The effect of short-term Cu exposure on the oxygen consumption and Cu accumulation of mudfish (Labeo capensis) and the largemouth bass (Micropteris salmoides) in hard water

Sediment samples from 3 dams near the gold-mining area in the Mooi River catchment, South Africa, and fish tissue from the mudfish (Labeo capensis) and largemouth bass (Micropteris salmoides) were analysed for Cu to assess environmental pollution. Copper concentrations of sediment samples in 50 mm deep profiles at Klerkskraal Dam (22.2 mg Cu·kg-1), Boskop Dam (14.1 mg Cu·kg-1) and Potchefstroom Dam (21.7 mg Cu·kg-1) and profiles 100 mm and 150 mm deep were above the risk assessment values for Cu, as implemented by the US EPA. Lowest Cu concentrations were found in gonads and blood samples in fish from both species in the 3 dams, but accumulated 3 to 5 times more, to 110.1±17.8 mg Cu·kg-1 dry mass in the liver. After 120 min Cu exposure at 20ºC to 10 mg Cu·ℓ-1 (157.3 mmol Cu·ℓ-1) and a 96 h Cu exposure to 1 mg Cu·ℓ-1 (15.73 mmol Cu·ℓ-1) Cu accumulated mainly in liver tissue and gills. For the mudfish, upon exposure to 10 mg Cu·ℓ-1 (157.3 mmol Cu·ℓ-1), the opercular frequency increased significantly from 80 (± 5.7) cycles·min-1 to above 100 (± 5.8) cycles·min-1 after 90 min, but thereafter decreased to zero cycles·min-1. For largemouth bass the same increase in opercular frequency was found during 10 mg Cu·ℓ-1 exposure, but this Cu level did not stop opercular frequency. For L. capensis the oxygen consumption rate M· O2 for the two hour exposure period at 10 mg Cu·ℓ-1 decrease significantly from 5.17 (± 0.32) mmol O2·ℓ-1·kg-1· h-1 for the controls to 4.5 (± 0.37) mmol O2.ℓ-1·kg-1·h-1 and for experimental M. salmoides from 4.91(± 0.45) mmol O2·ℓ-1·kg-1·h-1 to 3.13 (±0.74) mmol O2·ℓ-1·g-1·h-1. For the exposure period of 96 h at 1 mg Cu·ℓ-1, M· O2 for both fish species, decreased to 2.9 (± 0.3) mmol O2·ℓ-1·kg-1·h-1. It is concluded that:• The imported M. salmoides from the USA is biologically more tolerant to acute Cu exposure compared to the endemic mudfish, Labeo capensis• For the 2 fish species Cu accumulates mainly in the liver, followed by the gills and kidney• [Cu] above 20 mg Cu·kg-1 dry sediment may be released in the water column if the pH value decreases below 5 and, together with the physical disturbance of the sediment layer, acute Cu pollution will be the result• Copper is about 10 times more toxic for the 2 fish species studied compared to Pb and Cd in hard water as found in previous studies.Keywords: Cu, sediment, fish, M· O2, opercular frequency, hard wate

Learning strategies: An answer to our Christian responsibilities towards multicultural education?

In a country where development is currently a high priority, effective and efficient learning presents special imperatives for multicultural higher education. One of man's Christian responsibilities is that of education, and in the changing society of the RSA teaching will require a sensitivity to the variation in individual personalities as well as diversity in culture. Students, however, need to realise that they will have to assume a greater responsibility and accountability for their own learning. Knowledge of their own learning and study strategies and application of these can contribute significantly to the accomplishment of optimal learning. An emphasis shift from improved teaching to improved learning has resulted in a depiction of the learner as an active participant in the teaching-learning act. Various instruments for the assessment of learning and study strategies have been developed since the sixties. Two instruments of the past decade that have been tested at the Potchefstroom University since 1989 are discussed and the adoption o f the LASSI (Learning and Study Strategies Inventory) is motivated

Assessing industrial development influence on land use/cover drivers and change detection for West Bank East London, South Africa

