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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Nutrient dynamics at Matapouri Estuary, Northern New Zealand

Soliman, Nabil Zaki Gadalla Unknown Date (has links)
Mangrove forests are an integral part of coastal wetlands in temperate and tropical regions of the world, including New Zealand. These coastal plants act as a shelter,feeding and breeding grounds for marine and terrestrial organisms. Many overseas studies have investigated the importance of mangrove and seagrass habitats in sustaining coastal food chains. In New Zealand, however, only a few studies have addressed the ecology and food web dynamics of these temperate ecosystems.As a first step to investigate the nutrient dynamics of estuarine food webs in temperate estuaries, this study aimed to quantify the nutrient concentrations in the catchment and the estuary of Matapouri, northern New Zealand. Field studies involved the collection of surface fresh and estuarine water (during low and high tides). Plant material (mangrove and seagrass), and sediment samples were collected at various sites within the estuary. Chemical analyses were carried out to determine the concentration of C, N, P and Si macronutrients and Fe and Zn micronutrients during different seasonal rainfall events.The results suggest that mangrove habitats may act as a source of POC, but not DOC for the adjacent aquatic habitats (i.e., seagrass, sand flats, channels), while seasgrass beds contribute more N to the estuarine system than the mangrove forests. The concentrations of N and P nutrients are strongly influenced by both the freshwater inputs and the bio-chemical processes within the estuary. The results obtained point to the freshwater streams as the main source of Si and Fe in the estuary. However, Zn was higher in the estuarine water compared to the catchment freshwater. NO3 -, NH4 +, Fe and Zn concentrations showed strong responses to the higher rainfall months reaching their highest level during the winter and early spring seasons. Conversely, P concentrations showed a negative seasonal pattern, which was linked to monthly rainfall events.Mangrove sediments may operate as a sink for the heavy metal Zn in Matapouri estuary. Iron concentration in seagrass leaves exceeded that in mangrove leaves by 65 orders of magnitude. The study suggests that seagrass plants could be used as a biological indicator of iron concentration in the estuary. The complex dynamics of bio-chemical cycles in Matapouri indicate that each habitat within the estuary has specific nutrient contributions to the estuarine food web system. However, the catchment and oceanic influences must also be considered in the nutrient balance of these coastal environments.
12

Heavy metal concentrations in the Pacific oyster Crassostrea gigas

Perera, Percy Unknown Date (has links)
Heavy metals present in high concentrations in aquatic habitats are bioaccumulated within the tissues of intertidal organisms. The chemical analyses of animal tissues and sediments provide an indication of bioavailability of heavy metals in the environment. Monitoring of the coastal pollution using organisms is widely practiced all over the world.Chemical analysis of the tissues of Pacific oyster, Crassostrea gigas, and river sediments were used in this study to monitor the environmental concentrations, of cadmium, copper, lead and zinc of shallow coastal areas near to the river mouths of Mahurangi, Awaruku, Waiake, Taiorahi and Wairau. All of these river mouths are situated along the northeastern coast of Auckland. Each month, during the period of November 2002 to October 2003, three replicate samples of oysters, and sediments were collected from each of the river mouths for analysis. Three additional replicate samples of oysters were collected separately, in each month in order to calculate the condition index of oysters. Oyster tissues and sediments were analysed with Inductively Coupled Atomic Plasma Emission Spectrometer to detect the concentration levels of cadmium, copper, lead and zinc.The highest level of copper and zinc concentrations in the oyster tissues was observed in the river mouth of Wairau. Wairau river mouth receives water from heavily urbanised and industrialised catchments. A higher concentration of cadmium was observed in the oysters of the river mouth of Mahurangi than in the oysters in the other sites. The reason for this difference could be due to the heavy use of cadmium contaminated fertilizers at the pasture lands situated around the Mahurangi estuary. Therefore, the relationship between the land use of the catchments and the degree of pollution of the estuarine habitats could be established from the data obtained from this study. Higher concentrations of heavy metals were found in the sediments of Waiake, Taiorahi and Wairau compared to the sediments of Mahurangi and Awaruku. Significantly higher level of copper was observed in the sediments of Awaruku. However no clear co-relation was found between heavy metal concentration in oysters and in sediments. Variations of the condition of oysters were closely related to seasonal changes of the life cycle of the oysters. No clear relationship was found between the condition of the oysters and the heavy metal concentration of the river mouth habitats.This study provides evidence that Pacific oysters are good organisms to use as bioindicators of environmental heavy metal levels in shallow coastal waters. The results of this study suggest a clear relationship between the heavy metal concentration in river waters and the land use of the catchment areas of those rivers. The results may be useful in management strategies of the northeastern coastal areas of Auckland.
13

