PCB dechlorination hotspots and reductive dehalogenase genes in sediments from a contaminated wastewater lagoon

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants that are distributed worldwide. Although industrial PCB production has stopped, legacy contamination can be traced to several different commercial mixtures (e.g., Aroclors in the USA). Despite their persistence, PCBs are subject to naturally occurring biodegradation processes, although the microbes and enzymes involved are poorly understood. The biodegradation potential of PCB-contaminated sediments in a wastewater lagoon located in Virginia (USA) was studied. Total PCB concentrations in sediments ranged from 6.34 to 12,700 mg/kg. PCB congener profiles in sediment sample were similar to Aroclor 1248; however, PCB congener profiles at several locations showed evidence of dechlorination. The sediment microbial community structure varied among samples but was dominated by Proteobacteria and Firmicutes. The relative abundance of putative dechlorinating Chloroflexi (including Dehalococcoides sp.) was 0.01–0.19% among the sediment samples, with Dehalococcoides sp. representing 0.6–14.8% of this group. Other possible PCB dechlorinators present included the Clostridia and the Geobacteraceae. A PCR survey for potential PCB reductive dehalogenase genes (RDases) yielded 11 sequences related to RDase genes in PCB-respiring Dehalococcoides mccartyi strain CG5 and PCB-dechlorinating D. mccartyi strain CBDB1. This is the first study to retrieve potential PCB RDase genes from unenriched PCB-contaminated sediments.     

Sediment quality triad assessment of an industrialized estuary of the northeastern USA

The lower Passaic River in northern New Jersey (USA) has been heavily industrialized since the mid-nineteenth century and its shoreline and aquatic habitats degraded or destroyed. Similar to other urban systems, Passaic River sediments, both surface and buried, historically have contained elevated levels of numerous contaminants that may pose risks to ecological receptors and humans. Sediments from 15 stations in the lower Passaic River and 3 reference stations in the Mullica River in southern New Jersey were sampled in 1999 and characterized for chemical contamination, toxicity, and impairment of the benthic community. The objective of this study was to determine the incidence, degree, and nature of degraded surficial sediments in the area to support subsequent plans for restoration of the system. Results demonstrated that Passaic River sediments had concentrations of many organic and inorganic contaminants at levels significantly greater than the reference area and effect-based guidelines. Sediments were toxic to marine amphipods at 11 stations and the benthic assemblages were impaired relative to the reference area at all stations. The weight-of-evidence of this sediment quality triad (SQT) assessment indicates that impacts from multiple contaminants are occurring throughout the lower Passaic River and, that these impacts must be evaluated further and addressed as part of ongoing restoration initiatives for the river.     

Herbicide incorporation by irrigation and tillage impact on runoff loss

Runoff from farm fields is a common source of herbicide residues in surface waters. Incorporation by irrigation has the potential to reduce herbicide runoff risks. To assess impacts, rainfall was simulated on plots located in a peanut (Arachis hypogaea L.) field in Georgia's Atlantic Coastal Plain region after pre-emergence application of metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-[(1S)-2-methoxy-1-methylethyl]-acetamide) and pendimethalin (N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitro-benzenamine). Runoff, sediment, and herbicide loss as function of strip tillage (ST) versus conventional tillage (CT) were compared with and without irrigation (12.5 mm) after application of an herbicide tank mixture. For the CT system, metolachlor runoff was reduced 2x and pendimethalin 1.2x when compared with the non-irrigated treatment. The difference in irrigated and non-irrigated metolachlor means was significant (P = 0.05). Irrigation reduced metolachlor runoff by 1.3x in the ST system, but there was a 1.4x increase for pendimethalin. Overall results indicated that irrigation incorporation reduces herbicide runoff with the greatest impact when CT is practiced and products like metolachlor, which have relatively low K(oc) and high water solubility, are used. The lower ST system response was likely due to a combination of spray interception and retention by the ST system cover crop mulch and higher ST soil organic carbon content and less total runoff. During the study, the measured K(oc) of both herbicides on runoff sediment was found to vary with tillage and irrigation after herbicide application. Generally, K(oc) was higher for ST sediment and when irrigation incorporation was used with the CT system. These results have significant implications for simulation model parametization.     

Effect of sampling frequency on estimates of cumulative nitrous oxide emissions

It is generally recognized that soil N(2)O emissions can exhibit pronounced day-to-day variations; however, measurements of soil N(2)O flux with soil chambers typically are done only at discrete points in time. This study evaluated the impact of sampling frequency on the precision of cumulative N(2)O flux estimates calculated from field measurements. Automated chambers were deployed in a corn/soybean field and used to measure soil N(2)O fluxes every 6 h from 25 Feb. 2006 through 11 Oct. 2006. The chambers were located in two positions relative to the fertilizer bands-directly over a band or between fertilizer bands. Sampling frequency effects on cumulative N(2)O-N flux estimation were assessed using a jackknife technique where populations of N(2)O fluxes were constructed from the average daily fluxes measured in each chamber. These test populations were generated by selecting measured flux values at regular time intervals ranging from 1 to 21 d. It was observed that as sampling interval increased from 7 to 21 d, variances associated with cumulative flux estimates increased. At relatively frequent sampling intensities (i.e., once every 3 d) N(2)O-N flux estimates were within +/-10% of the expected value at both sampling positions. As the time interval between sampling was increased, the deviation in estimated cumulative N(2)O flux increased, such that sampling once every 21 d yielded estimates within +60% and -40% of the actual cumulative N(2)O flux. The variance of potential fluxes associated with the between-band positions was less than the over-band position, indicating that the underlying temporal variability impacts the efficacy of a given sampling protocol.     

