Massey Documents by Type
Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294
Browse
18 results
Search Results
Item Modelling and mapping of subsurface nitrate-attenuation index in agricultural landscapes(Elsevier Ltd, 2025-06) Collins SB; Singh R; Mead SR; Horne DJ; Zhang LEnvironmental management of nutrient losses from agricultural lands is required to reduce their potential impacts on the quality of groundwater and eutrophication of surface waters in agricultural landscapes. However, accurate accounting and management of nitrogen losses relies on a robust modelling of nitrogen leaching and its potential attenuation – specifically, the reduction of nitrate to gaseous forms of nitrogen – in subsurface flow pathways. Subsurface denitrification is a key process in potential nitrate attenuation, but the spatial and temporal dynamics of where and when it occurs remain poorly understood, especially at catchment-scale. In this paper, a novel Landscape Subsurface Nitrate-Attenuation Index (LSNAI) is developed to map spatially variable subsurface nitrate attenuation potential of diverse landscape units across the Manawatū-Whanganui region of New Zealand. A large data set of groundwater quality across New Zealand was collated and analysed to assess spatial and temporal variability of groundwater redox status (based on dissolved oxygen, nitrate and dissolved manganese) across different hydrogeological settings. The Extreme Gradient Boosting algorithm was used to predict landscape unit subsurface redox status by integrating the nationwide groundwater redox status data set with various landscape characteristics. Applying the hierarchical clustering analysis and unsupervised classification techniques, the LSNAI was then developed to identify and map five landscape subsurface nitrate attenuation classes, varying from very low to very high potential, based on the predicted groundwater redox status probabilities and identified soil drainage and rock type as key influencing landscape characteristics. Accuracy of the LSNAI mapping was further investigated and validated using a set of independent observations of groundwater quality and redox assessments in shallow groundwaters in the study area. This highlights the potential for further research in up-scaling mapping and modelling of landscape subsurface nitrate attenuation index to accurately account for spatial variability in subsurface nitrate attenuation potential in modelling and assessment of water quality management measures at catchment-scale in agricultural landscapes.Item Quantification of denitrification rate in shallow groundwater using the single-well, push-pull test technique(Elsevier BV, Amsterdam, 2025-02) Rivas A; Singh R; Horne D; Roygard J; Matthews A; Hedley MDenitrification has been identified as a significant nitrate attenuation process in groundwater systems. Hence, accurate quantification of denitrification rates is consequently important for the better understanding and assessment of nitrate contamination of groundwater systems. There are, however, few studies that have investigated quantification of shallow groundwater denitrification rates using different analytical approaches or assuming different kinetic reaction models. In this study, we assessed different analytical approaches (reactant versus product) and kinetic reaction (zero-order and first-order) models analysing observations from a single-well, push-pull tests to quantify denitrification rates in shallow groundwater at two sites in the Manawatū River catchment, Lower North Island of New Zealand. Shallow groundwater denitrification rates analysed using the measurements of denitrification reactant (nitrate reduction) and zero-order kinetic models were quantified at 0.42-1.07 mg N L-1 h-1 and 0.05-0.12 mg N L-1 h-1 at the Palmerston North (PNR) and Woodville (WDV) sites, respectively. However, using first-order kinetic models, the denitrification rates were quantified at 0.03-0.09 h-1 and 0.002-0.012 h-1 at the PNR and WDV sites, respectively. These denitrification rates based on the measurements of denitrification reactant (nitrate reduction) were quantified significantly higher (6 to 60 times) than the rates estimated using the measurements of denitrification product (nitrous oxide production). However, the denitrification rate quantified based on the nitrate reduction may provide representative value of denitrification characteristics of shallow groundwater systems. This is more so when lacking practical methods to quantify all nitrogen species (i.e., total N, organic N, nitrite, nitrate, ammoniacal N, nitrous oxide, nitric oxide, and nitrogen gas) in a push-pull test. While estimates of denitrification rates also differed depending on the kinetic model used, both a zero-order and a first-order model appear to be valid to analyse and estimate denitrification rate from push-pull tests. However, a discrepancy in estimates of denitrification rates using either reactant or product and using