Chemical Spills Research Articles

A Modified Porous Sponge with Selective Ability for Oil Removal from Oil-Water Mixtures

As oil and chemical spills pose a significant threat to the water environment, the need to develop efficient sorbent materials to remove oil and organic pollutants from water has arisen. This study aimed to develop a simple modification scheme to impart oil and water selective absorption capacity to a common three-dimensional porous material. Commercially available polyurethane sponges were used as the base material, and vinyl silica aerogel particles were loaded onto the sponges using polydimethylsiloxane as an adhesion agent. As a result, the water contact angle of the modified sponge increased from 118° to 149.2°, and the water absorption decreased from 106.5 g/g to 0.2 g/g; it could absorb oil in oil-water mixtures without absorbing water and maintain an excellent level of selective absorption ability after 20 cycles. This modification scheme is easy to operate and robust and is a scheme of practical application.

Impact of Nanotechnology on Environment – A Review

The world is facing significant environmental challenges like improving the standard of air, soil, and water. Currently, industry is that specialize in detecting pollutants (from chemical spills, fertilizer and pesticide run-off), improving industrial and mining sites, treating contaminants and stopping further pollution. A potential solution to those problems is to use nanomaterials. Nanomaterials are often wont to assist with cleaning the environment and even provide efficient energy solutions, like nanomaterial based solar cells additionally to the present, nanomaterials help to enhance the standard and performance of the many consumer products. As results of this, the exposure to made nanomaterials is increasing day-by-day. However, there are both positive and negative impacts on the environment thanks to nanotechnology.Recent advances in nanotechnology have shown numerous societal benefits through the event or improvement of smart materials. Several engineered nanomaterials (ENMs) are produced during the last years which will be found in related sectors like health, food, home, automotive, electronics, and computers (Hansen et al., 2016). The estimated output of ENMs produced was up to 270,000 metric tons/year and during this case considering only SiO2, TiO2, FeOx, AlOx, ZnO, and CeO2 nanoparticles.

Sustainable laboratory evaluations: Optimized fume-hood- intensive ventilation and energy efficiency without compromising occupational safety and comfort

Fume-hood-intensive laboratories consume enormous amounts of energy, especially in hot and humid climates, where the ambient air is dehumidified and cooled before it is brought into the building. Hence, excessive ventilation beyond what is needed to maintain a safe and comfortable laboratory environment is costly. This study aims to explore potential alternatives to conventional ventilation strategies in chemistry laboratories with high fume hood density, for optimizing energy efficiency without compromising safety and comfort during occupied periods. Due to the limited floor areas, these laboratories are increasingly used in high-density cities, like Singapore. First of all, the effects of conventional ventilation strategies and their alternatives on air quality and thermal comfort conditions are simulated in a target laboratory under 1) small chemical spills, 2) large chemical spills, and 3) large heat gains. Secondly, based on the evaluation of the simulation results, optimized ventilation strategies, compared with conventional ones, are explored. Thirdly, the potential energy savings of these optimized strategies are estimated. The findings suggest that it is feasible to optimize laboratory ventilation by better coordinating the local and general exhausts, while their coordination strategies vary in different scenarios. With the optimized strategies in the target laboratory, the conventional set points of 12 and 15 ACH (air change per hour) in normal (occupied) and emergency scenarios can drop to 8 ACH. Meanwhile, the corresponding hourly energy savings are up to 0.33 kWh (33.3%) and 0.58 kWh (46.7%). The findings derive a cleaner and more sustainable way to operate fume-hood-intensive laboratories. They complement the current laboratory ventilation standards, addressing the significance on better coordinating the general and local exhausts in fume-hood-intensive laboratories.