Reactive milling of organic compounds

Li, Ying Yu Unknown Date (has links)
Persistent organic pollutants are a well-known threat to the environment. Substances such as polycyclic aromatic hydrocarbons and chlorinated organic compounds in contaminated soil and groundwater can have severe and long-lasting effects on health in animals and humans. There is an urgent need for the development of safe technologies for their effective removal. Originally developed for mineral processing, mechanical treatment by ball milling is an extremely versatile technique for the degradation of toxic compounds. Reactive milling can rapidly destroy organic compounds without producing hazardous wastes. Complete breakdown of the organic molecules is achieved after relatively short milling times. Successful tests were conducted on polychlorobiphenyls (PCBs), DDT, DDD, DDE, Dieldrin and hexachlorobenzene with a conversion yield in the of greater than 99% (Hall et al., 1996; Monagheddu et al., 2000; Zhang et al., 2001; Zhang et al., 2002; Tanaka and Zhang, 2003; Pizzigallo et al., 2004; Nomura et al., 2005; Bellingham, 2006).In this study reactive ball milling was used to investigate the destruction of two classes of persistent organic pollutants environmental contaminants. The compounds studied are either known environmental pollutants or simple analogues. These were chosen as being representative of pollutants to investigate the pathway using ball milling destruction and in most cases were relatively small molecules so that the intermediates could be more easily identified. The first class of compounds was polycyclic aromatic compounds. Some smaller members of this class such as naphthalene, anthracene were investigated. The second class of compounds were some analogues of environmentally hazardous hydroxylated and halogenated compounds such as chloronaphthalene, bromonaphthalene, 1- naphthol, 2-naphthol and pentachlorophenol under reactive milling using GCMS analysis of the degradation pathway. Destruction efficiencies greater than 99% have been achieved for a number of organic compounds. Several different intermediates have been identified during the milling degradation. There was also some evidence from this study that halogens could be transferred between compounds during milling. The final products of the milling destruction of these compounds are an amorphous carbon residue and inorganic chloride or bromides. It was proposed that large amounts of halogens could be found however the results showed that small amounts detected. At early stages of milling a number of intermediate breakdown products were detected which were destroyed on extended milling. The core objective of this research was to clarify the reaction mechanisms pathways used of more complex polycyclic aromatic hydrocarbons and aromatic organ halogen compounds. This study is a part of a long-term research project on the destruction of toxic organic compounds by reactive milling.
14

Enviornmental Factors Effects on Asthma in the National population Health Survey

Gu, Rongfang 03 1900 (has links)
Asthma is one of the most common respiratory diseases in Canada. It not only brings pain to more than 7.8% of Canadians but it also costs millions of dollars every year. In this project we study the influence that environmental factors have on asthma based on the data from the National Population Health Survey (NPHS) conducted by Statistics Canada. A descriptive analysis is done first to get an initial understanding of the environmental factors' effects on asthma. Then we do a x2-test to test for the homogeneity of asthma distribution across the levels of each environmental factor. Most of the factors included in our study are significant except those representing whether living in the metropolitan areas of Montreal or Vancouver, the number of persons living in the household, and whether there are small children in the household. For ordinal variables we test for trend on asthma prevalence. The trend tests indicate that there are significant trends between asthma and most of the ordinal factors except for a few, including the number of bedrooms in the household and the number of cigarettes smoked daily by the daily smokers. Then odds ratio and relative risk analyses are done to obtain statistical insights on the relative risk of the factors. The result shows that living in Nova Scotia, Ontario and Quebec, urban areas, engaged in finance, community services, personal service, young, attend physical activities, born in Canada, white, single or widowed, separated, divorced, start smoking early, do not own the dwelling living in, female adult, male children, and overweight and underweight adult, are all contributing factors for asthma. To model and investigate the joint effect of factors on asthma prevalence, we use logistic and log-linear regression models. To avoid collinearity problems, a reduced number of predictors is used. The results suggest that environmental factors have a significant joint influence on asthma prevalence. / Thesis / Master of Science (MS)
15

Greening with Care: Exploring Environmental Justice in Philadelphia's Urban Green Infrastructure Through a Feminist Labor Lens

