Anthony J. Paulson

Possible evidence for enrichment of trace elements in the hydrous manganese oxide phases of suspended matter from an urbanized embayment

Abstract Total and weak-acid-soluble trace elements in suspended matter from the Duwamish River and Elliott Bay were determined from samples collected in February and September 1980. The results indicate that Mn scavenging in the water column is coincident with enrichments of Cr, Ni, Cu, Zn, and Pb in the suspended matter, suggesting a possible enrichment of these trace elements in a hydrous Mn oxide phase. This process occurs primarily in the sub-surface waters of Elliott Bay. Since mass balance calculations show a net export of Mn out of the bay, this mechanism may be an important means of transporting toxic trace metals from polluted estuaries and embayments to cleaner coastal environments.

The impact of scavenging on trace metal budgets in Puget Sound

Abstract The distributions of dissolved and particulate Mn, Pb, Cu and Zn in Puget Sound, its tributaries, and its sediments were determined to illustrate the impact of scavenging reactions on trace metal budgets of a large fjordlike estuary. About 75% of the dissolved Pb discharged into the main basin of Puget Sound was scavenged from the dissolved phase. The high particulate Pb concentrations in regions of high particulate Mn concentrations and the significant correlations between Pb and Mn concentrations on suspended particles demonstrate the importance of hydrous manganese oxide phases in scavenging dissolved Pb. Since particles are effectively retained within the main basin, scavenging results in the sedimentation of about 70% of the total Pb added to the main basin. Only isolated instances of scavenging of dissolved Cu and Zn were observed and the discharge rates of dissolved Cu and Zn from known sources were equal to their rates of advective removal within the errors of the budget. The remineralization of organically-bound particulate Cu is partly responsible for its quasi-conservative behavior within the main basin of Puget Sound. The fates of Cu and Zn are controlled mainly by physical processes such as advection and settling of particles. Advection removes about 60% of the total Cu and Zn added to the main basin while 40% is deposited in the sediments of Puget Sound.

Seasonal and vertical variations in the elemental composition of suspended and settling particulate matter in Puget Sound, Washington

Abstract The distributions of C, Al, Si, P, Cr, Mn, Fe, Ni, Cu, Zn and Pb in suspended and settling particulate matter from Puget Sound were studied to investigate the processes affecting the uptake of trace metals by particulate phases. Particulate material was collected by water filtration procedures and sequentially-sampling sediment traps during approximately bimonthly surveys from December 1980 through December 1981 at a station located in the center of the main basin of Puget Sound. The samples were selectively extracted for trace metals associated with oxide, organic, and residual phases and analysed by graphite furnace atomic absorption spectrophotometry and X-ray energy spectrometry. The results show that for Mn, Fe, Zn and Pb, residual and oxide phases were the most important phases controlling the vertical flux; whereas residual and organic phases controlled the vertical flux of Cu. The average annual flux data were used along with dissolved metal profiles to compute scavenging residence times for several trace metals in Puget Sound. Relatively short scavenging residence times (i.e. 100 days) were calculated for metals enriched in organic phases, such as Cu.

Partitioning of Cu in estuarine waters, I. Partitioning in a poisoned system

Abstract The importance of dissolved hydrophobic organic matter in controlling the partitioning of Cu between the dissolved and particulate phases in natural waters was determined. Estuarine particulate matter was suspended in two solutions: (1) filtered seawater, and (2) filtered seawater in which the hydrophobic organic matter had been removed. Radioactive Cu was then added to each suspension. The removal of hydrophobic dissolved organic matter resulted in a two-fold increase in the distribution coefficient ( K D ) of added radioactive Cu (from 10 4.50 to 10 4.81 1/kg). The partitioning of 64 Cu in the suspensions was controlled by chemical processes dominated by complexation with particulate and dissolved organic matter.

Estuarine transport of trace metals in a buoyant riverine plume

Abstract The distributions of dissolved and particulate trace metals in Elliott Bay, Washington were determined in April,1985 during the period of maximum discharge of freshwater for the year. The high freshwater discharge generated a thin buoyant plume (

REMOBILIZATION OF CU FROM MARINE PARTICULATE ORGANIC MATTER AND FROM SEWAGE

The possible causes of enrichments of dissolved Cu in the bottom waters of Puget Sound were examined in a series of experiments designed to measure the release of Cu from surface marine organic suspended matter and from sewage-derived particles under ambient conditions. Decomposition of organic matter and ion-exchange controlled the release of about one-third of the Cu bound to large particles (> 53 μm). In contrast, no Cu was released from smaller particles (< 53 μm) suspended in natural seawater and only 5% of the Cu on small particles was released into artificial seawater with a low dissolved Cu concentration. Within 15 min of mixing primary effluent with natural seawater, 40% of the dissolved Cu was lost from solution by flocculation. Between 15 min and 4 days, 25% of the total effluent Cu was released back into solution. This release could have originated either from particulate Cu on the original sewage particles or from the flocculated Cu that was formed from dissolved Cu within the first 15 min. The release of Cu into the bottom waters of Puget Sound from settling marine organic matter was calculated to have been between 1 and 8 μg Cu m−2 day−1, which is comparable with the diffusion of Cu from sediments. In contrast, the release of sewage-derived Cu could have been as high as 725 μg Cu m−2 day−1 within 10 km of outfall.

