Biogeochemical Investigation of Big Creek Marsh,Lake Erie,Ontario

Geochemical composition of sediment, uptake of nutrients and metals by macrophytes, and nutrient and metal concentration in the water was investigated at six selected stations in Big Creek Marsh, Ontario. The maximum concentrations of Pb, Ni, Cu, Cr, and Zn in marsh sediment (86, 48, 38,119, and 383 μg/g dry weight, respectively), were lower than the concentration of these metals found in fine-grained surficial sediments of Lake Erie, and maximum concentration of As and Hg in marsh sediment (112 and 0.930 μg/g dry weight, respectively) were higher than As and Hg concentration in most of Lake Erie surficial sediments. Occurrence of DDT metabolites in marsh sediment reflects extensive use of DDT in the Big Creek drainage basin prior to 1970. Increase of total Kjeldahl Nitrogen and NH₄-N in marshwater was observed at a few sampling stations in November. Submerged macrophytes Myriophyllum, Chara, and Elodea sps. accumulated larger quantities of Pb, Cu, Ni, Cd, and Cr than emergent macrophytes at the stage of maximum development. Correlation between Ca and Pb, Cu, Ni, and Cr concentration in sampled macrophytes was observed; however, there was no correlation between Ca and Zn in these plants.     

Comparative spatial metal concentrations and partitioning in bottom sediments of two tropical freshwater lake basins,Kenya

Metal concentrations in the water, sediments and biota in alkaline, near neutral water tropical freshwater lake basins were determined and a comparative analysis made on the spatial and accumulated trace metal concentrations, and geochemical partitioning of iron (Fe), manganese (Mn), copper (Cu), chromium (Cr), zinc (Zn), nickel (Ni), cadmium (Cd) and lead (Pb) in bottom lake sediments. Variable accumulated levels were found in the analysed sediments and aquatic biological tissues. Metal partitioning data in the present study from the two areas exhibits similar trends in magnitude. The residual fractions retained relatively higher amounts of metals. Relatively higher contents of Pb, Cr and Cu were found in Lake Victoria sediments. Cd, Ni, Mn and Pb are of concern because a higher percentage of these metals were retained in the more bioavailable fractions in Lake Naivasha. Total levels of sediment mercury were comparable for the two lake basins. Metals were found in significant levels in the tissues of aquatic organisms, highlighting the potential risks to other levels within the aquatic food chain. Although the exposure risk was not evaluated, it is important to continue monitoring these elements in fish, as sediments were found to contain considerable quantities of the metals. Numerous sediment extraction techniques data applied for evaluating metal partitioning in sediments cannot be compared because of the use of different methods. Nevertheless, the information is still useful in differentiating and understanding pollution loads from natural versus anthropogenic sources and their associated risks.     

青狮潭水库底泥重金属污染特征及潜在生态风险

广西桂林青狮潭水库由东湖和西湖两部分组成,为了研究青狮潭水库底泥重金属污染分布特征及潜在生态风险,测定了青狮潭水库不同位置底泥中5种重金属(As,Cd,Cr,Hg,Pb)的含量,并通过地累积指数法和潜在生态风险指数法评价了重金属的污染程度和潜在生态风险。结果表明:东湖底泥中As和Cd含量较西湖高,西湖Hg和Pb含量高于东湖;底泥中Cr主要来源于成土母质,船只通行是造成Pb污染的主要原因;东湖底泥中As和Cd可能主要来源于东江上游煤矿开采;西湖底泥中As,Cd,Hg与营养元素间存在显著相关性,其来源可能与周边农业活动和前期水库内网箱养鱼有关;根据地累积指数,重金属污染强度排序为Cd,As,Pb,Hg,Cr,Cd和As为主要污染元素;重金属潜在生态风险大小排序为Cd,Hg,As,Pb,Cr;东湖底泥重金属潜在生态风险强于西湖。     