Riedman, Elizabeth C, 0000-0001-6781-7523 05 1900 (has links)
Cities around the United States are looking to urban green infrastructure (UGI) as a critical investment to help address a host of urban challenges, including stormwater management, climate change mitigation, rising heat temperatures and increased risk of flooding. As a result, volunteers are being asked to help construct, maintain, and contribute to UGI projects. Current investigations of UGI highlight the need to consider UGI from an environmental justice perspective, emphasizing a three-pronged approach including distribution, recognition, and procedural justice. This dissertation seeks to investigate UGI equity from a labor perspective, specifically how volunteer labor is acknowledged, valued, and contributed among race, class, and gender. Using UGI initiatives in Philadelphia, PA as a case study, it asks; to what extent are urban sustainability initiatives in Philadelphia relying upon the unpaid labor of citizens in the construction of new, UGI? How might this labor exhibit unrecognized forms of social reproductive labor, when observed from an intersectional feminist perspective? How has the contribution of UGI (such as trees, parks) labor changed over time? Drawing from a range of qualitative methods, including ethnographic fieldwork, online surveys, semi-structured interviews, oral histories and archival analysis, results reveal how volunteers play a significant role in the construction and maintenance of UGI over the past hundred years, including the often-invisible contributions of women and women of color. In applying a feminist labor lens, findings suggest gender and racial inequities in how UGI labor is acknowledged and paid as infrastructure work. Future research must consider intersectional labor dimensions as a key component in achieving a more ‘just’ urban green environment for all. / Geography
16

Light intensity influences on algal pigments, proteins and carbohydrates: implications for pigment-based chemotaxonomy

Unknown Date (has links)
Phytoplankton Chlorophyll a (CHLa), total protein, colloidal carbohydrates, storage carbohydrates and taxonomic pigment relationships were studied in two cyanophytes (Microcystis aeruginosa and Synnechococcus elongatus), two chlorophytes (Dunaliella tertiolecta and Scenedesmus quadricauda), one cryptophyte (Rhodomonas salina), two diatoms (Cyclotella meneghiniana and Thalassiosira weissflogii) and one dinophyte (Amphidinium carterae) to assess if algal biomass could be expressed in other indices than just chlorophyll a alone. Protein and carbohydrates are more useful currencies for expressing algal biomass, with respect to energy flow amongst trophic levels. These phytoplankton were grown at low light (LL = 37 (So(Bmol photons m-2 s-1), medium light (ML = 70-75 (So(Bmol photons m-2 s-1), and high light (HL= 200 (So(Bmol photons m-2 s-1). / Even though pigment per cell increased with increasing light intensity, statistically light had very little effect on the CHL a : taxonomic marker pigment ratios, as they covaried in the same way. Protein, colloidal carbohydrates and storage carbohydrates per cell all increased with increasing light intensity, but they did not covary with CHLa. Statistical data showed that light intensity had a more noticeable effect on protein: CHL a, colloidal carbohydrate: CHLa, storage CHO: CHLa, therefore a general mathematical expression for these relationships cannot be generated. This study showed that light intensity does have an influence on these biomass indices, therefore, seasonal and latitudinal formulas may be required for meaningful algal biomass estimation. However, more studies are needed if that goal is to be realized. / While studying the effects of light intensity on algal pigment content and concentration, a new pigment was isolated from a cyanophyte (Scytonema hofmanii) growing between 300-1800 (So(Bmol photons¨m-2¨s-1 and from samples collected in areas of the Florida Everglades. This pigment was characterized and structurally determined to possess indolic and phenolic subunits that are characteristic of scytonemin and its derivatives. In addition, the pigment has a ketamine functionality which gives it its unique polarity and spectral properties. Based on the ultra violet/visible absorbance data, this pigment was postulated to be protecting the chlorophyll a and cytochrome Soret bands as well as a and (Sb (Bbands of the cytochromes (e.g. cytc-562) in the photosynthetic unit. / by Cidya Grant. / Thesis (Ph.D.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.
17

GIS model for assessment of land use and urban development effects on stormwater runoff: Puhinui Catchment case study

Krpo, Ana Unknown Date (has links)
As local authorities are becoming more interested in the assessment of pollutant loads, this study offers a Geographic Information System (GIS) model for assessing nonpoint source of pollution for two scenarios: the current and ultimate stage of urbanization. The Puhinui Catchment, Manukau City, has been used as a case study in developing and testing this model. This catchment has all the attributes of a "typical" urban area and gives a good representation of the effects of land use on the receiving waters of Puhinui Stream and its estuary. Annual mass contaminant loadings were calculated by firstly assessing the physical characteristics of the Puhinui catchment (case study catchment) and secondly describing the nature of storm water quality and calculating the annual mass contaminant loadings.GIS is used to multiply the annual runoff volume by a mean pollutant concentration to acquire an average annual pollutant load. The annual runoff volume is calculated from the drainage area, runoff coefficient and annual rainfall. To calculate the total mean pollutant load, the pollutant loads for all land use types within the catchment are summed and the process is applied for each pollutant. This GIS model determines the connection of typical pollutant concentrations with land uses in the catchment and offers a characterisation of nonpoint source pollution in that catchment. This model can be used for, identifying catchment areas that contribute considerably to the pollution of waterways, determining the appropriate treatment of the storm water runoff for particular sub catchment, storm water quality improvement prioritization and cost-benefit analysis, selecting locations for water-quality monitoring stations, improvement in maintenance practices, assessment of proposed development environmental effects.
18

