Remediation Sites Research Articles

How much heterogeneity? Flow versus area from a big data perspective

AbstractOver the past 10 years, there has been an increased recognition that matrix diffusion processes are a significant factor controlling the success of groundwater remediation. New field techniques and modeling tools have, consequently, been developed to understand how contaminants diffuse into and then out of low‐permeability (“low‐k”) zones and assess the resulting impact on groundwater quality. Matrix diffusion, in turn, is driven by one key factor: geologic heterogeneity. The importance of heterogeneity is being emphasized in the groundwater field by general rules of thumb such as “90% of the mass flux occurs in 10%‐20% of the cross‐sectional area” and conceptual models that show most of the groundwater flow occurs through the aquifer's “mobile porosity” which just a small fraction of commonly used effective porosity values (between 0.02 and 0.10 for mobile porosity vs. 0.25 for effective porosity). For this study, 141 boring logs from 43 groundwater remediation sites were evaluated to develop an empirically based estimate of the groundwater flow versus aquifer cross‐sectional area to confirm or reject the general flow versus area rules of thumb. This study indicated that at these 43 sites, an average of 30% of the cross‐sectional area carried 90% of the groundwater flow. Our flow‐only analysis does provide moderate (but not confirmatory) support for the “mobile porosity” concept with an estimated representative mobile porosity value of about 0.11 at the 43 sites.

Evaluation of soil treatment techniques on remediated brine spill sites in semi-arid rangelands

Unconventional oil and gas development (UOG) generates high volumes of flowback and produced water, byproducts of hydraulic fracturing operations, that are often released or spilled on the soil surface. Soil contamination with these wastewaters, commonly referred to as brine, has the potential to inhibit vegetation growth indefinitely. Natural attenuation of brine is not expedient in arid and semi-arid regions where most United States UOG developments are located, including the Bakken region of North Dakota. In situ (at-site) and ex situ (off-site) soil treatment techniques are commonly employed to remediate brine-contaminated soils in the Bakken. However, little is known regarding each technique's efficacy despite differences in application, cost, and efficiency. We selected 10 sites previously remediated with chemical amendments (in situ) and 11 sites with topsoil excavation (ex situ) in the United States Forest Service Little Missouri National Grasslands. We paired each remediated site with a reference to examine the ability of each strategy to return brine-contaminated sites to conditions reflective of the current state of the surrounding semi-arid rangeland ecosystem. At each site, we quantified soil electrical conductivity (ECe) as an indicator of soil salinity and measured vegetation cover, biomass production, bare ground, and litter. The difference between paired reference and remediated sites was used for analysis. Brine contamination was still evident as soil ECe was similarly increased on chemical amendment and topsoil excavation remediated sites over paired references at all soil depths tested. Due to the nature of the topsoil excavation treatment, elevated ECe in the 0–15 cm depth suggested resalinization of the new topsoil. Remediation techniques also resulted in similar plant community composition marked by an increase in exotic forb biomass, largely due to the invasion of kochia (Bassia scoparia) which was absent from reference sites. However, remediation techniques differed substantially in vegetation establishment. We found 15% more bare ground on sites remediated with chemical amendment treatment than paired references and 55% more with topsoil excavation. Our results indicate that in situ strategies may be more suitable than ex situ strategies for brine-spill remediation in semi-arid rangelands like the Bakken in North Dakota as they cause less disturbance and likely require less post-remediation management to establish adequate vegetation cover to protect the soil from further erosion.

Application of cross-hole electrical resistivity tomography to groundwater contaminated remediation site

Application of cross-hole electrical resistivity tomography to groundwater contaminated remediation site

Supporting aquatic habitat remediation in the Detroit River through numerical simulation

