Occurrence and Transport of Organic Microcontaminants in the Duluth-Superior Harbor

A large number of organic compounds were identified in sediments and suspended solids from St. Louis Bay in the Duluth harbor. Most of the organic compounds appeared to be naturally occurring plant decomposition products consisting of non-halogenated hydrocarbons, organic acids, aldehydes, ketones, amines, esters, alcohols, and phenols. However, the presence of polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAH) were confirmed by GC/MS methods. Particulate levels of PAH compounds such as fluorene, fluoranthene, and pyrene were found to lie in the 0.2 to 3 μg/g range. PCBs associated with suspended particles from St. Louis Bay and the Superior harbor were at concentrations of 0.2 to 0.9 μg/g and less than 0.1 μg/g, respectively. Measurements of PCBs in water from the St. Louis Bay showed an average value of 19 ng/L. Considering the concentration of PCBs in water and particulates in conjunction with average suspended solids levels, it was calculated that 81% of the PCBs were dissolved in water and 19% associated with suspended particles. It was estimated that suspended solid transport of PCBs and PAH to Lake Superior is less than 0.01% of airborne transport.     

Algal-Available Particulate Phosphorus in the Great Lakes Basin

For the purpose of comparing the relative availability of particulate phosphorus (P) from various sources to the Great Lakes, algal-available P was determined on suspended solids and bottom sediments from tributaries, wastewater suspended solids, lake bottom sediments, and eroding bluff solids from the region. Physicochemical and bioassay methods were used to estimate the rate and extent of available P release from particulates. Considering all types of particulates examined, ultimately available P ranged from nil to approximately 70 percent of total phosphorus (Total-P) content. During algal bioassays, changes in levels of base-extractable inorganic P (R-NaOH-P) in tributary suspended solids were nearly equivalent to the amounts of P used by algae during bioassays. For the tributary solids, ultimately available P averaged approximately 90 percent of R-NAOH-P. Consistent differences were found in amounts of available P among particles from different sources. Sources of particle-bound P ranked in order of decreasing availability were: wastewater solids, lake bottom sediments, tributary solids, and eroding bluff solids. Differences in available P release rates also existed among the different types of particles. Wastewater solids displayed the largest first-order release rates, eroding bluff samples and tributary-suspended solid samples that were high in apatite showed essentially no available P release, while other tributary suspended solids displayed intermediate release rates.     

Chlorinated Organic Contaminants in Water and Suspended Sediments of the Lower Niagara River

Suspended sediment and raw water samples have been collected and analyzed for organochlorines and PCBs from a fixed location in the lower Niagara River at Niagara-on-the-Lake approximately weekly since 1979. Eight of the 19 organochlorine compounds measured were detected in more than 50% of the water samples analyzed, while 11 of the 19 compounds were detected in more than 50% of the suspended sediments collected at Niagara-on-the-Lake. Of the 10 chlorobenzene isomers measured, the one with the greatest usage (1, 4-dichloro) occurs in largest concentrations in the suspended sediments at Niagara-on-the-Lake. Other chlorobenzene isomers commonly occurring in suspended sediments are 1, 2 and 1, 3 dichloro, 1, 2, 4-trichloro, 1,2, 3, 4-tetrachloro, pentachloro, and hexachloro. All isomers of chlorobenzene occurred in more than 70% of the suspended sediment samples collected. Total loadings to Lake Ontario calculated from these data indicate that PCB loadings are about twice as high as previously reported, while mirex and total DDT hate decreased slightly. Although concentrations of contaminants in suspended sediments are usually higher than those measured in water samples, they are responsible for only about 40% of the total loadings for PCBs, DDT, and HCB, and significantly less for other organochlorine contaminants. Therefore, the data indicate that, to estimate total contaminant loadings, the water fraction must be sampled. Lake Erie is not the major source of such organic contaminants as PCBs and chlorobenzenes because contaminant levels in Lake Erie bottom sediments are 10 times lower for PCBs and 20 times lower for chlorobenzenes than in Niagara-on-the-Lake suspended sediments.     

