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Guidelines for assessing single borehole yields in secondary aquifers

- Murray, Eric Charles

  • Authors: Murray, Eric Charles
  • Date: 1997
  • Subjects: Aquifers -- Measurement
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:6026 , http://hdl.handle.net/10962/d1005512
  • Description: The motivation for this research project arose from the realisation that many South African rural water supply schemes fail due to the over abstraction of groundwater from single boreholes. The main reason for this mis-management of groundwater is a result of inappropriate borehole yield recommendation methods. This research project set out to review existing borehole yield assessment methods and establish new methods which take the shortcomings of existing methods into account. The study is concerned with borehole yield assessment methods applicable to secondary aquifers, since these aquifers are by far the most common in South Africa. The yield assessment methods have been grouped into those that are based on aquifer yield analyses, and on the analysis of single borehole test pump data. In order to assess which methods give suitable yield recommendations, it was necessary to compare the yields obtained using the various methods, with established yields from production boreholes. The focus of the aquifer yield component of the study, was to develop a method for estimating the proportion of recharge that can be abstracted from a single borehole located in a relatively small aquifer. The method was developed by computer simulations of aquifers with different hydraulic properties, and by establishing a formula which describes the relationship between recharge and the abstractable proportion of recharge. Under specific hydrogeological conditions, the recharge based method proved to be reliable in relation to established yields from production boreholes. Of the borehole yield assessment methods based on the analysis of test pump data, none of the existing methods proved to be reliable. However, the yields obtained using the two newly developed methods compared favourably to the established yield of existing production boreholes. Both of these methods are based on the application of the Cooper-Jacob approximation of the Theis equation. This study reviews existing methods and presents newly developed methods for recommending borehole abstraction rates in secondary aquifers. While existing borehole yield assessment methods were found to be unreliable, some of the newly developed methods, if correctly applied, give acceptable yield recommendations.
  • Full Text:
  • Date Issued: 1997

Healing stories of the unconscious: past-life imagery in transpersonal psychotherapy

- Knight, Zelda Gillian

  • Authors: Knight, Zelda Gillian
  • Date: 1997
  • Subjects: Transpersonal psychotherapy Unconscious Reincarnation therapy
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3004 , http://hdl.handle.net/10962/d1002513
  • Description: Theoretically this thesis was grounded in the discourse of transpersonal psychology and the related discourse of transpersonal feminism. The focus was on a particular category of transpersonal phenomena - past-life experiences. These experiences were viewed from a poetic and therapeutic perspective as being healing stories of the unconscious that served to articulate psychological and spiritual realities of the human psyche within both the personal and the collective unconscious. They were thus not questioned in regard to their literal occurrence. The central aims of this thesis were to (a) document and faithfully describe a participant's past-life experiences that occurred during selected psychotherapy sessions, (b) engage in a hermeneutic dialogue between the participant's past-life experiences and contemporary transpersonal literature, and, in so doing, to evaluate and extend existing theory, (c) uncover the archetypal significance of past-life experience and its relationship to the re-emerging Feminine within patriarchal culture and, finally, (d) show how the past-life stories and images contribute to the process of inner healing and transformation, a process termed 'spiritual emergence'. The research was a phenomenological-hermeneutic case study, comprising the selection of eight consecutive psychotherapy sessions in which nine past-life experiences were identified. These sessions were reduced to narrative synopses, and a hermeneutically grounded thematic analysis of a total of six past-life themes were explicated. Principle conclusions reached were that past-life stories and images contribute to the process of spiritual emergence and empowerment as well as to the re-emergence of the Feminine consciousness. Moreover, as healing stories of the unconscious, these past-life experiences can be understood as expressions of the collective struggle with unresolved archetypal forces within the collective psyche, as well as echoes of personal conflicts and dilemmas from the individual unconscious.
  • Full Text:
  • Date Issued: 1997

Himani ngoku

- Performer not specified, Composer not specified, Group Composition, Dargie, Dave