Occupational Toxicity and Health Hazards of the Healthcare Providers at Healthcare Facilities in Sulaimani City, Iraq


 Objective: The present study aimed to evaluate the occupational health hazards that face health care providers in Sulaimani City.
 Methods: A cross-sectional study conducted utilizing quantitative data collection methods. It involved 159 respondents including Physicians, Pharmacists, Medical assistants, Laboratory Instructors and Nurses who worked in 8 major health facilities in Sulaimani city, Kurdistan region, Iraq.
 Results: Nurses were the most susceptible group to sharp related injuries 13.84%, cuts and wounds 10.69% than the others and they were more experiencing verbal abuse in the workplace 15%. Laboratory instructors represent the most exposed group to contaminated specimens/biohazards 17.6% and blood borne pathogens 13.84, while the physicians represent the most prone group to acquire infectious diseases 15.1% and both the physicians and the nurses were equally exposed to airborne diseases 11.32%. Furthermore, physicians were the most group that suffered from work related stress 13.8%; and medical assistants were the most susceptible to radiation 3.1%. Meanwhile, Laboratory instructors were the most exposed group to physical distress 15.1%, falls 5%, unsafe staffing 13.8%, chemical spills 8.8% and noise 5.4%.
 Conclusion: Healthcare providers in these settings experienced various types of occupational hazards in their workplaces, which became a dominant issue among the health care providers. Interventions should be established to alleviate these hazards.

Ecological Effects of Benzyl Chloride on Different Korean Aquatic Indigenous Species Using an Artificial Stream Mesocosm Simulating a Chemical Spill.

In this study, an artificial stream mesocosm consisting of a head tank, faster-flowing riffle section, gravel section, pool section, lower-run section, and tail tank was installed to simulate a chemical spill in a river. The responses of freshwater periphyton algae, crustacea (Moina macrocopa), freshwater worm (Limnodrilus hoffmeisteri), benthic midge (Glyptotendipes tokunagai), and fish (Zacco platypus and Aphyocypris chinensis) were observed after exposure to benzyl chloride (classified as an accident preparedness substance, APS) at concentrations of 1, 2, and 4 µL/L for 22.5 h. Higher concentrations increased the inhibition (photosynthetic efficiency decrease) of periphyton algae and the mortality of M. macrocopa, whereas the reproduction of the female cladoceran decreased in the 4 µL/L treatment. Mortality of fish did not occur or was lower (≤20%) at all concentrations; however, toxic symptoms were observed for some time after chemical exposure termination and later, symptoms receded. G. tokunagai mortality increased at all concentrations except the control after seven days, and no significant toxic effects were observed in L. hoffmeisteri. The hazardous concentration of benzyl chloride was calculated as 94 µg/L. This study showed the different sensitivities of each species to benzyl chloride. The findings can assist in environmental risk assessment of APSs after chemical spills to protect Korean aquatic species.

Surface active ionic liquid and Tween-80 blend as an effective dispersant for crude oil spill remediation

Chemical oil spill dispersants are toxic to the marine environment, spurring a search for environmentally friendly dispersant formulations. We have formulated an oil spill dispersant composed of two biocompatible surfactants, Tween 80 (T) and surface-active ionic liquid (SAIL), [BMIM] [Lausar] (1-butyl-3-methylimidazolium lauroyl sarcosinate). Various micellar, interfacial, and thermodynamic properties of Tween 80 and ionic liquid (T/IL) blends were studied. The T/IL blends were solubilized in simulated seawater, and their oil (light Arab crude oil) dispersion effectiveness was determined by the baffled flask test. A synergistic interaction was observed between T and IL, such that a blend is effective as an oil dispersant, but neither is effective on its own. The stability of crude oil droplets was maximized at a 40/60 (w/w) of T/IL. The dispersion effectiveness at this specific ratio was found to be 81.19%, with a dispersant to oil ratio (DOR) of 1:25 (volume). The size and size distribution of dispersed oil droplets at function of DOR were investigated using optical microscopy and particle size analyzer. The results showed that the sizes of oil droplets decreased with DOR. We conclude that T/IL blends have unique properties which make them viable alternatives for oil spill remediation.

