Characterization of soil organic matter content of two sample size populations along a climatic transect

Soil organic matter (SOM) content was determined in two populations of soil samples that were taken from 0–2 soil depth. One population represented soil samples that were takenfrom a square of 25 cm² in size (small-S population) and the other population represented soil samples that were taken from a square of 2500 cm² in size (large-L population). Thesamples were collected on hillslopes in different climatic regions: Mediterranean (GIV), semi-arid (MAL), mildly-arid (MIS) and arid (KAL). The results of both S and L populationsshowed decreasing SOM mean and variance from the Mediterranean site to the arid site. Statistical and spatial characteristics of each population were compared between the climatic regions. In addition, comparison between the two populations was made foreach site. The difference in sample size did not significantly affect the mean values of SOM of the two populations in sitesGIV, MAL and KAL, but did affect the mean at site MIS. At all study sites, except for site MAL, the variance increased with decreasing sample size. At sites GIV and KAL the coefficient ofvariation of S population was higher (more than 1.5 times) thanthat of L population, whereas at sites MAL and MIS, the differences were negligible. The relationships between the valuesof S and L samples at the individual sampling points defined thebackground of the study sites, which reflects the effect of vegetation (type), grazing, biological crust and soil properties.It was found that at the extreme sites GIV and KAL the backgroundwas characterized by relatively low SOM content with small areas of high organic matter content. At site MIS the background wascharacterized by relatively high SOM with small areas of low organic matter content. At site MAL the background was not dominated by high values of SOM nor by low ones. The spatial pattern of L population became more simple with increasing aridity. At the relatively wet sites the spatial pattern did notdepend on the sample size while in the more arid sites it was sample size dependent. It was indicated that the spatial structure of SOM at the semi-arid and mildly arid sites is anisotropic whereas at the Mediterranean and arid sites it is isotropic.     

Nitrous oxide emissions from waste water

The estimation of nitrous oxide emissions is complicated by the high degree of uncertainty on the emission factors involved and by the limited acquaintance with all significant nitrous oxide sources. A potentially important source for which emission data are lacking is the sewage system transporting waste water from human activities. For this study an experimental measurement campaign has been carried out on waste water sampled at different sewage treatment plants. The nitrous oxide developing from the water samples was monitored by means of gas chromatography. The methodological analysis was based on the concentration/time curves obtained. Our results indicate that the formation of nitrous oxide from the waste water matrices results from microbiological denitrification. We deduced tentative emission factors for the waste water types studied.     

Assessing the Response of Estuarine Intertidal Assemblages to Urbanised Catchment Discharge

Measurement of intertidal rock assemblages was investigated as a potential biological indicator to provide a quantitative estimate of the impact of urbanised catchment discharge on the estuaries of Sydney, Australia, from 1995 to 1999. Based on the presence and characteristics of adjacent human activities, sampling locations were categorised as: Bush; Urban; Urban with Sewer Overflows; and Industry with Sewer Overflows. In Sydney Harbour, variation in assemblage structure was measured between most impact categories, however differences between impact categories were not consistent for each year. Nevertheless, in years of above average rainfall (1998–1999), reference assemblages adjacent to national parks and distant from urbanisation were different to all other putatively impacted assemblages. Variability within assemblages was least at reference locations in each year and greatest at locations adjacent to stormwater canals and sewer overflows, particularly in 1998–1999. Variation in assemblage structure in Sydney estuaries was most strongly correlated with chlorophyll – a concentrations. Univariate analysis also identified highly significant differences for a number of factors, however, interactions between year, impact categories and location for numerous analyses, confounded the differentiation between impact categories. The results suggest that intertidal rock assemblages in Sydney Harbour and surrounding estuaries appear to be responding to the quality and quantity of discharge from urbanised catchments and, furthermore, that assemblages are more suitable than individual taxa to indicate the difference between Bush and anthropogenically disturbed estuarine locations.     

Evaluation of a novel structural model to describe the endogenous release of lead from bone

The aim of this paper was to assess the endogenous release of lead from bone to blood, in 204 exposed subjects. resuming their duties after a 10-month strike in a primary lead smelter in 1991. In vivo 109Cd K X-ray Fluorescence (109Cd K XRF) was used to measure the bone lead concentration in tibia and calcaneus in the smelter, in 1994 and five years later. The 1994 data were used to derive the post-strike bone lead concentrations retrospectively from the significant association between bone lead and the cumulative blood lead index (CBLI). When a linear model was used to predict the current blood lead upon the level of lead in bone, structural analysis of the data produced slopes for tibia (2.0, 95% CI 1.66-2.54) and calcaneus (0.19, 95% CI 0.16-0.23) that were significantly higher than those predicted by the commonly used simple linear regression method, for tibia (0.73, 95%, CI 0.58-0.88) and calcaneus (0.08, 95% CI 0.06-0.09). This suggests that more lead than previously predicted by regression is released from bone to blood. Furthermore, the structural analysis of the data produced an estimation of the contribution of the bone lead stores to the bloodstream that was more consistent with the 1999 epidemiological data than did the regression estimation. Moreover, a non-linear relationship between tibia lead and blood lead was suggested from the assumption checking procedures for regression. When a non-linear regression model was fit to the data, the method produced estimates of important parameters in human lead kinetics, namely the blood lead saturation constant, showing a good agreement with current knowledge of lead metabolism. Finally, the likelihood of a non-linear bone lead release seems to be supported by the recently described dependence of the half-life of lead in bone on age and intensity of occupational exposure.     

