Abstract:Flood hydrographs from ephemeral streams in arid areas provide valuable information for assessing run-off and groundwater recharge. However, such data are often scarce or incomplete, especially in hyper-arid regions. The hypothesis of this study was that it is possible to reconstruct a hydrograph of a specific point along an ephemeral stream with the knowledge of only the peak flow rate of a flood event at that point and that this can be done at almost every point along the stream. The feasibility of this approach lies in the shape of the recession stage of the flood hydrograph, which is known to be a repeating phenomenon. The recession stage comes immediately after the peak flow rate, when it begins its decline, and lasts until the flood is extinguished. A general shape of the flood recession stage can be provided. Because the recession stage represents~80% of the duration of a flood event, it can provide a general idea of the flood hydrograph's shape. A simple model based on geometric progression is suggested to describe the repeating recession stage of a flood. The advantage of the proposed model is that it requires only one parameter: the recession characteristic at a fixed point along the ephemeral stream, termed recession coefficient q. By knowing the recession coefficient of a fixed point and the peak flow rate of a flood event at that point, one can plot the flood hydrograph. A good agreement is shown between the observed and computed values of the recession stage.
Abstract. Policy regarding effluent water and reclamation aims to prevent environmental pollution while proposing an alternative water resource. Water makes up 99-99.9% of raw wastewater. Thus extracting organic and inorganic matter from water is a must. Worldwide, but especially in developed countries, great effort has been made to reuse wastewater, and it is becoming a reliable alternative source. Israel is the world leader in water reuse, allocating 85% of effluent water for agricultural 10 irrigation. As such, it constitutes a "living laboratory" in which to study the implications of the intensive use of treated wastewater for agricultural irrigation, leading to research and legislation regarding effluent quality and regulation. Effluent produced in Israel is subject to severe regulations and standards and is considered suitable for every use except drinking water.It is mostly allocated for agricultural irrigation with no restrictions. The irrigated lands are close to natural water sources, and therefore water leaching from the fields infiltrate those sources, becoming part of the water cycle. A group of persistent and 15 toxic nano-and micro-organic contaminants, including pharmaceutical residues, flows to water-treatment plants from hospitals, industry, agriculture and especially the domestic sector. These contaminants' chemical structure, characterized by a couple of aromatic rings and double bonds, makes them especially persistent; they are resistant to conventional biological treatment, used as a secondary treatment. As a result, the effluent that leaves the treatment plants, which is considered to be of high quality, actually contains pharmaceutical residues. After secondary and tertiary treatment, these persistent chemical 20 residues can still be found in surface water, groundwater and agricultural products. Pharmaceutical residues in effluent allocated for agricultural irrigation are undesirable. Expansion of the monitoring system for those contaminants, improvement of the tertiary treatment, and implementation of advanced technologies for decomposition and removal of pharmaceutical contaminants are thus needed.
High drug consumption and polypharmacy, especially in the elderly, is one of the 21 st century phenomenon. It has different undesirable side effects, which may directly affect the environment. It is known that pharmaceutical residues are excreted via patients' urine or feces to waste water, which is then discharged to the environment. Therefore high drug consumption is contributing to the continual rise in pharmaceutical residues in the aquatic environment, and address a rising cause for concern. Alternative treatments that can relieve or improve the patient's clinical condition, thereby reducing the consumption of pharmaceuticals, hold great potential for reducing drug residues in the environment. The purpose of this research was to evaluate the reduction in pharmaceutical consumption in a nursing home for the elderly, as a result of treatment with medical cannabis. With time, medical cannabis treatment dramatically improved patients' symptoms and their medical indexes. As a result, the local physicians stopped prescribing drugs that were defined as unnecessary. Overall, 39 dosages of prescription drugs were cancelled for the 19 elderly individuals included in this research, indicating that medical cannabis can be an effective treatment that also reduces the environmental drug load, thereby preventing water pollution.
This study represents, detailly, the validated method for the extraction and quantification of widespread phthalic acid esters (PAEs) bis(2-ethylhexyl) phthalate (DEHP), din -butyl phthalate (DBP) and din -octyl phthalate (DnOP) from solitary ascidians collected from a marine environment. The extraction was based on a pressurized liquid extraction method, using n-hexane as the solvent to extract the target PAEs from dry biological tissues, and was performed in an accelerated solvent extraction instrument. The average recovery of 89.2% was obtained from samples subjected to a pressure of ~1500 psi and 120˚C in two 10-min cycles. GC-MS was used for quantification, conducted in single-ion monitoring mode. Following careful and rigorous cleanup procedures to prevent cross-contamination from laboratory glassware, PAE standards showed signals with good specificity. The obtained limits of detection were 130, 122 and 89 ng/g for DEHP, DBP and DnOP, respectively. Accordingly, the calculated limits of quantification were 394, 370 and 270 ng/g for DEHP, DBP and DnOP, respectively. The obtained linearity ranged from 5.4 to 269 ng/ml (equivalent to 135-6725 ng/g dry weight), with R 2 ≥ 0.998. Concentrations in the range of 200 to 9000 and 400 to 5000 ng/g sample dry weight, for DEHP and DBP, respectively, were obtained from the ascidians. No DnOP was detected in any of the samples. These results indicate that the method presented in this study is applicable for detection of low and trace concentrations of the target PAEs in samples collected from a marine organism, which can serve as a bioindicator of plastic contamination.
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