Passive sampling methods also provide a simpler, less disruptive sampling approach than conventional porewater collection and measurement techniques, which can provide misleading information Chapman et al. The materials used to construct PSMs are relatively inexpensive and commercially available, and these materials can be used to detect a wide range of sediment-associated contaminants in porewater Lydy et al. Their use for characterizing conditions relevant to exposure and risks depends on using sampling and deployment designs that account for the small-scale variations that exist at the scales of the samplers.
Because in situ i. Those types of measurements can provide insights into the direction and intensity of the diffusive flux of contaminants. Finally, using PSMs to quantify C free can greatly assist in answering the 3 most important management questions related to contaminated sediments:. Do contaminated sediments pose an unacceptable risk to ecological receptors or to human health? If contaminants in sediments pose an unacceptable risk to ecological receptors or to human health, how can these risks be effectively mitigated? If surface water is contributing to unacceptable risk to fish, wildlife, or humans as a result of contaminants associated with point and nonpoint sources, including sediments, how can such risks be effectively managed and reduced?
The investigation, assessment, and management of contaminated sediment sites are typically guided by using conceptual site models CSMs.
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CSMs describe the processes contributing to risks at a site and are used to: develop hypotheses to be tested; organize data collection efforts; and direct the analyses, modeling, and interpretation of collected data. The process of developing and refining CSMs assists investigators and managers in identifying and understanding key physical, chemical, and biological processes that govern the exposure of contaminants to receptors.
Most importantly, CSMs can be used to evaluate and select which parameters e. As part of this evaluation, managers can identify where and when PSMs can be used to measure C free. Fate and transport of contaminants in sediments are influenced by macroscale processes that need to be retained in CSMs intended to reflect specific reaches or areas of water bodies in larger aquatic systems. At the macroscale, larger-scale hydrodynamic processes drive the transport and fate of contaminated sediments, and thus the potential redistribution, dilution, or burial of contaminated sediments.
Depending on site-specific conditions and the specific objectives of a given assessment or management activity, CSMs that incorporate pathways for which C free is a relevant metric may also need to integrate microscale exposure features with macroscale processes to provide the proper context for assessment and management.
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Conceptual site model showing transport and exposure pathways of sediment-associated contaminants at a macroscale. A Air—water exchange. Contaminant transport through air deposition into the water and volatilization from the water into the air. B Sediment—water flux. Diffusive and active transport processes of contaminants across the sediment—water interface, including biological processes that assist or retard transport e.
C Land—water exchange. Surface runoff from contaminated soil, erosion of contaminated soil particles. Deposition of contaminated water and sediment onto land during high-water or flood events. D Point-source inputs. Storm water discharge, combined sewer overflows, sanitary sewer overflows, industrial effluents and outfalls, spills. E Groundwater discharge. The discharge of groundwater contaminated from land-based sources. F Surface water transport. Movement of surface water containing dissolved, colloidal, and particulate-associated contaminants. G Sediment transport.
Movement of both clean and contaminated sediment particles through bed-load and suspended-sediment transport processes. H Bioaccumulation. Contaminant bioaccumulation through contact with dissolved-phase contaminants and the ingestion of contaminated sediment and prey trophic transfer. Conceptual site model showing transport and exposure pathways of sediment-associated contaminants at a microscale. Positions where contaminant flux is indicated are candidate locations for measurement of freely dissolved contaminant concentrations C free using passive sampling methods PSMs.
For contaminated sediment site assessments, 4 key exposure endpoints exist for which C free is the desired metric for risk assessment related to the 3 key management questions noted earlier:. Exposures of benthic invertebrates resulting in toxicity, which can result in: alterations in benthic community structure, sustainability of particular groups of species, or sustainability of a prey base for other species such as fish i. Bioaccumulation of chemicals into benthic invertebrates with subsequent exposures to fish and wildlife that feed on these invertebrates i.
Flux of freely dissolved contaminants from the sediments into the overlying water column with subsequent potential exposures of water column biota such as algae and fish directly as well as indirectly via trophic transfer i. Water column exposures that reflect the net result of processes or sources, including air—water exchange, sediment—water exchange, groundwater—sediment exchange, groundwater—surface water interactions, land—water exchange, and other point and nonpoint sources illustrated in Figure 1 i.