zero- or first-order kinetics models may have implications in assessment of nitrate transport and transformation in groundwater systems. This necessitates further research and analysis for appropriate measurements and representation of spatial and temporal variability in denitrification characteristics of the shallow groundwater system.Item Thin film electrochemical sensor for water quality monitoring : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering, Massey University, Auckland, New Zealand(Massey University, 2023-12-11) Lal, KartikayFreshwater is the most precious natural resource, essential for supporting life. Aquatic ecosystems flourish in freshwater sources, and many regions around the world depend on aquatic food sources, such as fish. Nitrogen and phosphorous are the two nutrients, in particular, that are essential for growth of aquatic plants and algae. However, with rising population and anthropogenic activities, excessive amounts of such nutrients enter our waterways through various natural processes, thereby degrading the quality of freshwater sources. Elevated levels of nitrate-nitrogen content, in particular, lead to consequences for both aquatic life as well as human health, which has been a cause for concern for many decades. As recommended by the World Health Organization, the maximum permissible nitrate level in water is 11.3 mg/L. These levels are often exceeded in coastal areas or freshwater bodies that are close to agricultural land. Therefore, it is essential to monitor nitrate levels in freshwater sources in real-time, which can be achieved by employing detection methods commonly used to detect ionic content in water. Hence, a comprehensive review was carried out on various field-deployable electrochemical and optical detection methods that could be employed for in-situ detection of nitrate ions in water. The primary focus was on electrochemical methods that could be integrated with low-cost planar electrodes to achieve targeted detection of nitrate ions in water. Designing resilient sensors for real-time monitoring of water quality is a challenging task due to the harsh environment to which they are subjected. There is a significant need for sensors with attributes such as repeatability, sensitivity, low-cost, and selectivity. These attributes were first explored by evaluating the performance of silver and copper materials on three distinct geometric patterns of electrodes. The experiments produced promising results with interdigitated pattern of copper electrodes that were successful in detecting 0.1-0.5 mg/L of nitrate ions in deionised water. The interdigitated geometric pattern of electrodes were further analyzed in four distinct materials namely, silver, gold, copper, and tin with real-world freshwater samples that were collected from three different freshwater bodies. The water samples were used to synthesize varying concentrations of nitrate ions. The results showed tin electrodes performed better over other materials for nitrate concentrations from 0.1-1 mg/L in complex matrix of real-world sample. The nitrate sensor eventually needs to be deployed in freshwater bodies, hence a real-time water quality monitoring system was also built that incorporated sensors to monitor five basic water quality parameters with the aim to monitor and study the quality of water around the local area.Item Nitrate enrichment does not affect enteropathogenic Escherichia coli in aquatic microcosms but may affect other strains present in aquatic habitats(PeerJ, Inc, 2022-09-27) Davis MT; Canning AD; Midwinter AC; Death RG; Oehlmann JEutrophication of the planet's aquatic systems is increasing at an unprecedented rate. In freshwater systems, nitrate-one of the nutrients responsible for eutrophication-is linked to biodiversity losses and ecosystem degradation. One of the main sources of freshwater nitrate pollution in New Zealand is agriculture. New Zealand's pastoral farming system relies heavily on the application of chemical fertilisers. These fertilisers in combination with animal urine, also high in nitrogen, result in high rates of nitrogen leaching into adjacent aquatic systems. In addition to nitrogen, livestock waste commonly carries human and animal enteropathogenic bacteria, many of which can survive in freshwater environments. Two strains of enteropathogenic bacteria found in New Zealand cattle, are K99 and Shiga-toxin producing Escherichia coli (STEC). To better understand the effects of ambient nitrate concentrations in the water column on environmental enteropathogenic bacteria survival, a microcosm experiment with three nitrate-nitrogen concentrations (0, 1, and 3 mg NO3-N /L), two enteropathogenic bacterial strains (STEC O26-human, and K99-animal), and two water types (sterile and containing natural microbiota) was run. Both STEC O26 and K99 reached 500 CFU/10 ml in both water types at all three nitrate concentrations within 24 hours and remained at those levels for the full 91 days