South Africa’s nationwide socio-economic industrial development zone drive focuses on alleviating of the apartheid social ills legacy. To ensure sustainable industrial ecological development, land-cover monitoring is needed though limited attention has been accorded. This study, aimed at assessing the influence of East London Industrial Development Zone (ELIDZ) on land-use/land-cover (LULC) drivers and detecting LULC changes for 15 years over the West Bank East London. An integration of remote sensing with qualitative approaches was adopted to provide robust temporal and spatial LULC change analysis. Object-based classification was performed on the satellite images for 1998, 2007 and 2013. Normalised Difference Vegetation Index (NDVI) and Normalised Difference Built-up Index (NDBI) complemented and validated observed land cover changes. The study reveals that industrial development has been a key driver for land-use changes in West Bank. The classification indicated that vegetation (5.97%) and bare land (-9.06%) classes had the highest percentage increase and decrease respectively. Water (0.02%) and bare land (-0.6%) classes had the lowest annual rate of change. Built-up and bare land classes varied considerably. An overall land-cover classification mean accuracy assessment of 97.24% and a mean Kappa coefficient of 0.95 were attained for the entire study period. This study offers the value of integrated methods in monitoring land-cover change to enhance informed decision-making especially in rapidly changing landscapes for conservation purposes.This manuscript stems from the corresponding authors’ postgraduate study and who performed most of the experiments.The University of Pretoria and the United State Geological Survey (USCS).http://www.ripublication.comam2019Geography, Geoinformatics and Meteorolog

Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure

Estimation of wood volume and height of olive tree plantations using airborne discrete-return LiDAR data

The aim of this study is to analyze methodologies based on airborne LiDAR (light detection and ranging) technology of low pulse density points (0.5m(-2)) for height and volume quantification of olive trees in Viver (Spain). A total of 29 circular plots, each with a radius of 20m, were sampled and their volumes and heights were obtained by dendrometric methods. For these estimations, several statistics derived from LiDAR data were calculated in each plot. Regression models were used to predict volume and height. The results showed good performance for estimating volume (R-2=0.70) and total height (R-2=0.67).The authors appreciate the financial support provided by the Spanish Ministerio de Ciencia e Innovacion (Ministry for Science & Innovation) within the framework of the project AGL2010-15334 and by the Vice-Rectorate for Research of the Universitat Politecnica de Valencia [Grant PAID-06-12-3297; SP20120534].Estornell Cremades, J.; Velázquez Martí, B.; López Cortés, I.; Salazar Hernández, DM.; Fernández-Sarría, A. (2014). Estimation of wood volume and height of olive tree plantations using airborne discrete-return LiDAR data. GIScience and Remote Sensing. 51(1):17-29. https://doi.org/10.1080/15481603.2014.883209S1729511Estornell, J., Ruiz, L. A., Velázquez-Martí, B., & Fernández-Sarría, A. (2011). Estimation of shrub biomass by airborne LiDAR data in small forest stands. Forest Ecology and Management, 262(9), 1697-1703. doi:10.1016/j.foreco.2011.07.026García, M., Riaño, D., Chuvieco, E., & Danson, F. M. (2010). Estimating biomass carbon stocks for a Mediterranean forest in central Spain using LiDAR height and intensity data. Remote Sensing of Environment, 114(4), 816-830. doi:10.1016/j.rse.2009.11.021Hyyppa, J., Kelle, O., Lehikoinen, M., & Inkinen, M. (2001). A segmentation-based method to retrieve stem volume estimates from 3-D tree height models produced by laser scanners. IEEE Transactions on Geoscience and Remote Sensing, 39(5), 969-975. doi:10.1109/36.921414Kim, Y., Yang, Z., Cohen, W. B., Pflugmacher, D., Lauver, C. L., & Vankat, J. L. (2009). Distinguishing between live and dead standing tree biomass on the North Rim of Grand Canyon National Park, USA using small-footprint lidar data. Remote Sensing of Environment, 113(11), 2499-2510. doi:10.1016/j.rse.2009.07.010Moorthy, I., Miller, J. R., Berni, J. A. J., Zarco-Tejada, P., Hu, B., & Chen, J. (2011). Field characterization of olive (Olea europaea L.) tree crown architecture using terrestrial laser scanning data. Agricultural and Forest Meteorology, 151(2), 204-214. doi:10.1016/j.agrformet.2010.10.005Næsset, E. (2004). Accuracy of forest inventory using airborne laser scanning: evaluating the first nordic full-scale operational project. Scandinavian Journal of Forest Research, 19(6), 554-557. doi:10.1080/02827580410019544Popescu, S. C. (2007). Estimating biomass of individual pine trees using airborne lidar. Biomass and Bioenergy, 31(9), 646-655. doi:10.1016/j.biombioe.2007.06.022Popescu, S. C., Wynne, R. H., & Nelson, R. F. (2002). Estimating plot-level tree heights with lidar: local filtering with a canopy-height based variable window size. Computers and Electronics in Agriculture, 37(1-3), 71-95. doi:10.1016/s0168-1699(02)00121-7Velázquez-Martí, B., Estornell, J., López-Cortés, I., & Martí-Gavilá, J. (2012). Calculation of biomass volume of citrus trees from an adapted dendrometry. Biosystems Engineering, 112(4), 285-292. doi:10.1016/j.biosystemseng.2012.04.011Velázquez-Martí, B., Fernández-González, E., Estornell, J., & Ruiz, L. A. (2010). Dendrometric and dasometric analysis of the bushy biomass in Mediterranean forests. Forest Ecology and Management, 259(5), 875-882. doi:10.1016/j.foreco.2009.11.027Velázquez-Martí, B., Fernández-González, E., López-Cortés, I., & Salazar-Hernández, D. M. (2011). Quantification of the residual biomass obtained from pruning of trees in Mediterranean olive groves. Biomass and Bioenergy, 35(7), 3208-3217. doi:10.1016/j.biombioe.2011.04.042Yu, X., Hyyppä, J., Kaartinen, H., & Maltamo, M. (2004). Automatic detection of harvested trees and determination of forest growth using airborne laser scanning. Remote Sensing of Environment, 90(4), 451-462. doi:10.1016/j.rse.2004.02.00

