Analysis of long-term water quality for effective river health monitoring in peri-urban landscapes—a case study of the Hawkesbury–Nepean river system in NSW, Australia

The Hawkesbury–Nepean River (HNR) system in South-Eastern Australia is the main source of water supply for the Sydney Metropolitan area and is one of the more complex river systems due to the influence of urbanisation and other activities in the peri-urban landscape through which it flows. The long-term monitoring of river water quality is likely to suffer from data gaps due to funding cuts, changes in priority and related reasons. Nevertheless, we need to assess river health based on the available information. In this study, we demonstrated how the Factor Analysis (FA), Hierarchical Agglomerative Cluster Analysis (HACA) and Trend Analysis (TA) can be applied to evaluate long-term historic data sets. Six water quality parameters, viz., temperature, chlorophyll-a, dissolved oxygen, oxides of nitrogen, suspended solids and reactive silicates, measured at weekly intervals between 1985 and 2008 at 12 monitoring stations located along the 300 km length of the HNR system were evaluated to understand the human and natural influences on the river system in a peri-urban landscape. The application of FA extracted three latent factors which explained more than 70 % of the total variance of the data and related to the ‘bio-geographical’, ‘natural’ and ‘nutrient pollutant’ dimensions of the HNR system. The bio-geographical and nutrient pollution factors more likely related to the direct influence of changes and activities of peri-urban natures and accounted for approximately 50 % of variability in water quality. The application of HACA indicated two major clusters representing clean and polluted zones of the river. On the spatial scale, one cluster was represented by the upper and lower sections of the river (clean zone) and accounted for approximately 158 km of the river. The other cluster was represented by the middle section (polluted zone) with a length of approximately 98 km. Trend Analysis indicated how the point sources influence river water quality on spatio-temporal scales, taking into account the various effects of nutrient and other pollutant loads from sewerage effluents, agriculture and other point and non-point sources along the river and major tributaries of the HNR. Over the past 26 years, water temperature has significantly increased while suspended solids have significantly decreased (p?<?0.05). The analysis of water quality data through FA, HACA and TA helped to characterise the key sections and cluster the key water quality variables of the HNR system. The insights gained from this study have the potential to improve the effectiveness of river health-monitoring programs in terms of cost, time and effort, particularly in a peri-urban context.     

Understanding the impact of waste disposal sites on soil quality for agricultural production: A case study of the Kiteezi landfill,Uganda

Leachate from waste disposal sites (WDS) can significantly affect the soil physical, chemical and biological qualities, reducing soil health and agricultural productivity. However, there is a paucity of data on soil quality for understanding soil health impact due to WDS in Uganda. This study's aim was to understand, using the Kiteezi landfill site, how WDS impact soil properties. Soil samples were collected over 4 months in and around the landfill from three locations, and the soil quality data of the nearby area were used as baseline data for assessing the impact on soil due to WDS in the area. There were significant increases in the concentration of all studied parameters at the landfill except total N. The concentrations of ammonium (14.84 ± 1.76 mg/kg), nitrate (127.96 ± 18.36 mg/kg), and pH (7.8) were above the optimum levels. The levels of available P (181.4 ± 28.9 mg/kg) and exchangeable bases; K (2.23 ± 0.24 mg/kg), Na (1.17 ± 0.14 mg/kg), Mg (3.35 ± 0.3 mg/kg) and Ca (14 ± 1.1 mg/kg) cmol (+)/kg were optimal for plant growth. The calculated CEC of 20.75 cmol (+)/kg) showed that soils have a good potential to supply plant nutrients. Heavy metal levels were still below the permissible limit. Hence, the study shows that although WDS may contribute to the increase of soil fertility, they can potentially reduce the overall productivity of soil by increasing nutrient levels beyond optimum levels.     

Groundwater purification by membrane technology

Hyperfiltration and nanofiltration membranes were tested with different water matrices for the removal of excess fluoride from underground water. Initially, the experiments were done with synthetic samples prepared by adding known amounts of sodium fluoride and calcium chloride in distilled water. The effect of feed water composition, pH, temperature of feed water, operating pressure, and feed water flow rate on separation efficiency of both types of membrane was studied by varying one parameter at a time and keeping all other parameters constant. Thus, the optimum operating conditions for the process were determined and after that ground water samples collected from three villages of district Gurgaon, Haryana, India (Farukhnagar, Wazirpur, and Mevka) were treated under optimum operational conditions. The mass transfer coefficient and membrane parameters were estimated for each data point using two-parameter model (Film theory and Solution-diffusion model) to study the concentration polarization on membrane surface. The nanofiltration membrane showed high percentage rejection of bivalent ions when compared to monovalent ions in a binary system. But in multicomponent system, when fluoride and calcium coexisted, the removal of fluoride was comparable to calcium removal because of the low solubility product of calcium fluoride. The results with RO membrane revealed that it removes practically all the ions present in water at high pressure, which need to be passed through a lime column to remineralize the water, to make it suitable for drinking purposes, whereas by running the system at low pressure which will further reduce the cost of operation, rejection percentage goes down to get permeate of required quality.     

Chronic study of arsenic trioxide-induced hepatotoxicity in relation to arsenic liver accumulation in rats

This study measured activities of serum enzymes alkaline phosphatase, acid phosphatase, glutamic oxaloacetic transaminase (SGOT), and glutamic pyruvic transaminase (SGPT), markers of liver function in albino rats after continuous ingestion of arsenic trioxide (As₂0₃). For the study, treated animals were given AS₂O₃ (0.2 mg/100 g/day) orally for 180 days. After the completion of treatment, the blood was collected for the estimation of serum biochemical markers. The results obtained were compared with control group. Data showed a significant increase in SGOT and SGPT activity after 60 days of As₂0₃ administration. The level of alkaline phosphatase and acid phosphatase increased significantly after 90 and 120 days, respectively. Since the elevation of these serum enzymes is an indicator of hepatic damage, data indicate that As₂O₃ produces hepatotoxicity. When taken continuously, arsenic was also deposited in liver and blood and affected the enzymatic pathways. Total accumulated arsenic was determined by HG-AAS at 193.7 nm.     

Sustainable use of stormwater for irrigation case study: Manly Golf Course

Sustainability has become an increasingly used term, but what does it mean in terms of practice. This research will look at the harvesting of captured stormwater for the irrigation of urban playing fields and what the implications are for catchment hydrology, local community, and local council. This research aims to identify, understand and determine the catchment conditions that may hinder the stormwater quality and quantity for capture and reuse, as well as determining whether the stormwater harvesting will be sustainable. Research methods for this project will include systemic analysis in order to further investigate the assumptions being made in the study. Manly Golf Club has relied on groundwater extraction supplemented by potable supplies for irrigation, however potable supplies are no longer available. It has been proposed to provide irrigation supplies from stormwater via onsite storage and groundwater recharge. Monitored stormwater entering the Golf Course from the adjacent Cemetery Creek sub-catchment for pollutants, have indicated that it may be suitable for irrigation with treatment and may reduce problems generated by overuse of groundwater. The proposal will provide environmental benefit through reduced pollution loads being discharged directly to receiving waters and cessation of use of potable supplies by the Club. Social and economic benefits are expected to be gained and will be monitored as part of an ongoing research program.