of the experiment. Although enteropathogenic strains showed no response to water column nitrate concentrations, the survival of background Escherichia coli, imported as part of the in-stream microbiota did, surviving longer in 1 and 3 mg NO3-N/Lconcentrations (P < 0.001). While further work is needed to fully understand how nitrate enrichment and in-stream microbiota may affect the viability of human and animal pathogens in freshwater systems, it is clear that these two New Zealand strains of STEC O26 and K99 can persist in river water for extended periods alongside some natural microbiota.Item Detecting genes associated with antimicrobial resistance and pathogen virulence in three New Zealand rivers(PeerJ, Inc, 2021-12-03) Davis M; Midwinter AC; Cosgrove R; Death RG; Oehlmann JThe emergence of clinically significant antimicrobial resistance (AMR) in bacteria is frequently attributed to the use of antimicrobials in humans and livestock and is often found concurrently with human and animal pathogens. However, the incidence and natural drivers of antimicrobial resistance and pathogenic virulence in the environment, including waterways and ground water, are poorly understood. Freshwater monitoring for microbial pollution relies on culturing bacterial species indicative of faecal pollution, but detection of genes linked to antimicrobial resistance and/or those linked to virulence is a potentially superior alternative. We collected water and sediment samples in the autumn and spring from three rivers in Canterbury, New Zealand; sites were above and below reaches draining intensive dairy farming. Samples were tested for loci associated with the AMR-related group 1 CTX-M enzyme production (bla CTX-M) and Shiga toxin producing Escherichia coli (STEC). The bla CTX-M locus was only detected during spring and was more prevalent downstream of intensive dairy farms. Loci associated with STEC were detected in both the autumn and spring, again predominantly downstream of intensive dairying. This cross-sectional study suggests that targeted testing of environmental DNA is a useful tool for monitoring waterways. Further studies are now needed to extend our observations across seasons and to examine the relationship between the presence of these genetic elements and the incidence of disease in humans.Item Ecology of ponds : anthropogenic and environmental effects on biodiversity : a thesis presented in partial fulfilment of the requirement for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Auckland, New Zealand(Massey University, 2022) Kuranchie, AbigailPonds are a vital component of the freshwater ecosystem but have been understudied worldwide. The paucity of research is especially disturbing due to increasing pressure on freshwater ecosystems. Pond ecosystems are vulnerable due to anthropogenic activities and changing environmental conditions. Ponds are the most ubiquitous freshwater ecosystems found in the Auckland Region of New Zealand. Despite their abundance (occurring in all landscapes) and significant ecological role, there is a lack of knowledge on the ecology of pond ecosystems in New Zealand. Further, literature on the impact of land use/ land cover (LULC) and human population density on pond water quality and biodiversity is lacking globally. I studied aspects of ponds (natural and man-made) ecology in the Auckland region by assessing both abiotic and biotic factors in the summer and winter seasons. Specifically, my study focused on six aspects of the ecology of pond ecosystems: i) the relationship between water quality and LULC at multiple spatial scales across the seasons, ii) the temporal community composition of macroinvertebrates and the relationship between the communities and the abiotic factors, iii) the influence of anthropogenic activities (measured as human population density and as pond types or function) on the macroinvertebrate communities, iv) the phytoplankton communities in ponds across the seasons, v) the limiting nutrient(s) in periphyton biomass in ponds using an in-situ experiment, and finally, vi) a single case study tracking a newly formed pond in a restoration area and development of its macroinvertebrate community over one year. I sampled 50 ponds in the Auckland region across two seasons (summer and winter) to assess pond water quality (evaluated using seven physicochemical variables: pH, percentage dissolved oxygen '% DO', conductivity, temperature, total dissolved solids 'TDS', salinity, nitrate, phosphate and ammoniacal nitrogen). My aim was to understand the relationship between water quality and the landscape features (physical variables and LULC types: ‘forest, grass, and impervious surface’) at multiple spatial scales (10m, 100m, 500m and pond catchment) from the pond. I found a significant seasonal difference in the water quality of ponds. All the water quality variables measured apart from ammoniacal nitrogen were higher in summer, suggesting that the water was of lower quality at