Investigating the effect of storm events on the particle size distribution in a combined sewer simulator.

The changes in particle size of sewer sediment particles rapidly eroded from a previously deposited sediment bed are described, using a rotating annular flume as a laboratory scale sewer simulator. This is the first time that particle size distributions of eroded sewer sediments from a previously deposited sediment bed have been monitored in such a controlled experimental environment. Sediments from Loenen, The Netherlands and Dundee, UK were used to form deposits in the base of the annular flume (WL Delft Netherlands) with varying conditions for consolidation in order to investigate the effect of changing consolidation time, temperature and sediment type on the amount and size of particles eroded from a bed under conditions of increasing shear. The median size of the eroded particles did not change significantly with temperature, although the eroded suspended solids concentration was greater for the higher temperature under the same shear stresses, indicating a weaker bed deposit. An increase in consolidation time caused an increase in median size of eroded solids at higher bed shear stresses, and this was accompanied by higher suspended solids concentrations. As the shear stress increased, the solids eroded from the bed developed under a longer consolidation time (56 hours) tended towards a broad unimodal distribution, whilst the size distribution of solids eroded from beds developed under shorter consolidation times (18 or 42 hours) retained a bi- or tri-modal distribution. Using different types of sediment in the flume had a marked effect on the size of particles eroded.     

Suspended solids transport in the regulated River Blithe,Staffordshire, U.K.

Suspended solids concentrations and turbidity were monitored on the regulated River Blithe at two sites downstream of the reservoir for a period of 18 months. Changes in the suspended solids loads transported and the nature of the material in suspension are related to dam overspill and tributary flood events. A hysteretic relationship between suspended solids concentrations and discharge is characteristic of both sites, sediment supply being limited within the regulated river. Downstream of the dam, rapid bank erosion occurred on meander bends but the suspended solids loads transported by the regulated river relate more to the resuspension and transport of tributary injected sediments and scouring of a dense periphyton. Close to the dam, fine biogenic matter dominated the seston, which scanning electron microscopy revealed to contain algal fragments and inorganic diatom frustules, but downstream, tributary-derived minerogenic particles were dominant.     

Trace Organic Contaminants in the Detroit River

Concentrations of polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PNAs), chlorobenzenes (CBs), chlorophenols (CPs), and a number of other organochlorine compounds (OCs) have been determined in the surface microlayer, subsurface water, suspended solids, sediments, and in sediment pore water at 20 sampling stations in the Detroit River. The data are discussed in terms of contaminant sources, pathways, and sinks. Spatial trends within the river and relationships of contaminant groups within and between compartments are described. The results indicate a continuing input of all contaminant groups to the river from a variety of sources, particularly from sewage treatment plant effluents and several tributaries. The contaminant distributions and intercorrelations also indicate that major sources of PCBs, PNAs, OCs, and CBs are concentrated on the westerly river shore, while CPs enter the river mainly from the easterly shore.     

Spatiotemporal trends of polychlorinated biphenyls (PCBs) in surface and suspended sediments from the Lake Ontario Canadian nearshore 1994–2018: A fish consumption advisory perspective

