Featured article / Contaminated Sediments - Introduction
Sediments are unconsolidated particulate materials found at the bottom of natural and manmade surface water bodies. They may include clay, silt, sand, gravel, decaying organic matter, or shells. Discharge of contaminants to surface water can result in contamination of sediments and potentially adverse impacts to receptors including benthic and water-column invertebrates, fish, wildlife, plants, and human populations. Contaminant sources include contaminated wastewater, surface water runoff, stormwater discharge, or groundwater, as well as atmospheric deposition, and spills and releases. Common contaminants include petroleum products, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), dioxins, pesticides, metals, radionuclides, and excess nutrients.
Introduction
Discharge of contaminants to lakes, rivers, and estuaries can result in contamination of the underlying sediments and potential adverse impacts to critical receptors including benthic and water-column invertebrates, fish, wildlife, plants and human populations. Contaminated sediments are often located in sensitive aquatic environments and sometimes may require corrective measures to reduce exposure to human and ecological receptors.
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Enviro Wiki Highlights
 Molecular diffusion slowly transports solutes into clay-rich, lower permeability zones  Typical subgrade biogeochemical reactor (SBGR) layout. The SBGR is an in situ remediation technology for treatment of contaminated source areas and groundwater plume hot spots  An Hydraulic Profiling Tool (HPT) log with electrical conductivity (EC) on left, injection pressure in middle, and flow rate on the right  Diagram of mineral surface exchanging hydrogen ions with varying pH. The surface of most aquifer minerals carries an electrical charge that varies with pH  Comparison of the longitudinal redox zonation concept (A) and the plume fringe concept (B). Both concepts describe the spatial distribution of electron acceptors and respiration processes in a hydrocarbon contaminant plume  Schematic of an Hydraulic Profiling Tool (HPT) probe. HPT were developed to better understand formation permeability and the distribution of permeable and low permeability zones in unconsolidated formations  In situ chemical oxidation using (a) direct-push injection probes or (b) well-to-well flushing to delivery oxidants (shown in blue) into a target treatment zone of groundwater contaminated by dense nonaqueous phase liquid compounds (shown in red)  High-resolution 3D cross-borehole electrical imaging of contaminated fractured rock at the former Naval Air Warfare Center in New Jersey. Cross-borehole resistivity tomography imaging is a geophysical technique that can be used for site characterization and monitoring by observing variations in the electrical properties of subsurface materials  Stable isotope probing (SIP) in use: Loading, deployment and recovery of Bio-Trap® passive sampler with 13C-labeled benzene. Stable isotope probing (SIP) is used to conclusively determine whether in situ biodegradation of a contaminant is occurring  Summary of anticipated, primary reaction pathways for degradation of 1,2,3-Trichloropropane (TCP). TCP is a man-made chemical that was used in the past primarily as a solvent and extractive agent, a paint and varnish remover, and as a cleaning and degreasing agent  Distribution of BTEX plume lengths from 604 hydrocarbon sites. Monitored Natural Attenuation (MNA) is one of the most commonly used remediation approaches for groundwater contaminated with petroleum hydrocarbons (PHCs) and certain fuel additives such as fuel oxygenates or lead scavengers  No-purge and passive sampling methods eliminate the pre-purging step for groundwater sample collection and represent alternatives to conventional sampling methods that rely on low-flow purging of a well prior to collection. The Snap SamplerTM is an example of a passive grab sampler  Conceptualization of Vapor Transport-related Natural Source Zone Depletion (NSZD) processes at a Petroleum Release Site  Conceptual diagram of basic Soil Vapor Extraction (SVE) system for vadose zone remediation. (SVE) is a common and typically effective physical treatment process for remediation of volatile contaminants in vadose zone (unsaturated) soils  Emulsified Vegetable Oil (EVO) mixed in field during early pilot test. EVO is commonly added as a slowly fermentable substrate to stimulate the in situ anaerobic bioremediation of chlorinated solvents, explosives, perchlorate, chromate, and other contaminants  Key elements of vapor intrusion pathways  Batch reactor experiments to generate points on a sorption isotherm  Results for metagenomic analysis of a groundwater sample obtained from a site impacted with petroleum hydrocarbons  Perchlorate releases and drinking water detections  Data input screen for ESTCP Mass Flux Toolkit  Amendment addition for biobarrier  Thermal Remediation - Desorption schematic  Key exposure pathways for human health risk from contaminated sediments  The PFAS family of compounds
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