that time. Also, the effect of LULC on the physicochemical water quality parameters varied spatially and seasonally. LULC at the catchment and 500m scale influenced the water quality in winter, while the LULC at 100m affected the water quality in summer. The results highlight the critical and complex role of environmental factors and LULC in determining the water quality in ponds. I assessed the macroinvertebrate community compositions and water quality in 12 ponds across two seasons for two years. I found an average of 15 macroinvertebrate taxa in focal ponds. Insects were the most diverse group found, although Crustacea were most abundant. The community composition of the macroinvertebrates varied among ponds and varied across seasons and years. Macroinvertebrates were more abundant, and the community was more diverse in summer. The % DO in the ponds was negatively correlated to the macroinvertebrate abundance. My results suggest that macroinvertebrates and water quality in ponds are temporally variable. I assessed the influence of anthropogenic activities on the macroinvertebrate communities of 11 ponds. Four categories of human population density were used (rural, small urban, large urban, and major urban; in order of increasing human population) to group ponds for analysis. By applying taxonomic and trait-based (functional feeding groups) approaches, I found that high human population density was negatively associated with the macroinvertebrate communities, especially in summer. Ponds in rural areas had the highest diversity of macroinvertebrates and the highest composition of functional foraging group relative to the other areas assessed. This finding suggests that ponds in rural areas had the lowest anthropogenic impact. Ornamental ponds were rich in macroinvertebrates, primarily due to a comparatively more heterogenous pond habitat. I sampled and analysed the phytoplankton community composition of 12 ponds in summer and winter. Overall, the communities were dominated by taxa in the phylum Chlorophyta (green algae) and class Bacillariophyceae (Diatoms). Although I did find seasonal differences in the phytoplankton communities, these were influenced by temperature and conductivity. In addition, ponds within areas of denser human populations had the most motile diatoms in summer, suggesting high siltation. Despite being moderately polluted, these results show that all ponds generally had healthy phytoplankton communities. Furthermore, by using an in-situ nutrient diffusion experiment, I found that nitrogen is likely to be the limiting nutrient for periphyton growth in ponds. Finally, I sampled and monitored a newly created and a nearby established pond for a year to obtain insights into the progression of a pond from creation into a functional ecosystem using macroinvertebrates as indicators. I found that Crustaceans were the first to colonise the new pond. The macroinvertebrate community in the new pond was more taxonomically distinct than the established pond at the end of the first year of its creation. Shannon Weiner's diversity index was similar between the ponds, and environmental factors influenced the macroinvertebrate abundance. My results indicate that new ponds can create new habitats and boost local freshwater biodiversity. By combining water quality analyses, and detailed biodiversity assessment, my thesis demonstrates that pond ecosystems support a high diversity of macroinvertebrates and phytoplankton. Environmental variables, LULC, and human population density influence the biodiversity in ponds, and the extent, relationship, and impact of these are complex and vary seasonally. My study provides new baseline information and valuable insights for future research on pond ecosystems in New Zealand.Item Self-assembled optical diffraction sensor for water quality monitoring : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering, Massey University, Albany, New Zealand(Massey University, 2020) Jaywant, SwapnaWater contamination is one of the current global issues; the freshwater sources being extremely restricted are causing a drinking water crisis in many countries. An increase in water contamination continuously decreases water quality. Generally, water pollution includes pathogenic, nutrients, and chemical (organic & inorganic) contaminants. Inorganic contamination involves metallic particles such as arsenic, lead, etc. Of these contaminants, arsenic (As) is a major concern due to its mutagenic and carcinogenic effects on human health. The World Health Organisation has recommended the maximum contamination limit (MCL) for arsenic in drinking water to be 10 µg/L. Countries like Bangladesh, China, Vietnam, India, Chile, USA, and Canada are contaminated with arsenic. Arsenic species are also found in New Zealand in 28 geothermal features from the Taupo Volcanic Zone and the Waikato region. Thus, a rising level of arsenic in drinking water creates the need to periodically monitor its levels in