Spatiotemporal trends for polychlorinated biphenyls (PCBs) were examined in surface and suspended sediments collected between 1994 and 2018 from over twenty nearshore stations on the Canadian side of Lake Ontario and the St. Lawrence River. In 2018, PCB concentrations ranged over an order-of-magnitude in surface (<10 ng/g?357 ng/g) and suspended sediments (<10 ng/g–330 ng/g), illustrating the presence of legacy hotspots as well as diffuse urban inputs. PCB concentrations in both surface and suspended sediments were consistently highest in Hamilton Harbour, but were also elevated at other stations around the perimeter of the Niagara basin as well as near Trenton and Kingston, Ontario. Generally, higher PCB concentrations were found in surface sediment relative to paired suspended sediment samples suggesting temporal improvements in nearshore sediment quality. However, many stations demonstrated temporal variability in PCB concentrations, a likely factor in the lack of an overall nearshore declining trend. Given that PCBs are listed as a consumption-limiting contaminant for all fish sampling blocks in the Canadian waters of Lake Ontario and are responsible for 78% of restricted advisories, sediment quality benchmarks that account for bioaccumulation potential should be considered over toxicologically-derived guidelines to gauge severity of PCB contamination of nearshore sediments. Relatively higher TOC-normalized PCB concentrations in the western end of Lake Ontario suggests additional research on PCB bioavailability from nearshore sediment would be beneficial in understanding basinwide trends of PCBs in fish, and that an adaptive approach to sediment management may be needed in the context of consumption advisories.     

Mass Balance Modeling of Heavy Metals in Saginaw Bay,Lake Huron

During the period 1976-1978, a study of hazardous materials in Saginaw Bay was conducted. This study included the fate and distribution of cadmium, copper, lead, and zinc in the bay. A spatially segmented, dynamic mass balance model was developed to describe concentrations of metals and suspended solids in the water column and in the sediments. A wind-driven resuspension mechanism was used to describe the sediment-water interactions. The distribution of metals in the water column was determined by equilibrium partitioning between the ambient suspended solids and the dissolved phase. Model output was calibrated to field data for the principal variables. Independent validation was obtained by comparing partition coefficients from the calibration to those calculated directly from the field observations. It was found that suspended solids were important in controlling the water column concentrations of the metals. The degree of control was a function of the partition coefficient between the metal and the solids, and the concentration of the solids. Adsorption of the metals to the solids was found to result in decreases to metals concentrations due to net sedimentation, as well as increases due to wind-driven resuspension. On an annual average basis, the net flux of the particulate components of all four metals was from the water column to the sediments except for copper in 1977.     

Distribution of Hydrocarbons and Chlorinated Hydrocarbons in Various Phases of the Detroit River

Concentrations of several chlorohydrocarbons, polychlorinated biphenyls, and polynuclear aromatic hydrocarbons in the Detroit River were measured. For purposes of this study, the river ecosystem was divided into six phases or compartments: sediments, pore water in the sediments, suspended solids, subsurface water, surface microlayer, and air. Significant amounts of the above mentioned compounds occur in all of these compartments except air (for which our detection was relatively insensitive). The sediments contained over 99% of the chlorinated compounds. The polynuclear aromatic hydrocarbons were distributed between the subsurface water and the sediments.     

Detection of Particle-Associated Enteroviruses from Raw and Treated Sewage and Lake Michigan Harbor Water

Suspended solids from raw sewage, various stages of wastewater treatment, and Milwaukee Harbor water were examined for associated enteroviruses. The solids were sedimented by centrifugation, and enteroviruses associated with them were eluted by homogenization in fetal bovine serum, analyzed quantitatively by plaque assay on Buffalo green monkey kidney cells, and identified by neutralization with Lim Benyesh-Melnick pooled antisera. Viruses were found at concentrations within approximately one order of magnitude in sediments from all samples. Nine different enteroviruses were identified. All three types of poliovirus were detected in terminally treated (chlorinated) sewage, but the temperature-sensitive marker was not detected in the poliovirus strains isolated from chlorinated samples. Together these data indicate that exploitation of the association of viruses with suspended particles leads to a simple rapid means of monitoring virus distribution in sewage and natural waters.     

Characterization of microparticles in raw, treated, and distributed waters by means of elemental and particle size analyses.

