Particulate Copper Concentrations Research Articles

Effect of stagnation period and flow rate on soluble and particulate Pb leaching in copper pipe water distribution systems

Extremely high lead level in tap water caused by particulates has attracted increasing attention in recent years. Despite extensive research on the role of particulate Pb in water supply systems with lead service lines, little information is available on the role of particulate Pb in copper (Cu) water distribution systems. In this study, the dissolved, colloidal, and particulate lead and copper concentrations in representative prototype copper pipe water distribution systems with leaded solder joints and brass fixtures are measured. The effects of flow rate and stagnation time on metal fractionation are investigated. For each experimental scenario, all the water that stagnated inside the system is sampled to have a comprehensive understanding of lead contamination. Sampled at flow rates of 200–250 mL/s, the soluble lead and copper make up 60–96 % of the total concentration in the samples after hours of stagnation. More than half of the Pb and Cu particles are larger than 0.8 μm. Higher flow rates result in substantial increases in particulate metal concentrations but have no apparent effect on dissolved metals. The soluble and particulate copper concentrations (∼ 100–250 μg/L) both increase with stagnation time. For the case of Pb, while the particulate concentration increases (up to ∼ 40 μg/L after 12 h), the soluble concentration does not change significantly beyond 4 h; this can be attributed to the different solubilities of Pb (∼ 20 μg/L) and Cu (∼ 200 μg/L) in tap water. The results also show that particulates suspended by clean “once through” water (without prior stagnation) can lead to high levels of Pb contamination (> 10 μg/L).

Invertebrate community responses to a particulate- and dissolved-copper exposure in model freshwater ecosystems.

Historical contamination has left a legacy of high copper concentrations in the sediments of freshwater ecosystems worldwide. Previous mesocosm studies have focused on dissolved-copper exposures in the overlying waters, which, because of altered exposure pathways, may not accurately predict the effects of copper exposure on invertebrate communities at historically contaminated sites. The present study assessed the effects of copper on the establishment of invertebrate communities within a large outdoor pond mesocosm facility containing environmentally relevant copper-spiked sediments. High particulate copper concentrations (>400 mg/kg dry wt) caused a pronounced effect on the benthic community richness, abundance, and structure in the mesocosms, but particulate copper concentrations below 100 mg/kg dry weight had no effect. Furthermore, there were no effects of copper on the invertebrate communities within the water column, even in the highest copper treatment. The response of the benthic community to copper was influenced by interspecific interactions, the stage of ecological succession, and interspecies variation in sensitivity to copper. The present study demonstrates the importance of using environmentally realistic exposure scenarios that provide both particulate and dissolved exposure pathways. It also emphasizes that risk assessments for aquatic ecosystems should consider the influence of interspecific interactions and interspecies variation in driving the biotic response to contamination.

Modelling diagnosis of heavy metal (copper) transport in an estuary

A vertical (laterally-averaged) two-dimensional heavy metal transport model was developed to simulate the fluxes of copper in the Danshuei River estuarine system. The toxic model was incorporated into the hydrodynamic, the salt transport and the sediment transport modules. The model has been validated with observed time series data of water surface elevation, current, salinity, and suspended sediment concentrations in 2001 and 2002. An exponential relationship was established to relate variation in partition coefficient of copper to salinity and suspended sediment concentrations in the Danshuei River estuary. Comparisons of the total, dissolved, and particulate copper concentrations calculated by the numerical model and field data along the Danshuei River-Tahan Stream show good agreement. It is noteworthy that the model requires a point source of total copper with the strength of 250 kg/day to account for the observed persistently high total copper concentration near Hsin-Hai Bridge in the Tahan Stream, about 24 km upriver from the river mouth. The huge garbage dump site near the Hsin-Hai Bridge is likely the source of heavy metal pollution. The validated model was then applied to investigate the tidally averaged salinity distributions, residual circulation, suspended sediment, and total copper concentrations under low flow condition. The residual circulation is characterized by the upriver movement of denser saline water in the lower layer and the downriver movement of fresher water in the upper layer. The circulation pattern is driven by the longitudinal gradient of salinity distribution. The residual circulation occurs in the deep channel of Kuan-Du Bridge and Taipei Bridge. Under low flow condition, the limits of salt intrusion are located at Hsin-Hai Bridge. The tidally-averaged sediment concentration distribution exhibits a local maximum concentration around the null point in the Danshuei River-Tahan Stream. A local maximum of total copper concentration, which is nearly as high as that near the point source, occurs around the null point, which is potentially a hot spot of heavy metal accumulation.