Homna Homna

- Performer not specified, Ntsikana, Group Composition, Dargie, Dave

Icamagu livumile

- Hogsback festival participants, Ntsikana, Dargie, Dave

Icamagu livumile

- Hogsback festival participants, Thukani, M. J., Dargie, Dave

Idolatry and the artist's role with special reference to the work and thought of Andy Warhol

- Waterkeyn, Linda Catherine

  • Authors: Waterkeyn, Linda Catherine
  • Date: 1997
  • Subjects: Warhol, Andy, 1928-1987 -- Criticism and interpretation
  • Language: English
  • Type: Thesis , Masters , MFA
  • Identifier: vital:2425 , http://hdl.handle.net/10962/d1002221
  • Description: This thesis uses Hirsch's dual notion of intention, i. e. conscious, intentional meaning and symptomatic, unconscious meaning, in order to avoid a dead end in the critical assessment of Warhol's work. T.S. Eliot's term "objective correlative" refers to a phenomenon whereby "an inner emotional reality" is evoked by its "external equivalent". (Benet, 1965). Thus, given that no work of art is purely self-referential (as distinct from its being autonomous),Hirsch's notion allows that viewerreconstruction of a painting involves shared values and concerns; that a painting reconstructed by a viewer acquires the status of an icon through which the viewer participates in the artist's sacred cosmos. Sociology of art tends on the whole to extrapolate from actual works to the alleged conditions that gave rise to them. That it cannot predict what specific works will arise from given conditions makes it unscientific. However, its usefulness lies in its ability to reveal what values and concerns are shared by artist and viewer. This is vital for an interpretation of Warhol's work. Warhol's biography leads directly into the meaning of his work. The sickly child of an immigrant steelworker, he grew up in Pittsburgh - an epitome of the technocratic-industrial environment - and was exposed from an early age to a violent and ugly world where the disparity between the super-wealthy and the struggling workers was deeply disturbing. That Warhol himself became a multi-millionaire artistic tycoon is significant, for it means that his works, his icons, were participatory in the very cultural myths and neuroses they appear to display or even despise. That his work has meaning and is open to interpretation there is no doubt. For example, a man-made soup can, as a manifestation and containment of the sacred, is coercive. Here the sacred becomes familiar, affordable and disposable. An electric chair, a man-made instrument of death, gives man supremacy over mortality and the divine prerogative of purging the world of all evil. The essay, however, does not attempt to answer the broader questions raised by Fromm and Roszak about the spiritual emptiness of the twentieth century and the existential crises experienced by those who hunger for meaning and fasten greedily onto anything that seems to proffer a glimpse of something beyond. The essay, nevertheless, strives within this context to elucidate the valid in Warhol's work
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  • Date Issued: 1997

Iinjongo ze Self-Employed Womens Union

- SEWU

  • Authors: SEWU
  • Date: 1997
  • Subjects: SEWU
  • Language: English,Xhosa,Afrikaans, Zulu
  • Type: text
  • Identifier: http://hdl.handle.net/10962/154981 , vital:39813
  • Description: ISEWU yimanyano yamakhosikazi azisebenzelayo ngokwawo abangenawo umsebenzi osisigxina. Ungazimanyaxa uyinkosikazi eziphilelayo ngoluhlobo lulandelayo: Xa uzisebenzela ngokwakho ungaqashanga bantu bangaphezu kwesithathu; Xa usebenzela abantu bengakuqashanga isigxina; Xa usenza umsebenzi ongekho phantsi kwayo nayiphi imanyano; Xa usebenza umsebenzi wethutyana (casual). Imali yokuzimanya ne SEWU yi Rl 0.00, umrhumo wenyanga yi R5.00 emva kokuba ujoyinile. Uyakuthi ufumane ikhadi lobulungu elizakuthi libonise imirhumo yakho, kunye ne risiti njalo xa ubhatala. ISEWU inazo nee ofisi zokucebisa (Advice Offices) amakhosikazi asebenzayo angekho phantsi kwayo nayiphi imanyano. Wamkelekile uze kuboniswane / ngengxaki yakho sibone indlela esinokuyisombulula ngayo.
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  • Date Issued: 1997