The elemental composition and particle size distribution of suspended particles in raw water, treated water, and distributed water were determined to understand the behavior of particles during the water treatment-distribution process. The weight of suspended particles collected on a 0.6-microm filter was 1.1 times (raw water), 1.4 times (treated water), and 1.5 times (distributed water) that collected on a 2.7-microm filter, suggesting that smaller particles may remain after conventional water treatment. Organic suspended particles were removed less efficiently than inorganic suspended particles. After sand filtration, the Al content in the fixed suspended solids (FSS) markedly increased, indicating that either a small percentage of aluminium floc passed through during sand filtration or dissolved aluminum precipitated after sand filtration. The Mn and Fe concentrations increased after chlorination. The percentages of carbon and nitrogen in the volatile suspended solids (VSS) were roughly the same in the raw, treated, and distributed waters. The carbon/nitrogen/phosphate/VSS ratios indicated that the VSS of the suspended particles consisted of organic matter originating from microorganisms. The major constituents of the FSS in the treated and distributed waters were compounds of Fe, Al, Ca, Mg, and Mn, but these compounds accounted for only 16% or less of the FSS in raw water, indicating the existence of Si compounds. In distribution pipes, the total suspended solids concentration, especially the FSS concentration, was higher than that of water just after treatment. The Fe concentration in distributed water increased, probably due to oxidation and rusting of iron pipes.     

Modeling PCB Bioaccumulation by the Zebra Mussel (Dreissena polymorpha) in Saginaw Bay,Lake Huron

Zebra mussels were collected from navigation buoys in Saginaw Bay and the lower Saginaw River and analyzed for PCBs. Total PCB concentrations ranged from 0.076 to 1.2 μg/g, with the highest values for zebra mussels collected near the mouth of the Saginaw River. These data were combined with PCB concentration measurements in water and suspended solids to calculate congener-specific partition coefficients and bioaccumulation factors. Lipid-normalized bioaccumulation factors for PCB congeners ranged from 10^5.6 to 10^7.0. A model based on three-phase equilibrium partitioning and a bioaccumulation mass balance were applied to simulate the concentration ratios. Model results provided an unbiased best fit of the observed partition coefficients and bioaccumulation factors, as well as optimum parameter estimates. PCB fluxes mediated by zebra mussels were calculated from the model. Transfer across the gut was found to be the predominant route of PCB uptake for zebra mussels. Egestion and fecal excretion were estimated to generate a PCB flux of 1 to 30 μg/m²/d at zebra mussel densities reported for the Great Lakes. This flux exceeds the gross settling flux of PCBs to inner Saginaw Bay, demonstrating the potential of zebra mussels to alter particle and contaminant fluxes in the Great Lakes ecosystem. Zebra mussels may contain as much PCBs as the surficial sediments in Saginaw Bay.     

Chemical Loadings to Southwestern Lake Superior from Red Clay Erosion and Resuspension

Inputs of chemical parameters were calculated from estimated erosion and resuspension data and by using experimental measurements of chemical releases from both bluff samples and Lake Superior sediments in suspensions with Lake Superior water. The ability of suspended clay particles to remove manganese and copper ions from Lake Superior water was investigated. The loadings of easily leachable dissolved solids, phosphorus, nitrogen, chloride, silica, sodium, potassium, calcium, magnesium, aluminum and heavy metals from shoreline erosion and resuspended sediment were small compared to Lake Superior tributary inputs. Suspended sediment particles have a large capacity to remove copper and manganese ions from Lake Superior water. Each kilogram of suspended sediment particles of clay size can remove 175 mg of copper and 11 mg of manganese in Lake Superior water spiked to contain 10 μg/L of each metal.     

