1,721,066 research outputs found
Physicochemical parameters of Bakun reservoir in Belaga, Sarawak, Malaysia, 13 months after reaching full supply level
No full textDetermining the water quality of Bakun Reservoir 13 months after it operates at full supply level is crucial for better understanding of changes in the physicochemical parameters, which may enable the prediction of its effects on the survival of aquatic life in the reservoir. This study determined 13 physicochemical parameters at six stations within the reservoir at fixed depths. The results showed that the minimum 5 mg/L of dissolved oxygen (DO) required for sensitive aquatic organisms was recorded at 6 m depth. However, DO was not detectable at depths exceeding 7 m. The water was acidic at depths of more than 10 m. Turbidity and total suspended solids increased corresponding with depth. Inorganic nitrogen were predominantly in the form of ammonia-nitrogen, creating an unhealthy environment for aquatic life. Concentration of Chl-a was significantly higher at the subsurface water than 30 m depth in four out of six stations. The present study shows changes in water quality as compared to the pre-impounded period and 15 months after the filling phase, in particular, stratification of dissolved oxygen, thermocline conditions and alkalinity. The changes varied according to the distance from the dam and may have been influenced by existing land developments within the area such as the construction of the Murum Hydroelectric Dam, oil palm plantations and timber concessionares. Though the water quality might have deteriorated, further study is needed to determine if this condition will prolong
Assessment of water quality of Batang Rajang at Pelagus area, Sarawak, Malaysia
No full textThis study was carried out to examine the water quality of Batang Rajang at Pelagus area, Sarawak, Malaysia. Water
quality was determined at 12 stations along Batang Rajang and its tributaries in terms of in-situ and ex-situ water
quality parameters. The results showed that most stations at main river were categorized as slightly polluted while
most tributaries were clean according to the Water Quality Index. The river is suffering from organic pollution where
almost all stations along the river contained high chemical oxygen demand (? 43.1 mg/L) and total ammonia nitrogen
(? 0.520 mg/L) and were classified as Class III and IV at most of the stations. High suspended solids (218.3 mg/L) and
low dissolved oxygen (4.6 mg/L) were observed at the main river. The low dissolved oxygen content from the Bakun
dam upstream of the study area has an impact on the river particularly during dry season where DO dropped below the
minimum required for sensitive aquatic organisms. As seven tributaries are within Class II indicating healthy freshwater
ecosystems, they should be conserved as habitats for sensitive aquatic organisms. Conversely, proper management need
to be initiated in particular, Sungai Merit tributary and the main river where DO were below the minimum required for
sensitive aquatic organisms
Impact of different land uses on the Escherichia coli concentrations, physical and chemical water quality parameters in a tropical stream
No full textRural streams are important source of water for the nearby communities. However, bacterial contamination from agriculture and human settlement may render the water unsuitable for drinking and body contact recreation. Hence, the objective of this study was to determine the impact of different land uses such as animal farming and human settlement on E. coli concentrations in the Serin River, a tropical stream. Samplings were conducted at 9 stations from September 2009 to March 2010. Results showed that E. coli concentrations ranged from 2,000-6,900,000 CFU/100 mL with E. coli concentrations in fish aquaculture water exceeding the WHO standard. Animal and crop farming stations showed the highest E. coli concentrations in the tributaries. Re-suspension from stream sediment and non-point sources such as runoff contributed to the high concentrations observed in the main river. Multiple linear regressions indicated that total suspended solids and
dissolved oxygen were significant water quality parameters and they explained 68.1% of the total E. coli variations observed
Modeling Escherichia Coli Concentration in Surface Runoff: the ECOLI Model.
Get PDFA biological model, ECOLI, is developed that is capable of continuously simulating E. coli concentration in surface runoff from agricultural land applied with manure. The model was calibrated and validated by using data from field-scale studies at Franklinton, Louisiana. During validation the model was interfaced with GLEAMS-SWT model to obtain the necessary hydrologic and erosion variables as input to the ECOLI model. The ECOLI model was found to perform best when simulating runoff concentration following the first application of waste. For reapplication of waste within 50 days, the trend of decrease over time was well-simulated but simulated E. coli concentrations were lower than the observed concentrations. The correlation coefficient of the simulated E. coli concentration versus the observed concentration was found to be 0.85. The regression intercept is significantly different from zero. The regression slope is 1.06 and is not significantly different from 1.0. The ECOLI model is not recommended for reapplied waste until more research is done on the effect of applied waste on subsequent E. coli density and decay. The ECOLI model is also not recommended for use in simulating fecal coliform concentration unless methods of enumerating fecal coliforms that exclude false positive counts are used. Two experiments were carried out to investigate E. coli adsorption in soil-water system of Tangi Silt Loam and Commerce Clay Loam. The adsorption of E. coli in Tangi Silt Loam was found to be significantly lower than that of Commerce Clay Loam. The distribution coefficient of loose adsorption of E. coli in Tangi soil water system was found to be significantly lower than that of tight adsorption. The distribution coefficient of loose adsorption of E. coli in Commerce soil-water system was found to be significantly higher than that of tight adsorption. Soil with higher clay content was found to adsorb significantly more E. coli than soil with lowerer clay content. Together with literature data, a high correlation (R2 = 0.89) was found between adsorption and clay content. Significant correlation (R2 = 0.67) was found between distribution coefficient and clay content. The relationships developed may be used in modeling purposes
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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