However, risk assessors and managers need to be aware of exposure endpoints for which C free is not an adequate metric. Examples include ingestion of sediment by foraging fish and wildlife or by children playing along shorelines or in shallow water, and direct human contact with sediment in shallow waters. Although trophic transfer pathways leading to fish that are eaten by wildlife and humans can be modeled using C free measurements in sediments and the water column, direct measurements of fish tissue concentrations are typically required for verification of predicted tissue concentrations used in site risk assessment.
Additionally, the application of PSMs to elucidate the exposure and uptake of metals by sediment-associated organisms, including dietary and incidental sediment ingestion pathways, is limited at this time see review by Peijnenburg et al. In addition to the macroscale processes depicted in Figure 1 , PSMs can also be used to resolve the roles of processes operating at smaller spatial scales. As with all field studies, sampling plans involving PSMs should be designed on spatial and temporal scales appropriate to address the specific study questions, as discussed in Ghosh et al. Whereas PSMs have as yet not been widely used for supporting regulatory programs, a number of possible applications exist.
The following sections discuss these potential applications. Guidance on optimizing sampling designs is available e. Assessing the extent of contamination at a sediment site can be a complex task with accompanying geographic, seasonal, financial, and cultural considerations. The key is to determine the questions that need to be answered to effectively assess and manage risks, such that targeted data collection can be effectively and usefully conducted within the limits of available resources. Project-specific questions related to C free include the 4 key exposure endpoints discussed previously under CSMs.
Spatial and temporal scales along with horizontal and vertical heterogeneity of sediment characteristics and contaminant distributions need to be factored into the sampling design. For example, exposures of benthic invertebrates occur at small scales Figure 2. In contrast, flux to the water column and associated water column exposures may be most relevant for larger areas or volumes inhabited by higher trophic-level organisms, including fish Figure 1.
Strategic approaches for collecting C free information differ depending on the scale of the investigation. Because not all transport or exposure pathways or receptors will be present at every site, use of PSMs should reflect site-specific conditions and data needs. Similarly, the extent of sediment contamination will vary across a site, with a consequent level of uncertainty dependent on the site assessment design.
This uncertainty can be reduced by deploying PSMs on multiple field-collected samples or with multiple in situ deployments. Although PSMs do not incorporate processes that can influence bioaccumulation such as dietary exposure, growth dilution, and transformation, sampling rates and equilibrium partitioning are better defined. A PSM-based sampling program should be designed to collect data that are valid representations of the situation being assessed and not compromised by confounding factors such as pre- or postdeployment contamination or analyte losses.
In situ PSM deployments should be in locations, at depths, and at times relevant to the objectives of the sampling program. For example, relative to source s of sediment contamination see next section , PSMs might be deployed along horizontal or vertical transects. Ex situ i. Additionally, the differences between field in situ and laboratory studies need to be considered.
For example, differences in accumulation between laboratory exposures for field-collected sediments that have been mixed and statically deployed samplers in situ may be attributable to the deployment procedure, not necessarily because C free is truly different. For samplers of identical surface areas, the uptake rate under static conditions in sediment has been shown to be lower than for sediments that have been mixed. Tomaszewski and Luthy found lower contaminant accumulations in PSMs under field conditions than in the laboratory, but they were able to adjust for this difference using performance reference compounds.
Because contaminants accumulated by a PSM constitute an extract from the sediment in which the PSM was deployed, some factors cause uncertainties in the rate of transfer of contaminants from the sediment. Because lower molecular weight chemicals will reach equilibrium faster than higher molecular weight chemicals, the duration of the deployment of a PSM in sediment is a factor that influences the results.
In addition, the development of bacterial, fungal, or algal films on the surface of the PSM can occur over time, and these biological films would presumably affect the sorption performance of the device, thus complicating interpretation of PSM data. Although one may not always be able to obtain absolute measures, relative estimates of exposures concentrations and bioavailability can be achieved by comparing masses of contaminants accumulated by PSMs deployed under comparable conditions and for the same deployment periods Ghosh et al.
Quantifying the contributions of land-based sources to sediment contamination at urban sites poses a difficult challenge because of nonpoint sources Environment Canada ; USEPA Although PSMs have not been widely used for source identification or for supporting regulatory programs, a number of applications are possible. PSMs measuring C free can be used to indicate sources and relevant exposure pathways, including those associated with bedded and resuspended sediments, as well as changes in emissions from sources and resulting exposures. PSMs also can assist in determining whether contaminants might be mobile, or to signal changes in contaminant mobility caused by changes in biophysical conditions.
