Tissue-based environmental quality benchmarks and standards

Although the use of tissue concentrations (residues) of chemical contaminants as the dose metric to characterize chemical toxicity to aquatic organisms has been gaining acceptance over the past 20 years, tissue concentrations are less commonly used in water quality management and have yet to be formally adopted as benchmarks or environmental quality standards (EQS). This synthesis paper addresses advantages and disadvantages for the development and application of tissue-based EQS as an alternative and supplement to exposure-based EQS determined with water and sediment concentration data. Tissue-based EQS can be readily developed in parallel with conventional toxicity tests, and achieved by quantification of chemical concentrations in tissue alongside traditional concentration-response toxicity testing. Tissue-residue toxicity metrics can be used as benchmarks for screening and monitoring water and sediment quality, to derive equivalent water or sediment EQS, and for ecological risk assessments and weight of evidence approaches for assessing ecosystem impairment. Tissue-based toxicity metrics and associated EQS provide several advantages; however, there are some limitations to consider and key knowledge gaps to fill.     

Application of an Adapted Version of MT3DMS for Modeling Back‐Diffusion Remediation Timeframes

Simulation of back‐diffusion remediation timeframe for thin silt/clay layers, or when contaminant degradation is occurring, typically requires the use of a numerical model. Given the centimeter‐scale vertical grid spacing required to represent diffusion‐dominated transport, simulation of back‐diffusion in a 3‐D model may be computationally prohibitive. Use of a local 1‐D model domain approach for simulating back‐diffusion is demonstrated to have advantages but is limited to only some applications. Incorporation of a local domain approach for simulating back‐diffusion in a new model, In Situ Remediation‐MT3DMS (ISR‐MT3DMS) is validated based on a benchmark with MT3DMS and comparisons with a highly discretized finite difference numerical model. The approach used to estimate the vertical hydrodynamic dispersion coefficient is shown to have a significant influence on the simulated flux into and out of silt/clay layers in early time periods. Previously documented back‐diffusion at a Florida site is modeled for the purpose of evaluating the sensitivity of the back‐diffusion controlled remediation timeframe to various site characteristics. A base case simulation with a clay lens having a thickness of 0.2 m and a length of 100 m indicates that even after 99.96 percent aqueous TCE removal from the clay lens, the down‐gradient concentrations still exceed the MCL in groundwater monitoring wells. This shows that partial mass reduction from a NAPL source zone via in situ treatment may have little benefit for the long‐term management of contaminated sites, given that back‐diffusion will sustain a groundwater plume for a long period of time. Back‐diffusion model input parameters that have the greatest influence on remediation timeframe and thus may warrant more attention during field investigations, include the thickness of silt/clay lenses, retardation coefficient representing sorbed mass in silt/clay, and the groundwater velocity in adjacent higher permeability zones. Therefore, pump‐and‐treat systems implemented for the purpose of providing containment may have an additional benefit of reducing back‐diffusion remediation timeframe due to enhanced transverse advective fluxes at the sand/clay interface. Remediation timeframes are also moderately sensitive to the length of the silt/clay layers and transverse vertical dispersivity, but are less sensitive to degradation rates within silt/clay, contaminant solubility, contact time, tortuosity coefficient, and monitoring well‐screen length for the scenarios examined. ©2015 Wiley Periodicals, Inc.     

Odontological characteristics of European brown bears from the Central Forest Biosphere Nature Reserve

Forty-five skulls of European brown bears from the Central Forest Nature Reserve and adjacent regions were examined in detail. The frequencies of oligodonty, dental caries, parodontosis, and traumatized teeth were estimated. A total of 12 variants of the tooth formula were described. The sample under study was distinguished from the populations examined previously by the lowest frequency of oligodonty. Dental caries in one or several teeth, caused by mechanical damage or malocclusion, occurred in 14% of animals. Strong wear marks on the canines caused by feeding on oats frequently resulted in broken canines in bears of the senior age groups.     

Continuous high-frequency monitoring of estuarine water quality as a decision support tool: a Dublin Port case study

High-frequency, continuous monitoring using in situ sensors offers a comprehensive and improved insight into the temporal and spatial variability of any water body. In this paper, we describe a 7-month exploratory monitoring programme in Dublin Port, demonstrating the value of high-frequency data in enhancing knowledge of processes, informing discrete sampling, and ultimately increasing the efficiency of port and environmental management. Kruskal–Wallis and Mann–Whitney tests were used to show that shipping operating in Dublin Port has a small–medium effect on turbidity readings collected by in situ sensors. Turbidity events are largely related to vessel activity in Dublin Port, caused by re-suspension of sediments by vessel propulsion systems. The magnitudes of such events are strongly related to water level and tidal state at vessel arrival times. Crucially, measurements of Escherichia coli and enterococci contamination from discrete samples taken at key periods related to detected turbidity events were up to nine times higher after vessel arrival than prior to disturbance. Daily in situ turbidity patterns revealed time-dependent water quality “hot spots” during a 24-h period. We demonstrate conclusively that if representative environmental assessment of water quality is to be performed at such sites, sampling times, informed by continous monitoring data, should take into account these daily variations. This work outlines the potential of sensor technologies and continuous monitoring, to act as a decision support tool in both environmental and port management.     

