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121.
Two small piped sources deriving from a single farmyard together with the receiving second order stream above and below the farmyard region were sampled over a two-year period. Although not measured directly, observations at the time of sampling suggested that maximum drain flow was about 2% of downstream base flow. Both point sources were flowing on each sampling occasion (~62) and usually had concentrations of phosphorus (P), nitrate (NO(3)-N) and biological oxygen demand (BOD) well above those from the upstream site. Individual sample concentrations ranged over more than two orders of magnitude for most determinants and a large proportion of the total P was present as soluble (inorganic and organic) and therefore labile forms. More than 70% of samples collected at the downstream site had concentrations that were >1.2 times those of the corresponding upstream site. On certain sampling occasions >80% of total dissolved phosphorus (TDP) and >90% of the BOD and NO(3) instantaneous load appeared to originate from the farmyard region with the composition of downstream samples being completely overwhelmed after the passage through the farmyard. Extrapolations using instantaneous loads suggest that the farmyard and adjacent areas contributed on average 25-30% of the total and dissolved annual downstream P load of 3 kg P ha(-1) and 1.7 kg P ha(-1), respectively. There was no clear relationship between the relative proportion of the contaminant loading originating from the farmyard region and hydrological events. This emphasises the potential localised significance that small, highly concentrated, continuous or semi-continuous farmyard sources can impact headwater streams during periods of low stream flow. 相似文献
122.
生化需氧量(BOD5)作为环境监测重要参数之一,是一项重要的反应有机污染的指标。 BOD5分析过程一个复杂的生化过程,受到许多客观环境因素的影响,如样品温度、环境温度、搅拌速度,仪器校正等。采用膜电极法测定BOD5时,综合考虑,做好质量控制,可获得满意的测定结果。 相似文献
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为促进干旱区湖泊健康发展,分析了博斯腾湖大湖区湖水多年溶解氧与五日生化需氧量、高锰酸盐指数、总磷、总氮和氨氮的动态特征:1991年-2014年(2009、2012除外)水体溶解氧为6.71~9.20 mg/L,最高值与最低值分别在2005年和2006年,此与2005年水位最高,而后下降的特征一致;五日生化需氧量在0.5~6.99 mg/L变幅较大,并与溶解氧同年出现最高值,且二者符合线性回归关系y=0.213x+7.053;高锰酸盐指数波动明显;总氮和总磷则较平稳;氨氮从0.01 mg/L升至最高值0.45 mg/L.高锰酸盐指数和总氮对水质影响最大. 相似文献
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从接种液种类、空白BOD5大小、接种液最佳添加范围等方面对BOD5测定进行探讨,提出以接纳工业废水的河水作为最佳接种液,雨季时以土壤浸取液更适合。探讨了接种液空白值对BOD5标液和工业废水的影响,结果表明,河水空白应控制在0.1-0.8mg/L土壤浸取液空白控制在0.01-0.10mg/L为宜。 相似文献
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Emerald M. Roider Donald Dean Adrian 《Journal of the American Water Resources Association》2007,43(2):322-333
Abstract: Selection of a biochemical oxygen demand (BOD) reaction model to incorporate into dissolved oxygen (DO) water quality models is an overlooked choice available to river water quality modelers. Data from rivers can serve in screening methods to discriminate between competing water quality models. In this study, 15 published BOD and DO datasets based on a 7 year long study of the Bormida River in Italy are used to calibrate three‐multiorder BOD models: first‐order, three‐halves order, and second‐order, which are then included in three corresponding DO models which incorporate these BOD models. The adequacy of the first‐order, three‐halves order and second‐order BOD models was evaluated by calculating the root mean square error between a model and data. A similar procedure was followed to evaluate three DO models, each of which incorporated one of the three BOD models. The first‐order BOD model most frequently fit the river data best, followed by the three‐halves order and the second‐order BOD models. The DO model incorporating a first‐order BOD model most frequently fit the data best, followed by the DO order incorporating second‐order BOD and the DO model incorporating three‐halves order BOD. 相似文献
129.
Removal of copper from aqueous solutions containing 100–1000 ppm, using different Indian bark species, was performed on laboratory scale. The percentage removal of metal ions depends on the solution pH, bark species and time. The efficiency of copper removal by the used raw barks increases with a rise of solution pH and reaches a maximum of about 65–78% around pH 4–5. However, the decontaminated aqueous solutions were colored due to the dissolution of soluble organic compounds contained in the raw bark. This increases the biological and chemical oxygen demand (BOD and COD) of the solutions as well as the total organic carbon content (TOC). For this reason, raw bark should be treated either by chemical or biological means. Such treatment will allow the extraction of the soluble organic compounds and increase the chelating capacity and efficiency of the treated bark. Depending on the pH value, the chelating efficiency of treated barks is about 1.2–2.2 times that of the raw ones. Moreover, the retention capacity of the Indian treated bark varies from about 42–51 mg/g of dry bark. It is equal to or higher than that of common European species. About 1.8 mols of H3O+ are released, by the treated barks, for every mol of chelated copper ions. Moreover, scanning electron microscopy (SEM) observations show uniform distribution of metal ions throughout the copper saturated bark. Infra red (IR) spectra suggest that the copper ions are chelated to hydroxyl and/or carboxyl functional groups of organic compounds contained in the treated bark. It seems that the interaction of the copper ions with the bark follows a cation exchange mechanism. This hypothesis is supported by elution experiments that allow recovery of about 99% of the contained copper. The retention capacity of the treated bark is almost constant after five cycles of chelation–elution, suggesting that the ‘life time cycle' is sufficiently long for continuous industrial application. The spent copper loaded barks can either be incinerated or pyrolysed. It generates solids containing either ≈80% of CuO or ≈14% of Cu°, respectively. Such materials can be used either in the secondary or primary copper production, thus offering a friendly environmental solution of effluents' treatment. The suggested process can be used as an alternative to the classical technologies for effluent decontamination. It is also efficient for polishing effluents treated by other methods. 相似文献
130.
生化需氧量的差压式测定方法的研究 总被引:1,自引:0,他引:1
本文研究了用差压式直读测定实验装置测定生化需氧量(BOD5)的方法,验证了用该新技术测定BOD5的可行性。该方法操作简单、直观性好,简化了大量烦琐操作并可连续测定。经对水样分析并用标准稀释法的分析结果加以比较,获得良好的效果。 相似文献