When deployed over relevant spatial or temporal scales, PSMs can be used to identify and characterize contaminant concentration gradients and phase distributions. These data can, in turn, be used to indicate potential sources of contaminants. Management decisions addressing both point and nonpoint contaminant sources, such as the establishment of total maximum daily loads, are based on evaluations of the relationship of sediments to other potential sources or environmental compartments.
Measurement of C free can inform current and future roles of sediment as a source of contaminants to the surface water and biota, or as a sink for contaminants. Measurements of C free using synoptic sampling strategies can provide information to support comprehensive assessments of multiple sources and the implications of alternative watershed management strategies, including implementation of best management practices for attaining water quality—based objectives. Information on contaminant desorption and release from both bedded and suspended particles into the dissolved phase i.
Quantifying the rate and total amount of contaminant released into the dissolved phase through resuspension will improve the accuracy of baseline risk assessments see section on Using C free in multiple lines of evidence risk assessment and will provide critical information for informing the design of remedies e. Characterizing or predicting exposures under current and future conditions e. Use of PSMs to measure C free will improve characterization of these processes, and thus reduce uncertainties in site investigations and in risk analyses based solely on total mass of contaminants.
Executing remedial actions for contaminated sediments involves a progression of activities: remedy evaluation, design, implementation, and monitoring. Designing monitored natural recovery, in situ treatment, capping, and dredging components of a site-wide remedy is undertaken by applying mechanistic information about contaminant behavior and exposure pathways to develop a strategy that will reduce long-term exposures to acceptable levels while minimizing short-term exposures resulting from management actions USEPA ; Apitz ; Chapman and Smith Given the importance of accurately characterizing exposure in remedy design, C free represents a critical engineering parameter.
For example, because a cap needs to be designed such that exposure point concentrations in the biologically active zone of the cap do not exceed concentrations that would cause toxicity to benthic invertebrates colonizing the surface layer of the cap, C free is required for effective cap design, because this exposure endpoint determines toxicity.
Remedy construction activities will result in the physical disturbance of sediment and overlying water. For example, dredging will resuspend sediments, resulting in the release of contaminants into the water column in particulate, colloidal, and freely dissolved C free form Bridges et al. For large projects these releases, while individually short term in generation, can exist in the water column for extended periods over the course of the project. In many cases, biological monitors such as mussels have been used to assess the implications of these releases from suspended sediments.
PSMs also may serve this purpose. Because mussels and PSMs provide indications of exposure over longer time frames typically weeks to months , they may not be suitable for assessing shorter-term events e. Consequently, monitoring of construction activities is performed to actively manage short-term risks resulting from those activities and so that remedy implementation will not compromise the long-term objectives of the remediation project or regulatory action USEPA ; Wenning et al. PSMs provide a practical means for monitoring exposures and risks during remedy implementation.
However, monitoring and other investigative strategies should be designed such that the timescales requiring evaluation are compatible with PSM measurements, or that temporal issues are addressed in data interpretation. Guidelines for selecting PSMs to effectively address a particular set of investigative questions are provided in Ghosh et al.
Remedy performance monitoring is conducted to determine whether the risk reduction objectives established for the project have been achieved, or are being achieved over time i. In the case of dredged material disposal whether in uncontrolled disposal sites or in controlled containment , monitoring can be carried out to provide early warning of any unanticipated releases or exposures.
Both in situ and ex situ applications of PSMs can be used to measure temporal trends, or to signal changes in exposure point concentrations, relative to remedial predictions. Modeling is undertaken to describe and inform investigation and remedial processes that include contaminant fate and transport, remedial design, and postremedial risk reduction monitoring Sanchez et al.
Because models play a critical role, one must consider how measurements or estimates of C free will contribute to modeling efforts and decision making that is informed by models. Measurements that distinguish contaminants present in particulate and colloidal form from C free are critical for accurately representing exposure and effect processes that may be incorporated into models. Figure 3 presents an example of fate and transport processes that are commonly represented in models applied at contaminated sediment sites.
PSMs have been used in the parameterization and validation of models used to estimate the fate and risks of chemicals in contaminated sediments, particularly for nonpolar organic compounds Vinturella et al. Fate and transport processes subject to modeling at contaminated sediment sites. Estimates of freely dissolved contaminant concentrations C free using passive sampling methods PSMs are expected to reduce uncertainty in the dissolved chemical term.
Many fate and transport models start with the total concentration of an organic contaminant in the whole sediment, or C total , to estimate C free in porewater. Bulk chemical measures such as C total , which ignore bioavailability, are typically given lower weightings in WOE approaches than other LOEs.
