A practical look at the variable area transect

The variable area transect (VAT) is a plotless density estimator that has received little attention in the ecological literature despite having potentially robust estimation properties. VAT allows for density estimations without the lengthy search times associated with other plotless density estimators. In spite of this, little has been written about the effect of varying transect widths on its density estimation properties or on the practical implementation of the VAT in field settings. An artificial population sampler was used to examine the effect of transect width on density estimates obtained using the VAT. Three transect widths were chosen corresponding to the mean object size, the largest object size, and twice the size of the largest object. Transect width had a marked effect on the quality of the density estimation, with the largest transect width resulting in significant negative biases in estimation. For the narrowest width, most estimates were within 10% of the true value for a nonrandomly distributed population. The practical considerations of choosing a VAT transect width are enumerated.     

PCDD/Fs in ambient air collected in Zagreb, Croatia

Levels of PCDD/Fs were measured at four different sites in Zagreb, capital of Croatia. Also one sample was taken during spontaneously initiated open fire on a landfill and one sample where garden waste of unknown content was burnt. Over period 1997–2000, 28 samples were collected and levels ranged between 9 and 306 fg I-TEQ m⁻³, except in the sample collected during landfill fire. Air PCDD/F levels in Zagreb at four sites were different and the highest levels were observed in industrial area. Seasonal variation of levels is also evident with higher levels in winter than in summer. Our results show that PCDD/F levels in ambient air collected in Zagreb are at lower end of the published data range. In general, homologue profiles were quite similar for all locations, the concentration of PCDD homologues increased while the concentration of PCDF homologues decreased with increasing degree of chlorination. PCDD/F levels in the landfill fire sample was 13 200 fg I-TEQ m⁻³ which are much higher than levels in garden waste burning sample or in sample collected at industrial site. During landfill fire, the concentration of 2,3,7,8-TCDF becomes even higher than the concentration of OCDF and is equal to the concentration of 1,2,3,4,6,7,8-HpCDF.     

Bromate formation on the non-porous TiO2 photoanode in the photoelectrocatalytic system

The increasing use of ozone in water disinfection processes has been the focus of considerable concern in regards to inorganic disinfection by product formation of bromate in waters containing bromide. Due to the public health risk caused by the presence of bromate as a suspected carcinogen, attention had been addressed to the conditions under which bromate is formed. In this study, photoanodic bromine generation and bromate (BrO(3)(-)) formation were investigated using a TiO(2) electrode in a photoelectrocatalytic (PEC) treatment process. The separation of anodic and cathodic reactions in the PEC system resulted in a pH decrease from 9.3 to 3.0 in the photoanode compartment and an increase to 11.0 in the cathode compartment. Under a photo-illumination intensity of 5.7 m W cm(-2) UV, a biasing potential of +1.0V vs SCE, a pH of 6.0 and at a NaBr concentration of 1.0 x 10(-2) M, active bromine formation increased over time with 2.4 x 10(-6) M min(-6) rate and reached a steady-state concentration of 1.44 x 10(-4) M in 60 min. Bromate formation was detected after a lag-period of 15 min and exhibited a continuous increasing trend with respect to irradiation time. No bromate formation was observed below pH 6.5 whereas an increasing bromate concentrations and pH up to pH=8.5 were noted.     

137Cs budget during the period of 1960s in a small drainage basin on the Loess Plateau of China