Successful habitat remediation begins with an understanding of the geomorphic processes (e.g., flow regime and sediment transport) that maintain desired habitats. Although field surveys can provide information on site conditions, field measurements are limited to spatial-temporal extents and resolutions that do not always meet the level of detail required to determine the best remediation design for the underling geomorphic processes at a given site. However, hydraulic models are capable of predicting flow characteristics at fine resolutions over large spatial extents and can be developed to supplement field surveys. Hydraulic models were used in conjunction with field surveys to guide the placement of three fish spawning habitats (reefs) in the Detroit River. Model predictions were used to identify reef placement minimizing flow disruptions that could encourage sediment deposition over the reefs. Following reef construction, we revisited the hydraulic models to evaluate their ability to predict the influence of reef design and placement on flow patterns and further examine the influence of the reefs on localized flow heterogeneity at a resolution relevant to fish (<1 m). Three-dimensional computational fluid dynamics (CFD) models were used to predict the flow field over the remediation sites with and without the virtual addition of the three fish spawning reefs. The pre-reef model was calibrated using water velocity measurements made with an acoustic Doppler current profiler (ADCP) prior to reef construction. Following calibration, the three reefs were virtually added by manipulating the bathymetry to reflect post-construction conditions and the CFD model was repeated with the post-construction bathymetry. Comparison between measured and predicted post-construction water velocities revealed a mean difference of 18%, with the largest differences in shallow areas where detailed bathymetry was lacking. Near the reefs the CFD model was able to more accurately capture flow patterns. Post-construction predictions showed shear stress over the reefs was capable of maintaining transport of sand. Lake sturgeon spawning habitat suitability, vorticity and flow heterogeneity also increased locally over the reefs, suggesting the remediation projects created flow conditions favorable to spawning fishes. Hydraulic models allowed examination of detailed flow patterns over a large spatial extent and provided a valuable tool for guiding reef remediation projects.

Population-based morality data suggests remediation is only modestly effective in two Superfund counties

TPS 641: Policies, interventions, communication, Exhibition Hall, Ground floor, August 28, 2019, 3:00 PM - 4:30 PM Background: The health effects of living in proximity to both active copper and molybdenum mining as well as remediation sites were evaluated for residents of two contiguous counties in the US state of Montana. The open pit copper and molybdenum mine has been open since 1984; it operates with crushers and concentrator facilities where tons of raw ore are processed. Simultaneously, the Superfund remediation efforts were established in 1983 at the site of a closed mine and smelter. Methods: Employing county level death certificate data obtained from the US Centers for Disease Control WONDER site, sex and age- adjusted standardized mortality ratios (SMRs) for targeted causes of death were calculated using observed versus expected mortality for both counties, and compared to the expected mortality from the remaining Montana counties. Results: Cancers, cerebro- and cardiovascular diseases (CCVD), and organ failure were elevated for the two counties during the study period, 2000–2016, with SMRs of 1.19 (95% CI 1.10, 1.29); 1.36 (95% CI 1.29, 1.43); and 1.24 (95% CI 1.10, 1.38). Neurological conditions were not elevated for the two counties. Time trend analyses performed using Cox regression models indicate that deaths from cancers (HR = 0.97; p = 0.0004), CCVDs (HR = 0.95; p B 0.0001), and neurological conditions (HR = 0.97; p = 0.01) decreased over the study period. Conclusions: Our approach of using publicly available death certificate data over time, along with an understanding of the potential risks associated with specific metal exposures, can be utilized to monitor population health impacts during continued mining and remediation efforts. The time trends indicate there is a small downward trajectory in the mortality rates for cancer, cerebro-cardiovascular, and neurological conditions. These findings suggests there is a continuing need for monitoring mortality, in order to keep the public aware of ongoing risks.

1,4‐Dioxane: Emerging technologies for an emerging contaminant

AbstractThe synthetic chemical, 1,4‐dioxane, is classified by the U.S. Environmental Protection Agency (EPA) as a probable human carcinogen. Between 2013 and 2015, the EPA detected 1,4‐dioxane in public drinking water supplies in 45 states at concentrations up to 33 µg/L and in groundwater from releases at hazardous waste sites across the United States. Although a Federal maximum contaminant level drinking water standard has not yet been proposed, state‐specific standards and criteria are as low as 0.3 µg/L. 1,4‐Dioxane is a recalcitrant chemical in that applications of conventional treatment technologies have had limited success in reducing concentrations in water to meet current and proposed health‐protective levels. Although mainly used as a stabilizer for the solvent 1,1,1‐trichloroethane, it has been used in other industrial processes and has been detected in a variety of consumer products, such as foods, pharmaceuticals, cosmetics, and detergents. The high aqueous solubility of 1,4‐dioxane coupled with limited solubility of chlorinated solvents typically found in conjunction with 1,4‐dioxane contamination is the primary reason for its treatment challenges. In the last several years, an alternative, cost‐effective technology has been developed that has demonstrated treatment to levels significantly lower than the Federal and state‐specific goals. This article provides a Federal and state‐by‐state summary of 1,4‐dioxane‐specific drinking water and groundwater concentration criteria and qualitative comparison of the effectiveness of conventional treatment technologies compared to the effectiveness of an alternative treatment technology. A case study is also provided to present details regarding the application of an alternative treatment technology at an active groundwater remediation site in California.