Metals and Essential Elements in Herring Gulls from the Great Lakes, 1983

Adult and prefledged herring gulls were collected from one location each in Lakes Ontario, Erie, Huron, and Superior. Composite samples of liver, kidney, and feather were analyzed for 24 elements and composite samples of bone for 22 elements. After consideration of quality assurance results, concentrations of 16 elements (Al, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, P, Pb, Sr, Ti, Zn) in liver, kidney, and feather were accepted for presentation while 6 elements were accepted from bone (Ca, Cd, Hg, P, Pb, Zn). Only lead, cadmium, and mercury values were of toxicological interest. Data on other trace elements are presented as baseline values among locations for each tissue and age class. Concentrations of Cd, Pb, and Hg were higher in adults than in prefledged young. Metal levels varied among different tissues with Cd highest in kidney (2.16 μg/g; Hamilton Harbour, Lake Ontario), Pb highest in bone (30.0 μg/g; Double Island, Lake Huron), and Hg highest in feather (6.11 μg/g; Middle Island, Lake Erie). Lead levels in both age classes were generally higher in tissues from the two upper lakes colonies than in samples from the lower lakes. Cadmium and mercury levels did not vary greatly among locations. Levels found are below those associated with metal toxicoses in laboratory studies with other avian species.     

Heavy metals in sediments and uptake by burrowing mayflies in western Lake Erie basin

During the past two decades, burrowing Hexagenia mayflies have returned to the western basin of Lake Erie. Because of their importance as a prey resource for higher trophic levels and their extensive residence time in potentially contaminated sediment, Hexagenia may be a source of heavy metal transfer. To better understand the distribution and transfer of heavy metals in sediment and mayflies, sediment and mayfly nymphs were collected from 24 locations across the western basin of Lake Erie in May 2007. Following USEPA protocols, samples were analyzed for 16 elements using ICP-OES or ICP-MS. Metal concentrations in the sediments exceeded the Threshold Effect Level for at least one metal at all sample sites. Sediment heavy metal distribution profiles indicate metal concentrations are correlated with organic matter content, and the highest heavy metal concentrations were found in the central deeper region of the western basin where organic content in the sediments was greatest. Hexagenia were distributed throughout the western basin, with greatest density (1350/m²) within the Detroit River plume. The Cd and Zn levels in mayflies were on average approximately 4 and 2 times greater, respectively, than sediment levels, and the Cd concentrations in the sediments exceeded the Threshold Effect Level at 27 of 28 sites and exceeded the Probable Effect Level at 9 of 28 sites. Spatial representation of heavy metal concentrations in mayflies exhibited a similar pattern to the spatial distribution of heavy metals and organic matter in the sediments with higher concentrations of metals found in mayflies residing in the central deeper region of the western basin.     

Distribution of Metals in Different Size Fractions of Sediment from the Niagara River

This study was carried out to demonstrate that the concentration of major and trace elements, determined in sediment samples separated mechanically into different size fractions, gives better information for assessing a potential hazard of in situ, dredged, or resuspended sediments than the bulk total concentration. The concentrations of major elements (Si, Al, Ca, Mg, Na, K, Fe, Ti, Mn, and P), trace elements (Cr, Co, Cu, Zn, V, Ni, and Pb), and organic and carbonate C were determined in six size fractions (< 13 μm, 13–19 μm, 19–27 μm, 27–40 μm, 40–54 μm, and 54–150 μm) of bottom sediments collected at eight stations along the Niagara River. Fine particles (< 13 μm) separated from the river sediments exposed to pollution sources accumulated greater metal quantities than particles in the other size fractions. The contribution of trace elements from specific size fractions was calculated from the particle size distribution and trace elements concentration. With the exception of Ni, significant differences were found between trace elements concentration in specif ic particle size fractions of Niagara River sediments and that from the nearshore zone of Lake Erie.     

Distribution of Pb, As, Cd, Sn and Hg in soil, sediment and surface water of the tropical river watershed, Terengganu (Malaysia)

Hydrogeochemistry and distribution of Pb, As, Cd, Sn and Hg in soils (n = 53), sediments (n = 42) and surface waters (n = 51) of the tropical Terengganu River basin, northeast coast of Peninsular Malaysia, were investigated. The order of abundance of the elements in soils followed granite > metasedimentary > Quaternary deposit ? volcanic with slight enrichment as compared to the upper continental crust. Both soils and sediments registered the order of concentration of Pb > Sn > As ? Cd ? Hg with an enrichment factor (EF) < 6 for sediments indicating slight enrichment representing the regional background and less likely due to the anthropogenic activity related input. SEM analysis revealed the presence of Malayaite (CaSnOSiO₄) explaining elevated Sn concentration (up to ∼34 mg/kg; 3 times the upper continental crust) in soils. Soil Pb distribution showed the geology as the primary control.Dissolved concentrations of As showed an increasing and Cd decreasing with distance from upstream to downstream along the river flow path. Lake surface waters registered 16 times higher Cd concentrations (average ∼ 14.21 μg/L) than the river waters, but lake sediments registered lower Cd concentration than the river sediments (average ∼ 0.45 mg/kg) revealing Eh, pH and TDS control. Dissolved average Hg concentration (∼0.04 μg/L) was measured to be lower than the tropical river waters from the Central Africa river, but higher than the Mekong and the Amazon Rivers.     