Toward Computational Accuracy in Realistic Systems to Aid Understanding of Field-Level Water Quality Issues

Contemplating what will unfold in this new decade and those after, it is not difficult to imagine the increasing importance of conservation and protection of clean water supplies. A worrying but predictable offshoot of humanity’s technological advances is the seemingly ever-increasing chemical load burdening our waterways. In this perspective are presented a few modest areas where computational chemistry modelling could provide benefit to these efforts by harnessing the continually improving computational power available to the field. In the acute event of a chemical spill incident, true quantum-chemistry-based predictions of physicochemical properties and surface-binding behaviors can be used to help decision making in remediating the spill threat. The chronic burdens of microplastics and perfluorinated “forever chemicals” can also be addressed with computational modelling to fill the gap between feasible laboratory experiment timescales and the much-longer material lifetimes. For all of these systems, field-level accuracy models will avail themselves as the model computational systems are able to incorporate more realistic features that are relevant to water quality issues.

Multi-element isotopic evidence for monochlorobenzene and benzene degradation under anaerobic conditions in contaminated sediments

Industrial chemicals are frequently detected in sediments due to a legacy of chemical spills. Globally, site remedies for groundwater and sediment decontamination include natural attenuation by in situ abiotic and biotic processes. Compound-specific isotope analysis (CSIA) is a diagnostic tool to identify, quantify, and characterize degradation processes in situ, and in some cases can differentiate between abiotic degradation and biodegradation. This study reports high-resolution carbon, chlorine, and hydrogen stable isotope profiles for monochlorobenzene (MCB), and carbon and hydrogen stable isotope profiles for benzene, coupled with measurements of pore water concentrations in contaminated sediments. Multi-element isotopic analysis of δ13C and δ37Cl for MCB were used to generate dual-isotope plots, which for 2 locations at the study site resulted in ΛC/Cl(130) values of 1.42 ± 0.19 and ΛC/Cl(131) values of 1.70 ± 0.15, consistent with theoretical calculations for carbon-chlorine bond cleavage (ΛT = 1.80 ± 0.31) via microbial reductive dechlorination. For benzene, significant δ2H (122‰) and δ13C (6‰) depletion trends, followed by enrichment trends in δ13C (1.6‰) in the upper part of the sediment, were observed at the same location, indicating not only production of benzene due to biodegradation of MCB, but subsequent biotransformation of benzene itself to nontoxic end-products. Degradation rate constants calculated independently using chlorine isotopic data and carbon isotopic data, respectively, agreed within uncertainty thus providing multiple lines of evidence for in situ contaminant degradation via reductive dechlorination and providing the foundation for a novel approach to determine site-specific in situ rate estimates essential for the prediction of remediation outcomes and timelines.

Comparative Analysis of Hydrogen Fluoride-Exposed Patients Based on Major Burn Criteria After the 2012 Gumi City Chemical Leak Disaster.

This study conducted to analyze and compare the epidemiological and clinical characteristics of hydrogen fluoride-exposed patients based on major burn criteria for the appropriate emergency department (ED) response to a mass casualty chemical spill. This retrospective cross-sectional study included the records of patients (n = 199) who visited the ED of Gumi City University Hospital from September 27, 2012, to October 20, 2012. Subjects were included in the major burn group (MBG) if they presented with wounds that required referral to a burn center according to the American Burn Association guidelines or in the nonmajor burn group (NMBG) if not. Males were predominant in both the MBG (n = 55, 48 males) and NMBG (n = 144, 84 males; P < .05). The most prevalent timeline for visiting the ED was the phase which included 9-32 hours post-leak of hydrogen fluoride, including 45 patients (81.8%) in the MBG and 122 patients (84.7%) in the NMBG (P < .001). The respiratory tract was the site of greatest damage in patients in both the MBG and NMBG (n = 47, 85.5% vs n = 142, 98.6%, P < .001). Regarding dispositions, all patients in the NMBG were discharged (n = 144, 100%); however, eight patients (14.5%) in the MBG underwent other dispositions (discharge against medical advice, five patients; admission, one patient; death, two patients, P < .05). Patient outcomes after major chemical contamination events should be characterized in future studies to maximize the quality of patient care.