Особливості екологічної ніші молюска Monacha (Monacha) cartusiana (O. F. Muller, 1774) у техноземі на сіро-зеленій глині (Нікопольський марганцеворудний басейн)

У роботі встановлено особливосто екологічної ніші молюска Monacha (Monacha) cartusiana (O. F. Muller, 1774) у техноземі на сіро-зеленій глині (Нікопольський марганцеворудний басейн) та показано стаціонарність у часі одержаного результату. Дослідження проводили протягом 2012–2014 рр. на ділянці рекультивації Нікопольського марганцеворудного басейну в м. Покров. Як екогеографічні предиктори екологічної ніші молюсків виміряно такі показники, як електропровідність ґрунту, агрегатний склад, твердість ґрунту на глибині до 0,5 м, проективне покриття фізіономічних типів рослинності та фітоіндикаційні оцінки екологічних режимів. Для кількісної характеристики екологічної ніші застосовано ENFA-аналіз. У результаті дослідження встановлено, що маргінальність екологічної ніші M. cartusiana визначають такі екогеографічні предиктори, як уміст агрегатів розміром 1–2 та 2–3 мм (позитивна маргінальність) і &gt; 10 мм (негативна маргінальність), твердість ґрунту на глибинні 0–5, 20–25 та 35–40 см і фізіономічний вигляд рослинного покриву. Цей вид надає перевагу ділянкам із більшим проективним покриттям фізіономічного типу ІІІ та уникає ділянок із переважанням фізіономічного типу V і VI. Надають перевагу ділянкам із підвищеною аерацією ґрунту. Спеціалізацію екологічної ніші M. cartusiana визначають такі екогеографічні предиктори, як уміст агрегатів розміром 0,5–1,0 та &gt; 10 мм, твердість на різних глибинах, електрична провідність ґрунту, кріоклімат і континентальність, проективне покриття фізіономічних типів ІІІ та VI. Установлені особливості екологічної ніші є стаціонарними за період досліджень.

Environmental Health Education for Asbestos-Contaminated Communities in Italy: The Casale Monferrato Case Study.

Background:Environmental health education contributes towards increasing awareness of communities to prevent exposure to hazardous substances. Casale Monferrato, the operating site for the Eternit asbestos-cement factory from 1907 to 1986, is a prioritized asbestos-contaminated site for remediation in Italy. The area is prone to severe asbestos-related diseases. About 50 cases of mesothelioma are diagnosed in Casale Monferrato annually; mesothelioma has been shown to be caused by occupational, environmental and domestic asbestos exposure.Objectives:The goal of this paper is to analyze the Casale Monferrato case study in terms of youth engagement in environmental health education initiatives on asbestos risk and health impact. The paper aims at underlining the lessons learned in order to share the success of this initiative with other communities living in asbestos-contaminated sites in different countries.Methods:Peer education methodology has been used through the Asbestos Classroom to involve teachers, students and other local stakeholders in training activities, in selection of the contents for educational materials and interactive tools, as well as in choosing the presentation process for the aforementioned knowledge sharing instruments.Findings:From November 2014 to June 2018, 185 high school students and teachers were trained through the Asbestos Classroom. Through December 2018, they trained 3,241 classroom visitors. The Classroom relies on an inclusive participative process in which young people play a key role in the network of relationships within their community.Conclusions:The paper corroborates the importance of engaging the educational system in communication efforts aimed at fostering collective awareness on environmental risk and health-related impacts for communities living in industrially contaminated sites. Considering the global dimension of the asbestos contamination and disease burden, this experience might be of relevance both in countries that banned asbestos and in those where asbestos is not yet prohibited.