Investigations into the dietary protein requirements of juvenile spotted grunter, Pomadasys commersonnii (Haemulidae : Pisces)

- Irish, Abigail

  • Authors: Irish, Abigail
  • Date: 1997
  • Subjects: Fishes -- Nutrition , Pomadasys -- Nutrition , Grunts (Fishes) -- Nutrition
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5292 , http://hdl.handle.net/10962/d1005137 , Fishes -- Nutrition , Pomadasys -- Nutrition , Grunts (Fishes) -- Nutrition
  • Description: The proximate composition of juvenile spotted grunter, Pomadasys commersonnii and their major prey items were analyzed to test the hypothesis that the dietary protein requirements would approximate the composition of the natural diet. The amino acid profile of juvenile P. commersonnii was analyzed to establish the pattern of limiting amino acids for this species. Juvenile P. commersonnii feed primarily on the mysid, Mesopodopsis slabberi, which has a protein content of 58.27±0.04% and a calorific value of 19.2kJ/g. The first-limiting essential amino acid for this fish was found to be lysine and it was predicted that the optimal dietary protein requirement would be between 50 and 60%. The optimal dietary protein inclusion level was investigated by feeding semi-purified diets containing graded levels of protein, ranging from 37-62%. Maximum growth was found to occur at dietary protein levels ranging from 40-51%. The best food conversion ratio was achieved at 56% dietary protein and the best protein efficiency ratio was obtained at a dietary protein inclusion level of 37-40%. The protein to energy ratio was defined by feeding 3 different protein levels at 3 different P:E levels. These semi-purified diets contained 35, 45 or 55% protein and 6, 8 or 12% dietary lipid, resulting in protein to energy ratios ranging from 21.1 to 42.3mg/kJ. The optimal P:E ratio for this species was found to be 26.7mg/kJ. This diet effected a low food conversion ratio (1.72±0.19), a low hepatosomatic index (4.01±0.23) and a high specific growth rate (5.96±0.36). The essential amino acid requirements of juvenile P. commersonnii were investigated. Semi-purified diets were formulated to contain graded levels of crystalline lysine based on the amino acid profile of the whole body and fed to the fish for a period of 60 days. Fish fed the "ideal protein" diet had significantly higher (p<0.05) specific growth rates (2.95±0.18), protein efficiency ratios (0.41±0.05) and significantly lower (p<0.05) food conversion ratios (3.02±0.29). Lysine levels in the whole body increased with increasing levels of supplemented lysine. The dietary requirement of lysine was found to be 4.30% of dietary protein. The crude protein digestibility of six protein sources was investigated. Diets were prepared with 1% chromic oxide as an internal marker. The tested protein sources included low temperature Danish fishmeal, steam dried Chilean fishmeal, blood meal, carcass meal, defatted soyabean meal and Spirulina meal. These potential fishmeal substitutes were selected due to their favourable amino acid profiles, and in particular their high levels of lysine, and their high protein content. Both the animal and the plant protein sources were highly digestible. Digestibility co-efficients ranged from 66.09% for Spirulina meal to 73.38% for low temperature Danish fishmeal. The results have shown that juvenile spotted grunter require a minimum of 40% crude protein in their diet, a P:E ratio of 26.7mg/kJ and a lysine concentration of 4.30% of the dietary protein. Long term growth trials are needed to confirm these results. The hypothesis that the proximate composition of the natural diet, and the proximate composition of the animal under investigation, provides a reliable indication of the animals' nutritional requirements was shown to be valid. Differences between the predicted, and the empirically determined optimal protein and protein:energy ratios were slight.
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  • Date Issued: 1997