Toxicity of Cuyahoga River and Nearshore Lake Erie Sediments to Photobacterium phosphoreum

The Cuyahoga River Basin and Lake Erie (nearshore of Cleveland) sediments were assayed with Photobacterium phosphoreum during the summer of 1991. Of the 33 sediments tested, 23 exhibited toxicity using either interstitial or extract water. Nearly all (93%) of the “navigation channel” (i.e., the lower 8 km of the river) and nearshore lake samples were toxic. No statistical difference was observed between river sediment interstitial and extract waters. With the limited number of lake samples (seven), more toxicity was observed with extract water than with interstitial water.     

Record of mercury pollution in sediments of lakes Nakaumi and Shinji in Japan

Two sediment core profiles from lakes Shinji and Nakaumi were studied in order to understand the level of mercury (Hg) pollution in lakes in northwestern Japan. The sedimentation rates were established on the basis of the activity of [²¹⁰Pb] and [¹³¹Cs] in the sediments. In Lake Shinji, the highest level of Hg (130 ng g^–1) in the sediment was found at a depth of 20–22 cm, while 195 ng g^–1 was found at a depth of 10–12 cm in the core profiles from Lake Nakaumi. The relative increase in Hg concentration in lake sediments started after 1960 and significant contamination events occurred in the early 1960s. Mercury profiles in lake sediments from lakes Shinji and Nakaumi are found to reflect the anthropogenic Hg released into the environment in the 1950s and 1960s. A pronounced maximun concentration of Hg is found in both lakes, where sediment accumulation rates differ.     

The relative importance of anammox and denitrification to total N2 production in Lake Erie

Production of dinitrogen gas via microbially mediated anaerobic ammonium oxidation (anammox) and denitrification plays an important role in removal of fixed N from aquatic ecosystems. Here, we investigated anammox and denitrification potentials via the ¹⁵N isotope pairing technique in the helium flushed bottom water (~0.2 m above the sediment) of Sandusky Bay, Sandusky Subbasin, and Central Basin in Lake Erie in three consecutive summers (2010?2012). Potential rates of anammox (0–922 nM/day) and denitrification (1 to 355 nM/day) varied greatly among sampling sites during the 3 years we studied. The relative importance of anammox to total N₂ production potentially ranged from 0 to 100% and varied temporally and spatially. Our study represents one of the first efforts to measure potential activities of both anammox and denitrification in the water column of Lake Erie and our results indicate the Central Basin of Lake Erie is a hot spot for N removal through anammox and denitrification activities. Further, our data indicate that the water column, specifically hypolimnion, and the surface sediment of the Lake Erie Central Basin are comparatively important for microbially mediated N removal.     

How Non-native Species in Lake Erie Influence Trophic Transfer of Mercury and Lead to Top Predators