Dextran Sulfate Polymer Wafer Promotes Corneal Wound Healing.

Eye injuries due to corneal abrasions, chemical spills, penetrating wounds, and microbial infections cause corneal scarring and opacification that result in impaired vision or blindness. However, presently available eye drop formulations of anti-inflammatory and antibiotic drugs are not effective due to their rapid clearance from the ocular surface or due to drug-related side effects such as cataract formation or increased intraocular pressure. In this article, we presented the development of a dextran sulfate-based polymer wafer (DS-wafer) for the effective modulation of inflammation and fibrosis and demonstrated its efficacy in two corneal injury models: corneal abrasion mouse model and alkali induced ocular burn mouse model. The DS-wafers were fabricated by the electrospinning method. We assessed the efficacy of the DS-wafer by light microscopy, qPCR, confocal fluorescence imaging, and histopathological analysis. These studies demonstrated that the DS-wafer treatment is significantly effective in modulating corneal inflammation and fibrosis and inhibited corneal scarring and opacification compared to the unsulfated dextran-wafer treated and untreated corneas. Furthermore, these studies have demonstrated the efficacy of dextran sulfate as an anti-inflammatory and antifibrotic polymer therapeutic.

The Contaminated Realities of a Post-IBM Endicott Today

Endicott, a small town in the Southern Tier of New York, experienced great economic success due to the birth of IBM in 1911 through the late 1900s. Today, the town is left with environmental degradation and is tainted by carcinogens as a result. The post-industrial town has endured corporate-state mitigation efforts for years. This research will explore the realities of the toxic plume in the twenty years since operations have ended at the IBM-Endicott plant. Through implementing participant observations and a myriad of interviews with experts, including NYSDEC (New York State Department of Environmental Conservation) officials and Endicott residents, the plume’s lingering situation was revealed. The chemical spill continues to leave mixed emotions within the community. Some are angered at IBM, some retain their loyalty and respect, and others have come to terms with the efforts made and now see the plume as a part of Endicott’s history. This “toxic plume” is the worst reality of the possible effects that powerful corporations can impose on small towns, a reality that has become a fear for many such communities around the world. The ongoing story of the Endicott plume fits into the greater picture for the need of environmental justice; it is an example of precautions needed to be put into place for other industrial towns to prevent pollution and contamination.

Lightweight, amphipathic and fire-resistant prGO/MXene spherical beads for rapid elimination of hazardous chemicals

Frequent leaks of hazardous chemicals have a huge impact on human lives, property and the ecological environment. Therefore, the three-dimensional functional porous materials with high absorption efficiency and special wettability for the disposal of hazardous chemical spills is an urgent demand. In this work, a series of spherical beads consisting of partially reduced graphene oxide (prGO) and MXene (Ti3C2Tx) nanosheets were constructed by hydrogen bond induced self-assembly along with freeze-drying and thermal treatment. The lightweight and amphipathic prGO/MXene spherical beads (prGMSBDs) had millimeter-level size, spherical morphology and highly porous internal structure, which were especially suitable for eliminating hazardous chemicals. Because of their excellent thermal stability and fire retardance, the prGMSBDs could be used to absorb flammable organic liquids, reducing the fire risk of the flammable hazardous chemical spills. Indeed, the prGMSBDs exhibited outstanding absorption performances for various hazardous chemicals, including organic solvents and water-based concentrated acid and alkali. Moreover, the prGMSBDs showed relatively stable absorption performance after five absorption-drying cycles. Due to meeting the requirements of both amphipathic characteristic and flame retardancy, the prGMSBDs reported in this work may offer a promising strategy for rapidly cleaning up various hazardous chemicals and open a feasible route to protecting the combustible hazardous chemical spills from fire.