C free , as either a replacement or supplemental measure to C total , will reduce uncertainty in the chemical LOE and thus provide a better technical basis for WOE. If monitoring programs are tiered, C free measurements also can be used as a higher-tiered LOE to address bioavailability, thus providing for an improved understanding of potential risks.
Given that C free measurements provide estimates of chemical exposure, analyses of actual risks should also typically be supported by relevant measures to estimate possible adverse effects e. The use of sediment toxicity testing provides a bridge between estimated chemical exposure and adverse effects, which is often used to support risk-based decision making. Benefits may arise from incorporating the use of PSMs in laboratory sediment toxicity testing of field collected sediments i. However, differences may well exist between measures of C free in laboratory test vessels and under field conditions, and such potential differences must be understood when considering site-specific risks.
At locations where PSMs are deployed, additional lines of evidence could include measurements of porewater e. The latter 2 measurements can be useful for building confidence in the C free measurements obtained from PSMs. Additionally, vertical gradients of C free in sediments and at the sediment—water interface can provide insights into contaminant flux.
When combined with other metrics as part of a WOE analysis, measurements of C free via PSMs provide information useful for understanding contaminant bioavailability, exposure—effects relationships, and possible chemical causes for observed toxicity. Measurements of C free can be used for initial screening as a separate LOE i. With the cautions noted regarding potential differences between laboratory-based and field-based measures of C free using PSMs, C free data can be used as a dose metric to evaluate toxicity test response data relative to concentrations of contaminants that elicit toxic effects.
When exposure pathways are understood and reflected in a sound CSM, PSM data can inform and improve risk assessments involving higher trophic-level biota wildlife and humans. As previously discussed, measured C free concentrations in sediments and overlying water can be used as inputs to food-chain modeling. Further, PSM-derived estimates of tissue concentrations can be compared with measured tissue concentrations and tissue quality benchmarks i.
Many food-chain models begin with estimates of chemical exposure concentrations in the water column and sediment. Again, for those situations in which the exposure pathways have been properly identified and characterized, measurements of C free via PSMs could be used to help parameterize models. Allan et al. Although the sampling of biota tissues will remain central to human health risk assessments or contaminants transferred via food webs, measurements of C free can help inform managers concerning the potential that a site would contribute to concentrations of contaminants in biota tissues.
Furthermore, the PSM data would provide a basis for assessment that is unaffected by the variability inherent in sampling in sampling biota, which often provide limited specific spatial or temporal information relative to sources of contaminants and human consumer exposures USDOI ; Schwartz et al. Whereas measurements of C free cannot substitute directly as a risk metric because water does not behave as fish , these measurements provide insight into the potential for bioaccumulation NRC ; Walker et al.
To date, the measurement of C free via PSMs has not been used consistently in regulatory programs involving contaminated sediments. This section, written from a prospective standpoint, considers the use of C free as measured by PSMs for a range of management applications. The selection and implementation of remedies to manage unacceptable risks from contaminants in sediments and surface water in terms of the 3 key management questions detailed earlier Why use PSMs to measure C free? C free determinations can be used to map areas of potential concern, which can be linked to site remedial goals and used to support the development of remedial zones action areas.
Three-dimensional remedial zones can be defined by coupling exposure and risk factors with other site characteristics e. Remedy designs are based on information that relates the behavior of risk-driving contaminants to risk-reduction objectives e. Data on contaminant desorption and release from particles, combined with measurements of C free , provide critical insights needed to estimate the flux of contaminants within the sediment bed, contaminant release from resuspended particles, and the magnitude of resulting exposures.
Monitoring before i.
Monitoring of remedy effectiveness is a critical aspect of contaminated sediment management Gustavson and Greenberg Design of in situ treatment using amendments to sequester contaminants e. PSMs measuring C free , deployed in situ and ex situ, are ideally suited to provide this specific information. Cap designs make use of information regarding contaminant movement, largely through porewater diffusion and advection, to determine design features that will limit flux to the surface of the cap and the overlying water.
Ex situ application of PSMs as part of bench-scale column studies can provide valuable information on predicted flux and exposure in response to sediment amendments.
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The effectiveness of caps depends on the creation of a clean surface through the burial and isolation of contaminated sediments and the maintenance of clean conditions through the prevention of flux or migration of contaminants e. Isolation of contamination below a cap may involve chemical or physical sequestration.
