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    Microfibres and health: State of the evidence and research gaps
    (Elsevier B V, 2025-08-01) Taptiklis P; Boulic M; Phipps R; van Heerden H; Shaw C
    Microfibres are ubiquitous in the environment and there has been an increasing focus on health harms from them in recent decades. The current WHO guidelines defining health risks from microfibres focus on just the subset of microfibres that are inorganic and respirable. Recent studies have revealed large volumes of textile microfibres are present throughout the environment and that non-plastic microfibres are as common or more common than plastic microfibres. However, these are rarely included in the analysis of harms. This narrative review of textile microfibres sets out the state of our understanding of exposure to and harms from textile microfibres. We found that the epidemiological research reviewed here does not support the continued focus solely on the respiratory route of exposure nor only on plastic microfibres as hazardous to health. In fact, gastrointestinal as well as upper airway effects may also be increased by exposure to textile microfibres. Importantly, microfibres behave differently in the environment, and within the body in comparison to non-fibre particles, and therefore warrant separate investigation from particles and microplastics. The conclusion of this cross-disciplinary review is an urgent call for greater investigation of textile microfibres, separately from the also important issue of microplastics, and therefore, the inclusion of non-plastic fibre types in research going forward.
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    Organic contaminants in Ganga basin: from the Green Revolution to the emerging concerns of modern India.
    (Elsevier B.V., 2021-02-17) Ghirardelli A; Tarolli P; Kameswari Rajasekaran M; Mudbhatkal A; Macklin MG; Masin R
    The Ganga basin includes some of the most densely populated areas in the world, in a region characterized by extremely high demographic and economic growth rates. Although anthropogenic pressure in this area is increasing, the pollution status of the Ganga is still poorly studied and understood. In the light of this, we have carried out a systematic literature review of the sources, levels and spatiotemporal distribution of organic pollutants in surface water and sediment of the Ganga basin, including for the first time emerging contaminants (ECs). We have identified 61 publications over the past thirty years, with data on a total of 271 organic compounds, including pesticides, industrial chemicals, and by-products, artificial sweeteners, pharmaceuticals, and personal care products (PPCPs). The most studied organic contaminants are pesticides, whereas knowledge of industrial compounds and PPCPs, among which some of the major ECs, is highly fragmentary. Most studies focus on the main channel of the Ganga, the Yamuna, the Gomti, and the deltaic region, while most of the Ganga's major tributaries, and the entire southern part of the catchment, have not been investigated. Hotspots of contamination coincide with major urban agglomerations, including Delhi, Kolkata, Kanpur, Varanasi, and Patna. Pesticides levels have decreased at most of the sites over recent decades, while potentially harmful concentrations of polychlorinated biphenyls (PCBs), organotin compounds (OTCs), and some PPCPs have been detected in the last ten years. Considering the limited geographical coverage of sampling and number of analyzed compounds, this review highlights the need for a more careful selection of locations, compounds and environmental matrices, prioritizing PPCPs and catchment-scale, source-to-sink studies.
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    Machine learning based calibration techniques for low-cost air quality sensors : thesis for Doctor of Philosophy, Electronic and Computer Engineering, Massey University
    (Massey University, 2024-05-28) Ali, Mohammad Sharafat
    Breathable air is the single most essential element for life on earth. Polluted air poses numerous risks to health and the environment, especially in urban areas with large populations and many active sources of air pollution. Therefore, researchers from a wide range of disciplines have been working on mitigating the impact of air pollution. Monitoring ambient air pollution is one of the means to ensure public health safety, raise public awareness and build a sustainable urban environment. However, conventional air quality monitoring stations are mostly confined to a few locations due to their costly equipment and large sizes. As a result, although these monitoring stations provide accurate air pollution data, they can only offer a low-fidelity picture of air quality in a large city, leading to a poor spatial resolution of urban pollution data. Low-cost sensor (LCS) technologies aim to address this challenge and intend to make it possible to monitor air quality at a high spatio-temporal resolution. The pollutant data captured by these LCSs are less accurate than their conventional counterparts and thus require calibration techniques to improve their accuracy and reliability. Researchers have proposed different calibration methods and techniques to improve the accuracy of the LCSs, including machine learning based calibration models. This thesis investigates and proposes several machine learning-based calibration techniques and rigorously benchmarks their performance using a robust training, validation and testing method. Based on the findings, One Dimensional Convolutional Neural Network (1DCNN) and Gradient Boosting Regression (GBR) based calibration techniques provide consistently accurate performance. Both of these machine learning techniques, which have not been widely used or evaluated for low-cost ambient gas sensor calibration, can improve the state of the art. This research also demonstrates that readily available and previously unemployed co-variate data, namely the number of days the sensor has been deployed and the time of day at which the reading is taken, can significantly improve the accuracy of Machine Learning based calibration algorithms.