Calibration of turbidity meter and acoustic doppler velocimetry (Triton‐ADV) for sediment types present in drained peatland headwaters: Focus on particulate organic peat

Suspended sediments have a clear impact on fluvial water quality and aquatic habitats. As the concentrations are highly variable, continuous measurement offers a good way to provide accurate and precise values of sediment concentration and yield. However, there is a lack of information regarding the effect of organic peat particles, which typically appear in boreal fluvial systems. In the present study, the effect of different types of suspended sediments on calibration of a turbidity meter and an acoustic Doppler velocimetry (Triton‐ADV) was studied in laboratory conditions. The measurements were performed using particulate organic peat, clay and silt with several concentrations ranging from clear water to 3500 mg L^?1. The present study primarily provides organic peat sediment calibration data for used sensors. Regression equations were developed for the different sediment. The results indicate that particle size, shape, concentration and sediment type have an effect on calibration. When the turbidity and the ADV calibration were performed for different particle size groups, sediment types and concentrations, the calibration and suspended solids calculation error was reduced. For the turbidity sensor used, the reliable upper continuous measurement limit for clay, peat and silt sediments was found to be at 1000, 2500 and 3500 mg L^?1, respectively. The ADV‐sensor was noticed to be reliable only with fine particles. The results enable easy and first step calibration and error assessment for automatic turbidity and acoustic monitoring of the suspended sediment quality typically present in headwater fluvial systems. This study can be used to evaluate the effect of different sediments on turbidity and ADV‐measuring error and reliability during changing particles size distributions, characteristics and concentrations. The laboratory‐based approach used in this study indicates that the shape of organic peat particles has an influence on sensor calibration, especially when suspended sediment concentrations are high. Copyright © 2009 John Wiley & Sons, Ltd.     

引滦输水过程中悬浮物的沉降迁移特征

受黎河河道两岸铁矿砂影响,引滦输水黎河段水体中悬浮物含量远远高于引滦入津隧洞出口水的悬浮物含量。本文对引滦输水过程中悬浮物的沉降迁移特征进行了研究。结果表明:影响水体中悬浮物沉降速率的主要因素为悬浮颗粒粒径,影响悬浮物迁移量的主要因素为悬浮物的初始浓度。结合引滦输水过程中的悬浮物实际迁移情况,得出悬浮物主要影响引滦输水黎河河道,而汇入于桥水库的悬浮物含量较少且主要为粒径10μm的颗粒。应用研究成果,针对引滦输水工程的悬浮物污染特征,提出降低输水过程流速、增加入库前河道深度及种植水生植物等建议,以减少引滦输水过程中悬浮物含量。     

Distribution of Contaminants in Clams and Sediments from the Huron-Erie Corridor. I–PCBs and Octachlorostyrene

Samples of surficial sediments and the clam species Lampsilis radiata siliquoidea were collected from 102 sites covering all of Lake St. Clair and the Canadian shoreline of the St. Clair and Detroit rivers. The distribution patterns of both octachlorostyrene (OCS) and PCBs were mapped throughout this area. The mean level of PCBs in sediments of 3.9 μg kg^?1 (Aroclor 1254) was much lower than values for “total PCBs” reported in studies carried out in the early 1970s. This reduction does not appear to reflect a real decrease in PCB levels in the environment, but rather changes that have been made in sampling procedures and analytical techniques. Highest levels of PCBs in both sample types were found along the western shore of Lake St. Clair. Mean levels of OCS in whole clam tissue and surficial sediment (0–10 cm) were 43.0 and 5.1 μg kg^?1, respectively. The distribution pattern of OCS in the Huron-Erie corridor in both clams and sediments suggests that the primary source is in the St. Clair River. The mean chemical concentration factor was 59 for OCS, indicating considerable bioaccumulation in the biota of Huron-Erie corridor.     

An investigation on suspended solids sources in urban stormwater runoff using 7Be and 210 Pb as tracers

Radionuclides 7Be and 210Pb were used as tracers to identify suspended solid sources and transport pathways in the storm runoff events from urban catchments. Water samples were collected in runoff of storm events in Wuhan City, China. Suspended solids, COD, TN, TP, and the 7Be and 210Pb activities in the suspended solids were analyzed. Following the pathway of urban runoff pollution, the rain precipitation, urban ground dust, gutter sediments, and sewer deposit samples were analyzed for 7Be and 210Pb activities. The results show that the 7Be/210Pb ratio decreased through the system from a value of 0.86+/-0.44 in ground dust, to 0.63+/-0.18 in suspended solids in storm runoff from the sewer outlet, to 0.55+/-0.31 in gutter sediments, and to 0.41+/-0.13 in combined sewer deposits. The 7Be/210Pb ratio decrease suggests that 60+/-12% of suspended solids at sewer outlet originated from the drainage system sediments, the rest was from the wash-off of urban ground dust during the rainfall events. The 7Be and 210Pb trace approach can give insight into the short-term source and transport of pollutant during storm runoff in urban drainage systems and it can help to develop management strategies.     