potable water. Commercially available methods are either laboratory-based or kit based techniques. The most common laboratory-based arsenic detection methods are reliable. However, these are expensive due to the requirement for specific instrumentation. Hence, they are not considered to be field-effective for arsenic detection. On the other hand, commercially available kit-based methods are portable but are not considered to be safe and reliable due to the production of toxic by-products. The development of a portable and sensitive arsenic sensor with high throughput could be an asset. In this research, we present a novel sensor with a unique surface modification technique to detect arsenite (As(III)) contamination of water. Here, the approach involves the potential usage of self-assembled optical diffraction patterns of a thiol compound (dithiothreitol or glutathione) on the gold-coated glass. The self-assembled patterns are obtained through a microcontact printing (µCP) procedure. Gold binds with the thiol compound through an Au-S linkage. In addition to this, As(III) has an affinity towards amino acids, amines, peptides, and organic micro molecules due to As-O or As-S linkages. The research indicates that the total time taken by the µCP process to transfer the patterns successfully on to the gold-coated substrate is inversely proportional to the concentration of the thiol molecules and pH value of the solvent. Further, the signal enhancement of these thiol-based self-assembled patterns allows for detection of the As(III) contamination. Simultaneously, the automated fluidic system is designed to provide fluid handling. The system is developed with the help of off-the-shelf and/or in-house fabricated components. The characterisation of fluidic components proved that the low-cost fluidic components work reliably in the fluidic network and can be used in sensing applications for pumping, mixing, and circulation purposes. We also explore the possibility of using fused deposition modelling and selective laser sintering technology for the printing of the flow chamber through printing microchannels. These two technologies have been compared in terms of the minimum possible channel size, fluid ow-rate, and leakage. Overall, we developed a sensing scheme of a portable self-assembled diffraction sensor for As(III) detection. The developed sensor can detect dissolved As(III) up to 20 µg/L. The µCP of a dithiothreitol pattern has not been found in the literature yet. Hence, this research also provides a guide towards µCP of dithiothreitol on a gold-coated substrate.Item Pollution of the aquatic biosphere by arsenic and other elements in the Taupo volcanic zone : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biology at Massey University(Massey University, 1994) Robinson, Brett HarveyAn introduction to the Taupo Volcanic Zone and probable sources of polluting elements entering the aquatic environment is followed by a description of collection and treatment of samples used in this study. The construction of a hydride generation apparatus for use with an atomic absorption spectrophotometer for the determination of arsenic and other hydride forming elements is described. Flame emission, flame atomic absorption and inductively coupled plasma emission spectroscopy (I.C.P.-E.S.) were used for the determination of other elements. Determinations of arsenic and other elements were made on some geothermal waters of the area. It was found that these waters contribute large (relative to background levels) amounts of arsenic, boron and alkali metals to the aquatic environment. Some terrestrial vegetation surrounding hot pools at Lake Rotokawa and the Champagne Pool at Waiotapu was found to have high arsenic concentrations. Arsenic determinations made on the waters of the Waikato River and some lakes of the Taupo Volcanic Zone revealed that water from the Waikato River between Lake Aratiatia and Whakamaru as well as Lakes Rotokawa, Rotomahana and Rotoehu was above the World Health Organisation limit for arsenic in drinking water (0.05 µg/mL) at the time of sampling. Arsenic accumulates in the sediments of the Waikato River and Lakes of the Taupo Volcanic Zone. The levels were variable, but characteristically around 100 µg/g. Trout taken from the Waikato River and some lakes in the Taupo Volcanic Zone, had flesh arsenic concentrations of the same order of magnitude as the water from which they were taken. Trout from Lakes Rotorua, Rotoiti and Rotomahana contained average flesh mercury concentrations above the World Health Organisations limit for mercury in foodstuffs (0.5 µg/g). There were positive correlations between weight, length and flesh mercury concentration. Freshwater mussels from Lakes Rotorua and Tarawera had arsenic concentrations above the World Health Organisations limit for arsenic in foodstuffs (2 µg/g). Shellfish taken from the mouth of the Waikato river and from Raglan were below the World Health Organisation's limit