Estimates of trace metal inputs from non-point sources discharged into estuaries

Abstract Elliott Bay and the Duwamish Waterway, Washington were sampled for dissolved trace metals during a period of wet weather in January 1986. High concentrations of dissolved Cu, Zn, Pb, Cd and less elevated concentrations of dissolved Ni were found in marine waters adjacent to operating shipyards and a combined sewer overflow pipe that was discharging. Changes in the transports of dissolved trace metals, which have been deduced from trace metal-salinity plots, were attributed to emissions from anthropogenic sources. While 65% of the dissolved Cu and Zn transported from Elliott Bay were attributed to emissions from shipyards along Elliott Bays shoreline, an additional 30% of the Zn was added by industrial areas adjacent to waterways supplying freshwater. Only 20% of the Elliott Bay dissolved Ni transport was contributed by shoreline sources. In contrast, anthropogenic sources did not increase the transport of dissolved Fe.

Behavior of Fe, Mn, Cu and Cd in the duwamish river estuary downstream of a sewage treatment plant

Abstract The behavior of dissolved Fe, Mn, Cu and Cd in the Duwamish River downstream of a sewage treatment plant located near Seattle, Washington, was investigated in three distinct zones: (1) immediately downstream of the effluent outfall, (2) further downstream in the freshwater portion of the river and (3) in the estuarine mixing zone. A three-end-member tracer model utilizing salinity and dissolved inorganic nitrogen was developed to distinguish physical mixing processes from biogeochemical reactions. The results of this investigation indicate that Fe was removed from the dissolved phase onto particulates near the plant. Although no additional reactions controlled the distribution of dissolved Fe, Mn and Cu in the freshwater portion of the river, Cd was removed from the dissolved phase. In the estuarine mixing zone, a significant fraction of the dissolved Fe and Cu was removed from solution, while Mn and Cd desorbed from particulates. The chemical forms of the trace metals rather than their sources appear to determine their participation in these reactions.

Partitioning of Cu in estuarine waters, II. Control of partitioning by the biota

Abstract In two sets of suspensions containing biotic particles, organisms indirectly controlled the partitioning of added Cu between the dissolved and particulate phases by releasing dissolved organic ligands. Organisms present at total suspended matter concentrations as low as 10 mg/l released enough organic compounds during 1 day to negate the initial removal of the hydrophobic dissolved organic matter by Sep-Pak columns. In these experiments, the coating of particulate inorganic surfaces with organic matter may have also prevented Cu from establishing a chemical equilibrium between these particulate surfaces and the solution. The behavior of added radioactive Cu is consistent with an equilibrium model if the transfer of organic matter between dissolved and particulate phases by organisms is considered. In contrast, the behavior of natural Cu in these biotic suspension indicate that the partitioning of Cu was controlled as much by active biological processes as by chemical equilibria.

Separate dissolved and particulate trace metal budgets for an estuarine system: An aid for management decisions☆

The sources and sinks of dissolved and particulate Pb, Cu and Zn were determined for the main basin of Puget Sound to understand the effect man has had on metal concentrations in both the water column and in the sediments. Municipal, industrial and atmospheric sources contributed about 66% of the total Pb added to the main basin of Puget Sound during the early 1980s. Advective inputs were the major sources of total Cu and Zn (approximately 40%) while riverine and erosional sources contributed about 30%. The discharge of the particle-bound trace metals from rivers minimized the influence of particulate anthropogenic sources, which constituted 50%, 23% and 18% of the total particulate Pb, Cu and Zn inputs, respectively. While advective transport was the major source of dissolved Cu and Zn (approximately 60% of all dissolved inputs), industrial, municipal and atmospheric inputs contributed about 85%, 30% and 38% of the dissolved Pb, Cu and Zn inputs, respectively. The sources of dissolved and particulate Cu and Zn were comparable with the sinks within the errors of the analyses indicating their quasi-conservative nature. Advection removed about 60% of the total Cu and Zn added to the main basin while 40% was deposited in the sediments of Puget Sound. Because of this quasi-conservative nature of Cu and Zn, anthropogenic inputs of Cu and Zn were dispersed from the system more than they were contained within main basin sediments. About 75% of the dissolved Pb discharged into the main basin of Puget Sound was lost from the dissolved phase and was balanced by a similar gain in the particulate phase. Because of this extensive scavenging and the effective retention of particles within the main basin, about 70% of the total Pb added to the main basin was retained within its sediments. These separate mass balances have utility in management decisions because they show the relative contributions from different sources and demonstrate whether the influences of dissolved and particulate inputs are reflected solely in the water column or the sediments, respectively.