Applications of numerical sediment quality targets for assessing sediment quality conditions in a US Great Lakes Area of Concern

Distribution, Source, and Contamination of Heavy Metals in Coastal Sediments of Jeddah, Red Sea, Saudi Arabia

The study investigates heavy metal (HM) contamination in coastal sediments of Jeddah along Red Sea coast, analyzing spatial distribution and sources. 24 samples underwent (ICP-AES) for Fe, Al, Mn, Ni, Pb, Zn, Cu, Cr, Co, Sr, V, and As. HM averages followed Fe ˃ Al ˃ Sr ˃ Mn ˃ Zn ˃ V ˃ Cu ˃ Ni ˃ Cr ˃ As ˃ Co ˃ Pb. Contamination indices revealed severe Sr enrichment, minor As and Co enrichment, and no enrichment for other HMs. Sediment quality guidelines suggest Ni, Cu, Zn, and As risks to benthic communities at some sites, while Cr and Pb pose minimal risk. Multivariate analysis indicates natural sources for Fe, Al, Mn, Ni, Zn, Cu, Cr, Co, and V, and anthropogenic sources for Sr, As, and Pb, linked to agriculture, industry, and urbanization. Increased Sr values may stem from seawater acidification impacting calcitic corals and molluscs.

Human-induced metals accumulation in sediments of an industrialized bay of northern Chile. An enrichment and ecological risk assessment based on preindustrial values

Environmental assessment in marine systems is difficult because most of the time their preindustrial characteristics are not available. Four sediment cores taken in Mejillones bay (northern Chile) were used to establish preindustrial metals concentrations, and to assess the environmental status of this industrialized zone. According to historical documents, the beginning of the industrial era start in 1850 CE. Considering this, the preindustrial concentration of some metals was established, by mean of a statistical approach. Most of the metals increase their concentration from the preindustrial to the industrial period. Environmental assessment showed an enrichment of Zr and Cr, a moderately polluted condition, and a low probability of toxic effect on the biological communities. The preindustrial values derived from sediment cores are a good tool to evaluate the environmental condition of Mejillones bay. However new information (backgrounds with a higher spatial representativity, toxicological threshold, and others) it is necessary to improve the environmental assessment of this environment.

Foraging Ecology Differentiates Life Stages and Mercury Exposure in Common Terns (Sterna hirundo)

Some populations of common terns (Sterna hirundo) breeding at inland lakes in North America are declining, including the Laurentian Great Lakes. Terns nesting at inland colonies forage in freshwater during the breeding season and primarily in coastal marine environments during the nonbreeding season. As piscivores, they are susceptible to dietary Hg exposure. To characterize patterns of Hg exposure in this population, we 1) quantified within and among season differences in total mercury (THg) concentrations (μg/g) in blood and feathers at 2 Lake Superior breeding colonies, and 2) documented spatial and temporal variation in exposure by studying adult foraging ecology using geospatial tracking devices and stable isotopes. We used general linear models to assess the relationship between isotopic composition and THg concentrations in bird tissues relative to sex, age, colony location, and season. The THg concentrations were lowest in winter-grown feathers (geometric mean [95% confidence limits]): 1.32 (1.09-1.59) μg/g dw (n = 60), higher at the more industrially influenced colony (chick feathers: 4.95 [4.62-5.37] μg/g dw [n = 20]), and increased with a riverine-based diet. During the breeding season, Hg exposure varied along a gradient from lake to river, with adult females having lower blood THg concentrations than males (females: 0.83 [0.67-1.03]) μg/g ww (n = 7); males: 1.15 (0.92-1.45) μg/g ww (n = 5). Stable isotope values suggested adults obtained 42 ± 12% (n = 12) of their diet from the river during incubation, which was validated with tracking data. During chick-rearing, chicks obtained 68 ± 19% (n = 44) of their diet from the river. Our results indicate colony location, foraging behavior, and season influenced Hg exposure for these Lake Superior colonies and underscores the importance of local contamination with respect to exposure. Integr Environ Assess Manag 2021;17:398-410. © 2020 SETAC.

