Distribution of Major Elements and Metals in Sediment Cores from the Western Basin of Lake Ontario

An investigation was made of the relationship between the changes in metal concentrations in sediments with the distance from the Niagara River mouth and the chemical and physical characteristics of the sediments. Sediment cores were obtained at nine sampling stations in the western basin of Lake Ontario. In addition, surface sediment was collected at three stations on the Niagara Bar. Minerals present at all stations were silica, feldspars, illite/muscovite, chlorite, kaolinite, and calcite. Dolomite was found at some sampling stations as grains of 2 to 63 μm size. Significantly elevated concentrations of calcite (up to 20%) in the surface sediment (about 0 to 10 cm) at four sampling stations in the western basin and in the entire 25-cm sediment column at the Niagara River mouth indicated increased input of this mineral into Lake Ontario during the past 100 years. Furthermore, sediment concentration profiles of Zn, Pb, Cr, Cu, Ni, and especially Hg at all sampling stations indicated major transport of metals associated with the clay- and silt-size particles from the Niagara River into Lake Ontario (especially north-north-east and east of the river mouth). A significant decrease in Hg loading from the Niagara River during the past 20 years was also observed. Although smaller in magnitude, a similar decrease was found for Pb, Zn, Cr, Ni, and Cu loading. However, elevated Hg concentrations (up to 7 μg g～^l above background values) existed in the surface 10 cm of sediment at eight sampling stations.     

Fates of Organic Compounds from Niagara Falls Dumpsites in Lake Ontario

Sediment samples from the western portion of Lake Ontario were analyzed for chlorinated organic compounds using gas chromatography and gas chromatographic mass spectrometry. Both electron impact and negative chemical ionization mass spectrometry were employed. Many of the chlorinated compounds previously found to be leaking into the Niagara River from waste disposal sites in the city of Niagara Falls were identified in the sediments of Lake Ontario. In particular, two unique chlorofluorinated compounds were found in the lake's sediment, showing that stable compounds introduced into the Niagara River accumulate to detectable levels 100 km away in Lake Ontario. Chlorinated styrenes as well as several highly chlorinated poly cyclic aromatic hydrocarbons were also found. Their exact origin is uncertain at this time.     

Compartmental Distribution of Organochlorine Contaminants in the Niagara River and the Western Basin of Lake Ontario

Ten chlorobenzenes, hexachlorobutadiene, and PCBs were measured in Niagara River water and suspended solids, and in western Lake Ontario sediments and benthic fauna. High levels of these contaminants were found on all fractions of the river suspended solids, but the larger particles contained much higher concentrations than the smaller particles. A portion of the CBs, HCBD, and PCBs present in the lake sediments was available to benthic organisms. A trend toward greater bioaccumulation for compounds having higher octanol-water partition coefficients was observed at all trophic levels.     

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.     

Grain Size and Mineralogy of Sediment Cores from Western Lake Huron

Grain size and mineralogical analyses along the lengths of 12 cores recovered from the Alpena and Manitoulin Basins, when combined with ages determined by C-14 dating of surficial and basal sediments, reveal an approximate sedimentary history of this part of Lake Huron. Reddish glaciolacustrine clays, essentially all 10 ?, crop out on the flanks of the sublacustrine basins and underlie gray post-glacial muds in the central basin regions. The post-glacial muds become more coarse in their upper portions where they are very fine silt. Detrital carbonates which comprise approximately 30% of older sediments are reduced in abundance by an order of magnitude in more recent deposits. We interpet these phenomena as recording lowered lake levels and reduced sedimentation rates since the Nipissing high stand which ended about 4,000 years ago.     

