity even under nutrient and trace metal replete conditions. Our data imply that Cd/PO 4 3− in coastal surface Antarctic seawater is higher than open ocean areas. Furthermore, the sinking of some proportion of this high Cd/PO 4 3− water into Antarctic Bottom Water, followed by mixing into Circumpolar Deep Water, impacts Southern Ocean preformed nutrient and trace metal composition. A simple model of endmember water mass mixing with a particle fractionation of Cd/P ( α Cd–P) determined by the local environment can be used to account for the Cd/PO 4 3− relationship in different parts of the ocean. The high Cd/PO 4 3− of the coastal water is a consequence of two factors: the high input from terrestrial and continental shelf sediments and changes in biological fractionation with respect to P during uptake of Cd in regions of high Fe and Zn. This implies that the Cd/PO 4 3− ratio of the Southern Ocean will vary on glacial–interglacial timescales as the proportion of deep water originating on the continental shelves of the Weddell Sea is reduced during glaciations because the ice shelf is pinned at the edge of the continental shelf. There could also be variations in biological fractionation of Cd/P in the surface waters of the Southern Ocean on these timescales as a result of changes in atmospheric inputs of trace metals. Further variations in the relationship between Cd and PO 4 3− in seawater arise from changes in population structure and community requirements for macro- and micronutrients.

A trace metal (Pb, Cd, Zn, Cu) balance for surface waters in the eastern Gotland Basin, Baltic Sea

Trace metal inventories and transboundary fluxes were estimated for the surface waters of the eastern Gotland Basin, and a mass balance for this water body was derived. The study area was delineated by a box which bordered vertically by the sea surface and the halocline and horizontally by the coast of Gotland and the coast of Latvia/Lithuania. For the calculation of the trace metal inventories in the box, a high-resolution sampling was carried out during different seasons. Additional sediment trap studies were performed to calculate the vertical particulate trace metal fluxes through the halocline. The following transboundary fluxes have been estimated: (a) atmospheric input of trace metals; (b) lateral transport from adjacent bodies of surface water; (c) diapycnal fluxes of dissolved trace metals at the halocline; (d) sinking of trace metals, associated with particles, through the halocline, (e) vertical advection through the halocline. The lateral transport into and out of the surface box is important for the metals (Cd, Cu, Zn) with “nutrient-like” behaviour. For particle reactive elements like lead, vertical sedimentation and lateral transport out of the box as much as atmospheric input and lateral input into the box are in the same order of magnitude. Turbulent diapycnal mixing plays a minor role compared to the advective fluxes. The estimated range for the residence times for the region under investigation are ∼ 0.5–1.3 years for Pb; ∼ 2–11 years for Zn, ∼ 7–36 years for Cd and 42–89 years for Cu. This demonstrates that the system reacts very fast for particle reactive elements like Pb, while for copper sedimentation processes are not the preferential sink and can be neglected.

Atmospheric inputs of trace metals to the northeast Atlantic Ocean: the importance of southeasterly flow

The study of aerosols and rainwater presented here demonstrates that episodic atmospheric deposition events associated with southeasterly flow are quantitatively significant for large areas of the North Atlantic Ocean. This paper considers aluminium and manganese, with predominantly crustal sources, and lead and zinc, which are mobilised into the atmosphere primarily through anthropogenic activity. High levels of all trace metals are associated with southeasterly flow from Europe as the air passes over heavily populated and industrialised regions before reaching the northeast Atlantic Ocean. Fluxes calculated using the 1% HNO3 acid soluble metal concentration show that, although the climatological norm for this area is westerly flow, short-lived southeasterly transport events dominate the input of trace metals to this ocean region. This material may be toxic to phytoplankton or may be represent a new source of nutrients to the biological community. A significant decrease in atmospheric lead levels in polluted air is seen between June 1996 and May 1997, reflecting the decrease in use of leaded fuels in Europe. Comparing atmospheric flux values to sediment trap metal fluxes shows that the atmosphere represents the dominant source of zinc to the deep ocean, whereas an additional, non-atmospheric, manganese source this required, perhaps from mobilisation of sedimentary material from the continental shelf or long range advection of manganese rich Saharan material.