Lake Erie's food web has been dramatically modified by exotic species. Both exotic dreissenid mussels and the round goby Neogobius melanastomus have shifted the food web from a pelagicbased to a benthic-based one, potentially creating a new pathway for contaminant transfer to top predators. Before the invasion of round gobies, few predators of dreissenids occurred in Lake Erie, allowing contaminants to be confined to these benthic organisms. The invasion of the round goby has produced a new pathway through which these contaminants can enter the food web. To characterize heavy-metal transfer through this new food web and to assess risk to humans, water, surficial sediment, dreissenid, round goby, and smallmouth bass Micropterus dolomieui samples were collected at three sites during summers, 2002 and 2003, and analyzed for total lead (Pb), total mercury (Hg), and methyl mercury (MeHg). In addition, we compared smallmouth bass Pb and Hg concentrations to those measured in 1993/1994, before round gobies were prevalent. Pb biodiminished and MeHg biomagnified through the food web to smallmouth bass; patterns were similar among our three sites. Total Pb concentrations in smallmouth bass were higher before the incorporation of round gobies into their diet. We attributed this decline to changes in food web structure, changes in contaminant burdens in prey, or declines in sediment Pb concentrations in Lake Erie. By comparison, Hg concentrations in smallmouth bass changed little, before and after the round goby invasion, possibly due to a shift in diet that increased growth. Despite a decline in sediment Hg concentrations in Lake Erie, smallmouth bass continued to accumulate Hg at historical rates possibly because of their high consumption rates of benthivorous round gobies. As smallmouth bass continue to consume round gobies during their lives, their Hg concentrations may well continue to increase, potentially increasing the risk of Hg contamination to humans.     

Estimates of the remineralization and burial of organic carbon in Lake Baikal sediments

Sediment cores collected from several stations throughout Lake Baikal in water depths from 100 m off the Selenga River delta to the deepest basin of the lake (~1640 m), have been analyzed for sedimentary organic carbon, nitrogen, and the remineralized components in pore water. The organic carbon content of surface sediments generally varied from 2.3 to 3.2% by weight, and profiles typically showed an exponential decrease in both organic carbon and nitrogen in the upper 20–30 cm of the sediment column. Steady state models of organic matter diagenesis yield first order decomposition rate constants which range from 0.0009 to 0.022 y⁻¹. The calculated residence times for the metabolizable fraction of the organic matter in these sediments increases roughly with increasing water depth and is on the order of 50–300 years. Pore water concentration profiles were determined for dissolved inorganic carbon, dissolved organic carbon (DOC), methane, and dissolved ammonium. At depth (25–30 cm) methane concentrations ranged from 50 to 800 μmol L_pw⁻¹ and DOC from 400 to 900 μmol L_pw⁻¹. Estimation of carbon recycling rates based upon diffusion along pore water concentration gradients at the sediment-water interface, indicate that combined DOC and methane fluxes generally contribute <15% of the overall turnover of sedimentary organic carbon. Comparisons to Laurentian Great Lakes environments show trends in sediment deposition, organic matter remineralization, and the time scales of carbon recycling across nearly two orders of magnitude with the fraction of organic content buried generally decreasing with decreasing sedimentation rates.     

Burrowing mayfly (Ephemeroptera: Ephemeridae: Hexagenia spp.) bioturbation and bioirrigation: A source of internal phosphorus loading in Lake Erie

Traditional lake eutrophication models predict lower phosphorus concentrations with decreased external loads. However, in lakes where decreased external phosphorus loads are accompanied by increasing phosphorus concentrations, a seeming “trophic paradox” exists. Western Lake Erie is an example of such a paradox. Internal phosphorus loads may help explain this paradox. We examined bioturbation and bioirrigation created from burrowing mayfly, Hexagenia spp., as a possible source of internal phosphorus loading. Phosphorus concentrations of experimental microcosms containing lake sediments, filtered lake water, and nymphs (417/m²) collected from western Lake Erie were compared to control microcosms containing sediments and lake water over a 7-day period. Phosphorus concentrations in microcosms containing Hexagenia were significantly greater than microcosms without nymphs. Further, we estimate the soluble reactive phosphorus flux from the sediments due to Hexagenia is 1.03 mg/m²/day. Thus, Hexagenia are a source of internal phosphorus loading. High densities of Hexagenia nymphs in western Lake Erie may help explain the “trophic paradox.” Furthermore, Hexagenia may be a neglected source of internal phosphorus loading in any lake in which they are abundant. Future studies of phosphorus dynamics in lakes with Hexagenia must account for the ability of these organisms to increase lake internal phosphorus loading.     