Investigations into the larval rearing of two South African sparid species

- Davis, Jerome Adam

  • Authors: Davis, Jerome Adam
  • Date: 1997
  • Subjects: Sparidae
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5293 , http://hdl.handle.net/10962/d1005138 , Sparidae
  • Description: The most significant bottleneck to the development of marine finfish culture is a reliable production of juveniles for growout. This is due to the small size at hatch and delicate nature of the pelagic larvae produced by most commercially desirable species. However, over the last 30 years, improved larviculture techniques have been developed to the extent that many species are being successfully cultured worldwide. These techniques were applied to two endemic species as a preliminary step towards establishing marine finfish aquaculture in South Africa. Adult roman Chtysoblephus laticeps and carpenter Argyrozona argyrozona (Pisces: Sparidae) were caught in the Tsitsikamma National Park. Both species responded to injection with pituitary extract, HCG and LHRHa, and were succesfully stripped up to 48 hours after injection. Fish were stripped twice, the second stripping producing better quality eggs. Chyrysoblephus laticeps also spawned naturally after injection with LHRHa. The fertilised eggs were incubated and the larvae reared in a fully recirculating seawater system. One batch of A. argyrozona and three batches of C. laticeps were reared through metamorphosis on a diet of enriched rotifers and Anemia, and inert foods, following commonly used rearing procedures. Both species followed developmental patterns of other cultured larvae, displaying typical critical stages; high mortalities at first-feeding and cannibalism from 26-30 days after hatch resulted in survival rates ranging from 0.1-0.5%. Growth, survival, size of gape at first-feeding, and ease of weaning onto an inert diet of C. laticeps was comparable to other species being reared for the first time, indicating some potential as a candidate species. The numbers of A. argyrozona larvae reared were insufficient to make comparisons with other studies. The adults also proved to be susceptible to physical damage while in captivity and were, therefore, considered unsuitable for aquaculture. The thesis describes the spawning procedure, the systems developed and the larval rearing process. The critical stages of first-feeding, swim bladder inflation, settlement and cannibalism are discussed and the development of the larvae described. The ontogeny of both species is described in detail. Both species displayed typical sparid developmental patterns, but differed with respect to pigmentation, head spination and morphometrics.
  • Full Text:
  • Date Issued: 1997

Isolation and identification of Beta-Lactam Producing Microorganisms using PCR based methodologies

- Krallis, Myrsini

  • Authors: Krallis, Myrsini
  • Date: 1997
  • Subjects: Polymerase chain reaction , Bacterial genetics , Fungi -- Genetics , Beta lactam antibiotics , Microbial enzymes
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4155 , http://hdl.handle.net/10962/d1018237
  • Description: The polymerase chain reaction (PCR) was investigated as a potential tool in microbial screening for 13-lactam. producing organisms. Optimization of PCR conditions and the addition of acetamide to the PCR reaction allowed for the successful amplification of the isopenicillin N synthetase (lPNS) gene in S. clavuligerus, S. tanashiensis, S. griseus, S. olivaceus, S. lipmanii, and S. chartreusis. PCR was used to produce a radiolabelled probe from S. clavuligerus that was used to detect analogous genes in bacteria and fungi. Southern blot and dot blot analysis using the lPNS probe revealed the presence of IPNS-like sequences in seventeen organisms. Fourteen of these sequences belonged to known 13-lactam. producing organisms; one unidentified soil isolate; and two non-/3-lactam. producing organisms viz. S. venezuelae ATCC 10712 and S. hygroscopicus ATCC 21703. The lPNS gene was also detected in a 13-lactam producer (S. chartreusis) that had lost its ability to produce antibiotic. It would therefore have been overlooked in a conventional antibiotic screening program. The use of PCR, coupled with Southern hybridization and dot blot analysis, increased the sensitivity and specificity of the antibiotic screening procedures and allowed for the investigation of evolutionary relationships between the eukaryotes and the prokaryotes. A preliminary investigation into the potential use of RAPD PCR and protein fmgerprinting as tools for solving discrepancies in streptomycete identification was conducted. A variety of streptomycete species that were chosen as being representative of a number of numerical taxonomic classes were amplified using various RAPD primers. Streptomycetes appear to be genetically diverse organisms as was reflected by their RAPD and protein profiles. The application of PCR in an antibiotic screening program showed great potential as a specific and sensitive tool in the detection of /3-lactam producers and in the elimination of duplicate strains.
  • Full Text:
  • Date Issued: 1997