Linking Land Use to Atlantic Salmon Production to Guide Recovery Planning

AbstractQuantifying functional relationships between abundance and land use is critical during recovery planning for endangered freshwater and diadromous fishes. However, there is little practical guidance on how much abundance might be expected to change from specific types or magnitudes of land use, making it difficult to identify specific sites for restoration or to prioritize among remediation actions. To address these needs for endangered Atlantic Salmon Salmo salar inhabiting the Southern Upland region of Nova Scotia, Canada, we developed a suite of hierarchical models to evaluate the functional form and magnitude of response of populations to land use at two spatial scales. Juvenile distribution patterns showed a strong longitudinal gradient throughout the stream network, with higher densities occurring in headwaters, which suggests that maintaining connectivity as well as unmodified landscapes in the upper reaches of rivers should be prioritized to aid recovery. Relative to threats, there was no single type of land use that was primarily associated with changes in juvenile abundance. Instead, responses to the combined suite of land‐use types were nonlinear and did not appear dependent on spatial scale. When the proportion of natural forest cover was high, populations appeared to benefit from low levels of anthropogenic land use, declining with increasing human activity only once the average proportion of natural forest cover was low. To use threat relationships in recovery planning, we propose a simple quantitative index based on the extent of development in the vicinity of rivers to identify sites for remediation or protection. To aid future monitoring, we demonstrate why site‐specific electrofishing catchability must be estimated when evaluating population responses to landscape change.

Rhizoremediation of weathered PCBs in a heavily contaminated agricultural soil: Results of a biostimulation trial in semi field conditions

This paper describes the results of a rhizoremediation greenhouse experiment planned to select the best plant species and soil management for the bioremediation of weathered polychlorinated biphenyls (PCBs). We evaluated the ability of different plant species to stimulate activity and diversity of the soil microbial community leading to the reduction of PCB concentrations in a heavily contaminated soil (at mg kg-1 dw level), of the national priority site for remediation (SIN) “Brescia-Caffaro” in Italy. Biostimulation was determined in large size (6kg) pots, to reflect semi-field conditions with a soil/root volume ratio larger than in most rhizoremediation experiments present in the literature. In total, 10 treatments were tested in triplicates comparing 7 plant species (grass and trees) and 5 soil/cultivation conditions (i.e., only one plant species, plant consociation, redox cycle, compost or ammonium thiosulfate addition) with the appropriate unplanted controls. After 18months of biostimulation the overall reduction of total PCBs varied between 14 and 20%. Microbial analysis revealed a shift in the microbial community structure over time and showed that all the planted treatments significantly enhanced microbial hydrolytic activity and the abundance of bacterial populations, including potential PCB degraders, in the soil surrounding plant roots. The plant species most effective in reducing the contaminant concentrations were Festuca arundinacea cultivated adding compost or in consociation with Cucurbita pepo ssp. pepo and Medicago sativa cultivated with Rhizobium spp. and mycorrhizal fungi; they reduced total PCB concentrations of about 20% and showed the significant depletion of a high number of PCB congeners (29, 37 and 23, respectively, out of the 79 measured). Our results suggest that these plant species are particularly efficient in increasing soil PCB bioavailability and in stimulating microbial degradation. They could be used in field rhizoremediation strategies to enhance the natural attenuation process and reduce PCB levels in historically contaminated sites.

Modelling PAH Degradation in Contaminated Soils in Canada using a Modified Process‐Based Model (DNDC)

Core Ideas A novel process‐based model for degradation of soil PAHs is proposed. Model is based on dynamic interactions between water, soil, vegetation and climate. Model effectively simulates biogeochemical processes of PAH degradation in soils. Simulated results agree well with data from remediation sites in Alberta. Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants of concern. A process‐based model of the PAH degradation can improve our understanding of ecological drivers and processes. In this paper, a process‐based biogeochemistry model, DeNitrification‐DeComposition (DNDC) is modified to simulate the dynamics of PAHs degradation in soils at abandoned oil and gas well sites. This new version of DNDC‐Organic Pollutants, called DNDC‐OP, coupled the rates of PAH degradation with dynamics of soil, vegetation and climate, such as soil moisture and temperature. The model was parameterized and validated against datasets of four soil PAHs: pyrene, fluorene, chrysene and anthracene, at three different abandoned oil and gas well site locations in Alberta, Canada. The sensitivity of the parameters was analyzed and tested. The simulated results were in good agreement with the measured data with a coefficient of determination (R2) of 70 to 97%, and the root mean square error (RMSE) of 4.5 to 9.1 at all three sites. We also evaluated the influence of environmental factors, such as soil temperature and moisture, on the degradation of PAHs. An increased degradation of all four PAHs occurred with increasing soil moisture content. An increase of soil temperature from 10 to 20°C and subsequently to 25°C resulted in a decreased appearance of all four PAHs from the three well sites. The result shows that this model can be used as a tool for evaluating PAH degradation for effective reclamation strategies.