Seasonal variations of dissolved and particulate copper species in estuarine waters

This one-year survey conducted in the macrotidal estuary of Penzé (Brittany, Western part of the Channel, France) was aimed at examining the variations of the various dissolved and particulate copper species. Ten field stations along the whole freshwater–seawater mixing zone were sampled each month. Different biogeochemical parameters (SPM, chl- a, pH and DOC) were also measured. The levels in total dissolved and total particulate copper ranged from 1.8 to 9.5 nM and from 5 to 98 μg g −1, respectively; such amounts are indicative of a pollution-free system. Extractable C 18 copper (non-polar hydrophobic organic copper species), in winter and spring, accounted for 30–40% of the total dissolved copper. In summer, this contribution rapidly rose to 60% in the salinity range 20–30; over the same period of time, total particulate copper decreased. The change in dissolved copper speciation and the lowering of particulate copper concentrations were attributed to the release of strong organic ligands by phytoplankton. Our field data evidenced a highly variable behaviour for the various copper species over the seasonal cycle, and then led us to identify the following mechanisms: (i) metal desorption from organic river-flown particles (winter and spring), (ii) metal desorption from resuspended sediment in the upstream section (summer), (iii) competition between particles, non-extractable C 18 organic ligands and phytoplankton-released extractable C 18 organic ligands to complex copper in the downstream section (summer), and (iv) removal of non-extractable C 18 organic copper by adsorption (autumn). Dissolved copper species fluxes were assessed: most of metal inputs to the estuary (60–74%) corresponded to non-extractable C 18 organic copper. Winter and spring metal output fluxes were mainly constituted of non-extractable C 18 organic complexes; on the other hand, extractable C 18 organic complexes were predominant in summer and autumn output fluxes.

Dissolved and particulate fluxes of copper through the Morlaix river estuary (Brittany, France): mass balance in a small estuary with strong agricultural catchment

Dissolved and particulate copper were measured over an annual cycle (12 surveys between February 1998 and January 1999) in the Morlaix Estuary (Brittany, France). These variations were investigated in both the water column and the benthic compartment in order to calculate fluxes of copper within estuary. In the water column, dissolved and particulate copper concentrations ranged from 0.6 to 19.0 nM and from 0.03 to 2.3 μmol g −1, respectively. In the benthic compartment, copper concentrations in superficial sediment varied from 0.04 to 0.32 μmol g −1 and from 7.6 to 80.5 nM in the pore waters. The results show that copper contents in the water column reached levels commonly observed in estuaries affected by heavy industrial activities. Agricultural activities, extensively developed on the drainage basin, may be responsible for the copper excess. Mass balance of copper indicates that the metal accumulated within the estuary with a rate ranging from 97 to 119 kg yr −1.

Geochemical cycling and speciation of copper in waters and sediments of Macquarie Harbour, Western Tasmania

The factors determining the concentration and speciation of copper in the waters and sediments of Macquarie Harbour, Tasmania were investigated. This harbour is the most extensively copper-contaminated estuarine water body in Australia owing to current and historical inputs of metal-rich waters and sediments from the nearby Mount Lyell copper mine. The dissolved copper concentrations in the harbour water column were highly variable (4–560 μg l −1) and displayed a north to south gradient, decreasing with distance from the King River, which carries the inputs from the mine. The most significant process affecting dissolved copper concentrations was the neutralisation of acidic river waters with seawater and the resulting coprecipitation with iron oxyhydroxide flocs. Approximately 60% of the riverine dissolved copper input was removed from solution by this process. Particulate copper concentrations in surficial benthic sediments were high in most regions of the harbour (typically 0.5–1 mg g −1). In the north, sediments were dominated by fine, mine-derived material and showed uniform particulate copper concentrations with depth. Sediment acid-volatile sulphide concentrations were highest (11–142 μmol g −1) in the southern harbour and were barely detectable in the northern harbour region (<0.46 μmol g −1). A similar north–south gradient of sediment organic carbon concentrations was observed. Very high porewater concentrations of copper (up to 520 μg l −1) and iron (200 mg l −1) were found at sites in the northern harbour. The high porewater copper concentrations are believed to result from the oxidation of porewater Fe(II), formation of amorphous iron oxyhydroxide and the associated pH-related dissolution of particulate copper. Calculations indicated a positive flux of dissolved copper from the sediments at sites in the northern harbour. However, in the southern harbour, the high acid volatile sulphide concentrations of the sediments meant that they acted as a sink for dissolved copper, resulting in low porewater copper concentrations (<1–10 μg l −1) and a significant copper flux from the overlying water to the sediment. The study illustrates the roles of iron redox chemistry, associated pH gradients, and acid volatile sulphide in controlling copper mobility in contaminated estuarine environments.