Izani Marhanuga

- Performer not specified, Composer not specified, Group Composition, Dargie, Dave

Juvenile diversion: keeping children out of prison

- Lewis, Sharon

  • Authors: Lewis, Sharon
  • Date: 1997
  • Subjects: Juvenile delinquents -- South Africa , Juvenile justice, Administration of -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: vital:3682 , http://hdl.handle.net/10962/d1003197 , Juvenile delinquents -- South Africa , Juvenile justice, Administration of -- South Africa
  • Description: This thesis covers the topic of juvenile diversion with respect to keeping juveniles from progressing further into the justice system as well as keeping them out of prison. It deals with a number of areas. The first is diversion before an offence has been committed - prevention. Here a number of recommendations are made with respect to education of the child and the community in order to make prevention a priority when new diversion programmes are considered and introduced. The second area is that of diversion after the offence has taken place. This deals with diversion by the police at the moment of apprehension and recommends the introduction of cautions as a diversionary measure. The third aspect that is considered is diversion after the juvenile has been arrested and/or charged. The establishment of Reception and Assessment Centres and the setting up of Family Group Conferences are especially highlighted. The detention of the child until his/her trial is also investigated and it is concluded that this is an unnecessary measure except in extreme circumstances. The progression of the child's case to court is the fifth area considered. Here, recommendations are made as to the necessity for the proper training of court personnel and the need for the introduction of court imposed diversionary programmes before sentencing. With respect to diversion after the child has been found guilty, a number of suggestions are made as to the introduction of new sentencing options and new or improved institutions. Finally, recent reforms are discussed. The conclusion reached is that juveniles should not be imprisoned except in the most extreme cases, and that diversion programmes should be instituted as soon as possible as the basis of SouthAfrica's juvenile justice system. It is deemed essential that diversion begins with prevention and continues until sentencing is completed, and that all children are diverted unless this is not possible.
  • Full Text:
  • Date Issued: 1997

Knowledge of safe sex practices and HIV transmission, propensity for risk taking, and alcohol/drug use in the aetiology of unprotected sex

- Simpson, Malcolm Robert

  • Authors: Simpson, Malcolm Robert
  • Date: 1997
  • Subjects: HIV infections -- Prevention , Safe sex in AIDS prevention
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:3146 , http://hdl.handle.net/10962/d1007421 , HIV infections -- Prevention , Safe sex in AIDS prevention
  • Description: Second year psychology students (N=176) from Rhodes University were surveyed using an anonymous questionnaire to obtain information on sexual behaviour and knowledge of the acquired immunodeficiency syndrome (AIDS) among young people. The following information was obtained: Knowledge of safe sex practices and HIV transmission was high although a number of misconceptions were noted. Only fifty six percent of students viewed oral sex with a condom as safe and thirty one percent do not consider mutual masturbation with a condom safe. Thirteen percent and twenty five percent respectively identified insects and saliva as being routes of HIV transmission. Magazines (96%), informal discussions with friends (95%), public pamphlets (86%) and public television (79%) were preferred sources of information. The students' knowledge did not appear to significantly affect sexual behaviour. Eighty percent of respondents were intimately involved with another person during the past twelve months, and only fifteen percent always made use of a latex barrier when being sexually intimate. Despite high rates of alcohol and/or drug consumption (80% of students use such substances), and the belief by the majority of respondents that alcohol and/or drugs facilitate higher risk behaviours, no support for the alcohol/risky sex hypothesis was found. Students were found to score highly on proneness to psychological and behavioural risk taking, and no significant relationship between this and unprotected sex was found. It can be concluded that educational programmes need to focus on what constitutes safe sexual practices in order to equip young adults with the knowledge they need to make informed choices regarding the relative risks of various sexual activities.
  • Full Text:
  • Date Issued: 1997