Screening-level assessment of cancer risk associated with ambient air exposure in Aamjiwnaang First Nation

BACKGROUND AND AIM: The manuscript reports findings from a screening-level assessment of cancer risk from outdoor air in and around Aamjiwnaang First Nation. Aamjiwnaang is situated in the Sarnia-Lambton area, which is known for its industrial and petrochemical industry. The area is also known for poor air quality, chemical spills and other environmental events. Residents are concerned about the health impacts of these exposures. Ambient air pollution can contribute to cardiovascular, respiratory diseases, and certain types of cancer. Some communities may be at higher risk to these negative health impacts due to their geographical proximity to pollution sources. METHODS: Outdoor air concentrations were collected from four monitoring stations in the Aamjiwnaang region for known carcinogens benzene and 1,3-butadiene. Air quality data from both current (2015-2016) and historical (1995-1996, 2005-2006) records were examined. Air concentrations were mapped with geographic information systems to assess spatial variations. Outdoor air concentrations were compiled and the Lifetime Excess Cancer Risks (LECR) associated with long-term exposure to known carcinogens were estimated. RESULTS:LECR results for both benzene and 1,3-butadiene were above one per million. The LECR for benzene was 6.4 per million when the Health Canada slope factor was applied and 12.0 when using the US EPA. For 1,3-butadiene the LECR estimate was 8.8 per million. While air quality has improved over time, in 2015-2016 benzene and 1,3 butadiene levels were higher in Aamjiwnaang than provincial averages. Furthermore, benzene levels were above the Ambient Air Quality Criteria target. CONCLUSIONS:We found that ambient air in and around Aamjiwnaang contains a higher annual average concentration of benzene than recommended and may be related to higher cancer risks. This work provides a better understanding of environmental exposures and potential associated cancer risks for residents in the Aamjiwnaang community. This study highlights the need for further air monitoring and a more detailed risk assessment. KEYWORDS: Cancer and cancer-precursors, Risk assessment, Air pollution

Geographical discrimination of ethanol based on stable isotope ratio analysis coupled with statistical methods: The Chinese case study

The demand for the effective traceability of hazardous chemicals is crucial for preventing and controlling chemical spills and other accidents involving hazardous chemicals. The aim of the study was to investigate the correlation between the geographical location of ethanol-producing industrial sites and the carbon, hydrogen, and oxygen stable isotope ratios of the Chinese-manufactured ethanol using statistical classification analysis to enable the traceability of the ethanol. The isotopic data of 54 ethanol samples obtained from 18 different ethanol manufacturing plants in China between 2019 and 2020. The results of the statistical analysis demonstrated that the δ18O values of the ethanol positively correlated with latitudes of the production plants but negatively correlated with the δ13C values of the ethanol. A small number of samples derived from sites that were geographically close to each other could not be visually distinguished by PCA and HCA. However, by applying and comparing the results of classification by LDA, K-NN and Ensemble, an optimal classification model was obtained. Upon application of these models, 96.3% of the ethanol samples were correctly classified based on their geographical origin, indicating that the combination of isotopic ratios and latitude data is practical and effective for measuring the traceability of ethanol.

Acidified paper substrates for microfluidic solution sampling integrated with potentiometric sensors for determination of heavy metals

To address analysis of heavy metals in samples containing low volumes and/or high solid-to-liquid contents, microfluidic paper-based solution sampling coupled with Pb2+-ISEs was investigated. The acidification of paper substrates prior to their use was found effective at eliminating the otherwise observed super-Nernstian response of Pb2+-ISEs. Acidified paper substrates (at different pH) were evaluated and through 3D approximate (concentration-EMF-pH) analyses of the Pb2+-ISEs responses coupled with acidified paper substrates, the acceptable operational pH range (for paper substrate containing sample solution) of the potentiometric sensors was found to be between 3–4. Furthermore, to simplify the analytical protocol of heavy metal sensing using Pb2+-ISEs coupled with microfluidic paper-based solution sampling, a colour-coded matching graph was proposed to match the appropriate acidified paper substrate to the pH of the unbuffered sample solution. Such an approach was used for determination of Pb2+ in various complex environmental samples with small volumes of solution and/or high solid-to-liquid ratios, such as wet soil, street runoff, chemical spillage and plant dew. Although the samples were characterized with high ionic complexity, determinations by potentiometry and ICP-OES were found to be comparable, which validates the use of acidified paper substrates in reliable determination of lead(II) in complex sample matrices.