Bioaccumulation Potential of Sediment-Associated Polychlorinated Biphenyls (PCBs) in Ashtabula Harbor,Ohio

Ashtabula Harbor, Ohio is designated as a Great Lakes Area of Concern contaminated by PCBs. Information on the bioaccumulation of PCBs from sediments is important for sediment management strategies such as dredging to restore navigable depths in the harbor. To ascertain the bioaccumulation of these PCBs, the aquatic earthworm Lumbriculus variegatus was exposed in the laboratory to contaminated sediments collected from 15 areas in the harbor. Data from these bioaccumulation experiments were used to determine the bioaccumulation potential of PCBs through the calculation of Biota- Sediment Accumulation Factors (BSAFs). The results showed that the mean values of the experimentally derived BSAFs for individual harbor areas ranged from 0.27 to 1.69. The median BSAF for sediments in the lower river sector of the harbor (0.38) was significantly lower than that for upper river sediments (1.34), indicating that the high adsorptive properties of coal soot particles constrained PCB bioavailability in the lower river sediments. These results indicate that the origin of total organic carbon (TOC) has a major influence on the bioavailability of total PCBs in harbor sediments. Moreover, the empirical BSAFs were well below the 4.0 default BSAF value recommended in joint USEPA/USACE protocols that are used to evaluate the Theoretical Bioaccumulation Potential, or bioavailability, of neutral organic chemicals in Great Lakes sediments. These empirical values should be used to more precisely predict the bioavailability of total PCBs in Ashtabula Harbor sediments.     

PCB Concentrations and Congener Composition in Macrophytes and Sediments in the St. Lawrence River near Cornwall,Ontario

PCB concentration and congener composition were examined in sediments and two species of macrophytes in the St. Lawrence River downstream of Cornwall, Ontario. Total PCBs in the macrophytes ranged from 37 to 585 ng/g dry weight, with biota to sediment accumulation factors ranging from 0.3 to 10. The floating-leaved species Nuphar variegatum had generally higher PCB concentrations than the submerged species Myriophyllum spicatum, but the latter had higher biota to sediment accumulation factors. N. variegatum also had a higher lipid content, but lipid levels were not a good predictor of plant PCB concentrations. Congener specific analysis showed congener patterns shifted between plants and sediments; macrophytes tended to have higher levels of tetrachlorobiphenyl congeners. Given that contaminant levels in plants reflect those found in the sediments, the high biomass of macrophytes within the river and particularly in Lake St. Francis represents an important reserve of PCBs which may be transferred to the herbivorous and detrital food webs.     

Mobility of contaminants in relation to dredging operations in a mesotidal estuary (Tagus Estuary,Portugal)

During the construction of a New Bridge over the Tagus estuary 2.5 million tons of sediments were dredged, part of this quantity being contaminated material. The extension and intensity of the water turbidity associated with dredging operating varied with the tidal conditions but the resuspended material collected near the bucket dredger did not present a concnetration increment in metals and PCB, when compared to the estuarine suspended sediments. The calculated distribution coefficients suggest that some contaminants in solids near the dredger were not in equilibrium with the water. A 24-hour laboratory experiment demonstrated the complexity and quickness of anoxic sediments oxidation. In such a short period of time metals in the solids change their fractionation. A second laboratory simulation showed that mussels accumulate metals and PCB congeners when placed in turbid aerated water.