An assessment of the levels of phthalate esters and metals in the Muledane open dump, Thohoyandou, Limpopo Province, South Africa

<p>Abstract</p> <p>Background</p> <p>This work reports the determination of the levels of phthalate esters (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diethyl hexyl phthalate (DEHP)) and metals (lead, cadmium, manganese, zinc, iron, calcium) in composite soil samples. The soil samples were collected randomly within the Muledane open dump, Thohoyandou, Limpopo province, South Africa. Control samples were collected about 200 m away from the open dump. The phthalate esters were separated and determined by capillary gas chromatography with a flame ionization detector, whilst the metals were determined by atomic absorption spectrophotometry.</p> <p>Results</p> <p>Open dump values for the phthalate esters and metals to be generally higher in comparison to control samples for DMP, DEP, DBP and DEHP – the mean values calculated were 0.31 ± 0.12, 0.21 ± 0.05, 0.30 ± 0.07, and 0.03 ± 0.01 mg/kg, respectively, for the open dump soil samples. Nonetheless, the mean open dump values for lead, cadmium, manganese, zinc, iron and calcium were 0.07 ± 0.04, 0.003 ± 0.001, 5.02 ± 1.92, 0.31 ± 0.02, 11.62 ± 9.48 and 0.12 ± 0.13 mg/kg, respectively. The results were compared statistically.</p> <p>Conclusion</p> <p>Our results revealed that the discarding of wastes into the open dump is a potential source of soil contamination in the immediate vicinity and beyond, <it>via </it>dispersal. Increased levels of phthalate esters and metals in the soil pose a risk to public health, plants and animals. Sustained monitoring of these contaminants is recommended, in addition to upgrading the facility to a landfill.</p

Trends in poverty and inequality since the political transition

Using a constructed data series and another data series based on the All Media and Products surveys (AMPS), this paper explores trends in poverty and income distribution over the post-transition period. To steer clear of an unduly optimistic conclusion, assumptions are chosen that would tend to show the least decline in poverty. Whilst there were no strong trends in poverty for the period 1995 to 2000, both data series show a considerable decline in poverty after 2000, particularly in the period 2002-2004. Poverty dominance testing shows that this decline is independent of the poverty line chosen or whether the poverty headcount, the poverty ratio or the poverty severity ratio are used as measure. We find likely explanations for this strong and robust decline in poverty in the massive expansion of the social grant system as well as possibly in improved job creation in recent years. Whilst the collective income of the poor (using our definition of poverty) was only R27 billion in 2000, the grants (in constant 2000 Rand values) have expanded by R22 billion since. Even if the grants were not well targeted at the poor (and in the past they have been), a large proportion of this spending must have reached the poor, thus leaving little doubt that poverty must have declined substantially

The use of airborne laser scanning to develop a pixel-based stratification for a verified carbon offset project

Background The voluntary carbon market is a new and growing market that is increasingly important to consider in managing forestland. Monitoring, reporting, and verifying carbon stocks and fluxes at a project level is the single largest direct cost of a forest carbon offset project. There are now many methods for estimating forest stocks with high accuracy that use both Airborne Laser Scanning (ALS) and high-resolution optical remote sensing data. However, many of these methods are not appropriate for use under existing carbon offset standards and most have not been field tested. Results This paper presents a pixel-based forest stratification method that uses both ALS and optical remote sensing data to optimally partition the variability across an ~10,000 ha forest ownership in Mendocino County, CA, USA. This new stratification approach improved the accuracy of the forest inventory, reduced the cost of field-based inventory, and provides a powerful tool for future management planning. This approach also details a method of determining the optimum pixel size to best partition a forest. Conclusions The use of ALS and optical remote sensing data can help reduce the cost of field inventory and can help to locate areas that need the most intensive inventory effort. This pixel-based stratification method may provide a cost-effective approach to reducing inventory costs over larger areas when the remote sensing data acquisition costs can be kept low on a per acre basis