Search

Op de hogere zandgronden treedt verminderde vitaliteit en sterfte van eikenbomen op, vooral door verzuring en vermesting. Toediening van steenmeel zou kunnen helpen tegen de nadelige effecten van verzuring. Daarom zijn in 2016 in Het Nationale Park De Hoge Veluwe en in het Mastbos (Breda) experimenten gestart met steenmeeltoediening. Na zes jaar onderzoek beschrijven we de belangrijkste effecten op de bodemchemie en het bodemleven, en de betekenis voor het beheer. Met name is gekeken naar pH, basenverzadiging en nutriënten in relatie tot fijne wortels van eikenbomen, micro-organismen en bodemfauna waaronder mycorrhizaschimmels en schimmeletende microarthropoden. Bovendien werden de effecten van fosfortoediening en de toediening van bodemfauna met strooisel van donorlocaties onderzocht.

Fluoride (F) is an emerging pollutant that originates from multiple sources and adversely affects plant growth and nutrient bioavailability in soil. This greenhouse study investigated the effects of soil F (0, 10, 20, 50, 100, 200 mg kg

Rapid anthropogenic environmental change is expected to impact a host of ecological parameters in Southern Ocean ecosystems. Of critical concern are the consequences of these changes on the range of species that show fidelity to migratory destinations, as philopatry is hypothesized to help or hinder adaptation to climate change depending on the circumstances. Many baleen whales show philopatry to feeding grounds and are also capital breeders that meet migratory and reproductive costs through seasonal energy intake. Southern right whales (Eubalaena australis, SRWs) are capital breeders that have a strong relationship between reproductive output and foraging success. The population dynamics of South Africa's population of SRWs are characterized by two distinct periods: the 1990s, a period of high calving rates; and the late 2010s, a period associated with lowered calving rates. Here we use analyses of stable carbon (δ13C) and nitrogen (δ15N) isotope values from SRW biopsy samples (n = 122) collected during these two distinct periods to investigate foraging ecology of the South African population of SRWs over a time period coincident with the demographic shift. We show that South African SRWs underwent a dramatic northward shift, and diversification, in foraging strategy from 1990s to 2010s. Bayesian mixing model results suggest that during the 1990s, South African SRWs foraged on prey isotopically similar to South Georgia/Islas Georgias del Sur krill. In contrast, in the 2010s, South African SRWs foraged on prey isotopically consistent with the waters of the Subtropical Convergence, Polar Front and Marion Island. We hypothesize that this shift represents a response to changes in preferred habitat or prey, for example, the decrease in abundance and southward range contraction of Antarctic krill. By linking reproductive decline to changing foraging strategies for the first time in SRWs, we show that altering foraging strategies may not be sufficient to adapt to a changing ocean.

Australian underground mines are inevitably getting deeper particularly where steep dipping ore bodies are involved. The mining depths will eventually extend beyond original mine design horizons at which point the installed ventilation infrastructure will generally not be able to sustain mining needs. The ventilation systems will become strained due to system resistance, higher leakage, auto-compression and rock temperatures. Furthermore, with increasing depth, more trucks will generally be required to sustain production rates. These mines will start to experience local hot zones and areas of flow stagnation along the trucking declines. At this stage, the primary ventilation systems will require upgrades, and this could include ventilation raises [surface and u/g], additional refrigeration capacity and high pressure fans [or booster fans]. These infrastructure upgrades will require significant investment with long project lead times. At depth, the technical feasibility of successfully establishing longer raises also becomes an important consideration. Strategies that employ controlled recirculation of the primary ventilation, with reconditioning, can offer solutions that allow deferral of the new infrastructure. Furthermore, if effective scrubber technology can be developed, primary ventilation upgrades could perhaps be avoided. The reconditioning of primary ventilation is technically feasible and advantageous from a mine cooling perspective. However, the issue that has prevented mines from adopting the technology on a wide spread basis has been gas and respirable particulate management. This paper considers the merits of controlled recirculation, advantages of employing these strategies and scrubbing technologies that should be the subject of further research. The paper also examines how a controlled recirculation strategy could conceptually be implemented in a deep mechanized mine. It is argued that the significant cost associated with primary ventilation upgrades warrants a critical review of controlled recirculation and R + D investment into related technologies.

In both gold and platinum mines, deep South African operations use extremely large refrigeration capacities with high power consumption to cool their workings. With the increasing costs of power and global carbon concerns, there have been many effective and innovative energy management programmes installed in these systems over the past five years. These have included extensive control of ventilation systems and also the control of the refrigeration systems. Much work has been done on enhancing refrigeration machine efficiency with improved heat exchangers and compressor design. The returns gained through intelligent system operation and cyclical process controls have been particularly impressive. These systems generally include storing cooling at certain times of the day and releasing the stored cooling capacity at other strategic periods. The thermal storage concepts include: The thermal storage systems are charged-up during the cold periods of the day when the plants operate at high efficiencies. Subsequent discharging of the cooling storage takes place during hot periods of the day with low refrigeration machine load. Thus, these control systems achieve an improved operational efficiency as well as load shifting out of peak tariff periods. This paper describes a selection of these systems and their performance.