Spatial monitoring of metals and As in coastal sediments of northern Chile: An evaluation of background values for the analysis of local environmental conditions

To assess environmental conditions along the coast of northern Chile, 457 sediment samples were collected between 22° S and 28° S in order to evaluate the Cu, Zn, Pb, Ni, V, Cd, As and Al content as well as its corresponding relationship to nearby anthropogenic activities. In general, the results of most metals showed that bays without industrial activity accumulate lower concentrations of contaminant elements in the sediments and thus mostly represent natural conditions. The highest Cu, Pb and V levels were measured in coastal zones were different industrial mining activities have been developed during the last decades. Results of different indices of environmental evaluation and ecological impact suggest that, metal content of sediments from pollution-free zones characterized by similar oceanographic and geological conditions to those under study, would be the most appropriate background level for assessing the anthropogenic impact on coastal areas of northern Chile.

Ambient sediment quality conditions in Minnesota lakes, USA: Effects of watershed parameters and aquatic health implications

Surficial sediments were collected from 50 randomly selected Minnesota lakes, plus four a priori reference lakes, in 2007. The lakes encompassed broad geographic coverage of the state and included a variety of major land uses in the surrounding watersheds. Sediment samples were analyzed for a suite of metals, metalloids, persistent organic pollutants, total organic carbon, and particle size fractions. In addition, a small fish survey was conducted to assess PBDEs in both whole fish and fish tissues. Sediment quality in this set of lakes ranged from good (43%) to moderate (57%) based on an integrative measure of multiple contaminants. On an individual basis, some contaminants (e.g., arsenic, lead, DDD, and DDE) exceeded benchmark values in a small number of lakes that would be detrimental to benthic invertebrates. The sediments in two developed lakes tended to be more contaminated than sediments in lakes from other major watershed land uses. These differences were often statistically significant (p<0.05), particularly for lakes with developed versus cultivated land uses for arsenic, lead, zinc, and numerous PAH compounds. Multivariate statistical approaches were used on a subgroup of contaminants to show the two urban lakes, as well as a few northeastern Minnesota lakes, differed from the rest of the data set. Background threshold values were calculated for data with <80% nondetects. Source apportionment modeling of PAHs revealed that vehicle emissions and coal-related combustion were the most common sources. A general environmental forensic analysis of the PCDD/F data showed that ubiquitous combustion sources appeared to be important. BDE-209, a decaBDE, was detected in 84% of lake sediment samples, whereas fish at the top of the food chain (i.e., predator trophic group) had significantly higher (p<0.05) mean lipid-normalized concentrations of BDEs-47, 100, and 153 than lower trophic fish. These results will be used for future status and trends work.

Source apportionment and distribution of polycyclic aromatic hydrocarbons, risk considerations, and management implications for urban stormwater pond sediments in Minnesota, USA

High concentrations of polycyclic aromatic hydrocarbons (PAHs) are accumulating in many urban stormwater ponds in Minnesota, resulting in either expensive disposal of the excavated sediment or deferred maintenance by economically challenged municipalities. Fifteen stormwater ponds in the Minneapolis-St. Paul, MN, metropolitan area were studied to determine sources of PAHs to bed sediments through the application of several environmental forensic techniques, including a contaminant mass balance receptor model. The model results were quite robust and indicated that coal tar-based sealant (CT-sealant) particulate washoff and dust sources were the most important sources of PAHs (67.1%), followed by vehicle-related sources (29.5%), and pine wood combustion particles (3.4%). The distribution of 34 parent and alkylated PAHs was also evaluated regarding ancillary measurements of black carbon, total organic carbon, and particle size classes. None of these parameters were significantly different based on major land-use classifications (i.e., residential, commercial, and industrial) for pond watersheds. PAH contamination in three stormwater ponds was high enough to present a risk to benthic invertebrates, whereas nine ponds exceeded human health risk-based benchmarks that would prompt more expensive disposal of dredged sediment. The State of Minnesota has been addressing the broader issue of PAH-contaminated stormwater ponds by encouraging local municipalities to ban CT-sealants (29 in all) and to promote pollution prevention alternatives to businesses and homeowners, such as switching to asphalt-based sealants. A statewide CT-sealant ban was recently enacted. Other local and regional jurisdictions may benefit from using Minnesota's approach where CT-sealants are still used.