Organochlorine Insecticides and PCB in Surficial Sediments (1968) and Sediment Cores (1976) from Lake Ontario

Surficial sediments were collected in 1968 and core sediments in 1976 from Lake Ontario. These were analysed for organochlorine insecticides and PCB. Residues of organochlorine compounds were higher in the three Ontario depositional basins than in sediment in the non-depositional zones. PCB was present at the highest concentration, with mean levels of 57 ppb for the whole lake. Residues of PCB in the three basins exhibited only minimal differences.ΣDDT was the second most frequently found contaminant. Both parent DDT and its two metabolites were present in sediment, giving a mean residue of 42.8 ppb for the whole lake. Differences in residues for the three basins were again minimal. DDT was present in sediments estimated to be deposited between 1958 and 1976. HEOD was present in only 40% of sediments and the mean residue for the whole lake was 0.6 ppb. The Niagara basin contained mean residues (1.4 ppm) of HEOD much above the other basins.Chlordane was virtually absent from the lake in the sediments collected in 1968 but appeared in cores between 1964-1976. Endosulfan appeared in lake sediments as a spill of deck cargo at a location in the Niagara basin. This spill dispersed with the current down the south shore to deposit in the Rochester basin.     

History of Lake Ontario Contamination from the Niagara River by Sediment Radiodating and Chlorinated Hydrocarbon Analysis

Contamination of Lake Ontario by persistent organic compounds began with the development of the chemical industry along the Niagara River. These compounds are discharged to the river where they are scavenged from the water column by sedimenting particulates which in turn settle out in depositional areas of Lake Ontario. We have determined ²¹⁰Pb, ¹³⁷Cs, and chlorinated hydrocarbon profiles of sediment cores taken about 3 km from the mouth of the Niagara River. Age profiles of the sediments were constructed from the radionuclide measurements and used to determine historic trends of chlorinated hydrocarbon input to Lake Ontario. The historical record found in the sediments for chlorobenzenes, chlorotoluenes, hexachlorobutadiene, octachlorostyrene, mirex, and PCBs is in good agreement with known production and usage patterns of the chemicals. Pollution of Lake Ontario with chlorinated hydrocarbons from the Niagara River is still occurring, but the worst contamination of the lake occurred in the 1960s.     

Sedimentology and Geochemistry of Modern Sediments in the Kingston Basin of Lake Ontario

Accumulation of Recent fine sediment is limited to deep water areas in the Kingston basin and thicknesses of more than 50 cm are found only in the St. Lawrence trough; elsewhere, sands and silty sands are largely composed of reworked material. Local sources provide little input of fine sediment to the Kingston basin. Statistical relationships derived from geochemical analyses indicate several forms of association between heavy metals and organic carbon, sulphides, clays, hydrous Fe and Mn oxides, and carbonates. A comparison between Kingston and Niagara sediments shows that the combined effects of riverine and lacustrine erosion have resulted in a generally greater content of carbonates in the Niagara sediments. The content of Fe (which is partly influenced by redox potential) is highest, however, in sediment of the Kingston basin, where higher P values are also associated with an increased clay content. Differences in the concentrations of heavy metals in Lake Ontario, except for Hg, Co, Cu, and Zn, are largely explained by variations in silt and clay contents. Contaminant loadings from the Niagara River are largely responsible for the anomalously high concentrations of Hg and, to a lesser extent, Cu and Zn. Cobalt occurs at higher concentrations in the sediments of eastern Lake Ontario, where its presence is thought to reflect glacial dispersal patterns.     

Downflux of Sediment,Organic Matter,and Phosphorus in the Niagara River Area of Lake Ontario

Vertical arrays of sediment traps were installed near the mouth of the Niagara River and at nearshore and offshore sites. Surveys of temperature, turbidity, and conductivity were used to establish that the traps nearest the river mouth were under the river outflow plume. A single offshore array in 1980 indicated downfluxes of 1-2 g · m^?2 · d^?1 of dry matter in the mid-water column. These fluxes were similar to those of small lakes but much higher fluxes were found near the bottom of Lake Ontario. More extensive work in 1981 confirmed the presence of a near-bottom nepheloid layer and the effect it has on increasing downflux extimates. Sediment traps near shore and at the river mouth caught substantially more material at all depths than did traps at the offshore stations. Downfluxes of phosphorus and sediment were consistent with independent estimates of loading and retention.     