Contrasting sources and mobility of trace metals in recent sediments of western Lake Erie

Concentrations of the major and trace metals varied considerably in the western basin of Lake Erie, ranging from 0.9 to 25.3?mg/g for aluminum, from 2.9 to 36.5?mg/g for iron, from 6.4 to 74.8?mg/g for calcium, from 1.2 to 13.5?μg/g for cobalt, from 2.8 to 61.6?μg/g for copper, from 2.7 to 83.0?μg/g for lead, from 0.1 to 2.9?μg/g for cadmium, and from 7.1 to 127.3?μg/g for strontium. Distinct patterns of sediment metal variability allowed the identification of two major fluvial sources and some active in-lake biogeochemical processes. The inputs of Sr were largely from the Maumee River, the inputs of Cu, Pb, Cd, and Co were dominated by the Detroit River, and the inputs of Fe and Al were roughly evenly from the two rivers. The removal of Sr and Ca from the water column was mainly through coprecipitation with calcite. In contrast, the transfer of Cu, Pb, Cd, and Co was largely attributed to the removal of fine sediment particles from the Detroit River mouth and adjacent nearshore areas and the deposition of the metals scavenged by settling organic materials in the basin's central deeper areas. The mobility of the trace metals was different during the in-lake mass transfer, with Co being the most mobile and Cd being the least mobile. Furthermore, the trace metal mobility differences have decreased significantly during the past half-century due to a substantial increase in organic matter from eutrophication in the basin.     

Mineralogical and geochemical composition of Late Holocene bottom sediments of Lake Onego

The analysis of both the mineralogical and geochemical composition and the stratigraphy of Holocene sediments of Lake Onego provided a novel interpretation of their genesis. Their mineral composition suggests that Holocene bottom sediments generally inherit the composition of terrigenous material that enters the lake with river runoff. The predominant authigenic minerals include biogenic opal from diatom skeletons, Fe-illite, and Fe-chlorite, which are the main iron mineral forms in bottom sediments of Lake Onego. Unstable suspension components (illite and chlorite) transform into their ferruginous varieties under humid climate conditions and high concentrations of iron and silicon in the lake waters. Both the presence of ferromanganese nodules in the uppermost part of bottom sediments of Lake Onego and their formation result from the location of the lake in the northern humid zone, geological composition of Fennoscandian crystalline rocks on the Lake Onego watershed, and the presence of an oxidative geochemical barrier into the lake sediment sequence. Late Holocene bottom sediments are represented by two types of sequences: 1) Fe-Mn enriched layers are formed near the sediment-water interface under oxygenated near bottom waters, and 2) such layers are not formed due to low concentrations of oxygen in water; but there are also non-laminated, homogeneous greyish-green silts, similar to those present in the lower parts of the first type of cores. Sedimentation rates (~0.10 cm y⁻¹) were determined by ²¹⁰Pb- and ¹³⁷Cs geochronologies.     

Preliminary Investigation of the Algal Flora in the Sediments of Lake Erie

The algae in a 45-cm-long sediment core taken in the eastern basin of Lake Erie were examined to determine the extent and applicability of that flora in reflecting the history of the lake. Asterionella formosa, Melosira islandica, M. italica, Stephanodiscus niagarae, and Tabellaria fenestrata were the most abundant diatoms encountered. Quantitative diatom profiles reported as cells/cm³ sediment and relative abundance profiles each provide a contrasting history of post-settlement Lake Erie. In light of the known history of the lake, the relative frequency profiles appear to be most applicable. The C/P index of trophic status and diatom diversity support those profiles. The occurrence of non-diatom algae in the sediments was inadequate for detailed analyses; however, occurrence did correspond to the trophic history determined by the diatoms. Botryococcus braunii, Cosmarium formosulum, Pediastrum boryanum, and Staurastrum gracile were most commonly encountered.     

Chlorinated Contaminants in Surficial Sediments of Lakes Huron,St. Clair,and Erie: Implications Regarding Sources Along the St. Clair and Detroit Rivers

Surficial sediments from southern Lake Huron, Lake St. Clair, and Lake Erie have been analyzed for a broad spectrum of chlorinated organics including PCBs, chlorobenzenes, and several pesticides. The differences between sediment contaminant concentrations in Lake Huron and Lake St. Clair indicated sources of hexachlorobenzene, hexachlorobutadiene, octachlorostyrene, and several other chlorinated benzenes along the St. Clair River. Similar differences between sediment PCB concentrations in Lakes Huron/St. Clair and Lake Erie indicated major PCB sources along the Detroit River. Specific PCB congener analysis revealed that PCBs discharged to the Detroit River contained especially high concentrations of highly chlorinated hexa-, hepta-, and octachloro-biphenyls which are major constituents of the industrial mixture Aroclor 1260. The analysis of individual PCB congeners made it possible to trace PCBs of Detroit River origin to the central and eastern basins of Lake Erie, and to estimate the contribution of the Detroit River to the PCB burden in sediments of these basins.     