Monitoring the performance of a cap designed for long-term isolation or sequestration of contaminants to evaluate whether contaminant migration into the biologically active zone is present can be achieved through the use of PSMs configured to sample at specific depths in the sediment bed, to obtain a continuous depth profile Reible et al. A major advantage of using PSMs for cap performance monitoring is that sampling can be performed in situ with minimal disruption to the cap itself. Tissue concentrations of contaminants such as PCBs and dioxins, and some metals in edible tissues, are often the risk drivers at contaminated sediment sites.
Fish tissues from species targeted by anglers often receive the most attention, and many of these species are predominantly pelagic. PSMs can serve an additional purpose in the context of water column monitoring as an indicator but not necessarily a surrogate of contaminant bioaccumulation in edible fish and shellfish tissue. This use as an indicator reflects changes in overlying water concentrations of contaminants that can affect uptake into aquatic organisms.
The combined evidence of PSMs in the surface water and porewater—the latter an indicator of bioaccumulation by sediment-associated biota that may be prey items of fish—can be used to determine when fish tissue evaluations would be appropriate for assessing whether fish consumption advisories should be set, maintained, or relaxed. This approach reduces the need for regular e.
It also reduces costs by precluding the need for biota collection, preparation, extraction, cleanup, and analyses. Seasonal or other short-term fluctuations in live specimen conditions that complicate interpretation of bioaccumulation data also can be avoided using PSMs. Furthermore, this approach assists in explaining the importance of considering other sources of contaminants to biota, including trophic transfer, when target species have relatively large home ranges relative to the contaminated sediment site under consideration i.
Evaluating remedy success involves many of the uncertainties inherent to risk assessment, with the added complexity of temporal variability in the performance of engineered processes and features NRC Under an adaptive management approach Satterstrom et al. Because the performance of many remedial approaches involves 1 or more best management practices, such as containment, treatment, and attenuation of C free , PSMs can be used to evaluate remedy effectiveness at various stages in the remedial selection and implementation process.
PSMs also can be used to evaluate C free in sediment that is slated for disposal or beneficial reuse after management actions e. PSMs can provide a reference point for assessing long-term remediation success across different remedial strategies Chapman and Smith For example, monitored natural recovery relies on risk reduction through chemical transformation to less persistent or toxic moieties, chemical sequestration, and burial of contaminated sediments with cleaner materials through natural sedimentation processes.
PSMs can be placed in the sediments in situ, or ex situ using core samples, to evaluate whether transformation processes are ongoing and whether contaminant concentrations in the porewater are changing with time. Uses include revising CSMs, sediment risk assessment, and monitoring bioavailability and contaminant flux. The PSMs allowed for preremedial quantitation of low dissolved concentrations of PCBs and supported the CSM, which hypothesized that contaminants in the sediments enter the water column and are bioavailable to fish.
At the Grasse River Superfund site, a pilot study was conducted to evaluate whether granular activated carbon placed in sediments could effectively reduce the bioavailability of PCBs to benthic organisms and flux to the water column. In situ monitoring of the sediment and water column was performed using PSMs after application of activated carbon.
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In situ PSMs deployed in sediments and the water column have been used to evaluate groundwater transport and exposure pathways for metals and organic contaminants within the intertidal zone of a marine waterway Duncan et al. California assesses contaminated sediments based on a multiple LOE approach using bulk sediment chemistry, sediment toxicity, and benthic community structure SWRCB If the assessment indicates impairment, additional studies are required to determine whether adverse biological effects are caused by sediment contaminants and, if so, to identify causal chemical s.
The complex contaminant mixtures in the sediments that make up a significant portion of California's highly industrialized port and harbor sediments make causation determinations difficult. Measurements of C free would assist in determinations of causation and also could be used to supplement or replace bulk sediment chemistry measurements. Measurements of C free could also be applied retrospectively to historic impairment determinations to improve restoration strategies and to assist in refining total maximum daily loads implementation plans for contaminants of actual concern.
The Norwegian sediment risk assessment guidelines provide a tiered regulatory tool to identify contaminated sediment sites where remediation may be needed. Porewater contaminant concentrations are 1 of the key factors that is recognized to influence contaminant fate and movement in or out of sediment and accumulation by organisms. Other PSM applications relevant to these guidelines are in situ or ex situ measurements of sediment—surface water fluxes from benthic chambers or box cores Eek et al.