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    The effect of land disposal of dairy factory wastes on soil properties : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Soil Science, Massey University
    (Massey University, 1978) McAuliffe, Keith William
    Many New Zealand dairy factories dispose of their wastewater by spray irrigating onto pasture. Little is known, however, about the effects of this disposal on soil properties. Research was undertaken at three pasture disposal sites in order to determine whether certain soil property changes may have occurred as a result of the wastewater treatment. Of particular interest were those properties related to water movement. Laboratory studies using 'undisturbed' soil cores indicated that dairy factory wastewater can impede soil water movement. A single application of simulated whey effluent resulted in approximately a 50% decrease in saturated hydraulic conductivity (K) within two days. This reduction was observed to be caused by a combination of both physical and biological blockage processes. With repetitive doses of effluent a K decrease of over 99% was induced in some cores. Several cores, particularly those containing earthworms, showed signs of recovery, and in some cores the final hydraulic conductivity value was greater than the initial value. Analyses of soil samples from the disposal and control sites at Te Rehunga and Tokomaru suggest that fifteen years of wastewater irrigation have resulted in marked changes in soil physical, chemical and biological properties. Total carbon and nitrogen levels were found to be significantly higher at the disposal site; for the Te Rehunga site, the differences in the organic matter level down to 600mm represented an increase of 250 000 kg ha-1. Water balances for the Te Rehunga and Longburn sites indicate that, in the absence of wastewater, pasture is likely to be water stressed on average for approximately forty days per year. The water balance also shows that deep percolation will be greatly increased by the wastewater application. The period of maximum deep percolation loss is likely to be September to October at both the Te Rehunga and Longburn disposal sites. The major site management problems encountered at the disposal sites examined occurred as a result of poor soil drainage, pasture burning and pasture pulling. An infiltration problem was observed at the Longburn site and the recently established disposal site at Tokomaru, with two major causes of the low infiltration rate appearing to be blockage from the effluent and pugging; these observations illustrate the need for controlling the effluent application rate, the suspended solids level in the wastewater, and the stock grazing pattern, in order to minimise site drainage problems. A drainage problem over the winter-spring period at Te Rehunga was due to a high groundwater table. Pasture burning was observed at all three disposal sites. The pasture pulling problem at Te Rehunga is the only cited example of such a problem occurring at a dairy factory disposal site. Observations made at the established Te Rehunga and Tokomaru disposal sites show that long term spray irrigation of dairy factory wastewater can occur without inducing undesirable soil property changes. It appears as though considerable benefit can be gained from the wastewater irrigation, particularly in reducing the incidence of water stress in the pasture and decreasing the requirement for fertilizer.
