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Full-Text Articles in Earth Sciences
The Use Of Stable Isotopic Signatures Of Marine Biota To Map Sewage Effluent Disposed Into The Marine Environment, Adam Gartner
The Use Of Stable Isotopic Signatures Of Marine Biota To Map Sewage Effluent Disposed Into The Marine Environment, Adam Gartner
Theses : Honours
Recent work indicates that nitrogen stable isotopic signatures of aquatic biota can be used to link nutrient inputs in the marine environment to terrestrial sources. While this technique of tracing nutrients has been shown to be effective in environments that are not nutrient limited, it has not been proved that this method is effective in oligotrophic environments. This study examined whether nitrogen stable isotopic signatures of marine biota can be used to trace the distribution of sewage effluent in highly mixed, nitrogen limited waters, by examining the δ15N values of marine biota situated close to and distant from …
Identification Of Wetland Plant Hydrotypes On The Swan Coastal Plain Western Australia, Robyn Loomes
Identification Of Wetland Plant Hydrotypes On The Swan Coastal Plain Western Australia, Robyn Loomes
Theses : Honours
The hydrology of 19 Swan Coastal Plain wetlands was described in relation to its influence on the composition and stn1cturc of wetland vegetation. Sixty species were identified as ‘wetland’ plants. The water depth ranges, or hydrological envelopes, of these species were determined and species grouped together based on the water regimes they experienced. Descriptions of wetland hydrology suggested that the surface and groundwater levels of the majority of study wetlands had declined in both the short (3-5 years) and long-term (20-50 years). Wetlands belonging to the Bibra Suite did not follow this trend as surface water levels either increased or …
Detecting The Cause Of Acidification At A Seasonal Wetland On The Swan Coastal Plain, Western Australia, Through Laboratory And Field Mesocosm Experiments, Kelli O'Neill
Theses : Honours
Acidification (pH< 4.5) was detected at Lake Jandabup, a shallow, seasonal wetland on the Swan Coastal Plain. Western Australia. Concern has been raised because populations of invertebrate species have declined or disappeared since acidification, potentially compromising the status of the lake as a nature reserve. The Jake bed is underlain with pyrite (feS2), which oxidises when dry producing sulfates, hydrogen ions and ferrous iron. Being seasonal, Lake Jandabup would be expected to be naturally acidic, but the more recent trend has been a prolonged (> 1 year) and extreme acidification (pH < 4.0). This study endeavoured to explain why the Jake may have undergone an acidic change, why it may have recovered and whether it will happen again. It was hypothesised that the acidification may have been caused by prolonged drying of the lake causing excessive oxidation of pyrite which produced more acid than the wetland could neutralise through buffering. The hypothesis was tested through laboratory and field experiments. The laboratory experiment involved taking intact sediment cores from around the lake, drying them for various lengths of time, and measuring pH, sulfate, total iron, total alkalinity and total aridity upon rehydration. Dried sediment from diatomaceous earth under Fe(OH)3 precipitate gave the lowest pH of less than 4.0. High sulfates, low alkalinity and low pH were interrelated. While drying in its own right produced low pH, generally there was no significant difference between drying times for release of selected variables. The field experiment involved the establishment of small in situ mesocosms to test for the effects …