Particulate Trace Metal Concentrations Research Articles

Particulate trace metal and major element distributions over consecutive tidal cycles in Port Jackson Estuary, Australia

Particulate trace metal (Cu, Cr, Ni, Pb and Zn) and major element (Fe, Mn and Al) concentrations have been determined following intensive sampling over two consecutive spring tidal cycles in the 'turbidity maximum zone' (TMZ) of the Port Jackson estuary, Australia. Salinity, temperature, pH, dissolved oxygen, suspended particulate matter (SPM) and chlorophyll a were also determined. A three-factor analysis of variance was used to test temporal variability in concentrations of particulate trace metals and major elements as a result of tidal oscillation. Estuarine master variables, such as temperature and pH, varied within a narrow range; nevertheless, the tidal signal was clear for surface and bottom waters. In surface water, no variance was detected in SPM concentrations between consecutive tidal cycles or between tidal stages (i.e. flood, ebb and slack water). In bottom water, however, SPM concentrations were significantly higher (P≤0.05) at flood tide than at slack high water and ebb tide. Concentrations of particulate trace metals and major elements in surface water do not display significant variability between tidal cycles or stages. Nevertheless, differences within each tidal stage were significant (P≤0.05) for all elements. In bottom water, only particulate Fe and Al exhibited significant differences (P≤0.05) between tidal cycles, whereas particulate Ni was the only trace element that presented significant differences (P≤0.05) between tidal stages, following the distribution of SPM, with highest concentrations at flood tide. Among the metals studied, significant variation was found at all three temporal scales examined (i.e. from hours to consecutive tidal cycles), although the patterns of variation were different for each metal. The semi-diurnal fluctuation of SPM and particulate trace metal concentrations during spring tides is interpreted as a resuspension–deposition cycle caused by cyclical oscillations of bottom currents. The results are discussed in the context of the implications of tidal cycle influence on the geochemistry and cycling of particulate trace metals in the Port Jackson estuary.

Short-term biogeochemical influence of a diatom bloom on the nutrient and trace metal concentrations in South San Francisco Bay microcosm experiments

Two laboratory microcosm experiments were conducted to mimic an annual spring diatom bloom in South San Francisco Bay by isolating the phytoplankton community from the benthic grazing pressure to induce a phytoplankton bloom. The purpose of these experiments was to isolate the impact of a spring diatom bloom on the nutrient and trace metal geochemical cycling. Microcosms were created in 2.5 L incubation bottles and subjected to one of 4 treatments (control, copper [Cu] addition, manganese [Mn] addition, and both Cu and Mn addition) to investigate the toxicity of Cu on the resident plankton and the potential antagonistic effects of Mn on reducing Cu toxicity. Dissolved macronutrient (nitrate + nitrite, phosphate, and silicate), and dissolved and particulate trace metal (Cu, Ni, Mn) concentrations were monitored in the grow-out incubations on a daily basis. Chlorophylla concentrations were also monitored over the course of the experiment and used to calculate diatom-specific growth rates. In the experiments containing ambient South San Francisco Bay surface waters, average specific growth rates were on the order of 1.1 d−1. The induced diatom blooms resulted in significant removal of macronutrients from the microcosms over the course of the experiments. Our research supports previous suggestions that dissolved Ni and Cu concentrations in South San Francisco Bay have a very low biological availability as a result of organic chelation. Ni(EDTA)2− has been found to be the dominant dissolved Ni species by other researchers and Cu speciation analyses from this study and others indicate that > 99% of the dissolved Cu in South San Francisco Bay is strongly chelated as CuL1. The free cupric ion concentration was on the order of 10−12 M. Marked removal of dissolved Mn was observed in the control treatments, well exceeding expected dissolved Mn removal by diatom uptake. Additions of 375 nM Cu resulted in the complete titration of the chelating ligand (L1) concentrations. The elevated [Cu2+] (≈10−8MM) appeared to have a toxic effect on the diatom community observed in the significant decreases in their specific growth rates (μ=0.4 d−1). The suppression of dissolved Mn removal from solution was also observed in treatments spiked with high levels of dissolved Cu, providing support that Mn precipitation was due to biologically mediated oxidation not phytoplankton assimilation. The observed geochemical behavior in the concurrent Cu and Mn addition treatments provide evidence in support of Mn alleviation of Cu toxicity. The biological role in the ambient short-term biogeochemical cycling of Cu and Ni in South San Francisco Bay appears to be minimal due to the inert character of the organic ligand-metal complexes. A significant portion of the annual macronutrient and Mn cycling occurs as a result of spring diatom blooms in South San Francisco Bay.