A framework for increasing sustainability and reducing risk to ecological resources through integration of remediation planning and implementation

Remediation of lands contaminated with radionuclides and hazardous chemicals provides an ongoing challenge for many countries. It is particularly problematic for remediation of old industrial sites remaining from World War II and the Cold War. Remediating and restoring large sites is often costly, time-consuming, and involves complex planning and sequencing, as well as consideration of future land use policies. The goal of remediation is to reduce contamination, reduce risk to humans and the environment, and restore land to productive land uses, and ultimately, to sustainability. Often reducing risk to people takes precedence over protecting ecological resources in overall planning, characterization, and execution of remediation strategies. This paper examines when and how stakeholders, including anyone interested and affected by remediation on ecological resources, can become involved in the planning, decision-making, and implementation of remediation. There is a formal process under federal law (e.g. CERCLA) in the US for examining risk to resources, including indicator species. However, there are other informal points during the cleanup process when managers should consider the value of ecological resources, the public may express their concerns for particular ecological resources, and ecologists may provide data and expert advice early in the process as critical decisions are being made about remediation that impact ecological resources. The framework presented in this paper for increasing sustainability of ecological resources has three periods of intervention 1) major decision points, 2) process interdiction points, and 3) remediation action points. Major decision points include site and problem identification, regional ecological resource and local land use practice determination, remediation goals and options determination, and other local issues. Interdiction points include examining remediation options, and in-depth assessments of ecological resources on-site. Remediation action points are aimed at reducing risk to ecological resources during remediation, and include defining the remediation site and buffer, understanding the effects of timing and sequencing of remediation, education of all remediation personnel, and specific suggestions for reducing risk during active remediation. While this framework was developed for Department of Energy remediation sites, it is applicable to brownfields and other contaminated lands world-wide. The overall goal is to provide interested and affected parties with a framework for protecting and enhancing ecological resources during the planning and execution of remediation on contaminated lands.

Modelling the dispersion of radionuclides in dust from a landform covered by low uranium grade waste rock

The dispersion of radionuclides in dust and inhalation dose rates to the public from the planned remediation of the Ranger uranium mine in the wet-dry tropics of Australia was modelled using RESRAD-OFFSITE. Dust inhalation dose rates were predicted to be highest on the remediated site and decrease with an approximate inverse square to inverse cubic dependence with distance from the site. The annual dose above natural background to a hypothetical individual permanently occupying the remediated site (representing the worst case scenario for radionuclide in dust exposure) was estimated to be 5.3 × 10−3 mSv. The estimated doses from exposure to radionuclides in dust were two to three orders of magnitude lower than those from exposure to 222Rn. A sensitivity analysis showed that source-related and receptor-related model parameters had direct proportional influences on dust inhalation dose rates. Four transport-related model parameters (atmospheric stability class, deposition velocity of particulates, precipitation and wind speed) were also influential and generally had an increasing influence with distance from the source. The results of this study may provide general guidance to similar sites elsewhere on the relative importance of dust versus gaseous 222Rn transport pathways and the relative influence of dispersion modelling parameters on predicted exposures and doses.

Kinetics of phytoremediation of petroleum hydrocarbon contaminated soil

Earthmaster and the University of Waterloo have successfully developed plant growth promoting rhizobacteria (PGPR) – Enhanced Phytoremediation Systems (PEPSystems™) which have been deployed across Canada for the treatment of soil contaminated with petroleum hydrocarbons (PHCs), including CCME fractions F2 and F3. A challenge with phytoremediation is to predict the length of time to remediate a site so that site owners will be inclined to use the technology. In previous field trials of PEPSystems, it was determined that PHC was mostly degraded by microbes in the rhizosphere, following first-order exponential decay kinetics. Using new PEPSystems data collected from multiple commercial remediation sites across Western Canada, the kinetic equations of PHC decay were tested to determine if remediation time was accurately predicted. In general, when compared to the predicted time to remediation endpoint, data from recent commercial field applications showed that 35% and 20% less time was needed to reach remediation endpoints for fractions F2 and F3, respectively. As a result, the predictive kinetic equation for fraction F2 degradation was updated to reflect current remediation outcomes. Insufficient data were available to update the F3 equation. Being able to more accurately predict remediation timelines will enhance the value and utilization of PEPSystems.