Dry atmospheric inputs of trace metals at the Mediterranean coast of Israel (SE Mediterranean): sources and fluxes

This study presents the first detailed data on aerosol concentrations of trace metals (Cd, Pb, Cu, Zn, Cr, Mn, Fe and Al) at the SE Mediterranean coast of Israel, and assesses their sources and fluxes. Aerosol samples were collected at two sampling stations (Tel-Shikmona and Maagan Michael) along the coast between 1994 and 1997. Two broad categories of aerosol trace metal sources were defined; anthropogenic (Cd, Cu, Pb and Zn) and naturally derived elements (Al, Fe, Mn and Cr). The extent of the anthropogenic contribution was estimated by the degree of enrichment of these elements compared to the average crustal composition (EF crust). High values (median >100) were calculated for Cd, Pb and Zn, minor values for Cu and relatively low values (<10) for Fe, Mn and Cr. The crustal-derived elements exhibited a statistically significant seasonal pattern of higher concentrations during spring and autumn (e.g. Al concentrations in some cases during these periods were observed to be in excess of 1500 ng m −3). In the eastern Mediterranean basin crustal-dominated elements are enriched by 2–3 times while others (Cd and Pb) are comparable to the northwestern Mediterranean. The Pb : Cd ratios of ∼150 are higher than in coastal European sites (60–116) or emission materials (∼50). It is speculated that these differences are attributed mainly to the mixing of crustal material with local and European emissions. At present, it is impossible to quantify the latter two fractions. Back trajectory analysis and the subsequent categorization of two main aerosol populations, ‘European’ and ‘North Africa–Arabian’, exhibited a significantly different geochemical imprint on the aerosol chemical composition. ‘European’-derived air masses indicated significantly higher EF crust values for Cd and Pb due to the greater anthropogenic character of the aerosol population, with a dilution by crustal material of this population leading to comparatively lower EF crust values associated with the North African–Arabian air masses.

Airborne Trace Metal Contamination of Wetland Sediments at Indiana Dunes National Lakeshore

For more than 100 yr, the wetland sediments at theIndiana Dunes National Lakeshore (IDNL) and adjacentIndiana Dunes State Park have received atmosphericinput of trace metals from industrial sources locatedupwind and to the west. This study documents the tracemetal pollution of these sediments, both areally andwith depth, and identifies trends in metaldistribution and mobility. Twenty-five wetlandsediment cores were taken across IDNL, at varyingdistances from the principal industrial sources, andfrom environments with different disturbance histories(and thus different hydroperiods). Strong-acidextractable concentrations of Cd, Cr, Cu, Mn, Ni, Pb,Se, and Zn were determined at intervals for each ofthe cores. Total metal extractions and a 210Pbchronology also was determined for one of the cores.Metal concentrations in near-surface sediments arecomparable to those found in other soils and sedimentsin the region, and show surficial enrichment overbackground levels; including Zn concentrations as highas 1700 ppm, Pb as high as 280 ppm, and Mn as high as2700 ppm. Surficial sediment concentrations of Pb,Zn, Cr, and Cu are elevated at sites in closeproximity to anthropogenic sources, while the othermetals do not exhibit a trend in concentration withdistance from sources. Lead, Cr, and Cu appear to berelatively immobile after deposition, while Cd, Ni,and Se appear to have some mobility. The durationand/or frequency of flooding appear to be important indetermining the mobility of Zn and Mn. The findingsof this research provide important insight into theeffects of cumulated human impacts on wetland systems, and can serve as an aid in the planning of wetland restoration projects, several of which are currently underway at IDNL.

Dissolved and particulate trace metals in a Scottish sea loch: an example of a pristine environment?

In the near pristine environment of a silled fjord on the west coast of Scotland samples were taken for the determination of dissolved and particulate trace metals (Fe, Mn, Cu, Ni, Cd, Zn and Pb), together with nutrient and hydrographic data, during 19 surveys carried out over a year. An indication of the pristine nature of the environment are the low concentrations of dissolved silicon, phosphate and nitrate which are considerably lower than those of coastal waters which are subject to larger anthropogenic burdens. Distributions of dissolved Cu, Ni and Cd were found to broadly reflect conservative mixing of freshwater and seawater with both end members having similar concentrations. The concentration of dissolved Cu and Ni in seawater entering upper Loch Linnhe (Cu 0.28 μg l −1; Ni 0.26 μg l −1) was consistent with the 1:1 conservative mix of Irish Sea water and North Atlantic surface water predicted from radio-caesium tracer experiments (Mackay & Baxter, 1985). Atmospheric input of trace metals to upper Loch Linnhe appeared to be a relatively minor term in the mass balance relative to fluvial inputs. Values of distribution coefficients Kd were similar to those previously reported for the coastal environment. Iron showed the strongest affinity for the suspended sediments; with particulate percentages of the total load usually greater than 80%. Lead and Mn showed a similar strong affinity to the particle phase. For Cu, Ni and Zn the mass of the element in the dissolved phase was generally greater than that in the particulate fraction. Cadmium, was least associated with the particles, with typically greater than 90% existing in the dissolved phase.

