Item talk:Q228945
From geokb
{
"@context": "http://schema.org/", "@type": "WebPage", "additionalType": "Research", "url": "https://www.usgs.gov/centers/california-water-science-center/science/low-intensity-chemical-dosing-licd", "headline": "Low Intensity Chemical Dosing (LICD)", "datePublished": "June 27, 2018", "author": [ { "@type": "Person", "name": "Tamara Kraus", "url": "https://www.usgs.gov/staff-profiles/tamara-kraus", "identifier": { "@type": "PropertyValue", "propertyID": "orcid", "value": "0000-0002-5187-8644" } } ], "description": [ { "@type": "TextObject", "text": "Back to the top >>" }, { "@type": "TextObject", "text": "This low-intensity chemical-dosing (LICD) method is anticipated to remove considerable amounts of DOC and DBP precursors from island drainage water, thereby significantly reducing inputs of these constituents to the Delta. Accumulation of the flocculated material in wetlands, along with sequestration of wetland plant material, is expected to increase land-surface elevations. The project hypothesis is that the combination of coagulation and biotic wetland processes can improve water quality and reverse subsidence beyond that achievable by either technology alone." }, { "@type": "TextObject", "text": "Concentrations of mercury (Hg) particularly methyl mercury (MeHg), are also of great concern in the Delta. Sources of HG include historic inputs from the Gold Rush era, drainage from abandoned mines, and ongoing air deposition from power plants and industry. Recent dissolved in subsided-island drainage water (Hennebery et al., 2011: Hennebery et al., 2016). Field studies showed similar reductions along with lower methlmercury bioaccumulation in fish (Ackerman et al., 2015)." }, { "@type": "TextObject", "text": "Plant samples will be collected to assess whether the coagulation treatments influence plant primary productivity." }, { "@type": "TextObject", "text": "Levee Failure | Study Design | Water Quality | Accretion | Ecosystem | Feasibility" }, { "@type": "TextObject", "text": "The primary objective of this part of the study is to determine if the coagulation-wetland systems reduce DOC and DBP precursor loads from island drainage water. This will be accomplished both through regular water-quality monitoring of the inlet and outlet of each cell, as well as through synoptic studies focused on the production, loss, and transformation of constituents during transport through the wetland cells. Surface-water, pore-water, vegetation and sediment samples will be collected and analyzed to address these objectives." }, { "@type": "TextObject", "text": "Prior research conducted by the USGS on Twitchell Island has shown that constructed wetlands can increase land-surface elevations up to 3.5 inches per year (Miller et al. 2008). The LICD project is investigating whether a combination of wetland plant production and the addition of the metal-organic matter flocculate resulting from coagulation can exceed rates of land surface accumulation achieved by wetland plants alone." }, { "@type": "TextObject", "text": "Field experiments will focus on organic carbon fate and transport as well as assess potential ecosystem effects. All compartments (water, sediment, vegetation) will be sampled to achieve these objectives." }, { "@type": "TextObject", "text": "By determining whether there are differences in plant growth and sediment accretion rates between the different wetland treatments (iron coagulant vs, alluminum coagulant vs. verses no coagulant) we can assess whether any measured differences in the water quality are affecting rates of primary production and decomposition. Effects on aquatic organisms will be determined through EPA toxicity tests." }, { "@type": "TextObject", "text": "Rivers, wetlands, and agricultural operations supply natural organic material to the Sacramento-San Joaquin Delta (Delta) and the San Francisco Estuary. This natural organic matter provides many ecosystem benefits, but it also adversely affects drinking water. During drinking water treatment, chlorine added for purposes of pathogen control reacts with dissolved organic carbon (DOC) in the water to form carcinogenic and mutagenic disinfection by-products (DBPs), which are regulated in tap water by the U.S. Environmental Protection Agency." }, { "@type": "TextObject", "text": "On site coagulation with metal based salts, or low-intensity chemical-dosing (LICD), is anticipated to remove considerable amounts of DOC and DBP precursors from drainage water, thereby significantly reducing inputs of these constituents to the Delta. Coagulation may also remove mercury from solution. Accumulation of the flocculated material in constructed wetlands, along with sequestration of wetland plant material, is expected to increase land-surface elevations. The project hypothesis is the combination of coagulation and biotic wetland processes can