EPA is Mandating the Normal Distribution

The United States Environmental Protection Agency (USEPA) is responsible for overseeing the cleanup of sites that fall within the jurisdiction of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA; also known as “Superfund”). This process almost always involves a remedial investigation/feasibility (RI/FS) study, including deriving upper confidence, prediction, and/or tolerance limits based on concentrations from a designated “background” area which are subsequently used to determine whether a remediated site has achieved compliance. Past USEPA guidance states outlying observations in the background data should not be removed based solely on statistical tests, but rather on some scientific or quality assurance basis. However, recent USEPA guidance states “extreme” outliers, based on tests that assume a normal (Gaussian) distribution, should always be removed from background data, and because “extreme” is not defined, USEPA has interpreted this to mean all outliers identified by a test should be removed. This article discusses problems with current USEPA guidance and how it contradicts past guidance, and illustrates USEPA’s current policy via a case study of the Portland, Oregon Harbor Superfund site. Additional materials, including R code, data, and documentation of correspondence are available in the online supplement.

Research on Intelligent Supervision Method and System Developing of Soil Remediation Project Based on 3D Mobile GIS

At present, some problems such as inconvenient manual supervision, lack of real-time online supervision and poor online interaction during the implementation of soil remediation project. In order to solve the problems, the supervision method and system development of soil remediation project are studied based on sensing online and 3D mobile GIS technologies. The remediation environment are monitored with fixed sensors online and the heavy metal content are sampled with the mobile sensors. The status of soil remediation site is supervised in real time with video online. All the real-time sensing data are integrated and stored in the comprehensive database. The information of soil pollution and remediation environment is visualized with maps and charts in 3D geographic scenes in the system. In addition, the pollution degree evaluation and remediation effect analysis functions are implemented in system. It is proved with the project practice that the method and system are convenient for managers to monitor the environment on-site and supervise the status of soil remediation site in real time. The informationization and intelligence level of soil remediation project can be effectively improved.

An Approach for Passive Removal of Residual LNAPL from Groundwater

AbstractLight nonaqueous phase liquids (LNAPLs) are a problematic challenge for obtaining site closure or no further action remediation sites. The source of the LNAPLs varies from leaking underground petroleum storage tanks, to manufacturing facilities where oil leaks create LNAPL accumulations beneath factory floors. Active recovery using pumping or periodic vacuum recovery from wells or sumps is used for remediation, but usually has disappointing results when LNAPL reaccumulates to thicknesses exceeding the 0.01‐foot action level recognized by many states. This paper presents a simple passive approach for recovering persistent LNAPL using nonwoven hydrophobic oil absorbing cloth. The method used laboratory trials to assess physical properties of the cloth. Parameters observed and assessed included sorptive capacity and rate, buoyancy, and LNAPL wicking. It was determined that the cloth could be rolled and secured with cable ties for placement in the wells/sumps. Two placement designs were developed, one where rolled sorbent freely floated on the well/sump fluid surface and a second where the sorbent roll was placed in the fluid column at a fixed depth. Sorbents were then used at two manufacturing facilities where LNAPLs persisted for decades. In both instances, many wells/sumps were reduced to thicknesses below the action level in less than 2 months. In most wells, LNAPL did not reaccumulate. Where it did reaccumulate, it was less than 50% of the original thickness. Using laboratory‐derived recovery rates, cloth sorbents could be sized to minimize placement/recovery frequency while effectively recovering LNAPL.

Potential of Organic Mercury-resistant Bacteria Isolated from Mercury Contaminated Sites for Organic Mercury Remediation.