for arsenic and mercury. Aquatic macrophytes from the Waikato River had arsenic concentrations many times greater than the water from which they were taken. Some samples of Ceratophyllum demersum had arsenic concentrations above 1000 µg/g dry weight. Water cress from the Waikato River at Broadlands and Orakei Korako contained on average 400 µg/g and 30 µg/g arsenic respectively. An experiment was conducted on the uptake of arsenic by water cress. It was found that water cress does accumulate arsenic if placed in an arsenic solution.Item Indicator organism sources and recreational water quality : a study on the impact of duck droppings on the microbiological quality of water at Hataitai Beach : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University(Massey University, 2003) Abbott, Stanley EdwinThe aim of this study was to identify the possible sources of faecal pollution of recreational water at Hataitai Beach, a small Evans Bay beach that is a popular Wellington Harbour location for swimming, canoeing, kayaking and fishing. Since 1994 the water quality at Hataitai Beach had deteriorated to the extent where the beach was closed for bathing between February 1996 and January 1997, and again in January 1998. Results of routine membrane filtration tests for indicator organisms performed on marine water samples from Hataitai Beach by the Wellington City and Regional Councils' laboratories had been unable to determine if the source of raised bacterial levels were of animal or human origin. Consequently it was not firmly established if the ducks that frequented Hataitai Beach were the main reason for the high counts or whether they contributed to a pollution problem that was thought to be exacerbated by leaking sewers and private drain faults. Following remedial work on sewer and stormwater pipes carried out by the Wellington City Council in 1998, Hataitai Beach was re-opened for swimming in December 1998 and remained open throughout the 1999-bathing season. In this study 400 marine water samples (500 ml volumes) were collected from various sites at Hataitai Beach from July 1998 to April 2000. The EnterolertTM system (IDEXX Laboratories, USA) was used for the detection and enumeration of Enterococci and the Colilert-18TM system (IDEXX) for Total coliforms and Escherichia coli detection and enumeration. The results were analysed to: • Determine water quality compliance at Hataitai Beach. • Ascertain the impact of duck numbers on indicator organism levels. • Identify the principal sources of faecal pollution at Hataitai Beach. Six marine samples (130-500 litres) were also collected for the capture of Giardia and Cryptosporidium on filter cartridges for subsequent purification of (oo)cysts by the DYNAL® immunomagnetic bead separation technique (DYNAL A.S., Norway) and the detection of (oo)cysts by the Merifluor® Cryptosporidium/Giardia (Meridian Diagnostics, USA) direct immunofluorescent monoclonal antibody (IFA) procedure. In addition, 279 duck faecal samples were collected from Hataitai Beach for the detection of Giardia and Cryptosporidium by the Merifluor® Cryptosporidium/Giardia IFA procedure and subsequent DNA analysis of oo(cysts) by the Polymerase Chain Reaction (PCR) amplification procedure. The results from this study indicate that despite the stormwater and sewer upgrades by the Wellington City Council there is still a pollution problem at Hataitai Beach and that this pollution is primarily caused by a combination of duck droppings and meteorological events. The microbiological water quality can be degraded directly by the resident mallard ducks defaecating in the water or indirectly from droppings deposited on the beach sands. Faecal bacteria in the droppings on the beach sands can be carried into the water by tides, rain, and wind erosion or unwittingly by the action of beach users. On 64 occasions during this study there were exceedences of the water quality guidelines at Hataitai Beach, especially in water samples collected from the B3 site where ducks were frequently seen loafing on the beach or swimming in the water. Moreover, on 41 occasions the Enterococci levels in samples from the B3 site were strikingly over the Action Red mode guideline value of 277 Enterococci per 100 ml - exceedences that require local authorities and health authorities to warn the public that the beach is unsafe for recreational activities and erect warning signs. The median value of 63 Enterococci per 100 ml for samples collected from the B3 site was well above the Green – "safe for bathing" guideline value of less than 35 Enterococci per 100 ml. While no Giardia cysts or Cryptosporidium oocysts were detected in the marine water samples, protozoan cysts morphologically resembling Giardia spp. were detected in 29% of the duck faecal samples. However, since no detectable PCR amplification products were obtained in any cysts of the Merifluor®C/G IFA positive samples tested, attempts to genotype the Giardia cysts proved