The chemical speciation of dissolved nickel and cobalt in Mediterranean rainwaters

Twenty-six rainwater samples were collected from a sampling site situated on the Southeastern French Mediterranean coast, over a 9-month period in 1988–1989, to evaluate the atmospheric inputs of trace metals to the Western Mediterranean. Cathodic stripping voltammetry (CSV) was applied to samples before and after UV irradiation to determine the concentrations of dissolved Ni and Co. Results indicated the existence of very stable dissolved organic Ni and Co complexes.

Atmospheric versus river inputs of metals to the Gulf of Lions: Total concentrations, partitioning and fluxes

This study assesses the significance of the atmospheric input of trace metals as compared to the Rhône river input into the Northern part of the Western Mediterranean directly influenced by this river. For most dissolved metals, atmospheric input is higher than dissolved riverine inputs. Atmospheric particulate input increases rapidly as one moves seaward from the river mouth. It shows the predominance of dissolved over particulate fractions in rain for all studied trace metals, except iron. Dry and wet fallout are equivalent for Co, Cu, Mn, Ni, and Pb; in the case of Al, Cd, and Fe, dry fallout is predominant. However, total atmospheric input of particulate metals (scavenged by the wet fallout and deposited as dry fallout) represents at least 70% of total atmospheric fallout.

Atmospheric input of trace metals to the western Mediterranean: uncertainties in modelling dry deposition from cascade impactor data

Atmospheric input of trace metals to the western Mediterranean: uncertainties in modelling dry deposition from cascade impactor data

Atmospheric input of trace metals to the western Mediterranean: uncertainties in modelling dry deposition from cascade impactor data

The mass-particle size distributions (MSDs) of Na, Al, Cd, and Pb were determined from 17, 1–5 day, high-volume cascade impactor samples collected throughout the Western Mediterranean atmosphere between 1980 and 1983. As expected, the mass median diameter (MMD) was the largest for Na, representative of sea-salt aerosol, with a median value of 5.9 μm. The median value for the MMD for Al, representative of mineral aerosol, was 2.8 μm. The smallest values of the MMD were found for pollution-derived elements, Cd and Pb: 0.7 μm. In most cases, the MSDs, for each of the elements, were log-normal. Total dry deposition velocities were calculated from the two-layer deposition model of Slinn and Slinn (1980) using three approaches: (i) by characterizing the distribution as a MMD, (ii) by considering the size distribution as directly given by the cascade impactor, (iii) by fitting the assumed log-normal distribution and dividing it into 100 successive intervals. The first approach appeared to give underestimates. The two other approaches yielded similar results for Cd and Pb, of the order of 0.05 cms -1 . For these elements, however, more than 20% of the total dry deposition flux was due to particles with diameters of 7.2 μm or greater (collected by impactor stage 1). For Na and Al, the third approach yielded values at least one order of magnitude higher than when using the two others. This clearly underlines the major role played by large particles in controlling the dry deposition of sea-salt and mineral aerosol particles. Direct measurements of Al dry deposition, made in 1985–1986 on the northwestern coast of Corsica, agree best with the values predicted by the third approach (mean calculated and measured values of 1.8 and 3.0 cm s -1 respectively). Scanning electron microscopy examinations of samples confirm that mineral aerosol particles with diameters of 10 μm or greater dominate the dry deposition flux. Preliminary data indicate that for mineral aerosol particles, this flux is, on a yearly basis, about half of the wet deposition flux. However cascade impactor data are not adequate to retrieve true mass-particle size distribution in the size range which controls dry deposition ( D > 7 μm), and this is shown to be the source for one order of magnitude uncertainties in dry deposition calculations. DOI: 10.1111/j.1600-0889.1989.tb00315.x

Model simulation of the atmospheric input of lead and cadmium into the North Sea

The long-range transport of Pb and Cd over Europe is simulated with a three-dimensional transport model. The relevant meteorological input data such as wind or precipitation rates are prescribed according to 6-hourly analyses of the “European Centre for Medium Range Weather Forecasts” (ECMWF). Mixed-layer height analyses are from the Norwegian Weather Service. Estimates for the respective emissions are adopted from Pacyna [Norwegian Institute for Air Research Report No. 60/85 (1985)]. The input data are available on a 1.5° longitude-latitude grid. Measured concentrations of Pb and Cd in surface air and rainwater as well as wet deposition are used to validate the model. The simulations suggest that the North Sea pollution takes place predominantly in the vicinity of the main emission sources, i.e. in the southern and western parts of the North Sea. In the remaining part of the North Sea the deposition is smaller, i.e. approximately 30 % of the total. Accordingly, the total atmospheric input of trace metals into the North Sea is probably considerably smaller than suggested in earlier studies [e.g. van Aalst et al. (TNO Report C182/152) 1983a] which assume that the rainwater concentrations measured along the southern and western coasts are representative for the total area of the North Sea. The present model study yields an annual atmospheric input of 1531 t Pb and 14 t Cd, respectively.