Kuyasetyenzwa

- Group performance, Group composition, Dargie, Dave

Learning from the people : participatory rural appraisal, geography and rural development in the 'new' South Africa

- Binns, Tony, Hill, Trevor R, Nel, Etienne L

  • Authors: Binns, Tony , Hill, Trevor R , Nel, Etienne L
  • Date: 1997
  • Language: English
  • Type: Article
  • Identifier: vital:6675 , http://hdl.handle.net/10962/d1006649
  • Description: Top-down rural development strategies in Africa have generally not succeeded in raising living standards among the rural poor. It is argued that inappropriate development strategies have stemmed from methodologies that fail to appreciate the whole picture in rural communities, and in particular ignore local people's perceptions, needs and understanding. Participatory Rural Appraisal (PRA) represents a significant step forward in the design of methodologies and a selection of these techniques is evaluated. Many PRA methods have much in common with the field research methods that have been used by geographers over many years to interpret people-environment relationships. A research investigation in Eastern Cape Province, South Africa, suggests that geographers could have an important role to play in this area of applied research and, in particular, in the context of post-apartheid South Africa there is an urgent challenge to be met in promoting rural development in poor, former black Homeland areas.
  • Full Text:
  • Date Issued: 1997

LRA Trainers Course

- FAWU

  • Authors: FAWU
  • Date: 1997
  • Subjects: FAWU
  • Language: English
  • Type: text
  • Identifier: http://hdl.handle.net/10962/176123 , vital:42661
  • Full Text:
  • Date Issued: 1997

Macroinvertebrate community and species responses to chlorinated sewage effluent in the Umsunduze and Umbilo rivers, Kwa Zulu-Natal, South Africa

