The effect of the snow-albedo feedback (SAF) on 2m temperatures and their future changes in the European Alps is investigated in the ENSEMBLES regional climate models (RCMs) with a focus on the ...spring season. A total of 14 re-analysis-driven RCM experiments covering the period 1961–2000 and 10 GCM-driven transient climate change projections for 1950–2099 are analysed. A positive springtime SAF is found in all RCMs, but the range of the diagnosed SAF is large. Results are compared against an observation-based SAF estimate. For some RCMs, values very close to this estimate are found; other models show a considerable overestimation of the SAF. Net shortwave radiation has the largest influence of all components of the energy balance on the diagnosed SAF and can partly explain its spatial variability. Model deficiencies in reproducing 2m temperatures above snow and ice and associated cold temperature biases at high elevations seem to contribute to a SAF overestimation in several RCMs. The diagnosed SAF in the observational period strongly influences the estimated SAF contribution to twenty first century temperature changes in the European Alps. This contribution is subject to a clear elevation dependency that is governed by the elevation-dependent change in the number of snow days. Elevations of maximum SAF contribution range from 1500 to 2000 m in spring and are found above 2000 m in summer. Here, a SAF contribution to the total simulated temperature change between 0 and 0.5 °C until 2099 (multi-model mean in spring: 0.26 °C) or 0 and 14 % (multi-model mean in spring: 8 %) is obtained for models showing a realistic SAF. These numbers represent a well-funded but only approximate estimate of the SAF contribution to future warming, and a remaining contribution of model-specific SAF misrepresentations cannot be ruled out.
Eutrophication and cyanobacterial algal blooms present an increasing threat to the health of freshwater ecosystems and to humans who use these resources for drinking and recreation. Remote sensing is ...being used increasingly as a tool for monitoring these phenomena in inland and near-coastal waters. This study uses the Medium Resolution Imaging Spectrometer (MERIS) to view Zeekoevlei, a small hypertrophic freshwater lake situated on the Cape Flats in Cape Town, South Africa, dominated by
Microcystis cyanobacteria. The lake's small size, highly turbid water, and covariant water constituents present a challenging case for both algorithm development and atmospheric correction. The objectives of the study are to assess the optical properties of the lake, to evaluate various atmospheric correction procedures, and to compare the performance of empirical and semi-analytical algorithms in hypertrophic water.
In situ water quality parameter and radiometric measurements were made simultaneous to MERIS overpasses. Upwelling radiance measurements at depth 0.66
m were corrected for instrument self-shading and processed to water-leaving reflectance using downwelling irradiance measurements and estimates of the vertical attenuation coefficient for upward radiance,
K
u, generated from a simple bio-optical model estimating the total absorption,
a(
λ), and backscattering coefficients,
b
b(
λ). The normalised water-leaving reflectance was used for assessing the accuracy of image-based Dark Object Subtraction and 6S Radiative Transfer Code atmospheric correction procedures applied to MERIS. Empirical algorithms for estimating chlorophyll
a (Chl
a), Total Suspended Solids (TSS), Secchi Disk depth (
z
SD) and absorption by CDOM (
a
CDOM) were derived from simultaneously collected
in situ and MERIS measurements. The empirical algorithms gave high correlation coefficient values, although they have a limited ability to separate between signals from covariant water constituents. The MERIS Neural Network algorithms utilised in the standard Level 2 Case 2 waters product and Eutrophic Lakes processor were also used to derive water constituent concentrations. However, these failed to produce reasonable comparisons with
in situ measurements owing to the failure of atmospheric correction and divergence between the optical properties and ranges used to train the algorithms and those of Zeekoevlei. Maps produced using the empirical algorithms effectively show the spatial and temporal variability of the water quality parameters during April 2008. On the basis of the results it is argued that MERIS is the current optimal sensor for frequent change detection applications in inland waters. This study also demonstrates the considerable potential value for simple TOA algorithms for hypertrophic systems. It is recommended that regional algorithm development be prioritized in southern Africa and that remote sensing be integrated into future operational water quality monitoring systems.