Spatial Variability in Water Quality and Surface Sediment Diatom Assemblages in a Complex Lake Basin: Lake of the Woods,Ontario, Canada

Lake of the Woods (LOW) is an international waterbody spanning the Canadian provinces of Ontario and Manitoba, and the U.S. state of Minnesota. In recent years, there has been a perception that water quality has deteriorated in northern regions of the lake, with an increase in the frequency and intensity of toxin-producing cyanobacterial blooms. However, given the lack of long-term data these trends are difficult to verify. As a first step, we examine spatial and seasonal patterns in water quality in this highly complex lake on the Canadian Shield. Further, we examine surface sediment diatom assemblages across multiple sites to determine if they track within-lake differences in environmental conditions. Our results show that there are significant spatial patterns in water quality in LOW. Principal Component Analysis divides the lake into three geographic zones based primarily on algal nutrients (i.e., total phosphorus, TP), with the highest concentrations at sites proximal to Rainy River. This variation is closely tracked by sedimentary diatom assemblages, with [TP] explaining 43% of the variation in diatom assemblages across sites. The close correlation between water quality and the surface sediment diatom record indicate that paleoecological models could be used to provide data on the relative importance of natural and anthropogenic sources of nutrients to the lake.     

Tetrachloro-9H-Carbazole,a Previously Unrecognized Contaminant in Sediments of the Buffalo River

Three sediment samples taken from the Buffalo River, New York, have been analyzed for polychlorinated planar molecules similar in structure to the highly toxic 2,3,7,8-TCDD. Although no TCDD was found, residues of chlorinated dibenzofuran, fluorene, biphenylene, phenanthrene (anthracene), naphthalene, and 9H-carbazole were identified. l,3,6,8-tetrachloro-9H-carbazole was identified as the major chemical of this type in the sediments, and quantified at levels as high as 25 ng/g at one site.     

The Fate of Pentachlorophenol in the Bay of Quinte,Lake Ontario

Unfiltered water, surface film, sediment, and biota samples were collected from the Bay of Quinte between May and September 1978 and analyzed for chlorophenols (CPs). Sectioned sediment cores were dated using ²¹⁰Pb and ¹³⁷Cs analyses. Pentachlorophenol (PCP) was found at high concentrations adjacent to a point source and was detected in all compartments examined throughout the bay (a bioaccumulation factor of 10⁴ was observed for PCP in fish). The ratio of 2,3,4,6- and 2,3,5,6-tetrachlorophenols (TTCPs) to PCP increased with distance from the source in the water column and surface film. Photochemical reduction was proposed to account for the phenomenon. CP concentrations in sectioned cores suggested that settling particles adsorb CPs in similar proportion to that observed in the water column and little further change occurs after burial.     

固相微萃取-气相色谱-质谱联用测定环境水体中的痕量苯酚

研究快速而有效的苯酚检测手段具有重要的意义。本研究采用顶空固相微萃取-气相色谱-质谱联用技术对自来水和造纸厂污水中的痕量苯酚进行了萃取与分析。在不进行衍生化的情况下,对水中的苯酚进行直接萃取,并选用极性色谱柱进行分析,取得了良好的分析效果。同时研究和探讨了萃取纤维的选择,萃取时间,萃取温度等因素对萃取效果的影响。研究结果表明:100 mL水样,利用聚二甲基硅氧烷涂层纤维(100μm PDMS),pH值在2~3,并加入饱和的NaCl,在搅拌的条件下,萃取温度为90℃,萃取时间为40 min的萃取效果较好。本方法的检测限为0.5μg/L,在线性范围4.9~200μg/L内具有较好的线性关系,相关系数为0.9984。     

Recent Changes in the Near-Shore Phytoplankton of Lake Erie's Western Basin at Kingsville,Ontario