- Williams, Margot Lluttrell

  • Authors: Williams, Margot Lluttrell
  • Date: 1997
  • Subjects: Sewage -- Environmental aspects -- South Africa -- KwaZulu-Natal , Sewage -- Purification -- Chlorination -- South Africa -- KwaZulu-Natal , Baetis -- South Africa -- KwaZulu-Natal , Mayflies -- South Africa -- KwaZulu-Natal , Chlorine -- Environmental aspects -- South Africa -- KwaZulu-Natal
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5727 , http://hdl.handle.net/10962/d1005413 , Sewage -- Environmental aspects -- South Africa -- KwaZulu-Natal , Sewage -- Purification -- Chlorination -- South Africa -- KwaZulu-Natal , Baetis -- South Africa -- KwaZulu-Natal , Mayflies -- South Africa -- KwaZulu-Natal , Chlorine -- Environmental aspects -- South Africa -- KwaZulu-Natal
  • Description: Chlorine has a wide variety of applications in water treatment. Because of its disinfectant efficacy, it is used world wide for the treatment of potable water, sewage, swimming pools and for the control of nuisance organisms in cooling towers. A problem arises when such chlorinated water enters the natural environment, as chlorine's greatest advantage, i.e. its germicidal capacity, becomes its greatest disadvantage. In particular, the discharge of heated, chlorinated water from cooling towers and chlorinated, treated sewage into rivers have severe consequences for the riverine flora and fauna. This study focused on the effects of chlorinated, treated sewage effluent on the community structure of benthic macroinvertebrates in two rivers in KwaZulu-Natal viz. the Umsunduze River in the Pietermaritzburg area, and the Umbilo River in the Durban area. The study was conducted in three phases. The first two phases comprised a toxicological investigation of the effects of chlorine on a selected riverine macroinvertebrate, and the third phase comprised an ecotoxicological investigation of the effects of chlorinated treated sewage on benthic macroinvertebrate community structure. The first phase of the study involved the development of an artificial stream system which would be suitable for determining the response of a selected macroinvertebrate species to chlorine. Chlorine is both reactive and volatile, so this necessitated the development of a specialised flow-through system with apparatus which would allow continuous dosing of a sodium hypochlorite solution. The system was set up at the Process Evaluation Facility at Wiggins Waterworks, Durban, where raw water from lnanda Dam was used. The second phase involved the use of this artificial stream system to conduct acute 96 h toxicity tests. Baetid mayfly nymphs (Baetis harrisoni Barnard) were selected as the test organisms after a preliminary investigation found them to be suitable for survival under laboratory conditions. For comparative purposes, tests were run first on B. harrisoni from a relatively uncontaminated stream in a residential area of Westville, then on specimens from the severely impacted Umbilo River. The LC₅₀ of chlorine for organisms from both sources was found to be in the region of 0.004 mg/l (free chlorine). This value was well below the general effluent standard of 0.1 mg/l in effect at the time. The recommended acute environmental guideline is 0.001 mg/l. The third phase of the study involved field validation of the toxicity test results. It was hypothesised that since the LC₅₀ for free chlorine was 0.004 mg/l, B. harrisoni would not be found downstream from a point source of chlorinated effluent where the concentration of free chlorine ranged from 0.06 to 0.2 mg/l, and that the macroinvertebrate community structure would also be altered. In order to test these hypotheses, benthic macro invertebrate community structure was investigated at several sites up- and downstream from the outlets of the Darvill Wastewater Works in the Umsunduze River and the Umbilo Sewage Purification Works in the Umbilo River. In addition, in order to differentiate between the effects of chlorinated and unchlorinated treated sewage, a section of the Umbilo River (upstream from the chlorinated discharge) was exposed to unchlorinated, treated sewage. In this way, a limited "before and after" sewage and an "upstream and downstream" from sewage investigation could be carried out. Organisms were collected from riffles (and from pools in the Umbilo River) and the samples were then sorted and organisms were identified to species level, where possible, otherwise to genus or family. Changes in community composition were shown graphically as pie charts of relative proportions of organisms found at each site, graphs of the average number of taxa at each site; and graphs of the average number of individuals at each site; Data from the Umbilo River were also analysed using TWINSPAN (Two-way indicator species analysis). In both the Umsunduze and the Umbilo rivers, the deleterious effects of the chlorinated effluent were clearly evident. At Umsunduze Site 3 and Umbilo Site 5 (both immediately downstream from the chlorinated effluent) both the number of taxa and number of individuals were substantially reduced, sometimes to zero. Where organisms were found at the next sites downstream (Sites 4 and 6 respectively), the samples were dominated by Chironomus. In contrast, the unchlorinated effluent in the Umbilo River caused very little difference in community structure. As predicted, B. harrisoni was not found in downstream samples in which chlorine was present, yet appeared to be relatively unaffected by the unchlorinated effluent, suggesting that chlorine, rather than the effluent was responsible for its absence at downstream sites. In conclusion, it would appear that while treated sewage effluent certainly causes changes in macroinvertebrate community structure, chlorination of this effluent leads to large scale destruction of the riverine community. This in turn delays the recovery process of the river, rendering a longer stretch unfit for use. The consequences of this delayed recovery are that the failure to meet the water quality requirements of the natural environment results in those of the other water users (agriculture, industry, domestic and recreation) not being met. This reduces the natural capacity of the riverine community to process organic waste and recover from the discharge of sewage effluent. Chlorination increases the distance of impaired water quality and environmental integrity which result from organically enriched treated sewage effluent. The results of the study indicated that the draft water quality guidelines for aquatic ecosystems, derived from inadequate data, and calculated with a safety factor, were the correct order of magnitude. The approach followed in the study will be useful in the development and refinement of water quality guidelines for aquatic ecosystems.
  • Full Text:
  • Date Issued: 1997

Maguqela lendawo

- Performer not specified, Composer not specified, Dargie, Dave

Maguqela lendawo

- Group performance, Group composition, Dargie, Dave

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