Both team and individual sports require competition, whereas cooperation is more prevalent in team than in individual sports. In particular, team athletes have to compete (for starting roles) while ...cooperating (for team success) with the same teammates. For team athletes, competition and cooperative behavior, two mutually exclusive constructs according to earlier psychological research, might therefore be less incompatible than for individual athletes. In Study 1, team athletes attributed a higher demand to compete and cooperate with the same teammates or training partners to their sport than individual athletes to their sport. Study 2 showed that experiencing competition (vs. control) undermines information sharing less for team than for individual athletes. In addition, Study 2 demonstrated that priming competition undermines the accessibility of cooperative thoughts less for team than for individual athletes. Therefore, team athletes might be better at competing without ceasing to cooperate. Implications for collaboration in groups are discussed.
Abstract
Biofiltration holds one of the most promising options for removing environmental pollutants from water by reducing inorganic matter, and nutrient concentrations and removing pathogens. This ...study evaluates the performance of six large field-scale biofiltration cells and assesses the risk of reusing this treated water for irrigating food gardens. The study took place at an abandoned wastewater treatment work (WWTW) in Franschhoek, South Africa. A batch operation was used to measure physical water properties and nutrient concentrations. Large stone cells performed best in reducing ammonia nitrogen (NH3) and orthophosphate () by 98 and 95%, respectively, however, an overall increase in nitrate () and nitrites () was also observed in these and other cells. Phytoremediation made a marginal contribution to reducing contamination. The extent to which biofiltration can be used to clean and reuse contaminated surface water runoff from an informal settlement to safely reuse the water for irrigation purposes is poorly understood. Laboratory analyses revealed that the water quality from four successive harvests broadly met South African guidelines for irrigation and compared favourably with the quality of vegetables from local supermarkets.
Photosystem I (PSI) is a photoactive electron-transport protein found in plants that participates in the process of photosynthesis. Because of PSI’s abundance in nature and its efficiency with charge ...transfer and separation, there is a great interest in applying the protein in photoactive electrodes. Here, we developed a completely organic, transparent, conductive electrode using reduced graphene oxide (RGO) on which a multilayer of PSI could be deposited. The resulting photoactive electrode demonstrated current densities comparable to that of a gold electrode modified with a multilayer film of PSI and significantly higher than that of a graphene electrode modified with a monolayer film of PSI. The relatively large photocurrents produced by integrating PSI with RGO and using an opaque, organic mediator can be applied to the facile production of more economic solar energy conversion devices.
Globally insects are declining, but some guilds of pollinators are finding refuge in urban landscapes. The body of knowledge on urban pollinators is relatively mature, which means it is now possible ...to begin to make generalization. Unfortunately, studies do not represent climatic regions evenly and there is a gap in research from the African continent. This study aimed to address some of the gaps on urban pollination knowledge in South Africa and to identify opportunities to improve urban habitats for pollinators. We reviewed the international literature on urban pollinators and the South African literature on pollinators with a landscape ecology focus, drawing on literature with an emphasis on agricultural and ecosystem services. The findings show that some taxa (
. large-bodied, cavity nesting bees) will exploit urban environments increasing in abundance with urban intensity. Moderately sensitive taxa (such as small-bodied, ground-nesting bees) take advantage of urban environments only if local habitats are supportive of their needs for resource provision and habitat connectivity. The South African urban poor rely on pollination services for subsistence agriculture and the reproduction of wild-foraged medicines and food. Potential interventions to improve habitat quality include strategic mowing practices, conversion of turf-grass to floral rich habitats, scientific confirmation of lists of highly attractive flowers, and inclusion of small-scale flower patches throughout the urban matrix. Further research is needed to fill the Africa gap for both specialized and generalized pollinators (Diptera, Halictids, Lepidoptera and Hopliini) in urban areas where ornamental and indigenous flowering plants are valued.
