Air pollution dispersion within urban street canyons

A semi-empirical mathematical model, Urban Street Model (USM), is proposed to efficiently estimate the dispersion of vehicular air pollution in cities. This model describes urban building arrangements by combining building density, building heights and the permeability of building arrangements relative to wind flow. To estimate the level of air pollution in the city of Krasnoyarsk (in Eastern Siberia), the spatial distribution of pollutant concentrations off roadways is calculated using Markov's processes in USM. The USM-predicted numerical results were compared with field measurements and with results obtained from other frequently used models, CALINE-4 and OSPM. USM consistently yielded the best results. OSPM usually overestimated pollutant concentration values. CALINE-4 consistently underestimated these values. For OSPM, the maximum differences were 160% and for CALINE-4 about 400%. Permeability and building density are necessary parameters for accurately modeling urban air pollution and influencing regulatory requirements for building planning.     

Transformation kinetics of 6-methoxybenzoxazolin-2-one in soil

Wheat (Triticum aestivum L.) and other cereals produce allelochemicals as natural defense compounds against weeds, fungi, insects and soil-borne diseases. The main benzoxazinoid allelochemical of wheat is 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), bound as beta-glucoside and released upon plant injury. When leached from wheat to soil, DIMBOA is microbially transformed to 6-methoxy-benzoxazolin-2-one (MBOA). Exploiting benzoxazinoids and their degradation products as substitutes for synthetic pesticides depends on knowledge of transformation pathways and kinetics. In an MBOA degradation experiment at a concentration of 2400 nmol g(-1) soil, the previously identified transformation products 2-amino-7-methoxy-phenoxazin-3-one (AMPO) and 2-acetylamino-7-methoxy-phenoxazin-3-one (AAMPO) were quantified. Three different kinetic models were applied to MBOA transformation kinetics; single first-order (SFO), first-order multi-compartment, and double first-order in parallel. SFO proved to be adequate and was subsequently applied to the transformations of MBOA, AMPO and AAMPO. Degradation endpoints, expressed as degradation time (DT), were calculated for MBOA, AMPO and AAMPO to test whether the maximum values for synthetic pesticides set by the European Commission and the Danish Environmental Protection Agency were exceeded. DT(50) values for MBOA and AMPO were 5.4 d and 321.5 d, respectively, and DT(90) values were 18.1 d and 1068 d, respectively. The DT(50) value for AMPO exceeded the maximum value. The persistence, concentrations and toxicity of metabolites such as AMPO should be considered when breeding cereal crops with increased levels of benzoxazinoids.     

Assessment of liquid disposal originated by uranium enrichment at Aramar Experimental Center São Paulo--Brazil

This work presents a liquid disposal monitoring originated from uranium enrichment process at Aramar Experimental Center from 1990 to 1998. Assessment of uranium, fluorides, ammoniacal nitrogen, chemical oxygen demand, and pH measurements were made in water samples and compared with results achieved in other countries, as North America and India. The liquid disposal evaluation, generated by uranium enrichment process, showed low levels, considering most parameters established by Federal and State Legislation, aiming environmental pollution control. However, uranium levels were above the limits established by Conselho Nacional do Meio Ambiente, Environment Protection Agency and mainly by the World Health Organization.     

Arctic terrestrial biodiversity status and trends: A synopsis of science supporting the CBMP State of Arctic Terrestrial Biodiversity Report

Ambio - This review provides a synopsis of the main findings of individual papers in the special issue Terrestrial Biodiversity in a Rapidly Changing Arctic. The special issue was developed to...     

Mercury Concentration in the Atmosphere in Chicago A New Ultrasensitive Method Employing Amalgamation

During the past two years, the Chicago Department of Environmental Control chemistry laboratory has developed a prototype sensor for measuring low levels of mercury found in the free or ambient atmosphere. Earlier studies of mercury in the Chicago area postulated that most of the mercury in the atmosphere should condense onto particulates and be collectable on filters. The results of the work presented here show that this may not occur. Analysis of composites of Chicago high volume particulate filters results in an average of 4 nanograms/m³ (range 2-10 nanograms/m³). This compared with a typical average of elemental mercury measurements of 22 nanograms/m³ (range 5-60 nanograms/m³). Thus, it is obvious that particulate borne mercury, at least as analyzed from a high volume filter paper, is not as significant as the total or elemental mercury existing in the metropolitan area. A direct method for collecting mercury and measuring in a flameless atomic absorption unit yields very good results.     