Bioavailability of Apparent Fulvic Acid Complexed Copper to Fish Gills

It is well recognized that only the bioavailable species, rather than all metals, are of concern with regard to bioaccumulation by and toxicity to aquatic organisms. It would be desirable to establish the relative bioavailability of various chemical species of metals and to understand the fundamental interactions that control the speciation and bioavailability of inorganic contaminants to organisms (Hudson 1998). It is generally known that the dominant bioavailable species of trace metals available for fish in aquatic environments include the hydrated metal ions along with the metal hydroxo complexes, although these account for only a small fraction of the total metal content surface waters (Andrew et al. 1977). In natural waters containing various amounts of suspended solids and humic substances, a large portion of metals are those adsorbed on to particulate matter and those that are complexed to naturally occurring organic ligands as a result of the relatively high affinity metals have for these carriers, Sufficient evidence exists indicating that the addition of humic substances to aquatic systems can significantly reduce the bioavailability of metals to aquatic organisms (Holli s et al. 1996). It was, therefore, generally understand that organic metal complexes were unavailable to fish via uptake by the gills, Recently, however, Tao and colleagues evaluated the bioavailability of particulate copper to fish gills by exposing Paracheirodon innesi to copper in a synthetic river water spiked with kaolin clay .The concentrations of ‘free metal’ were maintained at a constant level while the particulate copper concentrations varied from one tank to another based on the measured isomer of the copper-kaolin system and the equilibrium calculation. The results indicated that although the kaolin clay could reduce fish uptake of copper, a stoichiometric analysis indicated that a fraction of the kaolin clay adsorbed copper was available for fish uptake via gills (Tao et al. 2000a) .As such, a mechanism of particulate metal uptake by the fish gills was suggested, with the key point of the proposed mechanism being the desorption of the metal from the particles within the gill microenvironment where the particles adhered to mucus (Tao et al. 1999a). Additional strong support for this hypothesis was provided by evidence collected in another experiment where Carassius auratus and gibbsite adsorbed lead were used (Tao et al. 1999b). It was assumed, therefore, that the mechanism for particulate metal uptake via fish gill mucus might also be applicable to naturally occurring organic compound complexed

Use of oysters as indicators of copper contamination in the Patuxent River, Maryland

The Patuxent River flows into the Chesapeake Bay from its western shore. Historically, the river has been implicated as having been contaminated with copper since the mid-1960's when a steam electric generating plant was built at Chalk Point, 35 km from the mouth of the river . Greening of oysters was noted by Roosenberg (1969) who reported copper levels in oysters from trays set close to the outfall in excess of 1000 μg g dry weight ' . It was claimed that the copper contamination derived from the coppernickel condenser tubing used for cooling two of the four generating units at the Chalk Point Plant . Units 3 and 4 used cooling towers for cooling purposes . In the early 1980's, a detailed study of copper output from the plant was undertaken in this laboratory and by Abbe & Sanders (1986) . The Abbe and Sanders (1986) study was confined to the immediate vicinity of Chalk Point, whereas the current study was extended from Holland Cliff (River Km 45) to Solomons, 3 km from the river mouth. Data describing dissolved and particulate copper concentrations in Patuxent River water have been described in a companion paper (Wright & Zamuda, 1990), which creates a budget for copper input to the river . In the current paper, we describe the bioavailable copper in the Patuxent River as defined by body burdens in

Vertical profiles of copper in sediments from the Fly delta and Gulf of Papua (Papua New Guinea)

We examined the vertical profiles of disolved and particulate copper concentrations in the sediments within this region to determine whether any metal pollution has yet occurred as a result of the Ok Tedi mining operation, and to evaluate the spatial extent of copper levels in relation to sediment organic content, grain size and nutrient chemistry

Dissolved organic copper isolated by C 18 reverse-phase extraction in an anoxic basin located in the Pettaquamscutt River Estuary

The upper region of the Pettaquamscutt River, Rhode Island, is a fjord-type estuary with two deep basins separated by a shallow sill. The water column in these basins remains stable for periods of several years with only partial mixing occurring. Dissolved organic copper isolated by C 18 reverse-phase extraction was determined in the uppermost basin; these values ranged from 0.29 μg kg −1 in the oxic surface waters to <0.001 μg kg −1 in the deeper anoxic waters. Total dissolved and particulate copper concentrations ranged from 0.53 to 0.13 μg kg −1 and 0.46 to <0.03 μg kg −1, respectively. Dissolved concentrations were highest at the surface while particulate copper values were greatest in the suboxic deeper waters. Organically bound copper accounted for 42–60% of the total dissolved copper in the oxic surface waters; however, these values progressively decreased to < 1% through the redox transition zone. Chromatographic profiles of isolated dissolved organic matter were obtained using high-performance liquid chromatography. These profiles indicate that dissolved organic matter (DOM), which complexes copper in oxic waters, is present in the suboxic region. However, binding of copper by this fraction of DOM is reduced or eliminated by competition with dissolved sulfide complexes.