unsuccessful. After closer inspections and measurements of these Merifluor®C/G IFA positive protozoan cysts it was established that the organisms were in fact Caryospora spp. and not Giardia cysts. Since Caryospora are phylogenetically related to Cryptosporidium, it appears that Caryospora can cross-react with Cryptosporidium antibody preparations but have the appearance of Giardia cysts when viewed under fluorescence microscopy. Because of their aquatic lifestyle and highly mobile behaviour, ducks may be exposed to a diverse array of potentially pathogenic organisms such as Campylobacter jejuni, Escherichia coli OI57:H7, Salmonella spp., Pasteurella multocida, Giardia and Cryptosporidium spp., and Cercarial trematodes. These organisms can originate from several sources including human sewage, agricultural runoff, and animal faecal matter. The microbiological health risk of humans acquiring infections from the ducks at Hataitai Beach depends on several factors, including the presence and survival of pathogenic organisms in the droppings after their deposition on the beach sands and in the water, as well as the types of recreational activities that expose humans to these droppings. In order for the public to be adequately informed of the risk so that they can make informed personal choices about engaging in recreational activities at Hataitai Beach, it seems prudent that efforts should be made to grade this beach so that the beach's suitability for recreation can be established. This should include a catchment risk assessment that considers the potential sources and transmission routes of faecally derived pollution at Hataitai Beach with an assessment of the microbiological data. In the meantime common sense dictates that at Hataitai Beach the authorities should limit the food sources of ducks in the areas surrounding the beach by officially prohibiting people from feeding the ducks.Item The impact of the closure and decommissioning of the Wainuiomata Waste Water Treatment Plant on the water quality of the Wainuiomata River : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Water Quality at Massey University(Massey University, 2004) De Silva, JosephineThe quality of the Wainuiomata River (particularly downstream of the Wainuiomata Waste Water Treatment Plant) has been affected over the years (e.g. eutrophication) by a number of contaminants, such as nutrients and faecal bacteria. The main source of these contaminants has been the treated effluent discharged into the river from the Wainuiomata Waste Water Treatment Plant (WWTP). The WWTP has been discharging treated effluent into the river since the 1950's. This sewage treatment plant was decommissioned in November 2001 and is now used solely as a pumping station. Sewage from Wainuiomata is now piped over to the new sewage treatment plant in Seaview. This research project aimed to examine the impact of the WWTP closure on the water quality of the Wainuiomata River. Water samples were collected from a number of selected sites over a period of three months: January 2003 to March 2003, above and below the WWTP site. For this particular study, the microbiological, chemical (nutrients) and biological parameters were assessed as follows: Escherichia coli and total coliforms (microbiological) dissolved reactive phosphorus (DRP), nitrate nitrogen and ammoniacal nitrogen (chemical) and periphyton (biological) for biomass and taxa identification. The results for each of the above parameters sites were compared with historical data obtained from Greater Wellington Regional Council (2003). Overall this research has shown that the closure of the WWTP has impacted on the J5 site (Golf Course), which is downstream of the WWTP, in a number of ways. The chemical indicator levels (NO3-N, NH4-N and DRP) have dropped significantly; periphyton was still in abundance at site J5 (no real improvement seen) and the median level of the microbiological indicator, E.coli has reduced. However, site J5 on a number of occasions, did not comply with the Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas (2003). Sites sampled upstream of the WWTP, particularly the tributary sites (Black Creek and Wainuiomata Stream), also did not comply with the guidelines on a number of occasions. This is a concern, as the public are known to swim near where these tributaries enter the Wainuiomata River. The effects of storm water or land runoff may have affected the results on two occasions (when there had been rainfall) however, on all other occasions where high E.coli levels were observed, the effects of storm water and runoff would have been minimal, as there had been very little rain. The Wainuiomata River is used for recreational activities such as swimming, canoeing and fishing; therefore an important resource. Any water quality concerns (namely, E.coli levels and periphyton proliferation), therefore need to be monitored by the Greater Wellington Regional Council and actions taken to eliminate these concerns.