Sources of PCDD/Fs, non-ortho PCBs and PAHs in sediments of high and low impacted transboundary rivers (Belgium-France)

PAHs, PCDD/Fs and non-ortho PCBs have been assessed in Yser and Upper-Scheldt river sediments. Higher contamination levels were observed in the Upper-Scheldt sediments: maximum concentrations for the 16 US-EPA PAHs, PCDD/Fs and non-ortho PCBs respectively amount to 8.9 mg kg⁻¹, 12 ng TEQ kg⁻¹ and 5.1 ng TEQ kg⁻¹. Diagnostic PAH ratios in sediments and atmospheric samples suggest that the PAH compounds are from pyrolytic origin, more specifically combustion processes. The huge consumption of coal in cokes-ovens and smelters and its use for house-heating in Northern France, although decreasing during the last decades, are in support of that suggestion. PCDD/F fingerprints in sediments and deposition material indicate that OCDD is the dominant congener. In addition use of pentachlorophenol (PCP) in the past led to a minor contribution of PCDD/Fs in our sediment samples. Non-ortho PCBs form a substantial fraction of the total TEQ concentrations observed in the sediments. Since the 1980s and 1990s a substantial reduction of the PCDD/F sediment concentrations is observed, but this is not the case for the PAHs.     

The relation of non-culpable traffic incidents to bus drivers' celeration behavior

PROBLEM: The driver celeration behavior theory predicts that celerations are associated with incidents for which the driver has some responsibility in causing, but not other incidents. METHOD: The hypothesis was tested in 25 samples of repeated measurements of bus drivers' celeration behavior against their incidents for two years. RESULTS: The results confirmed the prediction; in 18 samples, the correlation for culpable incidents only was higher than for all incidents, despite the higher means of the latter. Non-culpable incidents had correlations close to zero with celeration. DISCUSSION: It was pointed out that most individual crash prediction studies have not made this differentiation, and thus probably yielded underestimates of the associations sought, although the effect is not strong, due to non-culpable accident involvements being few (less than a third of the total). The methods for correct identification of culpable incident involvements were discussed.     

Ammonia assessment from agriculture: U.S. status and needs

Recent studies suggest that human activities accelerate the production of reactive nitrogen on a global scale. Increased nitrogen emissions may lead to environmental impacts including photochemical air pollution, reduced visibility, changes in biodiversity, and stratospheric ozone depletion. In the last 50 yr, emissions of ammonia (NH3), which is the most abundant form of reduced reactive nitrogen in the atmosphere, have significantly increased as a result of intensive agricultural management and greater livestock production in many developed countries. These agricultural production practices are increasingly subject to governmental regulations intended to protect air resources. It is therefore important that an accurate and robust agricultural emission factors database exist to provide valid scientific support of these regulations. This paper highlights some of the recent work that was presented at the 2006 Workshop on Agricultural Air Quality in Washington, D.C. regarding NH3 emissions estimates and emission factors from agricultural sources in the U.S. and Europe. In addition, several best management practices are explored as the scientific community attempts to maximize the beneficial use of reactive nitrogen while simultaneously minimizing negative environmental impacts.     

Utilization of washed MSWI fly ash as partial cement substitute with the addition of dithiocarbamic chelate

The management of the big amount of fly ash as hazardous waste from the municipal solid waste incinerator (MSWI) has encountered many problems in China. In this study, a feasibility research on MSWI fly ash utilization as partial cement substitute in cement mortars was therefore carried out. MSWI fly ash was subjected to washing process to reduce its chlorine content (from 10.16% to 1.28%). Consequently, it was used in cement mortars. Ten percent and 20% replacement of cement by washed ash showed acceptable strength properties. In TCLP and 180-day monolithic tests, the mortars with washed ash presented a little stronger heavy metal leachability, but this fell to the blank level (mortar without washed ash) with the addition of 0.25% chelate. Therefore, this method is proposed as an environment-friendly technology to achieve a satisfactory solution for MSWI fly ash management.     

Modeling Residential Lawn Fertilization Practices: Integrating High Resolution Remote Sensing with Socioeconomic Data

This article investigates how remotely sensed lawn characteristics, such as parcel lawn area and parcel lawn greenness, combined with household characteristics, can be used to predict household lawn fertilization practices on private residential lands. This study involves two watersheds, Glyndon and Baisman’s Run, in Baltimore County, Maryland, USA. Parcel lawn area and lawn greenness were derived from high-resolution aerial imagery using an object-oriented classification approach. Four indicators of household characteristics, including lot size, square footage of the house, housing value, and housing age were obtained from a property database. Residential lawn care survey data combined with remotely sensed parcel lawn area and greenness data were used to estimate two measures of household lawn fertilization practices, household annual fertilizer nitrogen application amount (N_yr) and household annual fertilizer nitrogen application rate (N_ha_yr). Using multiple regression with multi-model inferential procedures, we found that a combination of parcel lawn area and parcel lawn greenness best predicts N_yr, whereas a combination of parcel lawn greenness and lot size best predicts variation in N_ha_yr. Our analyses show that household fertilization practices can be effectively predicted by remotely sensed lawn indices and household characteristics. This has significant implications for urban watershed managers and modelers.     

