Beryllium-7 in near-surface air and deposition at Brisbane, Australia

Measurements of 7Be concentrations in near-surface air and 7Be deposition were carried out at Brisbane, Australia. Concentrations of 7Be in near-surface air measured over 4 years show seasonal variations with values above the annual mean occurring mainly in the spring and summer months of each year. These higher concentrations coincide with the expected influx of stratospheric air to the planetary boundary layer in early spring and higher rates of convective circulation within the troposphere during summer. 7Be deposition measurements over 3 years show seasonal variations similar to the seasonal rainfall pattern. There is a statistically significant (p<0.001) linear relationship between monthly (7)Be deposition and rainfall amount. This relationship is used to calculate the net cumulative (7)Be areal activity density.     

Naturally occurring radionuclides in materials derived from urban water treatment plants in southeast Queensland, Australia

An assessment of radiologically enhanced residual materials generated during treatment of domestic water supplies in southeast Queensland, Australia, was conducted. Radioactivity concentrations of U-238, Th-232, Ra-226, Rn-222, and Po-210 in water, sourced from both surface water catchments and groundwater resources were examined both pre- and post-treatment under typical water treatment operations. Surface water treatment processes included sedimentation, coagulation, flocculation and filtration, while the groundwater was treated using cation exchange, reverse osmosis, activated charcoal or methods similar to surface water treatment. Waste products generated as a result of treatment included sediments and sludges, filtration media, exhausted ion exchange resin, backwash and wastewaters. Elevated residual concentrations of radionuclides were identified in these waste products. The waste product activity concentrations were used to model the radiological impact of the materials when either utilised for beneficial purposes, or upon disposal. The results indicate that, under current water resource exploitation programs, reuse or disposal of the treatment wastes from large scale urban water treatment plants in Australia do not pose a significant radiological risk.     

Describing the annual cyclic behaviour of 7Be concentrations in surface air in Oceania

Surface air concentrations of (7)Be at a number of stations in Oceania show a distinct annual cycle. We apply a sinusoidal model to describe this cycle. The results show that peak (7)Be concentrations in surface air occur during early spring at tropical latitudes and during mid-to-late summer at middle latitudes. Comparison with available (90)Sr surface air data for the southern hemisphere indicates that stratosphere-to-troposphere exchange is an active atmospheric process controlling the (7)Be annual cycle throughout the Oceania region. Vertical transport of air within the troposphere also seems to influence the observed annual cycle. Seasonality in rainfall is not thought to control the annual cyclic behaviour of (7)Be in surface air.     

Conditional effect of governance quality on the finance-environment nexus in a multivariate EKC framework: evidence from the method of moments-quantile regression with fixed-effects models

This paper investigates the mitigating effect of governance quality on the finance-environment nexus in a multivariate EKC framework in 123 selected countries during the 1990–2017 period. We mainly employ the method of moments-quantile regression (MM-QR) with the fixed-effects model, among others. First, the MM-QR estimator reveals that financial development reduces environmental quality more significantly in countries with initially higher levels (the 75^th and 90^th quantiles) of CO₂ emissions than in other countries (the 25^th and 10^th quantiles). Second, the attenuating effect of governance quality on the finance-environment nexus is more remarkable in nations with low initial levels (the 25^th and 10^th quantiles) of CO₂ emissions. Third, we find that the marginal positive effect of financial development on CO₂ emissions is smaller under a good regulatory framework than under corruption control and the rule of law, especially in the top emitters (the 75^th and 90^th quantiles). Fourth, unlike oil, which has a considerable negative impact on the environmental quality of the major emitters, renewable energy usage reduces CO₂ emissions in countries in all quantiles, primarily in the lowest quantiles. Fifth, the findings also show that urbanization dramatically worsens environmental quality in all economies, particularly those in the lowest quantiles. Finally, we confirm that the EKC hypothesis holds in all countries across different quantiles. The study’s final section discusses policy implications for sustainable development in all countries.

     

Dissipation of the herbicide clopyralid in an allophanic soil: laboratory and field studies

Soil dissipation of the herbicide clopyralid (3,6-dichloropicolinic acid) was measured in laboratory incubations and in field plots under different management regimes. In laboratory studies, soil was spiked with commercial grade liquid formulation of clopyralid (Versatill, 300 g a.i. L(-1) soluble concentrate) @ 0.8 microg a.i. g(-1) dry soil and the soil water content was maintained at 60% of water holding capacity of the soil. Treatments included incubation at 10 degrees C, 20 degrees C, 30 degrees C, day/night cycles (25/15 degrees C) and sterilized soil (20 degrees C). Furthermore, a field study was conducted at the Waikato Research Orchard near Hamilton, New Zealand starting in November 2000 to measure dissipation rates of clopyralid under differing agricultural situations. The management regimes were: permanent pasture, permanent pasture shielded from direct sunlight, bare ground, and bare ground shielded from direct sunlight. Clopyralid was sprayed in dilute solution @ 600 g a.i. ha(-1) on to field plots. Herbicide residue concentrations in soil samples taken at regular intervals after application were determined by gas chromatograph with electron capture detector. The laboratory experiments showed that dissipation rate of clopyralid was markedly faster in non-sterilized soil (20 degrees C), with a half-life (t1/2) of 7.3 d, than in sterilized soil (20 degrees C) with t1/2 of 57.8 d, demonstrating the importance of micro-organisms in the breakdown process. Higher temperatures led to more rapid dissipation of clopyralid (t1/2, 4.1 d at 30 degrees C vs 46.2 d at 10 degrees C). Dissipation was also faster in the day/night (25/15 degrees C) treatment (t1/2, 5.4 d), which could be partly due to activation of soil microbes by temperature fluctuations. In the field experiment, decomposition of clopyralid was much slower in the shaded plots under pasture (t1/2, 71.5 d) and bare ground (t1/2, 23.9 d) than in the unshaded pasture (t1/2, 5.0 d) and bare ground plots (t1/2, 12.9 d). These studies suggest that environmental factors such as temperature, soil water content, shading, and different management practices would have considerable influence on rate of clopyralid dissipation.     

Synthesis and characterization of chitosan-supported Fe2O3 nanohybrids for rapid sonophotocatalytic degradation of 2,4,6-trichlorophenol

Environmental Science and Pollution Research - The present study reports the design of heterogeneous photocatalytic system using Fe2O3 with chitosan (CS) as a matrix for the sonophotocatalytic...     

Design of unsurfaced roads constructed with large-size shredded rubber tires: a case study

Stockpiles of scrap tires are serious fire hazard, public health hazard, and an environmental burden. The construction of road embankments, using tire shreds as a lightweight fill, can consume large quantities of scrap tires and has certain engineering benefits. All the previous research focused on small size tire shreds (3–6 in. size) in terms of its use in civil engineering applications and determination of the engineering/environmental properties. This research specifically focuses on large size tire shreds (12 in. size) and its direct comparison with the other sizes of the tire shreds to develop mechanistic-empirical practical design model and so that the use of tire shreds in road bases could be used on regular basis with enhanced reliability instead of on an empirical basis. The research also examines the potential environmental implications of the use of shredded rubber tires and the comparison of the short-term results with other long-term monitoring studies.     

Measuring sorption of hydrophilic organic compounds in soils by an unsaturated transient flow method

Determination of sorption of hydrophilic, weakly sorbing organic compounds in soil by conventional batch methods using a slurried suspension is often prone to considerable errors because small changes in the solution concentration on equilibration must be accurately determined. This difficulty is exacerbated for compounds susceptible to degradation, which also decreases the solution concentration. The objective of this study was to determine sorption of hydrophilic pesticides by applying an unsaturated transient flow method, which enables determination of sorption at sufficiently small solution to soil ratios. The method makes use of piston-like displacement of the antecedent solution in equilibrium with sorbed phase when pesticide-free water is infiltrated into a soil column spiked with a pesticide. Pesticide sorption and the solution concentration are inferred from a plot of total pesticide content per unit mass of soil vs. water content in a region where the antecedent solution is accumulated. Thus, extraction of solution from relative dry soil is unnecessary. We tested this method for two hydrophilic pesticides, monocrotophos [dimethyl (E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] and dichlorvos (2,2-dichlorovinyl dimethyl phosphate). The sorption coefficient, K(d), obtained for monocrotophos was slightly lower than that by batch method (K(d) = 0.10 vs. 0.19 L kg(-1)), whereas for dichlorvos, a compound highly susceptible to degradation, the unsaturated flow method yielded a much smaller K(d) (0.19 vs. 3.22 L kg(-1)). The K(d) values for both compounds were consistent with the observed retardation in the pesticide displacement in the columns. The proposed method is more representative of field conditions and particularly suitable for weakly sorbing organic compounds in soils.     

Developing the first halophytic turfgrasses for the urban landscape from native Arabian desert grass

Environmental Science and Pollution Research - Climate change is occurring and is influencing biological systems through augmented temperatures, more inconstant precipitation, and rising CO2 in the...     

Pesticide residues in fruits and vegetables from Pakistan: a review of the occurrence and associated human health risks

The main objective of the review is to document, assess and analyze the results of the previously reported data on levels of different pesticides in selected fruits and vegetables from Pakistan. The findings of the previous studies clearly indicated that more than 50 % of the samples were contaminated with organophosphate, pyrethroids and organochlorine pesticides. Many studies reported that among fresh fruits and vegetables tomato, apple, melon, mango, grapes, and plum crossed the FAO/WHO permissible limits for these contaminants residual levels. The comparison of other regions showed that observed levels were found above maximum residue limits (MRLs) in 50 % of the samples but were in agreement with the studies from neighboring countries like China and Bangladesh. Higher hazard risk index (HRI) values were calculated for dieldrin, methamidophos, o,p′-DDT, diazinon and p,p′-DDT in apple, mango, banana, melon, potato and onion. The review also highlights that data on pesticide residues in foodstuff is scarce which should be overcome by further extending studies from different areas of Pakistan. In order to ascertain the provision of food suitable for human consumption, it is imperative to monitor pesticides in food commodities by the country’s authorities and enforce guidelines based on permissible limits.