improve water quality and reverse subsidence beyond that achievable by either technology alone." }, { "@type": "TextObject", "text": "The Solution" }, { "@type": "TextObject", "text": "Land Subsidence and Levee Stability" }, { "@type": "TextObject", "text": "Water samples will be collected regularly prior to coagulation, following coagulation, and after passage through the wetlands (wetland outflows). In addition, water samples will be collected across the cells to examine changes in water quality during passage through the wetlands. Water samples will be analyzed for dissolved and particulate organic matter, disinfection by-product formation, nutrients, and metals." }, { "@type": "TextObject", "text": "Sampling Approach" }, { "@type": "TextObject", "text": "The primary goals of this project are to assess the feasibility of the following:" }, { "@type": "TextObject", "text": "As land surface elevations decrease, costs for levee maintenance and repair increase, as do the risks of catastrophic levee failure. Currently 98 percent of the Delta is below sea-level (Knowles 2010). In addition to immediate loss of life and property associated with levee failure, saltwater intrusion into this freshwater system could result and halt water exports for an extended period of time (Mount and Twiss 2005). Management actions that reduce, or better yet reverse, subsidence in the Delta would reduce these costs and risks." }, { "@type": "TextObject", "text": "This project combines laboratory and field studies to assess the feasibility and ecosystem effects of LICD. Specific study objectives will includes assessments of water quality, accretion, and ecosytem dynamics. Laboratory studies will assess the efficacy of coagulant type and dosing rates for removing DOC, DBP precursors, and other constituents of concern (e.g. mercury) from island drainage water, as well as assess characteristics and stability of the flocculated material." }, { "@type": "TextObject", "text": "Construction of a replicated field experiment located on Twitchell Island will allow us to determine the effects of a coagulation treatment-wetland system on water quality. The experimental design includes three coagulation treatments\u2014an iron-based coagulant (iron sulfate), an aluminum-based coagulant (polyaluminum chloride), and a control (no coagulant addition). There are three replicates of each treatment for a total of nine wetland cells. This system is expected to run from Fall 2011 to Fall 2013. The effects of the treatment-wetland systems will be assessed by monitoring water quality, sediment accretion, plant production, and aquatic organism health." }, { "@type": "TextObject", "text": "The demonstration coagulation-wetland field study is composed of nine cells that include three coagulation treatments, each replicated three times. The three coagulation treatments include the following:" }, { "@type": "TextObject", "text": "Mercury" }, { "@type": "TextObject", "text": "Rivers, wetlands, and agricultural operations supply natural organic material to the Sacramento-San Joaquin Delta (Delta) and the San Francisco Estuary. This natural organic matter provides many ecosystem benefits, but it also adversely affects drinking water. This occurs because during drinking water treatment, chlorine added for purposes of pathogen control dissolved organic carbon (DOC) in the water to form carcinogenic and mutagenic disinfection by-products (DBPs). Concentrations of these compounds in tap water are regulated by the Environmental Protection Agency." }, { "@type": "TextObject", "text": "Back to the top >" }, { "@type": "TextObject", "text": "In order to halt or reverse subsidence, accumulation of material has to equal or exceed its loss. In the case of organic matter, production of organic matter by photosynthesis (i.e. plant growth) must exceed its loss through degradation by microorganisms. Wetlands that support emergent vegetation produce high rates of plant biomass (net primary production, NPP), whereas flooded conditions create oxygen-depleted (anaerobic) conditions which slow decomposition rates\u2014the net effect of this is accumulation of organic material." }, { "@type": "TextObject", "text": "Sediment samples will be collected to determine rates of accretion as well as the composition and quality of the accreted material. Sediment carbon, nutrient, and metal concentrations will be determined along with bulk density." }, { "@type": "TextObject", "text": "Dissolved Organic Matter and Water Quality" }, { "@type": "TextObject", "text": "Historically, the Sacramento\u2014San Joaquin Delta (Delta) in California was a vast inland freshwater wetland where organic soils over 50 feet deep formed over several millennia. Beginning in the late 1800\u2019s, levees were constructed and pumps were used to drain the area for agricultural use. Draining these lands has led to land-surface