Efforts at organic mercury detoxification can be carried out using resistant bacteria that can live in an environment contaminated with the compound. This study aimed at isolating and identifying resistant bacteria from mercury-contaminated environments and analysing their ability to detoxify organic mercury. Soil samples were obtained from 3 gold processing locations that make use of mercury in Tanoyan Village, Bolaang Mongondow district, North Sulawesi province. The identification was carried out on the mercury-resistant bacteria through morphological and molecular tests. Bacteria which were highly resistant to mercury were examined for their ability to detoxify phenyl mercury (organic mercury). The study showed that 8 mercury-resistant bacterial colonies could be isolated from the three soil samples. The bacteria were able to grow in LB broth containing 10 mg L-1 of phenyl mercury. Four isolates (AA, BB, CC and DD) were even able to grow in 40 mg L-1 of phenyl mercury. According to the identification tests, those bacteria were Pseudomonas sp. (AA, DD), Pseudomonas aeruginosa (BB) and Proteus mirabilis (CC). Testing of organic mercury against isolates of bacteria which are highly resistant to it in order to determine their detoxification capacity revealed that all four isolates could reduce levels of the compound in media, based on the results, starting from the highest was Pseudomonas sp. 74.99%, then Pseudomonas aeruginosa 60.23% and Proteus mirabilis 47.59% after 24 h of incubation. The study suggested that there are four bacteria that have potentials to remediate organic mercury contamination sites.

Resilient remediation: Addressing extreme weather and climate change, creating community value

AbstractRecent devastating hurricanes demonstrated that extreme weather and climate change can jeopardize contaminated land remediation and harm public health and the environment. Since early 2016, the Sustainable Remediation Forum (SURF) has led research and organized knowledge exchanges to examine (1) the impacts of climate change and extreme weather events on hazardous waste sites, and (2) how we can mitigate these impacts and create value for communities. The SURF team found that climate change and extreme weather events can undermine the effectiveness of the approved site remediation, and can also affect contaminant toxicity, exposure, organism sensitivity, fate and transport, long‐term operations, management, and stewardship of remediation sites. Further, failure to consider social vulnerability to climate change could compromise remediation and adaptation strategies. SURF's recommendations for resilient remediation build on resources and drivers from state, national, and international sources, and marry the practices of sustainable remediation and climate change adaptation. They outline both general principles and site‐specific protocols and provide global examples of mitigation and adaptation strategies. Opportunities for synergy include vulnerability assessments that benefit and build on established hazardous waste management law, policy, and practices. SURF's recommendations can guide owners and project managers in developing a site resiliency strategy. Resilient remediation can help expedite cleanup and redevelopment, decrease public health risks, and create jobs, parks, wetlands, and resilient energy sources. Resilient remediation and redevelopment can also positively contribute to achieving international goals for sustainable land management, climate action, clean energy, and sustainable cities.

Assessment of the Effect of Remediation Strategies on the Environmental Quality of Aquaculture Ponds in Marilao and Meycauayan, Bulacan, Philippines.

Background.Water quality in the Marilao-Meycauayan-Obando river system (MMORS) of Bulacan, the Philippines, is of great concern due to the pollution load from local industries. The river system is currently used as a source of water for the aquaculture industry in Bulacan.Objectives.In order to address organic and heavy metal pollution, several remediation strategies were tested in aquaculture ponds along the river system. Strategies such as phytoremediation (vetiver grass pontoons), application of probiotics and zeolite (with filtration as pre-treatment) were utilized in ponds to decrease or remove toxic pollutants in water and sediments.Methods.Two sites were chosen as the pilot remediation sites – ponds in Barangay Nagbalon, Marilao and Barangay Liputan, Meycauayan, Bulacan. Pond bottom preparation was done to improve the condition of the pond bottom sediments before stocking by adding zeolite. Physicochemical parameters of water such as dissolved oxygen (DO), temperature, pH, salinity, ammonia, phosphate, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were monitored throughout the culture period. Heavy metals in sediments and fish were monitored. Fish parameters such as average body weight and feed conversion ratio were determined.Results.The DO levels were below recommended levels in the morning and reached a supersaturated level in the afternoon. Ammonia and COD levels were above recommended limits. A decreasing trend was observed for ammonia levels in treatment ponds. In terms of the growth of milkfish, the pond with probiotics showed the highest growth and better feed conversion ratio in Nagbalon and in the phytoremediation pond in Liputan. Percentage survival of milkfish was much higher at Liputan. Copper, chromium, lead and manganese were detected in pond sediments. After application of zeolite, there was a decrease in lead levels throughout the culture period.Conclusions.The different remediation studies were compared in terms of cost, effectivity and application and phytoremediation (vetiver grass pontoons) was determined to be the most cost-effective remediation strategy.Competing Interests.The authors declare no competing financial interests.