Trace metal and total suspended solids concentrations in freshwater: the importance of small-scale temporal variation.

The temporal variation in the concentrations of particulate trace metals (Cu, Pb and Zn) and total suspended solids (TSS) was examined in three rivers that drain into the Port Jackson estuary, Australia, using a nested, hierarchical sampling design. Sampling was conducted between March and June 1999, under low flow conditions. The sampling design incorporated four temporal scales (hours, days, weeks and months). It was considered that hours, days, weeks and months were representative of such time scales and could be analyzed as random, nested sources of variation in an analysis of variance (ANOVA). Significant variation was found at temporal scales ranging from hours, within the same day, to months. The amount and scales of variation differed between particulate trace metals and TSS concentrations and between rivers. In many cases, differences between small-scale were as important as differences between months. The results suggest that higher anthropogenic influences cause higher variability at small temporal scale. Results indicate the need for nested sampling designs to be incorporated into studies of temporal variation in order to unconfound small-scale temporal variation. The conclusions of this study are likely to be applicable to other water quality variables and pollutants.

Trace metal concentrations in the Ross Sea and their relationship with nutrients and phytoplankton growth

Dissolved and particulate trace metal concentrations (dissolved Fe, Zn, Cd, Co, Cu and Ni; particulate Fe, Mn and Al) were measured along two transects in the Ross Sea during austral summer of 1990. Total Fe concentrations in southern Ross Sea and inshore waters were elevated >3.5 times that of northern waters. Dissolved Zn, Cd and Co concentrations were lower by factors of 4.5, 3.5 and 1.6 in southern surface waters relative to northern waters. Dissolved Cu and Ni concentrations were similar in both areas. Elevated Fe concentrations coincided with areas of increased productivity, phytoplankton biomass and nutrient drawdown, indicating that Fe is an important factor controlling the location of phytoplankton blooms in the Ross Sea. Particulate concentrations of Fe, Mn and Al indicate two possible sources of iron to the Ross Sea, resuspension of continental shelf sediments and iron incorporated in annual sea ice and released with meltwaters.

Temporal variability of trace metals in new jersey pinelands streams: relationships to discharge and pH

Dissolved and particulate trace metal (Al, Cd, Cu, Pb, and Zn) concentrations were determined over a 21 month time period at four streamwater sites in the Pinelands (New Jersey, USA), a coastal plain region characterized by low-pH waters and highly weathered soils. Al and Zn were also determined at two sites over a 5 day period following a major precipitation event. In the Batsto River (pH 4.4–6.3), a representative Pinelands stream draining a largely forested watershed moderately impacted by agriculture, discharge-weighted mean concentrations of dissolved metals were (in nM): Al = 4610; Cd = 0.39; Cu = 4.6; Pb = 1.0; and Zn = 149. Dissolved Cd, Cu, and Zn in the undeveloped Bass River (pH 4.1–4.8) are in a similar range, but Pb concentration is 2–3 times greater. Dissolved metals show highly significant positive correlations to discharge, and weaker inverse relationships to pH over both the long- and short-term time series. Overall, seasonal and short-term variability in dissolved metal concentrations is most consistent with control by hydrologic flow path changes during high discharge, when shallow groundwaters mobilize anthropogenic metals stored in near-surface soil horizons and bypass potential metal removal processes in bordering wetlands. The data also suggest that in-stream metal removal driven by summertime biological productivity may further reduce low-discharge metal concentrations, as a secondary effect. For these metals, the particulate fraction is generally minor, and variations in solution/particle partitioning are unimportant to spatial/temporal variations dissolved concentrations, except for Pb. Estimates of atmospheric input can account for riverine fluxes of these metals, and suggest that Zn retention is minimal in this system, while Pb, Cu and Cd are more strongly retained. The positive relationship between discharge and metals concentration, and the unusually high concentrations in Pinelands streams compared to other world rivers, suggest that riverine effects on metals distributions in the estuary and nearby coastal ocean will be measurable and strongly seasonal.