Air concentrations and urinary metabolites of polycyclic aromatic hydrocarbons among paving and remixing workers

The exposure of paving workers to polycyclic aromatic hydrocarbons (PAH) during stone mastic asphalt (SMA) paving and remixing was evaluated. The effects on the workers' PAH exposure were also evaluated during the use of an industrial by-product, coal fly ash (CFA), instead of limestone as the filler in the SMA. The PAH exposure was measured by personal air sampling and by analysing the levels of urinary naphthols, phenanthrols and 1-hydroxypyrene (1-OHP) in the workers' pre- and post-shift urine samples. The respiratory PAH exposure of the paving workers (geometric mean (GM) 5.7 microg m(-3)) was about ten-fold that of the traffic controllers (GM 0.43 microg m(-3)). The levels of PAH metabolites were significantly higher (p < 0.05) in the post-shift urine samples than in the pre-shift urine samples, and the levels of metabolites in the post-shift urine of paving workers were significantly higher than in that of the controls (p < 0.01). Urinary 1-naphthol correlated well with the airborne concentrations of the two- to three-ring PAHs (r = 0.544, p = 0.003) and naphthalene (r = 0.655, p < 0.001), when non-smoking paving workers were tested. A good correlation was observed between urinary 1-OHP and the airborne concentrations of the four- to six-ring PAHs (r = 0.524, p = 0.003) as well as total PAHs (r = 0.575, p = 0.001). The concentrations of 1-OHP and phenanthrols in the urine of the pavers were significantly higher (p < 0.01) during remixing than during SMA paving. The CFA in the asphalt had no effect on the airborne PAH exposure or on the concentrations of the PAH metabolites in the paving workers' urine.     

Investigation and proposal for reuse of effluents from beneficiated bentonite products

This work is intended to show the characterization of three effluents (X, Y, and Z) derived from laboratory analyses conducted in the quality control department of a beneficiated bentonite products factory in order to present alternatives for their treatment and final disposal according to Brazil's National Solid Waste Policy (Política Nacional de Resíduos Sólidos – PNRS, Law 12,305/2010, Brazil). Analyses to identify the characteristics of the effluents revealed that the pH, salinity, electroconductivity, and total dissolved solids were in agreement with the organic and mineral nature of the effluent constituents: solvent, clay minerals, water, and activating agent. To assess reuse proposals, the effluents were subjected to the following tests: (a) swelling characteristic with effluent X, (b) petrochemical characterization of Y, and (c) swelling characteristic using commercial solvent and activated clay produced with effluent Z. Preliminary results indicate that each of these effluents can be reused variously in the laboratory, as a fuel, or in the original analysis/process.     

Toward Explaining Nitrogen and Phosphorus Trends in Chesapeake Bay Tributaries, 1992–2012

Understanding trends in stream chemistry is critical to watershed management, and often complicated by multiple contaminant sources and landscape conditions changing over varying time scales. We adapted spatially referenced regression (SPARROW) to infer causes of recent nutrient trends in Chesapeake Bay tributaries by relating observed fluxes during 1992, 2002, and 2012 to contemporary inputs and watershed conditions. The annual flow‐normalized nitrogen flux to the bay from its watershed declined by 14% to 127,000 Mg (metric tons) between 1992 and 2012, due primarily (more than 80% of the decline) to reduced point sources. The remainder of the decline was due to reduced atmospheric deposition (13%) and urban nonpoint sources. Agricultural inputs, which contribute most nitrogen to the bay, changed little, although trends in the average nitrogen yield (flux per unit area) from cropland and pasture to streams in some settings suggest possible effects of evolving nutrient applications or other land management practices. Point sources of phosphorus to local streams declined by half between 1992 and 2012, while nonpoint inputs were relatively unchanged. Annual phosphorus delivery to the bay increased by 9% to 9,570 Mg between 1992 and 2012, however, due mainly to reduced retention in the Susquehanna River at Conowingo Reservoir.     

Predominance of alcohol and illicit drugs among traffic accidents fatalities in an urban area of Brazil

Objective: The objective of this study was to determine the prevalence of alcohol and illicit drug use among victims of fatal traffic accidents in the Metropolitan Region of Vitória, Brazil, during the period 2011–2012.

Methods: Blood samples were collected and analyzed for the presence of drugs from 391 deceased victims of traffic crashes that occurred in the Metropolitan Region of Vitória, Brazil. The victims included drivers, passengers, and pedestrians. Sociodemographic variables such as age, gender, day of the week, and period of the year in which the accidents occurred were recorded. The analyses were performed by a gas chromatography–flame ionization method for alcohol and by a gas chromatography–mass spectrometry for amphetamines, cocaine, and cannabis.

Results: The results showed that 44.8% (n = 175) of all cases were positive for alcohol and/or illicit drugs. The detection of alcohol and/or drugs was more frequent in young males, aged 17 to 34, whose samples were positive in 46.8% of cases. Small differences among drivers, passengers, and pedestrians were observed (drivers = 45.9%, passengers = 46.4%, and pedestrians = 45.6%). In general, the most prevalent drug was alcohol, with 141 positive cases (36.1%), followed by cocaine, with 47 positive cases (12%). Amphetamines and cannabis had positivity rates of 4.1 and 4.3%, with 16 and 17 positive cases, respectively. The combined use of alcohol and other drugs was found in 36 cases (9.2%). Crack cocaine use was observed in 27.7% of the positive cases for cocaine.

Conclusions: For the effective reduction of traffic accidents related to driving under influence of drugs (DUID), we suggest the intensification of enforcement actions against the use of alcohol by drivers, the definition of which illicit drugs should be surveyed, as well the cutoff values, the promotion of changing legislation to oblige drivers to provide samples for toxicological testing, and the establishment of public information programs and specific actions aimed at young drivers to promote behavioral changes.