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The proposed method of computing the amount of sediments transported during floods as proposed by Howard H. Chang is worthy of consideration but it cannot be justified as a gravel-transport formula. The sediment transport formula is just one of the parts of the model that also include hydraulic and other processes. It is only when the other elements of the models give totally correct solutions that it could be used as a gravel-transport formula. Also, the reach selection and hydraulic conditions of the stream have to be analyzed beforehand in order to simplifythe hydraulic computation process.

A new analytical method has been developed and described for the rapid determination of pendimethalin and its major metabolite M455H001 in soil by liquid chromatography coupled with ion-spray tandem mass spectrometry (LC-MS/MS) after a single acidic solvent extraction. The chromatographic separation of the analytes was achieved using a Zorbax C18 reversed phase column and water/0.1% formic acid and methanol as the mobile phase at a flow rate of 0.2 mL min−1. The recoveries of the method ranged from 78.8% to 119.8% for pendimethalin and from 73.7% to 108.8% for M455H001, and the relative standard deviation was lower than 16% for both analytes. The validated limit of quantification was 0.01 µg g−1 soil dry weight for both compounds. The matrix effects were evaluated and were less than 20% for both substances in the examined soil samples. It is concluded that the method is easy, with reasonable consumption of reagents, characterized by reliability and sensitivity, and therefore, it is suitable for monitoring the levels of pendimethalin and its major metabolite M455H001 in soils. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: This study examines the efficiency of various natural systems in treating untreated OMW before it is discharged to the environment. The experimental set‐up consisted of two hybrid pilot‐scale natural systems. The first hybrid system (HS‐A) comprised two open tanks (OTs), one vertical flow (VF) constructed wetland (CW) and one free water surface flow (FWS) CW and the second one (HS‐B) comprised two OTs and one FWS CW. RESULTS: Regarding the HS‐A system, TSS, COD, TKN and phenols (PHE) removals in the two OTs were 83.0%, 21.6%, 62.3% and 12.9%, and cumulative removals in the VF and FWS CW systems were 52.0%, 54.1%, 44.4% and 60.1%, respectively. Regarding the HS‐B system, TSS, COD, TKN and PHE mean removals in the two OTs were 80.7%, 32.2%, 64.1% and 24.7%, and in the FWS CW were 72.0%, 49.4%, 26.9% and 51.1%, respectively. The final pollutant effluent concentrations remained high for disposal in water bodies or reuse for irrigation; further reduction could be achieved by adding additional FWS CWs in series. CONCLUSION: Hybrid natural systems can be used in efficiently and economically treating OMW. Such hybrid systems could be applied to small family‐owned olive oil producing enterprises to treat OMW economically. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Due to the extent of non-point source agricultural pollution, protective measures to control agrochemicals from entering aquatic systems are necessary. Measures may include, among others, vegetated buffer strips (VFS), no spray buffer zones, alley crops and agroforestry systems (AFS). The scope of the present work is to examine the pollution abatement potential of a maize-olive (MO) AFS. The efficiency of a combined MO trees system in reducing nutrients and herbicides is tested through soil monitoring in an experimental plot, located in Koropi, Eastern Attica, Greece, in the period May 2015 to November 2015. The monitored pollutants were nitrogen and phosphorus, as well as two herbicides: pendimethalin and nicosulfuron. Soil samples were collected every 3–5 weeks at various soil horizons and distances from the tree row. Pollutant concentrations were determined using liquid chromatography tandem mass spectrometry (LC–MS/MS), ion chromatography (IC) and spectrophotometry techniques. The studied MO tree system exhibited the potential to reduce pollutant migration, with removals ranging 36.8–78.9% for, 79.3–100% for, 76.7–100% for, 79.4–100% forand 70–100% for the examined herbicides. The higher removal percentages were observed in the upper soil layers (5–35 cm, below the crops), and where the finer tree roots extend. Thus, the results indicate that planting of trees in cultivated fields can contribute to the reduction of agrochemical pollution of the subsurface soil and in extension of groundwater. [ABSTRACT FROM AUTHOR]

Agricultural pollution consists a serious concern for environmental protection managers. Among the pollutants, nitrates, phosphoric compounds and organic pesticides from agricultural activities are the most common and hazardous to the environment and human health. Several mitigation techniques have been proposed to control these pollutants from entering aquatic systems. Agroforestry, which is the common cultivation of crops and trees, is one such mitigation technique. In the present study, the efficiency of agroforestry systems in pollutant reduction is reviewed. A search of relevant international literature was conducted using Scopus, