Ambiental dust speciation and metal content variation in TSP, PM10 and PM2.5 in urban atmospheric air of Harare (Zimbabwe)

The effects of timber harvesting on stream water quality and efficiency of alternate streamside management zones were evaluated in Pockwock Lake and Five Mile Lake watersheds in central Nova Scotia, Canada. The streamside management zone (SMZ) included a 20 m no cut, 20 m select cut and a 30 m select cut buffer strips along the stream. Water quality of eight streams, six in harvested and two in not-harvested watersheds were monitored for two years before and two years after the harvesting of timber. Nonparametric statistical tests on stream water quality showed that there was significant change in the concentration of potassium in six streams, manganese in five streams, zinc in two streams and total nitrogen in one stream after timber harvesting. There was no significant change in the quality of water in two streams used as control sites in the neighboring watersheds of similar size and hydrological characteristics. The results show that forest management practices were most favorable in streams maintained with 30 m select cut followed by 20 m no cut and 20 m select cut SMZ. The streamside zone width and treatment of select cut or no cut in the zone played an important role in filtering or retaining the minerals in surface water runoff. In buffer zones of similar width, the buffer zone with no cut or forested buffer was relatively more effective at protecting stream water quality than select cut SMZ. The vegetation in the zone may have decreased the flow velocity and increased residence time and thus increased filtration and retention of minerals in the riparian soil.     

Accumulation of Endosulfan in Wild Rat, Rattus norvegious as a Result of Application to Soya Bean in Mazoe (Zimbabwe)

An assessment of levels of endosulfan and endosulfan sulphate in rats collected from a plot sprayed with endosulfan was carried out for a period of four months. The analysis was carried out in the livers, muscles and fatty tissues of the rats using Gas Chromatography. Samples were ground with sodium sulphate and aluminium oxide and the analyte soxhlet extracted with hexane. The extract was then cleaned by florisil column chromatography. Levels of endosulfan in rats were found to range in livers from 0.356 to 5.807 ppb, in muscles from 0.089 to 5.167 ppb and in fatty tissues from 0.083 to 4.785 ppb. Levels of endosulfan sulphate correlated well with those of endosulfan and ranged in livers from 0.00 to 3.96 ppb, in muscles from 0.00 to 3.37 ppb and in fatty tissue from 0.00 to 2.93 ppb. In the control rats samples, collected from an unsprayed area in the city of Harare (University of Zimbabwe), no endosulfan could be detected.     

Synthesis and characterisation of Pd-modified N-doped TiO2 for photocatalytic degradation of natural organic matter (NOM) fractions

Introduction

The removal of natural organic matter (NOM) from water is becoming increasingly important in order to prevent the formation of carcinogenic disinfection by-products. The inadequate removal of NOM has a bearing on the capacity of the other treatment processes to remove organic micro-pollutants or inorganic species that may be present in the water. New methods are therefore currently being sought to effectively characterise NOM and also to ensure that it is sufficiently removed from drinking water sources.

Methodology

Nitrogen- and palladium-co-doped TiO₂ was synthesised by a modified sol?Cgel method and evaluated for its photocatalytic degradation activity on NOM fractions under simulated solar radiation. The photocatalyst was characterised by FT-IR, Raman, XRD, DRUV?Cvis, SEM, TEM, EDS, XPS and TGA. FT-IR confirmed the presence of OH groups on thermally stable, nearly spherical anatase nanoparticles with an average diameter of 20?nm. PdO species appeared on the surface of the TiO₂ as small uniformly dispersed particles (2 to 3?nm). A red shift in the absorption edge compared to commercial anatase TiO₂ was confirmed by DRUV?Cvis. In order to gain a better insight into the response of NOM to photodegradation, the NOM was divided into three different fractions based on its chemical nature.

Results and discussion

Photodegradation efficiencies of 96, 38 and 15?% were realised for the hydrophobic, hydrophilic and transphilic NOM fractions, respectively. A reasonable mechanism was proposed to explain the photocatalytic degradation of the NOM fractions. The high photocatalytic activity could be attributed to the larger surface area, smaller crystalline size and synergistic effects of the co-dopants N and Pd in the TiO₂ crystal.     

Titanium dioxide and graphitic carbon nitride–based nanocomposites and nanofibres for the degradation of organic pollutants in water: a review

Environmental Science and Pollution Research - The paper reviews graphitic carbon nitride–based nanostructured photocatalytic materials and nanofibres for applications in water purification....     

MOVEMENT AND WAYFINDING IN THE KING SAUD UNIVERSITY BUILT ENVIRONMENT: A LOOK AT FRESHMAN ORIENTATION AND ENVIRONMENTAL INFORMATION

One potentially significant, yet hardly investigated, criterion for postoccupancy evaluation is the legibility of a setting—the degree to which a building or group of buildings facilitate the ability of users to find their way around. Legibility is one of the foundation concepts of environmental psychology, yet it has not often been considered enough as a guiding principle in design. The purpose of this paper is to analyse spatial orientation and wayfinding problems encountered by newcomers (freshman students) at the King Saud University (KSU) campus, Saudi Arabia, and to test/relate this to Lynch's elements of the image of cities. The analysis draws on previous research findings, theories, and more general observations, as well as observations made of wayfinding performance and map sketching by 30 high-school students likely to soon enroll at the university. Many specific problems with orientation and the architectural legibility of the buildings are identified and discussed. Emphasis is placed upon physical-setting variables that are likely to affect the ease with which spatial orientation and wayfinding are accomplished. These include the following facets of the KSU built environment: degree of differentiation; degree of visual access; and complexity of spatial layout.Legible buildings within which people can effectively maintain their orientation and find their way, according to this research, are in no way simplistic, dull, or boring; on the contrary, settings must possess distinctive landmarks and regions which, along with understandable path networks, allow users to know where they are and how to make their way to desired destinations. Coherent and legible environments are important in the lives of the people who use them. The movement of people through buildings and the factors that influence whether or not they are able to find their way need to continue to be of significance to both researchers and practitioners.