An Iterative Power Regulation Technique in Emergency Cognitive Radio Network Based on Firefly Algorithm

Background: Manmade disasters like explosion, toxic wastes, chemical spills etc. have become an imperative concern for our society. Manmade disasters are not everyday phenomenon. Thus, the allocation of separate resources is not realistic. The idea is to use existing cellular infrastructure to implement single hop cognitive radio sensor network for protecting human being from manmade disasters. Objective: The main objectives of this paper are as follows: (a) design of an efficient iterative power regulation algorithm based on the Firefly Algorithm for the proposed network, (b) computation of sensor nodes’ optimal power for different position of the cellular user from the base station assuming that cellular user compromises power for its own sensor node, (c) computation of the maximum number of sensor nodes coupled with single cellular user for different distances from the base station in worst channel condition, and (d) comparative performance analysis with state-of-the-art algorithms. Method: In the presence of explosive and toxic gases, cognitive radio in sensor node establishes a connection with the nearest base station to send pre-disaster alert signal utilizing cellular user’s resources. The power is distributed among sensor nodes maintaining the fundamental requirements of cellular users. Here, an iterative power regulation mechanism is employed for distributing the power between sensor node and cellular user to achieve reliable utility of the network. The fitness function is designed under the constraints of interference and the designed algorithm is implemented in MATLAB platform towards the search of optimal power of sensor nodes by maximizing the fitness function. Results: Comparative performance analysis demonstrates the effectiveness of the proposed algorithm in terms of speed of convergence, the position of mobile phone user from the base station, number of coupled sensor nodes with single cellular user, and Jain’s fairness factor. Conclusion: The proposed network controls the occurrence of manmade disasters and achieves reliable transmission of emergency information prior to disaster without disrupting cellular phone users. Simulation results validate that the proposed IPRFA algorithm outperforms with respect to state-ofthe- art methods in terms of sharing power and Jain’s fairness factor.

Acid and Alkali‐Resistant Textile Triboelectric Nanogenerator as a Smart Protective Suit for Liquid Energy Harvesting and Self‐Powered Monitoring in High‐Risk Environments

AbstractIndustrialization and anthropogenic activities are expected and unavoidable to consummate the current resources of humankind, which also lead to accidents in the laboratory, chemical plants, or other high risk areas that cause severe burns, or even casualties. Increased casualties in such accidents are due to inappropriate safety measures and prevention. Here, a smart anti‐chemical protective suit with a bio‐motion energy harvesting and self‐powered safety monitoring system is demonstrated, which can protect the body from chemical harm, detect sudden chemical spills, monitor human real‐time living signals, and trigger alarms in an emergency. Particularly, a fabric triboelectric nanogenerator (F‐TENG), which is fabricated by the all‐fiber single‐electrode triboelectric nanogenerator yarn (SETY), works as the basic elements of the intelligent suit. The SETY with core‐shell structured design shows a high sensitivity to the corrosive liquids including acids and alkalis. Furthermore, the working principle of the yarn based nanogenerator that is powered by contacting with acid liquid droplets is demonstrated for the first time. In addition, discretionary thickness, permeability, and any other functionalities are also achieved by taking advantage of the fabric structure. This self‐powered smart anti‐chemical protective suit equipped with a real time monitoring system will benefit the wearer who works in a very high‐risk environment.