Diagnosis of Chemical Reactivity and Pollution Sources from Particulate Trace Metal Distributions in Estuaries

A simple approach is outlined for the diagnosis of chemical reactivity and pollution sources from distributions of suspended particulate constituents in estuaries of low turbidity and limited bed-water column particle exchange. The approach is demonstrated using acetic acid-extractable particulate trace metal data for the Clyde Estuary, where water and particle mixing in the vertical is restricted by a strong pycnocline, resuspension is limited by slow subsurface currents and internal sediment cycling is inhibited by the topography of the outer estuary. The salinity distributions of particulate Fe and Mn result from end-member particle mixing, modified by the geochemical mechanisms controlling their particle–water exchange (salt-induced flocculation of riverine, Fe-bearing colloidal material and autocatalytic oxidation-sorption of dissolved Mn). The axial distributions of particulate Cu, Cr, Pb and Zn are, additionally, affected by external inputs to the tidal estuary. The magnitudes of internal (e.g. particle–water exchange) or external (e.g. pollution) sources are calculated from the deviation of metal concentrations from a theoretical dilution line adjoining estuarine end-members, via chemical mass balances and empirical equations defining particle–water partitioning as a function of salinity. Calculated particle–water exchanges of Fe and Mn are compatible with independent dissolved metal measurements in the Clyde Estuary. Calculated external sources of Cu and Pb are in reasonable agreement with monitored trace metal input data to the estuary, but discrepancies exist between calculated and monitored external sources of Cr and Zn because of the significance of unmonitored inputs and chemical reactivity for these metals.Although suspended particulate trace metal concentrations in the Clyde are among the highest of industrialized estuaries in the U.K., it is argued that this, in part, reflects the inability of the Clyde to buffer pollution inputs because of the restricted internal cycling and bed-suspension exchange of particles in the system. A more general implication is that the mobility of the sediment reservoir and standing stock of suspended particles, in addition to concentration of particulate constituents (w/w), should be accounted for in any estuarine pollution impact evaluation.

Trace metals at two sites in the southern North Sea: Results from a sediment resuspension study

Particulate and dissolved trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) have been determined following intensive sampling in January and May 1989 at two sites in the southern North Sea. Site A (52° 39.5′N, 003° 40.0′E) had sandy sediments, a permanently well-mixed water column and salinities >34.5, associated with waters from the English Channel. Particulate trace metal concentrations were higher in January than in May. The concentrations in the dissolved phase were unchanged between the two periods, except for dissolved Mn which had low concentrations in January, as a result of uptake onto particles. Atmospheric inputs to surface waters were evident in January, mainly for particulate Pb. Tidally induced resuspension processes produced temporary changes in the particulate and dissolved trace metal concentrations of the bottom waters for Mn, Pb and Zn. The variation in particulate trace metal concentrations, in May, fitted a two-component particle mixing model. It is argued that a significant source of dissolved metals was from the remineralisation of particulate material held within biological fluff at the sea bed. Site B (54° 35.0′ N, 004° 50.0′ E) had sediments of muddy sand, a seasonally stratified water column and it was influenced mainly by Central North Sea Water, with salinities >34.5. Particulate and dissolved trace metal concentrations did not vary between the cruises, only particulate Pb had higher concentrations in January. The tidal resuspension of particulate metals was negligible and, in May, only the concentrations of dissolved Pb and Zn increased at higher current velocities. The results identify pathways and particle–water interactions that affect trace metal transport in the North Sea.

Distributions and fluxes of non-detrital particulate Fe, Mn, Cu, Zn in the Humber coastal zone, U.K.