A weekly net phytoplankton monitoring programme begun in 1967 at the Union water treatment plant, Kingsville, Ontario, was expanded in 1976 to include weekly chemical analyses of western Lake Erie water samples. Data from the Union intake monitoring programme have been examined in light of the significant reductions, since 1971, in phosphorus loading from the Detroit River. Total phosphorus concentrations in the “raw water” declined to an average of 30-35 μg P/L during 1977-78 from a pre-P control average of 63 μg P/L during 1967-70. Average annual net phytoplankton density during the pre-P control years averaged about 5000 Areal Standard Units per mL (A.S.U./mL), decreased steadily between 1971 and 1976 to a low of 2900 A.S.U./mL, but then increased again to 4490 A.S.U./mL by 1978. The recent increase was attributed almost entirely to massive mid-summer development of Fragilaria crotonensis. Winter densities of net phytoplankton during 1977 and 1978 were the lowest on record for the 12-year period. Similarly, average densities of green and blue-green algae showed a pre-P control density regime which was clearly higher than the post 1971 densities. Annual average diatom density was negatively correlated with annual average lake levels over the 12-year period and recent anomalous increases in Fragilaria may have been related to the observed drop in lake level which influenced turbulence and resuspension of this diatom.     

Sedimentary Records of Spheroidal Carbonaceous Particles from Fossil-Fuel Combustion in Western Lake Ontario

Spheroidal carbonaceous particles (SCPs) were quantified in three sediment cores collected from depositional areas in the western basin of Lake Ontario to examine the impact of fossil-fuel combustion on sediment metal concentrations. SCP profiles were similar for the three cores showing the initiation of the SCP record deep in the core, followed by a rapid increase to a sub-surface maximum, and a subsequent decrease towards the sediment surface. Subsurface maximum SCP concentrations ranged from 1.97 to 5.61 × 10⁵ per gram dry matter/gDM. For ²¹⁰Pb dated cores, dates for the initiation of the SCP record (1850 ± 10 years), the initiation of the rapid rise in SCPs (1880 ± 13 years), and the SCP subsurface maximum (1961 ± 3 years) agree well. The rapid increase in sediment SCPs also agrees well with the US bituminous coal consumption during this same period (1880 to 1980). SCPs in surface sediments decreased between 55 to 83% from the subsurface maximum (1961 to 1996) in these cores while U.S. coal usage continued to increase. SCP decreases were attributed to the increased use and efficiency of particle collection devices by utilities and industry. Lead, Cr, Cu, and Zn showed significant correlations (r² = 0.63 to 0.94) with SCPs within each respective sediment core. Calculations show that although SCPs are not the major source of anthropogenic metals in Lake Ontario sediments, they may account for between 4 to 55% of the Zn, 1 to 12% of the Cu, 2 to 22% of the Pb and 1 to 18% of the Cr in these sediments.     

Sediment Oxygen Demand in the Central Basin of Lake Erie

Three separate procedures were used to estimate the sediment oxygen demand (SOD) in the central basin of Lake Erie and were compared with other estimates determined previously and with historical data. First, whole core incubations involved sealing sediment cores at 12°C to ensure no interaction between the overlying water and the atmosphere and monitoring continuously to define the linear disappearance of oxygen. Second, sediment plugs were placed inside flow-through reactors and the influent and effluent concentrations were monitored to obtain steady-state reaction rates. Third, an extensive data set for the central basin of Lake Erie was compiled for input into the diagenetic BRNS model, and the SOD was calculated assuming all primary redox reactions, but no secondary reactions. All three procedures produced estimates of SOD that were in reasonable agreement with each other. Whole core incubations yield an average SOD of 7.40 × 10⁻¹² moles/cm²/sec, the flow-through experiments had an average SOD of 4.04 × 10⁻¹² moles/cm²/sec, and the BRNS model predicts an SOD of 7.87 × 10⁻¹² moles/cm²/sec over the top 10 cm of sediment and appears to be calibrated reasonably well to the conditions of the central basin of Lake Erie. These values compare reasonably well with the 8.29 × 10⁻¹² moles/cm²/sec obtained from diffusion modeling of oxygen profiles (Matisoff and Neeson 2005). In contrast, values reported from the 1960s to 1980s ranged from 10.5–32.1 × 10⁻¹² moles/cm²/sec suggesting that the SOD of the central basin has decreased over the last 35 years, presumably, in response to the decrease in phosphorus loadings to Lake Erie. However, since hypoxia in the hypolimnion persists these results suggest that improvement in hypolimnetic oxygen concentrations may lag decreases in loadings or that the hypolimnion in the central basin of Lake Erie is simply too thin to avoid summer hypoxia during most years.     