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    Investigating the transport and fate of nitrogen from farms to river in the Lower Rangitikei catchment : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Science at Massey University, Manawatu, New Zealand
    (Massey University, 2015) Collins, Stephen Brian
    A sound understanding of the transport and fate of leached nitrate-nitrogen (NO3--N) in shallow groundwater is key to understanding the impacts of land use intensification on the quality of groundwater and surface water bodies. However, these are not well understood in the Lower Rangitikei catchment. This study was undertaken to assess the groundwater flow pattern and its interactions with the Rangitikei River; the redox conditions of the groundwater; and the extent of NO3--N attenuation in shallow groundwater in the Lower Rangitikei catchment. Groundwater depths were collected from more than 100 wells to map the piezometric surface to inform the groundwater flow pattern within the study area. Groundwater interactions with the Rangitikei River were estimated qualitatively from two longitudinal river flow and water quality surveys (on 6th and 20th January 2015) under low-flow conditions. Fifteen wells were sampled and analysed in the study area during December 2014 to characterise the groundwater redox condition. A total of nine piezometers were installed at a range of depths (3 m and 6 m) on two dairy farms (sand country and river terrace) and one cropping farm (sand country). In these piezometers, NO3--N, dissolved oxygen (DO) and other parameters were monitored over March, April and May 2015. Single-well push-pull tests were used to measure NO3--N attenuation in shallow groundwater during May 2015. Groundwater flow was largely influenced by the regional topography, particularly shallow groundwater (<30 m), where it flows from elevated areas such as Marton in a southerly direction towards the Rangitikei River. The longitudinal river flow and water quality surveys revealed a dynamic relationship between the river and the underlying aquifer. The surveys suggested groundwater discharges into the river both upstream and downstream of Bulls. The groundwater redox characterisation showed generally anoxic/reduced groundwater across the lower Rangitikei catchment area. Groundwater typically has a low DO concentration (<1 mg/L) with elevated levels of available electron donors, particularly dissolved organic carbon and Fe2+. These groundwater characteristics provide for generally favourable conditions for NO3--N reduction. Monitoring at the installed piezometers showed a generally low NO3--N concentration at these sites. The push-pull tests revealed NO3--N reduction occurring at all three sites, with the rate of reduction varying between 0.04 mg N L-1 hr-1 to 1.57 mg N L-1 hr-1. These results suggest that groundwater is likely to be connected with the Lower Rangitikei River. However, NO3--N concentrations in the river and groundwater were generally low, especially for the river at low flows. This suggests NO3--N may be undergoing reduction within shallow groundwater before it has a chance to seep into the river. Further evidence for appreciable levels of NO3--N reduction in the shallow groundwater is provided by the redox characterisation of reduced groundwater and the push-pull tests. However, more spatial and temporal surveys and in-situ measurements of denitrification occurrence in the shallow groundwater of the study area are required.
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    Arsenic irrigated vegetables : risk assessment for South Asian horticulture : a thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Massey University, Palmerston North, New Zealand
    (Massey University, 2013) Bhatti, Saleem Maseeh
    Arsenic (As) contaminated water is often used in South Asia to irrigate vegetables. These vegetables accumulate As in their edible tissues and once ingested, increase As burden in humans. Despite the apparent risk, the As uptake potential of vegetable species when irrigated with As-contaminated water is not well defined. Most research on As-irrigated vegetables are monitoring surveys that only describe the As concentration levels in various vegetable species from affected areas. Because of the great variability in As concentration of irrigation water, soil type, vegetable species and cultivars, agronomic practices and climatic factors, As uptake potential of an individual vegetable species cannot be described from the monitoring data. Identifying vegetable species and soil conditions that result in high As concentrations in the edible tissues of vegetables is prerequisite for risk assessment and proposing As mitigation strategies. The objectives of this study were to (i) determine the As uptake response of common vegetable species when irrigated with As-contaminated water, (ii) calculate the risk to humans upon ingestion of As-contaminated vegetable species, (iii) elucidate factors that may increase As concentrations in vegetable species, and (iv) propose management strategies for South Asian countries where As-contaminated water is used for vegetable cultivation. In the first glasshouse experiment (Chapter 4), four common vegetables, carrot (Daucus carota), radish (Raphanus sativus), spinach (Spinacia oleracea), and tomato (Solanum esculentum) were