Steven P. Carroll

Sourcing faecal pollution from onsite wastewater treatment systems in surface waters using antibiotic resistance analysis

Aims:  To identify the sources of faecal contamination in investigated surface waters and to determine the significance of onsite wastewater treatment systems (OWTS) as a major contributor to faecal contamination.

Faecal pollution source identification in an urbanising catchment using antibiotic resistance profiling, discriminant analysis and partial least squares regression

Increasing urbanisation and changes in land use lead to adverse impacts on the quality of natural water resources. The specific sources of contamination are often difficult to identify using conventional water quality monitoring techniques. This acts as a significant constraint to the development of appropriate management techniques to protect natural water resources. Consequently, alternative means of identifying pollutant sources and their locality are necessary. In this study, Antibiotic Resistance Patterns (ARP) were established for a library of 1005 known Escherichia coli source isolates obtained from human and non-human (domesticated animals, livestock and wild) sources in an urbanizing catchment in Queensland State, Australia. Discriminant Analysis (DA) was used to differentiate between the ARP of source isolates and to identify the sources of faecal contamination. Partial Least Square (PLS) regression was then utilised on identified human source isolates to correlate their locality with specified sampling locations within the catchment. The resulting ARP DA indicated that a majority of the faecal contamination in the rural areas was non-human. However, the percentage of human isolates increased significantly in urbanized areas using on site systems for wastewater treatment. The PLS regression was able to develop predictive models which indicated a high correlation of human source isolates from the urban area. The study results confirm the feasibility of using ARP for source tracking faecal contamination in surface waters, as well as predicting their point of origin.

Role of Land Use and Seasonal Factors in Water Quality Degradations

Surface water and groundwater are the most important water sources in the natural environment. Land use and seasonal factors play an important role in influencing the quality of these water sources. An in-depth understanding of the role of these two influential factors can help to implement an effective catchment management strategy for the protection of these water sources. This paper discusses the outcomes of an extensive research study which investigated the role of land use and seasonal factors on surface water and groundwater pollution in a mixed land use coastal catchment. The study confirmed that the influence exerted on the water environment by seasonal factors is secondary to that of land use. Furthermore, the influence of land use and seasonal factors on surface water and groundwater quality varies with the pollutant species. This highlights the need to specifically take into consideration the targeted pollutants and the key influential factors for the effective protection of vulnerable receiving water environments.

Monitoring of a mixed land use catchment for pollutant source characterisation

Protection of surface water quality is a key driver in catchment management, particularly for areas undergoing land use change. Changing land use can result in the input of a range of pollutants to surface waters, resulting in water quality impairment, leading to eutrophication and the appearance of algae blooms. This study investigated a mixed land use coastal catchment by undertaking extensive field sampling and data analysis for pollutant source characterisation. The objective was to contribute to a greater understanding of pollutant inputs to surface water resources and for effective catchment management. Based on data analysis results, a diversity of pollutant sources was noted, including both natural areas and areas subject to anthropogenic activities such as agriculture and urban developments, with agricultural areas being comparatively more significant in exporting nutrients. Additionally, pollutant inputs into estuarine and freshwater areas were found to have specific characteristics influenced by land use. The pollutant inputs from these sources were found to be significantly affected by seasonal factors, with the dominant pollutant sources differing between the wet and dry seasons. This underlines the importance of taking seasonal factors into account in the development of effective catchment management strategies. Based on the study outcomes, a critical point monitoring program was developed with a focus on preventing algae blooms. This will allow the development of a decentralised catchment management strategy where resource-efficient monitoring of critical pollutant parameters at key locations can be undertaken for minimising the risk from algae blooms, rather than implementing a whole of catchment and resource-demanding large-scale monitoring program.

Translating a risk-based land-use planning issue to a decision making tool using simple GIS approaches

This paper presents the use of simple GIS approaches to translate a detailed risk-based decision framework for on-site-sewage-treatment-facility siting, design and management into the development assessment process. In 2001 the Gold Coast City Council and Queensland University of Technology collaborated in the development of a detailed risk-based approach to the siting-design and management of on-site sewage treatment systems (Septic and aerobic home sewage treatment systems). Within the Gold Coast City area, some 16,000 properties rely on on-site sewage treatment. Studies indicated that about 9,000 of these are septic tanks and that a high proportion of these do not operate to the required standard due to a combination of design, siting and maintenance failures. These data and the increasing recognition of the ecosystem services provided by the Gold Coast hinterland and waterways indicated the need for greater rigour in assessment and management on–site sewage treatment systems. To do this, a risk-based approach was developed that required translation into the development assessment framework. The GIS (MAPINFO - mapbasic) tool developed interrogates a series of existing maintained layers to derive on-site risk-levels for a given parcel of land based on the science from the studies. This tool connects with planning documents and codes that delineate the level of information needed from the applicant to address the identified risks. The tool provides a quick indication of the risks for the assessment officer, allowing information requests to be produced consistently. It is designed to work with layers that the Council has agreed to maintain rather than maps derived during the study. Among the relevant maintained layers are the waterways, geology, soils and slope. In addition, the tool connects with other layers that can assist with the interpretation, such as existing soil data from nearby sites. This approach leads to consistent and science-based approach to development assessment.

Water Quality Profile of an Urbanising Catchment

Contamination of waterways a critical issue, especially in areas undergoing rapid urban development. The Ningi Creek catchment in Caboolture Shire, Queensland State, Australia is a prime example of such an area. A recent study had revealed a serious faecal pollution problem. The catchment area of Ningi Creek contains a number of landuses, including forestry, farming, aquaculture, rural-residential and residential developments serviced by onsite wastewater treatment systems. Any of these can cause contamination of the ground and surface water, particularly during rainfall events.