Preparation and characterization of cellulose/attapulgite composite aerogels with high strength and hydrophobicity

The development of mechanical enhancement and sustainable absorbents for oil and chemical spills cleaning has attracted wide interest. In this work, novel and low-cost hydrophobic, cellulose/attapulgite (ATP) composite aerogels were prepared by freeze-drying and chemical vapor deposition. The composite aerogels were characterized by using X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron (XPS), scanning electron microscopy (SEM), Brunaur-Emmett-Teller (BET), and mercury intrusion porosimetry. The formation of Si-O-Si and C-H bonds observed according to FTIR and XPS indicated that the methyl groups from methyltrimethoxysilane (MTMS) had been grafted on the composite aerogels. The as-prepared composite aerogels showed high hydrophobicity with water contact angle up to 161.1 °. Moreover, the composite aerogels had three-dimensional pore structures and good thermal stability. Compared to the pure microcrystalline cellulose (MCC) aerogel, the maximum compressive strength of composite aerogel with hydroxyethyl cellulose (HEC) and ATP build blocks was able to reach 1.43 MPa. Therefore, this work provided a low-cost method to prepare robust and sustainable MCC/HEC/ATP composite cellulose aerogels, which could be ideal absorbents for oil adsorption.

Inverse identification of pollution source release information for surface river chemical spills using a hybrid optimization model

To evaluate the liability of the spilled contaminant and to design comprehensive emergency response schemes, it is essential to estimate the contaminant source characteristic and identify where, when and how much the spilled contaminant is injected into a surface river. In this study, an effective pollution source inverse method is developed to reconstruct the release history of the injection location, time, and quantity, and provide appropriate emergency response schemes for dealing with surface river environmental pollution. The pollution source inverse method IGSAA is developed by an integration of genetic algorithm (IGA) and simulated annealing algorithm (SAA) in order to guarantee both the global searching ability and convergence speed. The pollution source inverse method IGSAA is then applied to a hypothetical study, comparing with the traditional GA-based and SAA-based methods, to verify the accuracy and efficiency of the contaminant source inverse, and to a trace study of Truckee River in west America to identify the contaminant source release history and characteristic under different scenarios. The pollution source inversion results can help decision-makers (DMs) to identify the contaminant source characteristics of a chemical spill, and carry out emergency disposal scheme for an emergency rescue in a quick response, and enhance the supervision and management ability for a real surface river system.

Slow Recovery of Headwater-Stream Fishes Following a Catastrophic Poisoning Event

Abstract Accidental spills of chemicals and other pollutants can decimate populations of stream-dwelling species. Recovery from such accidents can be relatively fast and complete when the affected stream reaches can be recolonized from upstream and downstream sources. However, faunal recoveries from accidental spills that extirpate populations from entire headwater streams have not been extensively documented, and understanding resilience of headwater-stream biota is relevant for assessing threats to at-risk species. We assessed recovery of fish populations in a 5.7-km-long headwater stream in the southeastern United States following a complete, or nearly complete, fish-kill caused by a chemical spill near the source of the stream. We sampled for fishes at five stream locations, two downstream and three upstream from a perched, culverted road-crossing located 2.4 km upstream from the stream mouth, over a period of 18.5 mo following the poisoning event. We observed 11 fish species, representing ≤65% of the fish species expected based on occurrences in nearby tributary streams. In postpoisoning sampling, only three of these taxa were observed upstream of the culvert; all 11 species, including the federally threatened Cherokee Darter Etheostoma scotti, were found downstream of the culvert but were mostly represented by a few, large individuals. In contrast, dead individuals of at least eight taxa including the Cherokee Darter were observed upstream of the culvert at the time of the fish-kill. These observations provide evidence of slow recovery of a headwater fish fauna, and especially upstream of a barrier to fish movement, where the recolonization sources are primarily downstream. Additional case studies may reveal whether this result applies generally to headwater streams. Slow recovery could make species that primarily inhabit or maintain greatest abundances in headwaters, including multiple at-risk fishes, particularly vulnerable to the threat of accidental spills that result in local population extirpation.