Description, dueting, seasonal variations, and individual identification of the vocalisations of the brown kiwi (Apteryx mantelli)

Corfield, Jeremy Unknown Date (has links)
Vocalisations of the endangered Brown Kiwi (Apteryx mantelli) are currently used in a nationwide monitoring program to assess the health of a number of small remnant populations. Only an estimate of population health can be obtained from these surveys. This has to form the basis for a number of critical management decisions. The ability to identify kiwi individually during monitoring would greatly improve the accuracy and quality of information obtained and provide a wider base of knowledge when management decisions are made. This study produces a detailed description of the male and female kiwi call, including duetting and seasonal variations. It then explores whether kiwi demonstrate individually distinctive vocalisations, which could be used in conservation management of kiwi.Calls from seven male and four female kiwi were recorded from Rarewarewa, Whangarei between the 5th of May 2003 to the 31st of April 2004. Two call variables (call duration, number of syllables), two temporal syllable variables (syllable duration, syllable gap duration) and five syllable spectral variables (frequency with the most amplitude, high frequency, low frequency, start frequency, end frequency) were measured from 48 male and 14 female calls. Variables from each call were used to describe and classify calls using one way repeated measures ANOVAs and Discriminant Function Analysis. Males contained on average 24 syllables and females containing on average 22 syllables, with calls from both sexes lasting on average 28 seconds. Male and female kiwi calls differed in multiple spectral, temporal and structural features. Dueting rates and behaviour differed between pairs. Some pairs almost always called in duets, whereas others never dueted. Dueting behaviour also changed seasonally with fewer duets occurring in the non-breeding season and with females initiating more duets in the breeding season. Call structure did not differ between the breeding and non-breeding season. Although the sample size was not sufficient to test for this.Statistically significant differences occurred among nearly all variables between individual male and female kiwi calls, despite statistically significant difference occurring between syllables within calls. Frequency variables were the most important variables in discriminating between individuals, but multiple spectral and temporal variables were needed to separate all individuals. Discriminant Function Analysis was able to correctly classify 87.5% of male and 85.7% of female calls correctly when using the means of the seven syllable variables and the two call variables and 68.2% of male and 66.8% when using the values from each syllable. The latter was improved to 85.9% of male calls correctly classified when only 3 syllables from the middle of the calls were used in DFA, reflecting the variation found at the beginning and end of calls.Brown kiwi show strong signs of individually distinctive vocalisations, which remained consistent over a one year period. The conservation implications of individually distinctive vocalisations and how this feature could be incorporated into the current monitoring of kiwi are discussed.
19

The effectiveness of steel foundry by-product in the treatment of stormwater

Ren, Jiyang Unknown Date (has links)
The capacity and efficiency of melter slag (provided by New Zealand Steel) to remove heavy metals and suspended solids from stormwater samples are studied in this thesis. A series of batch tests were carried out to investigate the adsorption-desorption mechanism of the slag to remove heavy metals (Cd2+, Zn2+ and Cu2+) from working solutions. The results showed that all the tested metallic ions could be removed by mixing the melter slag with the working solutions. Adsorption and ion exchange are the dominant mechanisms in this process. The adsorption capacity follows the descending order of Cu2+ > Zn2+ = Cd2+. Varied binding energy of different metallic ions to the slag resulted in competitive adsorption between ions.A variety of substances: inorganic salts (KCl, NaCl, KNO3 and sea water), organic acids (citric and tartaric) and inorganic acids (nitric and carbonic), were tested as desorbing agents to recover the used slag. Citric acid in sea water was found to be the best in terms of desorption efficiency and cost-effectiveness.The column tests were carried out to simulate the filtration bed in laboratory conditions. Stormwater samples were collected from residential and commercial areas in Auckland. The synthetic stormwater samples were prepared from clay and metallic ion solution. Both samples were used as feeding solutions in the tests. The removal efficiencies of suspended solids and metallic ions (Zn2+, Cd2+ and Cu2+) vary depending on different operation conditions. They are in inverse proportion to the grain size of the melter slag and the influent flow rate. The higher removal efficiency of Zn2+ than that of suspended solids infers that metallic ions are removed by both precipitation and adsorption.
20

Economic valuation of the cultural heritage in Macao

Ma, Ruo Wei January 2007 (has links)
University of Macau / Faculty of Science and Technology / Department of Civil and Environmental Engineering

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