Heavy metal distribution and enrichment in sediments of Mejillones Bay (23° S), Chile: a spatial and temporal approach

Concentrations of Ni, Cd, Pb, Cu, and Zn were measured in the surface sediments of Mejillones Bay at 32 sites ranging in depth from 10 to 95 m. A similarity dendrogram analysis separated the study area into two large sedimentary facies: a coastal zone with low metal concentrations and a deep zone with high metal concentrations. The abundances of Zn, Ni, and Pb increased between two sampling periods (5 years apart) in association with greater anthropogenic activity along the coastline of the bay at the present. The results were analyzed with the index of geoaccumulation and by applying the sediment quality guideline. Although similar to preindustrial levels, current Cu and Ni concentrations pose a likely threat to communities of benthic organisms. Concentrations of Zn and Pb are enriched, probably in connection with the industrial development of the zone, but do not reach dangerous levels for the benthic communities. Cd concentrations are toxic to benthic life, even though those measured herein are similar to preindustrial levels. Thus, these Cd levels are a result of the bay's natural characteristics (e.g., high biological productivity, the microxic water-sediment interface). The results of the Chilean aquatic sediment quality standards and the international standard (sediment quality guideline) were similar but differed from those found using the index of geoaccumulation, which suggests that the proposed reference values for Chilean aquatic sediment should be reviewed.

Evaluation of sediment quality guidelines derived using the screening-level concentration approach for application at uranium operations in Saskatchewan, Canada

Sediment quality guidelines (SQGs) can be derived using different approaches and are commonly used in environmental management, reclamation, and risk assessment. The screening-level concentration (SLC) approach has been used in Ontario, Canada, to derive lowest effect levels (LELs) and severe effect levels for use as SQGs. This approach was adopted by the Canadian Nuclear Safety Commission (CNSC) to set guidelines for metals (As, Cr, Cu, Pb, Mo, Ni, Se, U, and V) and radionuclides (Ra-226, Pb-210, and Po-210) in sediment at northern Saskatchewan uranium mining and milling operations. The SLC approach is based on total metal and radionuclide concentrations in sediment, and corresponding benthic community composition data for a specific sampling site. In this study, sediment chemistry (total metals and radionuclides) and benthic community data from northern Saskatchewan uranium operations were compiled and examined. Results indicate that the CNSC-derived SQGs had limited relationships to observed effects, or lack thereof, on benthic invertebrate communities near uranium operations in Saskatchewan. The LELs were found to correctly align with effects at 95% of the sites that had effects, on a general basis, but on an element-specific basis many of the elements had concentrations at effect sites below their LELs. Furthermore, concentrations of the evaluated elements exceeded at least one LEL at 60% of the no-effect sites. The high number of exceedences of LELs at reference and no-effect sites (false-positives) calls to question the appropriateness of the CNSC-derived SQGs. It is suggested that alternatives to the SLC approach be explored.

Ecological risk assessment of heavy metals from the surficial sediments of a shallow coastal lagoon, Egypt

Sediment quality of Lake Maryout (one of the four Nile Delta shallow brackish water lakes on the south-eastern coast of the Mediterranean Sea) is of concern as this lake is used for land reclamation and aquaculture and is an important fishing source. The magnitude and ecological relevance of metal pollution in Lake Maryout Main Basin was investigated by applying different sediment quality assessment approaches. The aim of this study was to estimate ecological risk of trace elements (Cd, Ni, Pb, Cr, Cu and Zn) in the surficial sediments (<63 jtm fraction) of Lake Maryout. Heavily contaminated sediments were evaluated by the Sediment Quality Guideline (SQG) of the US Environmental Protection Agency. The degree of contamination (Cd) was estimated as very high for each site. Two sets of SQGs effect range-low/effect range-median values and threshold effect concentration (TEC) and probable effect concentration (PEC) values were used in this study. Sediments from each site were judged toxic when more of the PEC values exceeded EPA guidelines. Based on the geoaccumulation index (Ieo) of target trace elements, the Main Basin of Lake Maryout has to be considered as extremely polluted with Cd (Igeo > or =5), strongly polluted with Zn (2 < or = Igeo < or =3), moderately polluted with Cu (1 < or = Igeo < or = 2), unpolluted to moderately polluted with Cr and Pb (0 < or = Igeo < or = 1 for each) and unpolluted with Ni (Igeo < or = 0). Lake Maryout sediments had heavy accumulations of Cd, which apparently come from drains that include industrial and raw domestic wastes. Therefore, a sequential extraction technique was applied to assess the five fractions (exchangeable, metals bound to carbonate, acid-reducible, oxidizable-organic and residual) of Cd in surface sediments. The Cd concentration in most sampling stations was dominated by the non-resistant fraction (anthropogenic). The result showed that those stations located in the vicinity of municipal and mixed waste drains posed a high potential risk to fauna and flora of Maryout Lake.