subsidence to more than 20 feet below sea level in some areas, primarily due to oxidative loss of the organic rich soils. Because the Delta supplies drinking water for over 23 million Californians, protecting both water supply and water quality in this region is of great importance." }, { "@type": "TextObject", "text": "Land subsidence is a dropping of the land surface. While land-surface loss can be due to dewatering, groundwater pumping, or soil compaction, in the Delta the dominant cause is loss of the organic-rich peat soils due to microbial degradation. Put simply, microbial activity \u2014 which is enhanced under drained (oxygen rich) conditions compared to flooded (oxygen poor) conditions \u2014 converts the organic rich soil to carbon dioxide gas (CO2)." }, { "@type": "TextObject", "text": "Experimental Design" }, { "@type": "TextObject", "text": "Data will be used to develop a mass-balance model of DOC, DBP precursors, nutrients, and dosed chemicals (aluminum, Al, or iron, Fe) in the system. In addition, more detailed characterization of the DOC pool will help us determine the sources and processing of material within the wetland to assess whether plants, soils or algae are contributing DOC and DBP precursors." }, { "@type": "TextObject", "text": "The costs associated with constructing and maintaining a coagulation-wetland system will be calculated in order to assess the feasibility of implementing this system to improve water quality and reverse subsidence in the Delta." }, { "@type": "TextObject", "text": "Research under the \"Ecosystem Objective\" for this project will examine wheather the addition of coagulated drainage water affrects ecosytem health. the addition of the iron or aluminum-based coagulants could directly or indirectlt affect several things, including pH, redox conditions, nutrient availability and cycling, plant growth, and aquatic toxicity. The primary goal is to improve water quality by removal of constituents of concern (DOC, DBP precursors, mercury) during passage of island drainage water through the coagulation-wetland system. Conditions within the wetlands themselves, however, should provide a safe habitat for aquatic and other wildlife and alos lead to the beneficial accumulation of soil material." }, { "@type": "TextObject", "text": "Because much of the land in the Delta is below sea level, drainage water must be continuously pumped into adjacent Delta channels to prevent these areas from flooding. This drainage water typically contains high concentrations of DOC and DBP precursors because they have passed over and through high organic matter peat soils (Fujii et al. 1998, Fleck et al. 2007). Drainage water from Delta peat islands has been shown to represent a significant source of these constituents of concern to drinking water diverted from the Delta (Kraus et al. 2009). Management actions that reduce the export of these constituents from subsided islands will improve water quality in the Delta." } ], "funder": { "@type": "Organization", "name": "California Water Science Center", "url": "https://www.usgs.gov/centers/california-water-science-center" }, "about": [ { "@type": "Thing", "name": "Aquatic Ecosystems" }, { "@type": "Thing", "name": "Science Technology" }, { "@type": "Thing", "name": "DOC" }, { "@type": "Thing", "name": "Drinking-Water" }, { "@type": "Thing", "name": "Water Quality" }, { "@type": "Thing", "name": "Advanced Capabilities and Research" }, { "@type": "Thing", "name": "coagulation" }, { "@type": "Thing", "name": "Bay-Delta" }, { "@type": "Thing", "name": "land subsidence monitoring" }, { "@type": "Thing", "name": "Contaminants" }, { "@type": "Thing", "name": "Bay-Delta Monitoring Network" }, { "@type": "Thing", "name": "Low Intensity Chemical Dosing LICD" }, { "@type": "Thing", "name": "Water" }, { "@type": "Thing", "name": "Monitoring Technology" }, { "@type": "Thing", "name": "Surface Water" }, { "@type": "Thing", "name": "Information Systems" }, { "@type": "Thing", "name": "Mercury" }, { "@type": "Thing", "name": "Surface Water Quality" }, { "@type": "Thing", "name": "Aquatic Ecology" }, { "@type": "Thing", "name": "Methods and Analysis" }, { "@type": "Thing", "name": "Dissolved Organic Carbon" }, { "@type": "Thing", "name": "Measuring and Monitoring" }, { "@type": "Thing", "name": "Water Quality Monitoring" }, { "@type": "Thing", "name": "LICD" }, { "@type": "Thing", "name": "water quality methods" }, { "@type": "Thing", "name": "Organics/Nutrients" }, { "@type": "Thing", "name": "Low intensity chemical dosing" }, { "@type": "Thing", "name": "Energy" }, { "@type": "Thing", "name": "water quality degradation" }, { "@type": "Thing", "name": "Land Subsidence" }, { "@type": "Thing", "name": "Environmental Health" }, { "@type": "Thing", "name": "DBP" }, { "@type": "Thing", "name": "disinfection by-product precursor" }, { "@type": "Thing", "name": "Geology" } ]
}