irrigated with a range of AsV enriched water (50 to 1000 µg L-1) using two irrigation techniques. These irrigation techniques were (i) non-flooded, where soil moisture was maintained to 70% field capacity (Fc) of soil, and (ii) flooded, where the water was maintained at 110% Fc initially followed by drainage and onset of aerobic conditions until the next irrigation event. Only the 1000 µg As L-1 treatment showed a significant increase of As concentration in the vegetables compared to all other treatments. There was a higher concentration of As in the vegetables grown under flood irrigation relative to non-flood irrigation. The trend of As uptake among vegetable species was spinach > tomato > radish > carrot. Only in spinach leaves, the As concentration was above the Chinese food safety standard for inorganic As (0.05 µg g-1 fresh weight) by a factor of 1.6 to 6.4 times, when irrigated with 100, 200, and 1000 µg As L-1 under flood irrigation and with 1000 µg As L-1| ii under non-flood irrigation. The USEPA carcinogenic and non-carcinogenic risk parameters for the scenario where vegetables are consumed 500 grams per day were calculated. The USEPA Hazard Quotient (HQ) value for spinach leaves ranged from 0.32 to 1.26 for adults and 0.38 to 1.51 for adolescents while the Cancer Risk (CR) value ranged from 1.4 x 10-4 to 5.7 x 10-4 for adults and 1.7 x 10-4 to 6.8 x 10-4 for adolescents for treatment water concentrations 100 µg As L-1 or greater. An HQ value greater than 1 represents an unacceptable non-carcinogenic risk and a CR value greater than 10-4 represents an unacceptable carcinogenic risk. A laboratory batch experiment (Chapter 5) was conducted using four soils to determine their As adsorption behavior and the soil properties that control As retention in these soils. Soils used in this study were (i) Rangitikei silt loam (the soil which was used in glasshouse experiment 1), (ii) Rangitikei silt loam soil amended with calcium hydroxide to raise the pH to 7.5, to model the soil pH level of South Asian countries, and (iii) two New Zealand soils, Korokoro silt loam and Tokomaru silt loam. Both arsenate (AsV) and arsenite (AsIII) were investigated in the experiment because these As species are mainly present in irrigation water. The results showed that the AsV was adsorbed to a greater degree than AsIII as defined by high adsorption maxima, bonding energy and As partition coefficient values of Langmuir and Freundlich isotherms. Adsorption of both AsV and AsIII was mainly controlled by amorphous Al, total C and Olsen P content of selected soils. A glasshouse experiment (Chapter 6) was conducted to explore those factors which can promote As concentration in plants. The following factors which are likely to affect horticulture in South Asia were included: two As species (AsV and AsIII), four As concentration levels of irrigation water (50 to 1000 µg L-1), two soil pH levels (6.1 and 7.5), and two soil amendments (biochar and cattle manure). The control treatment for this experiment was no As in irrigation water and no soil amendment. Spinach was selected for this work due to its high uptake potential described in the earlier glasshouse experiment (Chapter 4). The findings of this experiment showed that the As concentration in spinach leaves was dependent on As concentrations in water and soil amendments and was independent of soil pH and As species under flood irrigation. Spinach plants grown in biochar and cattle manure amended soils had significantly higher As concentration in their leaves when compared with spinach plants grown with no amendment. In both biochar andcattle manure amended soils, the As concentration in spinach leaves exceeded the Chinese food safety standard (0.05 µg g-1 fresh weight) by a factor of 1.6 to 8.3 times, where the concentration of As in irrigation water was 200 µg L-1 or greater. The CR values for spinach grown in cattle manure amended soil was greater than the critical value of 1 x 10-4 for the scenarios where vegetable consumption is 205 grams and/or 500 grams per day. This increase was found where the As concentration in irrigation water was 200 µg L-1 or greater. The HQ value was above the critical value of 1 for the scenario where the vegetable consumption is 500 grams per day. This increase was observed for spinach grown in cattle manure amended soil with an As concentration in irrigation water 500 µg L-1 or greater. Arsenic daily intake (mg kg-1 body weight) associated with the ingestion of spinach leaves corresponds to proposed ATSDR (Agency for Toxic Substances and Disease Registry) and drinking water daily intake values that may lead to development of cancer (bladder, lung and skin), skin lesions, and intellectual impairment in children. The As intake through ingestion of spinach correlates to an As concentration in drinking water that is 10 µg L-1 or greater. Overall, the results of glasshouse studies indicate that the As concentrations greater than 50 µg L-1 should be avoided for spinach cultivation where flood irrigation is practiced. Addition of cattle manure can further intensify the risk by increasing the As concentration in plant tissues, therefore its usage in South Asian horticulture is questionable. I propose that the As concentration in vegetables should not be overlooked as they can alone be a major source of As poisoning in humans.