Samples of suspended particulate matter (SPM) were collected at an anchor station at the mouth of the Humber Estuary and in the Humber-Wash coastal zone (U.K.) during the winter (1988), spring (1990) and summer (1990). Non-detrital particulate trace metals (Fe, Mn, Cu and Zn) were determined in the SPM following digestion with 1M HCl. Concentrations of non-detrital particulate trace metals were higher at the anchor station than in the coastal waters, suggesting dilution of metal-polluted estuarine SPM with natural SPM originating from erosion of the adjacent coastline. The distribution of non-detrital Fe and Zn in the coastal waters could be explained in terms of the Humber Estuary being a primary source, whereas for non-detrital Mn and Cu, the estuarine source was less significant because of their participation in biogeochemical processes. A hydrodynamic model of the Humber-Wash region was used to quantify the fluxes of dissolved and non-detrital trace metals into and out of the Humber Plume. The calculations showed that 0–10% of Fe, 5–70% of Mn, 40–100% of Cu and 30–100% of Zn were transported in the dissolved phase. Interpretation of the mass balances showed that the additional source of non-detrital particulate trace metals was sediment resuspension, whereas important sources of dissolved trace metals were porewater infusions and, for Mn, photochemically induced dissolution of particulate Mn. The trace metal sinks were the sedimentation of particulate matter and adsorption from solution. The flux estimates were used to evaluate the likely impact of dissolved and non-detrital trace metals on the wider North Sea.

Trends of trace metal (Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb) distributions at the oxic-anoxic interface and in sulfidic water of the Drammensfjord

Anoxic sulfidic waters provide important media for studying the effect of reducing conditions on the cycling of trace metals. In 1987–1988, dissolved and particulate trace metal (Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb) concentrations were determined in the water column of the anoxic Drammensfjord basins, southeastern Norway. The iminodiacetic acid type chelating resin (Chelex 100) was used for the preconcentration of trace metals. The trace metal concentrations were determined using atomic absorption spectrophotometry (AAS), differential pulse polarography (DPP), and differential pulse-anodic stripping voltammetry (DP-ASV). It was observed that the trace metals Mn and Fe were actively involved in the processes of redox cycling (oxidationreduction and precipitation-dissolution) at the O2H2S interface. The dissolved concentrations of Mn, Fe and Co showed maxima just below the O2H2S interface. The seasonal enhancement in the maxima of both dissolved and particulate Mn and Fe at the redox cline is mainly governed by the downward movement of water which carries oxygen. An association of Co with the Mn cycle was observed, while the total dissolved Ni was decreased by only 10–35% in the anoxic waters. The dissolved concentrations of Cu, Zn, Pb and, to a lesser extent, Cd decreased in the anoxic zone.

Trace-metal chemistry of the Huanghe (Yellow River), China — Examination of the data from in situ measurements and laboratory approach

Water and suspended sediment samples from the Huanghe (Yellow River) were analysed to determine trace-metal (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) concentrations and partitioning. Levels of dissolved trace metals in this study are lower than previously reported values, but similar to those from less disturbed river systems. Laboratory modeling further emphasizes rapid removal of trace metals from solution on to solid phases upon any waste drainages to the river. Moreover, particulate trace-metal concentrations in the Huanghe are generally lower compared to other large Chinese rivers. The relatively stable distribution of partitioning coefficients ( K d) suggests significance of particle regulation on trace-metal bioavailability in the Huanghe and some other large world river/estuarine systems.

Particulate metals in five major North Sea estuaries

Suspended sediment samples collected from the North Sea and during axial surveys of five major North Sea estuaries (Humber, Thames, Scheldt, Weser, Elbe) have been analysed in a consistent manner for leachable metals, specific surface area and carbon. Particulate trace metal (Co, Cr, Cu, Ni, Pb and Zn) concentrations were similar in each estuary and estimates of fluxes to the North Sea based on an empirically derived prediction equation therefore reflected catchment size. Concentrations generally decreased seawards as a result of mixing of riverborne sediment of high metal concentration with material of marine origin of relatively low metal concentration, although in the Humber, substantial anthropogenic inputs at high salinities were responsible for more ambiguous distributions. In contrast, profiles and concentrations of Fe and Mn, implicated as being important to particle surface and compositional properties, exhibited significant yet explicable inter-estuarine variability (e.g. Humber during winter: Fe = 12·0 mg g −1, Mn = 0·99 mg g −1; Elbe during summer: Fe = 6·6 mg g −1, Mn = 3·08 mg g −1). Comparable data such as these serve as valuable baselines for any future international long-term water quality monitoring programme of European estuaries.