Transport of copper from the Bering Sea to the northwestern North Pacific

Dissolved copper concentrations in surface waters of the Bering Sea ranged from 106 to 882 ngl−1. Higher concentrations were found in continental shelf waters. In the northwestern North Pacific dissolved copper ranged from 54 to 140 ngl−1. Particulate copper concentrations varied regionally and seasonally from 6 to 79 ngl−1. Regionally averaged particulate copper concentrations decreased from 175 to 33Μg g−1 against an increase in suspended materials because of the dilution effects of biological fractions. Apparent sporadic increases in copper concentrations were found in the mixing area of the Kuroshio and the Oyashio waters. The feature is attributed to the lateral distribution of different water types rather than to the upwelling of deeper waters by eddies. In the same area west of 160‡E, waters with high concentrations of dissolved copper (96±9 ngl−1) were found. Their origin appears to be the continental shelf of the Bering Sea. In spite of intensive biological activity, a considerable fraction of copper added to shelf waters was transported to the area off Japan via the circulation in the Bering Sea and the Oyashio current.

Dissolved copper and copper-organic complexes in the Narragansett Bay estuary

The geochemistry of dissolved copper-organic complexes was investigated in the estuarine waters of Narragansett Bay. A transect survey was conducted in August 1980, while one mid-bay station was monitored from March through August of that year. The transect data indicated that most of the copper-organic complexes enter the bay via sewage effluent which is discharged into the Providence River at the head of the bay. Organic copper concentrations in the estuary ranged from 0.12 to 2.30 μg kg −1 and comprised from 14 to 70% of the total dissolved copper. The concentration of copper-organic complexes was not directly related to the amount of dissolved organic matter; and recently generated organic material from phytoplankton production within the bay had a negligible influence on the fraction of dissolved copper which was organically bound. The major source of total copper to the bay is anthropogenic inputs from sewage effluents. Particulate and dissolved copper concentrations ranged from 0.06 to 2.42 and 0.23 to 16.4 μg kg −1, respectively, giving average values of about 40% particulate and 60% dissolved copper. Particulate copper concentrations decreased rapidly from the upper to the lower bay as a result of both removal and dilution. About 75% of the dissolved copper entering the bay is rapidly removed in the Providence River and upper bay, and the remaining portion (which is largely organic copper) follows conservative mixing in the mid to lower bay. The data suggest that copper binding by dissolved organic matter may be an important control on the riverine flux of dissolved copper through estuaries into coastal and oceanic waters.

Environmental chemistry of copper in Lake Monona, Wisconsin

Lake Monona, located at Madison, Wisconsin, received over 1.5 × 10 6 pounds of copper sulfate in the past 50 yr to control excessive algal growth. Dissolved copper on Lake Monona epilimnion is inversely related to pH which indicates possible control of dissolved copper by basic copper carbonate. Concentrations as high as about 4 μg Cu l −1 were found in Lake Monona epilimnion, which also contains 3.3 me l −1 (milliequivalents per liter) of alkalinity, mostly bicarbonate. Concentrations of dissolved copper were consistently lower (0.3 μg Cu l −1) in the hypolimnion. Sulfide probably controls dissolved copper in the hypolimnion during anoxic conditions because of sulfide insolubility. Particulate copper concentrations of about 3 μg l −1 increased slightly with depth. The highest concentrations of copper in Lake Monona sediments (650 mg kg −1) were found approximately 60 cm below the current sediment surface. Surface sediments of Lake Monona contained approximately 250 mg Cu kg −1 sediment dry weight.

THE DISTRIBUTION OF COPPER IN TROPICAL SEAWATER1

The concentrations of the ionic, particulate, and total soluble copper in waters off Florida were determined spectrophotometrically. Most of the copper was in the soluble organic complex. Nearshore waters had significantly more total copper (approximately 20 µg/liter) than the waters flowing through the center of the Straits of Florida (approximately 10 µg/liter). Ionic copper concentrations were always less than 2µg/liter, and the particulate copper concentrations rarely exceeded 0.2 µg/liter.