Kinetics of reductive dechlorination of 1,2,3,4-TCDD in the presence of zero-valent zinc

Polychlorinated dibenzo-p-dioxins (PCDDs) are toxic and widespread persistent organic pollutants (POPs). Cost-effective technologies for destroying or detoxifying PCDDs are in high demand. The overall purpose of this study was to develop a zero-valent zinc based technology for transforming toxic PCDDs to less- or non-toxic forms. We measured the dechlorination rates of 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD) in the presence of zero-valent zinc under aqueous conditions, identified the daughter compounds of the reaction, and constructed possible pathways for the reactions. The reaction rates of daughter compounds with zero-valent zinc were also measured independently. Our results showed that the zero-valent zinc is a suitable candidate for reducing PCDDs. Reductive dechlorination of 1,2,3,4-TCDD was stepwise and complete to dibenzo-p-dioxin (DD) mainly via 1,2,4-trichlorodibenzo-p-dioxin (1,2,4-TrCDD), 1,3-dichlorodibenzo-p-dioxin (1,3-DCDD), 1-chlorodibenzo-p-dioxin (1-MCDD) to DD and via 1,2,4-TrCDD, 2,3-dichlorodibenzo-p-dioxin (2,3-DCDD), 2-chlorodibenzo-p-dioxin (2-MCDD) to DD. In each separate system, the observed half-lives of 1,2,3,4-TCDD, 1,2,3-TrCDD, 1,2,4-TrCDD, 1,2-DCDD, 1,3-DCDD, 1,4-DCDD and 2,3-DCDD are 0.56, 2.62, 5.71, 24.93, 41.53, 93.67 and 169.06 h respectively. The tendency of rate constant follows TCDD>TrCDD>DCDD. Our results suggest that zero-valent zinc is a suitable candidate for rapidly reducing highly chlorinated PCDDs to less or non-chlorinated daughter products.     

PCDDs/PCDFs and PCBs in water samples from the Three Gorge Reservoir

The Three Gorge Reservoir (TGR) is the largest reservoir in China and its water quality is an important health concern, we have determined the concentrations of PCDDs/PCDFs and PCBs in the water samples collected at three seasons: August 2004, January 2005 and August 2005. The results showed that the average WHO-TEQ of total dioxins-like compounds (PCDDs/PCDFs+PCBs) was 0.06558 pg l(-1), ranged from 0.0008 to 0.32439 pg l(-1), which are much lower than other reported water sources. The main dioxins (PCDDs/PCDFs) are hepta- and octa-chlorinated dibenzo-p-dioxins (CDDs) and chlorinated dibenzofurans (CDFs). Since the levels of dioxins may change after the last water-store stage, the present study provides important data to compare the water quality in the TGR in the future.     

Contamination of soils with organochlorine pesticides in urban parks in Beijing, China

Urban parks are an integral component of healthy urban living. Since they are frequently visited, an understanding of the environmental quality of these urban facilities is crucial. Here, a study was conducted on the contamination of soils in the parks of Beijing. Organochlorine pesticides (OCPs), which have the potential to cause endocrine disturbances, were considered study objectives. Hexachlorocyclohexanes (HCHs) were found at concentrations of 0.2490-197.0 ng g(-1) and dichlorodiphenyltrichloroethanes (DDTs) were found at concentrations of 5.942-1039 ng g(-1) in the soils investigated. The preliminary pollution assessment indicated that DDTs have caused high pollution levels in the soils of some parks. Analysis of the sources of contamination showed that HCHs in the soils were derived from an old mixed source of technical HCHs and lindane and that DDTs, which were suspected to have recent application to the soils at some sites, were derived mainly from a mixture of technical DDTs and dicofol containing DDT impurities. An independent sample t-test proved that pesticides containing DDTs had been used in large amounts in the soils of parks before 1983 (p<0.05) and that the levels of DDTs in the soils of parks administered by the Beijing municipal government were significantly higher than the levels in those administered by the district government (p<0.05). However, the main difference in this situation needs to be further studied. This study suggested that open spaces like urban parks were not as sound as was expected and that there was potential for exposure of visitors/workers in the parks to organochlorine pesticides.     

Probabilistic intake assessment of multiple compounds as a tool to quantify the nutritional-toxicological conflict related to seafood consumption

Seafood represents a natural source of valuable nutrients (e.g., long chain omega-3 poly-unsaturated fatty acids (LC n-3 PUFAs), vitamin D, and iodine), but the favourable health perception is troubled by the presence of contaminants (e.g., PCBs, dioxin-like compounds, and (methyl) mercury (MeHg)). This dualism forms the basis for an important public health conflict. The objective of this study was to calculate and evaluate the simultaneous intake of multiple beneficial and harmful compounds (LC n-3 PUFAs, vitamin D, iodine, (Me)Hg, PCBs, and dioxin-like compounds) via seafood consumption in Belgium. A methodology and a software module were developed for executing probabilistic assessments of the simultaneous intake of multiple compounds leading to better insight in the problematic nature of food items involving both health benefits and risks. The simulations concerning seafood consumption in Belgium predicted that, as far as only seafood consumption is concerned, the considered populations do not reach a sufficiently high intake for the three nutrients considered (LC n-3 PUFAs, vitamin D, and iodine). Regarding the contaminants, (Me)Hg contamination of seafood on the Belgian market does not seem to be an issue of major toxicological concern. In contrast, for dioxin-like compounds the tolerable daily intake is reached by people with high seafood consumption.