Leachability of printed wire boards containing leaded and lead-free solder

Due to environmental concerns and regulatory initiatives, electronics manufacturers are replacing the tin/lead solder commonly used on printed wire boards (PWBs) with alternative solders. To determine the potential waste management impacts of the alternative solders versus the tin/lead solder, two leaching tests on PWBs manufactured with five alternative types of solder were performed: the toxicity characteristic leaching procedure (TCLP) and the synthetic precipitation leaching procedure (SPLP). These tests are commonly used in the US regulatory community to assess pollutant leachability in different disposal scenarios. The article discusses the application and limitations of these tests. The five types of solders investigated were 63Sn/37Pb, 99.3Sn/0.7Cu, 95.5Sn/4Ag/0.5 Cu, 96Sn/2.5Ag/1Bi/0.5Cu, and 42Sn/1Ag/57Bi. The leaching tests were conducted on four PWB sections, each with a unique configuration and solder density. The largest lead concentrations were observed from the PWBs containing Sn/Pb solder, with concentrations exceeding the hazardous waste toxicity characteristic (TC) in TCLP leachates. Silver, the other regulated element used in the solders, was rarely detected, with none of the samples exceeding the TC limit for silver. High copper concentrations were observed and were determined to result from the PWB itself, not from the copper-containing solders.     

Establishing Green Roof Infrastructure Through Environmental Policy Instruments

Traditional construction practices provide little opportunity for environmental remediation to occur in urban areas. As concerns for environmental improvement in urban areas become more prevalent, innovative practices which create ecosystem services and ecologically functional land cover in cities will be in higher demand. Green roofs are a prime example of one of these practices. The past decade has seen the North American green roof industry rapidly expand through international green roof conferences, demonstration sites, case studies, and scientific research. This study evaluates existing international and North American green roof policies at the federal, municipal, and community levels. Green roof policies fall into a number of general categories, including direct and indirect regulation, direct and indirect financial incentives, and funding of demonstration or research projects. Advantages and disadvantages of each category are discussed. Salient features and a list of prompting standards common to successfully implemented green roof strategies are then distilled from these existing policies. By combining these features with data collected from an experimental green roof site in Athens, Georgia, the planning and regulatory framework for widespread green roof infrastructure can be developed. The authors propose policy instruments be multi-faceted and spatially focused, and also propose the following recommendations: (1) Identification of green roof overlay zones with specifications for green roofs built in these zones. This spatial analysis is important for prioritizing areas of the jurisdiction where green roofs will most efficiently function; (2) Offer financial incentives in the form of density credits and stormwater utility fee credits to help overcome the barriers to entry of the new technology; (3) Construct demonstration projects and institutionalize a commitment greening roofs on publicly-owned buildings as an effective way of establishing an educated roofing industry and experienced installers for future green roof construction.     

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.     

Bystander injury evaluation of children from midwestern agricultural operations

Background

With more than a million youth living on agricultural operations, it is important for parents to understand the consequences of bystander injuries that children experience in these environments. We identified the childhood injuries for bystander status and compared the severity of these injuries to the working children in the Regional Rural Injury Study-II (RRIS-II).

Methods

RRIS-II followed 16,546 children (∼ 85% of eligible) from rural communities in the Midwest for two six-month recall periods in 1999 and 2001. Demographic, injury, and exposure data were collected through comprehensive computer-assisted telephone interviews. Child injuries were cataloged using narrative scenarios into four categories: (a) directly work-related; (b) indirectly work-related; (c) non-working accomplice; and (d) non-working attendant; the latter three all being bystander categories. Poisson regression modeling was used to calculate rates of bystander injuries. Frequencies were used for comparison of severity measures.

Results

Among the 463 child injuries (aged < 20 yrs), 102 were bystander injuries. Of the bystander-related injuries, 14 were identified as indirectly work-related (working bystanders), 27 as non-working accomplice (passengers/tag-alongs), and 60 as non-working attendant (playing on the operation). The overall rate of bystander injuries was 6.4 per 1,000 people, 95% CI (5.0, 8.1). Males, compared with females, had more than twice the injury rate (8.7; 95% CI 6.4-11.8, and 3.9; 95% CI 2.7-5.7, per 1,000 people, respectively). Bystanders in this population had more severe injuries with 4% having life-threatening circumstances; of these, 4% of the accomplices and 2% of the attendants subsequently died.

Conclusions

Children who live or work on agricultural operations are vulnerable to many hazards. Therefore, this study examined child injuries and found a clear difference in the consequences of these injuries between working-related and bystanding-related injuries.

Impact on Industry

Unlike occupations such as construction and mining, where laws and organizations have been created for the protection of bystanders, agricultural bystanders have remained unprotected and have had to face the consequent injury and death outcomes. As public health professionals considering these risks, it is necessary that we work to develop more intervention studies and continue to propose suggestive guidelines for child safety in these environments so as to challenge family traditions and possibly spark public policies that will give further protection to this population.     

Sustainable remediation panel—Measuring the social and economic benefits of a sustainable remediation project

Remediation developed a Sustainable Remediation Panel in the Summer 2009 issue, which featured the Sustainable Remediation Forum White Paper. The panel is composed of leaders in the field of sustainable remediation who have volunteered to provide their opinions on difficult subjects related to the topic of how to integrate sustainability principles into the remediation practice. The panel's opinions are provided in a question‐and‐answer format, whereby selected experts provide an answer to a question. This issue's question is provided below, followed by opinions from five experts in the remediation field.

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