Methane and nitrous oxide measured throughout Lake Erie over all seasons indicate highest emissions from the eutrophic Western Basin

Eutrophication has been linked to increased greenhouse gas emissions from inland waters. Phytoplankton blooms in Lake Erie have increased since the 1990s, although its greenhouse gas emissions are not well characterized. We measured CH₄ and N₂O concentrations and diffusive fluxes in four seasons around the entire lake, and CO₂ fluxes in one summer season. Lake Erie is a source of CH₄ all year across the lake, concentrated in spring and summer in the Western Basin. Methane emissions ranged from 0.03 to 14.87 mg C m⁻² d^-1. Methane is predominantly biogenic, and natural gas leaks are an insignificant source. While Lake Erie is an overall N₂O source, it is an N₂O sink in winter and occasionally during summer. Emissions of N₂O ranged from −0.08 to 1.22 mg N m⁻² d^-1. We also measured CO₂ fluxes in summer only, when Lake Erie is a small atmospheric CO₂ sink. While areal fluxes of CH₄ and N₂O are similar to those observed elsewhere, total fluxes from Lake Erie are higher due to its surface area. Lake Erie emits ~ 6300 (±19%) metric tons of CH₄-C yr⁻¹ and ~600 (±37%) metric tons N₂O-N yr⁻¹: almost 500,000 metric tons CO₂-eq yr⁻¹ total. This is the first comprehensive dataset of CH₄ and N₂O concentrations and diffusive emissions in a very large lake. More measurements and monitoring are needed to determine whether increased eutrophication in the Great Lakes is tied to increased emissions of these powerful climate forcers in a possible positive feedback to climate warming.     

Anthropogenic,Polyhalogenated, Organic Compounds in Sedentary Fish from Lake Huron and Lake Superior Tributaries and Embayments

Composite samples of fish taken from some of the major tributaries and embayments of Lake Superior and Lake Huron were analyzed for halogenated xenobiotics with the objective of detecting potential environmental problem areas, point source discharges of toxic materials, and previously unrecognized pollutants. The analyses were done by gas chromatographic, methane enhanced, negative ion, mass spectrometry. A variety of halogen-containing organic compounds and pesticides were identified. The highest concentration and variety of compounds were found in the fish from the highly industrialized Saginaw Bay drainage basin; fish from Lake Superior tributaries showed much lower concentrations.     

Anthropogenic,Polyhalogenated, Organic Compounds in Non-Migratory Fish from the Niagara River Area and Tributaries to Lake Ontario

Non-migratory fish from the mouths of tributaries to Lake Ontario and from the Niagara River and its tributaries were analyzed for anthropogenic organic compounds by methane enhanced, negative ion, gas chromatographic mass spectrometry. The results indicate that non-migratory fish, sampled at distances of up to 300 km from Niagara Falls, New York, accumulate pollutants originating at a particular hazardous waste site in that city. Several brominated aromatic compounds that apparently come from Rochester, New York, were also identified. A variety of chlorinated pesticides and compounds of industrial origin were found.     

Sediment Trap Studies in Lake Michigan: Resuspension and Chemical Fluxes in the Southern Basin

The results of 4 years (1977–80) of sediment trap sample collection in the southeastern region of Lake Michigan are summarized and compared with water column and sediment characteristics. Mass flux data indicate strong seasonal patterns, with maximum fluxes recorded during the unstratified period. The large amount of winter resuspension is a mechanism which provides an intimate coupling of recent sediments and the water column. Also these trap study results indicate that there is a near-bottom (10-m-thick) benthic nepheloid layer whose chemical composition approaches that of deep water (fine grain) sediments. The amount of resuspended NaOH extractable phosphorus injected into the euphotic zone is estimated as approximately equal to the load of new phosphorus entering southern Lake Michigan. The role of resuspension in the cycling of organic carbon and contaminants associated with it appears to be important.