Characterization and pilot‐scale studies for chemical oxidation remediation of fractured shale

The distribution of volatile organic compounds (VOCs) in fractured shale overlain by thin (< 10 feet) overburden at the Watervliet Arsenal near Albany, New York, was initially determined by sampling water from the fracture network using packer systems in boreholes and also using conventional monitoring wells. Furthermore, short‐term pumping and injection tests were conducted and the boreholes were logged using a variety of geophysical and hydrophysical tools. Tetrachloroethene is the dominant VOC in the groundwater, with lesser concentrations of trichloroethene and degradation products (cis‐1,2‐dichloroethene, trans‐1,2‐dichloroethene, and vinyl chloride). The vertical VOC distributions in the rock matrix were obtained from continuous‐cored holes from which small rock samples, collected at many depths between 18 and 150 feet below ground surface, were analyzed. The rock core VOC concentrations were determined by methanol extraction of crushed rock followed by direct methanol injection onto a gas chromatograph and subsequent estimation of rock porewater VOC concentrations. The rock core data support the concept that diffusion‐driven mass transfer has caused nearly all the VOC mass initially present in the fractures to now reside in the rock matrix, which has a porosity three or four orders of magnitude larger than the bulk fracture porosity. The results of the site characterization indicate that an effective site investigation strategy in fractured shale must include characterization of both the fracture and matrix contaminant distribution. These results also indicate that the most favorable remediation technologies for this fractured shale are those that will destroy VOCs in the rock matrix, particularly contaminants in the sorbed phase, and also destroy the VOC mass in the fractures including both dissolved and immiscible phases. The site characterization resulted in the selection of potassium permanganate for an in situ chemical oxidation pilot study. © 2004 Wiley Periodicals, Inc.     

Developing safer passengers through a school-based injury prevention program

Motor vehicle crashes are a leading cause of death among young people. Fourteen percent of adolescents aged 13–14 report passenger-related injuries within three months. Intervention programs typically focus on young drivers and overlook passengers as potential protective influences. Graduated Driver Licensing restricts passenger numbers, and this study focuses on a complementary school-based intervention to increase passengers’ personal- and peer-protective behavior. The aim of this research was to assess the impact of the curriculum-based injury prevention program, Skills for Preventing Injury in Youth (SPIY), on passenger-related risk-taking and injuries, and intentions to intervene in friends’ risky road behavior. SPIY was implemented in Grade 8 Health classes and evaluated using survey and focus group data from 843 students across 10 Australian secondary schools. Intervention students reported less passenger-related risk-taking six months following the program. Their intention to protect friends from underage driving also increased. The results of this study show that a comprehensive, school-based program targeting individual and social changes can increase adolescent passenger safety.     

Persistence of granular and EC formulations of chlorpyrifos in a mineral and an organic soil incubated in open and closed containers

Abstract

Samples of a mineral soil (Plainfield sand) and an organic soil (muck) were treated with granular and EC formulations of chlorpyrifos and incubated at 27±1°C and 65±5% RH in open and closed containers. Duplicate samples of each soil‐formulation‐container combination were analyzed for residual chlorpyrifos during a 23 wk period. The disappearance rates observed demonstrate that the relative importance of formulation and containment on overall persistence depends on soil type. For the mineral soil, disappearance was slower from closed containers and formulation had only a slight effect while, in the organic soil the granular formulation disappeared slower than the EC and there was little difference between open and closed containers. The relative importance of degradation and volatilization in the disappearance of chlorpyrifos from soil is discussed.     

A self-contained instrument for logarithmic recording of submarine quantum irradiance

The construction of a recording quantum irradiance meter is described. A commercially available filtered silicon diode sensor provides signals which are amplified logarithmically and recorded on a strip-chart recorder. Recording range is 1 to 1000 E m^-2sec^-1 on three-decade chart paper. The unit will function unattended for periods of up to 7 days in 20 m of water.Supported by a Negotiated Development Grant from the National Research Council of Canada.     

Airborne uranium contamination--as revealed through elemental and isotopic analysis of tree bark

A new strategy for characterisation of airborne uranium contamination based on ICP mass spectrometric analysis of tree bark is described. The uranium content of tree barks (50 samples) obtained from diverse locations (remote, rural, industrial) varied over almost four orders of magnitude (0.001-8.3 micrograms/g U) with maximum concentrations recorded in the vicinity of a nuclear fuel fabrication plant (0.70-8.3 micrograms/g U). Elevated concentrations were also observed near a coal-fired power station (0.25-0.38 microgram/g U). Isotopic analysis revealed significant deviation from the natural uranium isotope ratio (235U/238U, 0.00725) at four nuclear installations (235U/238U, 0.0055-0.0097). These findings indicate that tree bark serves as an effective biomonitor for uranium and, with isotopic analysis, discrimination between nuclear and non-nuclear emissions is realised.     

Dioxins and polychlorinated biphenyls (PCDD/Fs and PCBs) in food from farms close to foot and mouth disease animal pyres

To control the outbreak of foot and mouth disease, which occurred in the UK in early 2001, a large number of farm animals were slaughtered. Where it was not possible to render or landfill the carcasses, they were destroyed by burning on open pyres, with wood, coal and other materials. Uncontrolled combustion such as this is known to produce small quantities of dioxins and an investigation was made into whether, as a result of the burning, there was an elevation in the concentrations of these compounds in food produced in the areas close to the pyres. With few exceptions, concentrations of PCDD/Fs and PCBs were within the expected ranges as predicted by reference data. No accumulation over time was evident from a repeat milk sampling exercise. Where elevated concentrations of PCDD/Fs and PCBs were found in chickens and eggs, they were in samples not destined for the food chain. Elevated levels in some samples of milk from Dumfries and Galloway were not found in earlier or later samples and may have been found as a result of a temporary feeding regime. Elevated concentrations in lamb from Carmarthenshire were from very young animals which would not have entered the food chain. There was no evidence of any significant increase in dietary exposure to PCDD/Fs and PCBs as a result of the FMD pyres.