Spatial patterns of chemical contamination (metals, PAHs, PCBs, PCDDs/PCDFS) in sediments of a non-industrialized but densely populated coral atoll/small island state (Bermuda)

There is a recognized dearth of standard environmental quality data in the wider Caribbean area, especially on coral atolls/small island states. Extensive surveys of sediment contamination (n=109 samples) in Bermuda revealed a wide spectrum of environmental quality. Zinc and especially copper levels were elevated at some locations, associated with boating (antifouling paints and boatyard discharges). Mercury contamination was surprisingly prevalent, with total levels as high as 12mg kg(-1)DW, although methyl mercury levels were quite low. PAH, PCB and PCDD/PCDF contamination was detected a several hotspots associated with road run-off, a marine landfill, and a former US Naval annexe. NOAA sediment quality guidelines were exceeded at several locations, indicating biological effects are possible, or at some locations probable. Overall, and despite lack of industrialization, anthropogenic chemicals in sediments of the atoll presented a risk to benthic biodiversity at a number of hotspots suggesting a need for sediment management strategies.

Environmental contamination associated with a marine landfill ('seafill') beside a coral reef

In Bermuda, bulk waste such as scrap metal, cars, etc., and blocks of cement-stabilized incinerator ash (produced from burning garbage) are disposed of in a foreshore reclamation site, i.e., a seafill. Chemical analyses show that seawater leaching out of the dump regularly exceeds water quality guidelines for Zn and Cu, and that the surrounding sediments are enriched in multiple contaminant classes (metals, polycyclic aromatic hydrocarbons, petroleum hydrocarbons, dioxins and furans, polychlorinated biphenyls and an organochlorine pesticide), i.e., there is a halo of contamination. When compared against biological effects-based sediment quality guidelines (SQGs), numerous sediment samples exceeded the low-range values (where biological effects become possible), and for Hg and Zn exceeded the mid-range value (where they become probable). A few metres away from the edge of the 25 acre dump lies a small coral patch reef, proposed here as most contaminated coral reef in the world.

Screening ecological risk assessment of persistent organic pollutants in Mediterranean sea sediments

A screening ecological risk assessment (ERA) was conducted for the first time in the Mediterranean basin in order to assess the toxicity posed to the benthic community by PCBs, DDTs and HCB in marine sediments. The characterization of the exposure was conducted by means of an extensive literature survey, generating a database with more than 2000 samples. The effects were assessed by the adoption of guidelines previously developed in the literature, because ecotoxicological information about persistent organic pollutants (POPs) in the Mediterranean sediments was lacking. Existing sediment quality guidelines (SQGs) for the target pollutants were compiled and consensus values were calculated for three different categories of toxicity, namely threshold effect concentration (TEC), probable effect concentration (PEC) and extreme effect concentration (EEC). The combination of exposure and effects characterization enabled the identification of some areas of concern in the vicinity of industrial and urban locations and in the mouths of the main Mediterranean rivers. Beyond the Mediterranean continental shelf, the level of toxicity for the benthic community was generally low. The evaluation of the toxicity induced by the mixture of the target pollutants spotted the importance of DDT contamination in the Mediterranean sediments, despite the fact that main inputs to the sea have been significantly reduced during the last decades.