Conspiracy theories often involve topics of uncertainty and ambivalence. One of those topics during the Covid-19 pandemic was the vaccination based on the new method using messenger RNA. In a ...preregistered study with N = 382 participants, we tested an intervention addressing the uncertainty concerning this new vaccination at a time when conspiracy theories about the vaccination method were not yet widely spread. Participants either only read short facts about the new vaccination (no explanation condition), or read these facts in addition to an explanation about the function of messenger RNA vaccines (relevant explanation condition), or they read the facts after the explanation of an alternative issue (irrelevant explanation condition). Results showed that individuals reading the relevant explanations addressing uncertainties surrounding the new vaccination method were less likely to agree with a Covid-19 vaccination conspiracy theory and were more willing to get a Covid-19 vaccination compared to the other conditions. An exploratory analysis showed that agreement with the Covid-19 vaccination conspiracy theory mediated the effect of explanation type on vaccination intentions. Potential implications and limitations are discussed.
The drought experienced in South Africa in 2016 – one of the worst in decades – has left many urbanised parts of the country with limited access to water, and food production has been affected. If a ...future water crisis is to be averted, the country needs to conserve current water supplies, reduce its reliance on conventional surface water schemes, and seek alternative sources of water supply. Within urban areas, municipalities must find ways to adapt to, and mitigate the threats from, water insecurity resulting from, inter alia, droughts, climate change and increasing water demand driven by population growth and rising standards of living. Stormwater harvesting (SWH) is one possible alternative water resource that could supplement traditional urban water supplies, as well as simultaneously offer a range of social and environmental benefits. We set out three position statements relating to how SWH can: improve water security and increase resilience to climate change in urban areas; prevent frequent flooding; and provide additional benefits to society. We also identify priority research areas for the future in order to target and support the appropriate uptake of SWH in South Africa, including testing the viability of SWH through the use of real-time control and managed aquifer recharge.Significance:Addresses water scarcity through building resilience to the impacts of climate change; improving the liveability of cities; and prioritising water-sensitive urban design.
Many of South Africa's current water quality problems have been attributed to diffuse pollution derived from poorly regulated land use/land cover (LULC) transformations. To mitigate these impacts, ...the preservation of an adequate amount of natural vegetation within catchment areas is an important management strategy. However, it is not clear how much natural vegetation cover is required to provide adequate levels of protection, nor at which scale(s) this strategy would be most effective. To investigate the possibility of estimating minimum thresholds of natural vegetation required to protect water resources, regression analysis was used to model relationships between water quality (measured using Nemerow's Pollution Index) and metrics of natural vegetation at multiple scales across a sample of sub-catchments located along the western, southern, and south-eastern coast of South Africa. With conspicuous outliers removed, the models were able to explain up to 82 % of the variability in the relationship between land use and water quality. Moreover, a statistically significant, nonlinear, and inverse relationship was found between proportions of natural vegetation cover and pollution levels. This relationship was strongest when measured (1) across the whole catchment and (2) within a 200 m riparian buffer zone. The models further indicated that approximately 80 to 90 % natural vegetation cover was necessary at these scales to maintain water quality at ecologically acceptable levels. Additional nonlinear thresholds estimated using breakpoint analysis suggested that if proportions of natural vegetation fall below 45 % (across the whole catchment) and 60 % (within a 200 m riparian buffer zone) a dramatic increase in pollution levels can be expected. The estimated thresholds are recommended as guidelines that can be used to inform integrated land and water resources management strategies aimed at protecting water quality in the study area. Likewise, the methods described are recommended for the estimation of similar thresholds in other regions.
Display omitted
•Management of the land-water nexus is vital for the protection of water resources.•The maintenance of adequate areas of natural vegetation is one important strategy.•Regression analysis was used to estimate minimum thresholds of natural vegetation.•Models indicated that 80–90 % vegetation cover is required to protect water quality.•This recommendation is applicable within riparian areas and across whole catchments.
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