Flocculation of Fine-Grained Lake Sediments Due to a Uniform Shear Stress

Experiments were performed to investigate the effects of fluid shear on the flocculation of fine-grained lake sediments in fresh water. In these experiments, a Couette viscometer was used to apply a uniform shear stress to a sediment suspension. The sediments were from the Detroit River inlet of Lake Erie. They were prepared such that the initial (unflocculated) size distribution contained approximately 90% of its mass in particles less than 10 μm in diameter with the average diameter being about 3.5 μm. Experiments were performed at shear stresses of 1, 2, and 4 dynes/cm² and sediment concentrations of 50, 100, 400, and 800 mg/L, values which are characteristic of those found in the Great Lakes. Data in the form of floc size distribution as a function of time were obtained. For steady-state conditions, the median diameters of the flocs formed were typically 20 to 100 μm depending on shear stress and sediment concentration. Quantitative results for the decrease in the steady-state floc size with increasing shear stress and with increasing sediment concentration were obtained. The times required for flocculation to occur under different conditions were also determined and were typically on the order of 1 hour.     

竺山湖及太湖西沿岸北段的重金属分布特征及其生态风险评价

对竺山湖及太湖西沿岸北段底泥沉积物中6种重金属Cd、As、Cr、Hg、Pb和Cu的质量比进行分析,结果表明,底泥沉积物中Cd、As、Cr、Hg、Pb和Cu的平均质量比分别为1.23 mg/kg、10.28 mg/kg、82.98 mg/kg、0.074 mg/kg、35.27 mg/kg和33.9 mg/kg,分别是各自背景值的4.6倍、1.1倍、1.0倍、0.7倍、2.2倍和1.8倍;底泥沉积物中重金属的垂向分布特点是:随底泥沉积物深度的增加,重金属质量比逐渐降低,并在底泥沉积物50 cm深处表现出明显的重金属质量比降低拐点。利用潜在生态风险指数法对竺山湖及太湖西沿岸北段的重金属生态风险进行评价,结果表明,该区域重金属生态风险值范围为34～444,平均值为117,太湖西沿岸大浦口区域的生态风险较大,Cd是生态风险的主要贡献元素。建议对竺山湖以及太湖西沿岸区大浦口区域Cd的污染进行必要的疏浚控制,疏浚深度在底泥50 cm深处,以有效去除该区域的Cd污染。     

Distribution,sources, and behavior of trace elements in the Clinton River Watershed,Michigan

The Clinton River watershed near Detroit, Michigan, USA was separated in six different land uses: agricultural, residential, mixed industrial and residential, downstream industrial, Clinton River Spillway, and Lake St. Clair, utilizing As, Cd, Cu, Ni, Pb, and Zn contents of the sediment that has median values of 3, 0.3, 15, 14, 13, and 57 mg kg^− 1, respectively. However, trace element concentrations in the lower Clinton River rivaled those in the most contaminated watersheds of the world. Enrichment factors and principal component analysis (PCA) separated trace elements into 2 categories: anthropogenic (Cd, Cu, Ni, Pb, and Zn) and geogenic (Al, As, Ca, Fe, K, Mg, TOC) sources. PCA linked agricultural, residential, and mixed industrial and residential land uses to anthropogenic Cd, Cu, Ni, Pb, and Zn, and lake sediments to geogenic elements, organic matter and clay contents. The downstream industrial zone has a unique source signature. Trace element concentrations varied with land use. The upper Clinton River (> 20 km from mouth; residential land use; median concentrations up to 25 mg kg^− 1) appeared to meet delisting criteria. Partitioning was also land use and element specific with: (1) exchangeable fraction (up to 94% of total) related to road salt and mobile chloride complex formation; (2) carbonate-bound fraction (up to 100%) resulting from Ca substitution or adsorption; (3) presence of immobile (hydr)oxide-bound fraction (up to 90%) instead of potentially mobile organic matter and sulphide-bound fraction (up to 20%); and (4) residual fraction (up to 65%) originating from geogenic and/or anthropogenic sources.