A sediment profile with a thickness of 28.12 m in a failed reservoir in a small catchment of the Yuntaishan Gully in the Loess Plateau of China consisted of 44 flood couplets deposited during the period from 1960 to 1970 with total volume of 2.36 x 10(6)m(3). Specific sediment yields for a flood event varied from 300 t km(-2) to 14,400 t km(-2) and annual sediment yields varied from 2500 t km(-2) in 1966 to 40,000 t km(-2) in 1964 with a mean value of 12,700 t km(-2)a(-1) for the period. Average annual (137)Cs concentrations of the sediments increased from 0.92 Bq kg(-1) in 1960 to 4.82 Bq kg(-1) in 1963, then decreased to 1.53 Bq kg(-1) in 1970. The total (137)Cs activity in the reservoir sediments was 9.22 x 10(9) Bq, which accounted for 31.9% of the total (137)Cs fallout precipitation of 2.89 x 10(10) Bq within the catchment during the period. The proportion of the (137)Cs loss from the catchment to the (137)Cs fallout precipitation within the catchment in a year varied between 8.01% and 66.8%, and it was 20.9% for the peak (137)Cs deposition year of 1963 and 52.0% in 1964. By analysis of the (137)Cs budget in the catchment for the (137)Cs peak precipitation period from 1962 to 1964, the (137)Cs surface enrichment coefficient Gamma should be much less than 0.23. And for calculation of soil losses on the cultivated land in the inter-gully area by using the Mass Balance Model II, the value of Gamma should be 0.05-0.1.     

Towards corporate environmental information disclosure: an empirical study in China

High levels of corporate environmental information disclosure (EID) have become pressing issues due to environmental protection around the world. Corporate EID refers to disclose their information on activities related to the natural environment, environmental protection and use of resource. Emerging economies in developing countries seem to face a formidable task for promoting corporate EID. Based on data of corporate EID for 871 listed manufacturing companies in China, this paper examines the status of corporate EID. The significant difference of selectively disclosing their environmental information for the listed companies is investigated. The relations among the level of EID, industrial sector, company size, and company ownership are also explored. Surprisingly, the result reveals the inverse relationship between the marketization level and corporate EID.     

Comparison of gas chromatography and immunoassay methods in quantifying fenitrothion residues in grape juice processed into alcoholic drinks.

Wine and Arak, the national alcoholic drink in Lebanon, were prepared from grape juice fortified with fenitrothion to a concentration of 20ppm. Samples of the 11 fractions produced by the fermentation and distillation steps were analyzed for fenitrothion residues using gas chromatography (GC) and enzyme-linked immunosorbent assay (ELISA). Results of residue analyses showed that the two techniques were highly correlated (r = 0.978) and indicated that fenitrothion was stable during the fermentation steps but not during distillation. The clarified wine 35 days later contained about 85% (15.3 ppm) of the fenitrothion concentration found in the juice as determined by GC analysis. Arak was prepared by a two-steps distillation of the clarified wine. The alcohol distillate and undistilled fraction from the first distillation contained 2.5 ppm and 5.8 ppm of fenitrothion, respectively. No fenitrothion residues were detected by both techniques in the four fractions collected from the second distillation step.     

Modelling feeding flow related shrinkage defects in aluminum castings

The process modelling of shape casting is geometrically complex and computationally very challenging. Besides the three-dimensional complex shapes with multiple domains, the defects of interest to industry arise as a consequence of the interaction amongst a range of phenomena. Conventionally, the key phenomena and defect prediction are modelled through empirical relations applied to the simulation results. Such approaches are neither comprehensive nor reliable. This paper presents a 3-D model that is capable of predicting the formation of shrinkage defects explicitly as a function of the interacting continuum phenomena, i.e. free surface flow, heat transfer, and solidification, in complex three-dimensional geometries which allows to identify the distinction between surface depression, surface connected cavities and internal cavities.The model solves the coupled macroscopic conservation equations for mass, momentum, and energy with a phase change during solidification. In the model, the volume deficit due to solidification can either be compensated by depression of the outside surface or by creating a cavity that initiates either on the surface or in the interior of the casting. The solidification morphology is taken into account by using a parameter, which depends on the fraction solid, in the momentum equation. By using an adapted free surface algorithm, it is suitable to predict surface connected defects: depressed surfaces and caved surfaces. A critical pressure serves as a criterion to open internal shrinkage cavities. The model does not need to search for connected zones to feed shrinkage, but the shrinkage distribution will automatically emerge from the continuity equation.This advanced shrinkage model has experimentally been validated successfully using two Al-Si alloys, a skin freezing eutectic alloy and a mushy freezing hypo-eutectic alloy.