Assessment of the environmental significance of heavy metal pollution in surficial sediments of the River Po

The magnitude and ecological relevance of metal pollution of the middle Po river deriving from the River Lambro tributary was investigated by applying different (complementary) sediment quality assessment approaches: (1) comparisons of concentrations with regional reference data, and (2) comparisons with consensus-based sediment quality guidelines (SQGs), as well as by investigations of the partitioning patterns of target heavy metals (Cd, Cu, Ni, Pb, Zn). Total metal concentrations in the surficial sediments revealed significant pollution inputs on the whole river stretch investigated, with a distinct peak at the inlet of the River Lambro. Based on the geoaccumulation index of target heavy metals, the middle reach of River Po has to be considered as moderately polluted with Cd (1<mean I(geo)<2). At the Lambro inlet the surficial sediments have to be considered as moderately to strongly polluted with Cd (2<mean I(geo)<3) and moderately polluted with Cu, Pb and Zn (1<mean I(geo)<2 for each). Sediment-bound Cd, and Zn were found to be predominantly associated with the exchangeable phase of the sediment (33-58% and 25-43%, respectively), whereas Cu, Ni and Pb showed the strongest association with the Fe/Mn oxides (34-64%, 34-46% and 29-45%, respectively). Based on the consensus-based SQGs, most samples (50-63%) had contamination characteristics associated with moderate probabilities (30-52%) of acute toxicity for all investigated metals, while Cu and Zn in approximately 13% of samples revealed contamination characteristics associated with high probabilities (74-85%) of toxicity.

Metallic and organic contaminants in sediments of Sydney Harbour, Australia and vicinity-- a chemical dataset for evaluating sediment quality guidelines

An internally consistent dataset comprising 103 surficial estuarine sediment samples were collected from Sydney Harbour, Australia and locations south of Sydney. This paper describes the chemical characteristics of the dataset and evaluates its suitability for use in evaluating biological effects-based sediment quality guidelines (SQGs). The sediments contained mixtures of chemicals, the most prevalent chemical classes being metals and polycyclic aromatic hydrocarbons, whereas sediments from coastal lakes/estuaries south of Sydney had low concentrations of contaminants. Maximum concentrations of the prevalent contaminants zinc, lead, copper and pyrene were 11,300, 1,420, 1,060 mg kg(-1) and 23,300 microg kg(-1), respectively. For the majority of samples, concentrations of individual chemicals exceeded most effects-based SQGs that have been adopted for use in Australia, implying occasional or frequent adverse biological effects are expected. Comparing mixtures of contaminants to ranges in numbers of SQGs exceeded and mean SQG quotients showed that most samples (57% to 68%) had contamination characteristics associated with moderate probabilities (30% to 52%) of acute toxicity, based on North American data. A smaller proportion of samples (15% to 17%) had contamination characteristics associated with high probabilities (74% to 85%) of toxicity. The wide range of chemicals and concentrations, associated with low, medium and high probabilities of toxicity, indicated that the dataset was suitable for future use in evaluating predictive abilities of SQGs. This is relevant, given the recent introduction of North American-derived SQGs for Australia.

Weight of evidence: a review of concept and methods

"Weight of evidence" (WOE) is a common term in the published scientific and policy-making literature, most often seen in the context of risk assessment (RA). Its definition, however, is unclear. A systematic review of the scientific literature was undertaken to characterize the concept. For the years 1994 through 2004, PubMed was searched for publications in which "weight of evidence" appeared in the abstract and/or title. Of the 276 papers that met these criteria, 92 were selected for review: 71 papers published in 2003 and 2004 (WOE appeared in abstract/title) and 21 from 1994 through 2002 (WOE appeared in title). WOE has three characteristic uses in this literature: (1) metaphorical, where WOE refers to a collection of studies or to an unspecified methodological approach; (2) methodological, where WOE points to established interpretative methodologies (e.g., systematic narrative review, meta-analysis, causal criteria, and/or quality criteria for toxicological studies) or where WOE means that "all" rather than some subset of the evidence is examined, or rarely, where WOE points to methods using quantitative weights for evidence; and (3) theoretical, where WOE serves as a label for a conceptual framework. Several problems are identified: the frequent lack of definition of the term "weight of evidence," multiple uses of the term and a lack of consensus about its meaning, and the many different kinds of weights, both qualitative and quantitative, which can be used in RA. A practical recommendation emerges: the WOE concept and its associated methods should be fully described when used. A research agenda should examine the advantages of quantitative versus qualitative weighting schemes, how best to improve existing methods, and how best to combine those methods (e.g., epidemiology's causal criteria with toxicology's quality criteria).