Atmospheric input of trace metals to the western Mediterranean Sea: 1. Factors controlling the variability of atmospheric concentrations

The factors controlling the variability of atmospheric trace metal concentrations over the western Mediterranean Sea have been investigated using a combination of geochemical and meteorological approaches. Al, Br, Cd, Na, Pb and 210Po concentrations from bulk filters and cascade impactor samples collected during five cruises (1980–1983) have been used to characterize the aerosol sources: the marine source (Na), the aeolian soil mobilization (Al), the anthropic sources (Cd, Pb), and the volcanic source (210Po). It has been confirmed that Cd and Pb directly derive from anthropic sources. As shown by three‐dimensional air mass trajectory analyses, the variability of daily atmospheric concentrations reflects both changes in continental source strengths and in airflow patterns. Atmospheric concentrations appear to be higher during episodes of short‐range transport of continental material from riparian countries. It is suggested that such source regions can be precisely identified by a careful examination of both geochemical data and three‐dimensional trajectories. From our data set, southwestern Europe would be responsible for the largest Pb and Cd inputs to the western Mediterranean atmosphere (30–40%), but the inputs from North Africa are also likely to be significant (20–25%). However, it cannot be ascertained whether this conclusion is valid on a yearly time scale. Indeed, whereas our sample set is representative of the yearly airflow climatology, it has not been possible to assess the effect of seasonal (for Pb) or sporadic (for Al) changes in source strengths. This points out that over such a marine environment, continuous sampling programs are needed to assess the respective contributions of individual source regions to the atmospheric burden of particulate trace elements.

Atmospheric input of trace metals to Lake Michigan

Atmospheric bulk deposition was collected on a monthly basis in the Lake Michigan basin from September 1975 through December 1976 to determine the atmospheric loading of trace elements to Lake Michigan. The sampling network consisted of bulk collectors located at 21 locations in the northern and southern basin. Atmospheric loading rates to Lake Michigan were estimated as (in units of 105 kg yr−1): Al-50; Fe-28; Mn-6.4; Zn-11; Cu-1.2; Pb-6.4; Cd-0.11; Co- <0.25; Ca-798; Mg-155; Na-110; K-64. Atmospheric deposition of all elements measured was greater in the southern basin than in the northern basin as a result of intense urban/industrial activity in the former. The percentage of total atmospheric deposition falling in the southern basin was: Fe-74%, Al-71%; Mn-75%; Zn-67%; Cu-62%; Pb-78%; Cd-74%; Co- ti 56%; Ca-79%; Mg-62%; Na-65%; K-61 %. Atmospheric loading rates reported are in general agreement with estimates made by others from emission inventories and aerosol concentrations. Atmospheric loadings were estimated to represent 10% or more of the total loadings to Lake Michigan from tributary and erosion sources for the trace elements Mn, Zn, Cu, Cd and Pb. Also, atmospheric deposition may account for recent accumulations of Zn, Cu, Cd, Pb and Co in southern Lake Michigan surficial sediments. The atmospheric Ph flux to southern Lake Michigan was estimated as ∼1.7 μg sm−2 yr−1 for 1975–1976 which compares favorably with the 1972 anthropogenic Pb flux of 1.3 μg cm−2 yr−1 (total − ∼1.5 μg cm−2 yr−1) as determined from Pb-210 dating (Edgington and Robbins, 1976). The geographical distribution of trace element loading implicates the southern periphery of Lake Michigan as the principal emission source area.

The influence of organic matter and atmospheric deposition on the particulate trace metal concentration of northwest Atlantic surface seawater

Particulate trace metals (PTM), organic carbon (POC), and organic nitrogen (PON) were measured in a series of surface bucket samples collected between the New England coast of the United States and Bermuda. PTM concentrations were lower or equivalent to the lowest PTM concentrations reported in the literature. Examination of the relative variations in PTM with respect to particulate aluminum and carbon led to the conclusion that organic matter was the probable regulator of PTM abundance in open-ocean surface waters and was important in this respect for continental shelf and slope waters as well. Enrichment factors of trace metals relative to their crustal abundances were found to be similar in the atmosphere sampled in Bermuda and in Sargasso Sea surface water particulate matter. A simplistic vertical flux model was constructed which showed atmospheric input of trace metals to the Sargasso Sea to be of the same approximate magnitude as the rate of removal of PTM from the mixed layer by sinking in association with POC. Essentially all of the particulate Al, Fe, and Mn in the Sargasso Sea mixed layer was attributed to aeolian sources. The fate of other atmospherically derived trace metals in the Sargasso Sea mixed layer was suggested to be a function of their solubility in seawater.