PSMs have been applied over the last decade in this region to assist in understanding contaminant fate and distribution between water and sediments and to evaluate various management options. Laboratory-based batch exposures with polyethylene sheets have been used to estimate sediment—porewater distribution coefficients for hexachlorobenzene, octachlorostyrene, and PCB in sediments from 1 of the fjords, Frierfjord. One key sediment management objective is to remove the advisory against consumption of seafood. The application of a thin-layer cap to a relatively wide area of the Eidangerfjord was considered as a means to reduce concentrations of chlorinated organic contaminants in edible biota e.
To evaluate this option, PSMs were used in laboratory boxcore experiments to measure diffusive fluxes of the contaminants, and to evaluate the effectiveness of various thin-layer cap designs incorporating a range of carbonaceous and mineral capping materials Josefsson et al. PSMs provided empirical data on the potential effectiveness of various possible remedial alternatives Cornelissen et al. Wu et al. In addition, semipermeable membrane devices have been successfully applied to monitor polycyclic aromatic hydrocarbons, petroleum hydrocarbons, polychlorinated biphenyls, and chlorinated pesticides in the coastal marine waters of Hong Kong Richardson et al.
Additional development work is required in the use of PSMs for metals within a modeling or decision-making framework Peijnenburg et al. Research is needed to understand what species of metals and organo-metallic compounds e.
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Current PSMs used to measure the bioavailable C free fraction in porewater provide no insights into biogeochemical processes that can affect the C free fraction in porewater. Changes in C free may be attributable to either changes in the biogeochemical cycling of a contaminant in the sediment or changes in the contaminant total concentration.
Pairing of PSMs with desorption measurements may assist in further defining biogeochemical processes or mechanisms leading to relevant porewater exposure conditions. Identification of chemicals causing toxicity within mixtures of contaminants in sediments can be done using an effects-directed approach or toxicity identification evaluation Reichenberg and Mayer ; both methods have limitations Burgess et al. PSMs, deployed and allowed to equilibrate in sediments, can be used as a passive dosing source to recreate C free exposure in ex situ toxicity tests that are performed in support of sediment toxicity identification evaluation Bandow et al.
Conventional sampling methods may overlook contaminants with unknown toxicological relevance Brack et al. PSMs can be designed to extract a wide range of contaminants from sediments, including emerging contaminants Booij et al. Ideally future PSMs will provide a multipurpose device that is capable of collecting data on multiple contaminants of interest. The extraction process and analyses also will need to be optimized for more polar compounds.
Although substantial resources have been devoted to post-omics tool development, how these tools can be used to assess exposures through integration with real exposure scenarios is still a significant topic of discussion. In addition, cross-linking an estrogen receptor to a solid-phase support to probe for estrogenic substances in sediments that could affect resident biota appears technically feasible.
Similar tools have been developed for biomedical research Sanghivi et al. PSMs can be integrated into in situ deployment systems incorporating other LOE such as bulk chemistry and toxicity Burton et al. Multisensor stations can provide complete, continuous data sets. These devices are equipped with sensors for collecting basic oceanographic data and can be equipped with specific sensors such as PSMs in water and on the sediment—water interface.
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Such continuous deployment would improve trend analyses by collecting data of high or medium temporal resolution. Ocean acidification has the potential to significantly increase toxicity from contaminated sediments as determined in experiments measuring the flux of metals under different ocean acidities using DGTs together with toxicity tests Roberts et al. Communication is essential to stakeholder e. Different stakeholders are likely to have different perceptions of PSMs and concerns about their use or applicability.
These perceptions must be acknowledged and addressed by effectively communicating with stakeholders the advantages, limitations, uncertainties, and appropriate uses of PSMs see also Ghosh et al. Stakeholder confidence in, and thus, adoption of PSMs for use at contaminated sediment sites, requires effective communication of PSM salience, credibility, and legitimacy. Their legitimacy is demonstrated by interlaboratory comparisons e. In addition, the major advantages and disadvantages of PSMs need to be effectively communicated. With effective communication, the use of PSMs may facilitate increased implementation of science-based, risk-based approaches as opposed to precautionary principle-influenced sediment management decisions that do not yield appreciable benefit to human health or the environment.
Five significant actions must occur to increase confidence in and thus encourage the use of PSMs:. Key information about PSMs and their applicability to sediment sites, such as those described previously, must be made readily accessible to potential users e. It can be ordered online and is expected to ship in days. Our stock data is updated overnight, and availability may change throughout the day for in-demand items. Please call the relevant shop for the most current stock information. Prices are subject to change without notice.
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