Effect of processing on the disappearance of pesticide residues in fresh-cut lettuce: Bioavailability and dietary risk

The aim of this research is to establish the processing factors of six pesticides durong the preparation of fresh-cut lettuce and to assess the risk of ingestion of pesticide residues associated with the consumption of the same. A field study was carried out on the dissipation of three insecticides (imidacloprid, tebufenozide, cypermethrin) and three fungicides (metalaxyl, tebuconazole, azoxystrobin) during treatment conditions simulating those used for commercial fresh-cut lettuce. A simultaneous residue analysis method is validated using QuEChERS extraction with acetonitrile and CG-MS and LC-MS/MS analysis. The residues detected after field application never exceed the established Maximum Residue Limits. The processing factors were generally less than 1 (between 0.34 for tebufenozide and 0.53 for imidacloprid), indicating that the process, as a whole, considerably reduces residue levels in processed lettuce compared to fresh lettuce. It is confirmed that cutting, followed by washing and drying, considerably reduces the residues. A matrix effect in the dialyzation of the pesticides is observed and the in vitro study of bioavailability establishes a low percentage of stomach absorption capacity (<15%). The EDI/ADI ratios found in all cases were well below their ADI values, and the dietary exposure assessed (EDI) in fresh-cut lettuce showed no concerns for consumer health.     

Effect of diet and paralarval development on digestive enzyme activity in the cephalopod <Emphasis Type="Italic">Robsonella</Emphasis><Emphasis Type="Italic">fontaniana</Emphasis>

This study aims at establishing the maturation of the digestive system in Robsonella fontaniana by means of measuring the digestive enzyme activity in paralarvae after hatching. Different groups of newly hatched paralarvae were fed with Artemia sp. (FA), Lithodes santolla zoea (FL) or were starved to serve as negative control (ST), the experimental period lasted 27 days after hatching (DAH). The semi-quantitative assay api^® ZYM (bioMérieux, France) was used to identify the pool of digestive enzymes present in paralarvae prior to selecting the specific enzymes acid phosphatase, total protease, trypsin and chymotrypsin for analysis. Mortality and larval protein content were also measured during the experiment. The survival of R. fontaniana hatchlings differed depending on the quality of the diet offered (ST < FA < FL), the same trend was observed with respect to paralarval protein content. Total protease and acid phosphatase activities were not related to either time of development or diet (P < 0.05). However, the activity of trypsin and chymotrypsin after DAH 10 was dependent on diet (P < 0.05). Paralarvae fed with Lithodes zoea (FL) performed better than paralarvae in the other two groups, exhibiting lower mortality, higher protein content and the highest proteolytic activity for trypsin and chymotrypsin. The results indicate that Lithodes-larvae are a better diet for R. fontaniana paralarvae than Artemia sp.     

Coastal erosion management and the European principles of ICZM: local versus strategic perspectives

The European Recommendation on Integrated Coastal Zone Management has six core principles. These form two groups, one concerned with strategic goals and one that has a local focus. The principles are presented as a menu of free-standing options, with no prioritization either within or between groups. In the case of coastal erosion management these characteristics result in irreconcilable conflicts, and actively hinder sustainable management of eroding coasts. The principles require clarification, and recognition that they are an indivisible integrated set which should not be used to select principles to advance a particular agenda. It is essential that the strategic principles are given priority, because only they can underpin a sustainable approach to the issue of coastal erosion.     

Putting time in perspective: How and why construal level buffers the relationship between wait time and aggressive tendencies

We spend a substantial part of our daily life waiting, and unfortunately, wait time can fuel aggressive tendencies. Our study examines the relationship between wait time, perceived wait time, and aggressive tendencies from a construal level perspective. In Study 1, we found that the higher the construal level, the stronger the relationship between actual and perceived wait time and the stronger relationship between perceived wait time and aggressive tendencies. In Study 2, we manipulated construal level and found that power explains the moderating impact of construal on the wait—aggressive tendencies relationships. Results demonstrate the role of construal in explaining both perceived wait time and aggressive responses to long wait times, suggesting that mental construal influences both the psychological experience of time and the subsequent reaction to that experience. Overall, these results contribute to research on subjective time perspective by enhancing the knowledge and understanding of the determinants and effects of perceived wait time.