Source control on the distribution of particulate trace metals in the North Sea atmosphere

Baseline data are presented on the concentrations of particulate atmospheric trace metals over open sea regions of the southern North Sea. It is shown that there is a south→north decreasing gradient in the emission of trace metals from the land masses surrounding the North Sea which imposes a control on the concentrations of the metals in the air masses which cross the source regions. However, air masses from a variety of sources can be transported to almost any region of the open southern North Sea. As a result, it is the origin of the air masses themselves, and not the location at which they are sampled, which constrains particulate trace metal concentrations in the North Sea atmosphere. Over long periods, a south→north decreasing gradient in particulate trace metal concentrations over the North Sea will therefore only be found if the prevailing winds to a specific location are dominantly from a similar source off the surrounding land masses. It is important, therefore, to take long term air mass flow trends into account when attempts are made to model the input of particulate trace metals to the surface of the North Sea.

Dissolved, particulate and acid‐leachable trace metal concentrations in North Atlantic precipitation collected on the Global Change Expedition

Rainwater samples from six precipitation events were collected on board ship during legs 3 and 4 of the Global Change Expedition over the North Atlantic Ocean and analyzed for dissolved, particulate (Al and Pb), and acid‐leachable trace metals (Al, Fe, Mn, Cd, Cu, Pb, Zn). Acid‐leachable concentrations of the elements (in 0.4% v/v HNO3) were similar to reported values from the North Atlantic and Pacific oceans which were measured using comparable acidification procedures. Concentrations of dissolved and particulate Al and Pb were determined in rain events concurrently sampled. Comparisons between acid‐leachable and total (dissolved plus particulate) trace metal concentrations suggest that the acid‐leachable fraction of metals can significantly underestimate total concentrations of crustal elements (e.g., Al) in rain). The solubilities of Al and Pb in precipitation were variable and mean solubilities of the elements were 13% and 45%, respectively. Recycled sea salt components were less than 14% for Al, Fe, Mn, Pb, Cd, Cu, and Zn, indicating that the net trace metal flux is from the atmosphere to the oceans. Deep‐sea particle fluxes for these metals through the western tropical North Atlantic exceed atmospheric deposition fluxes by a factor of 18‐41.

Trace metal speciation in the Yamaska and St. François Rivers (Quebec)

Water and suspended sediment samples were collected at 12 stations on the Yamaska and St. François Rivers, located in southeastern Quebec, and were analyzed for the trace metals Cd, Co, Cu, Ni, Pb, Zn, Fe, and Mn. The suspended sediment samples were subjected to a sequential extraction procedure designed to partition the particulate trace metals into five fractions: (1) exchangeable; (2) bound to carbonates; (3) bound to Fe–Mn oxides; (4) bound to organic matter; and (5) residual.Although suspended sediment levels as well as total soluble and particulate trace metal concentrations were highly variable in time and space, speciation patterns for each metal proved reasonably constant. Very small proportions of all metals, except Cd and Mn, were found in the exchangeable fraction, whereas high levels of all metals were present in the residual fraction; Fe–Mn oxides and organic matter constituted important transport phases for most metals. Deviations from this general behaviour were occasioned by man-induced perturbations (e.g., inputs of municipal sewage or mine waste water). At stations influenced by such factors, total particulate metal concentrations increased and the relative contribution of the residual fraction decreased. The trace metal content of fraction 3 proved to be particularly sensitive to anthropogenic inputs; other phases acting as trace metal sinks included those liberated in fractions 1 (Cd, Cu, Ni, Zn), 2(Cu, Ni, Zn), and 4(Cu, Ni).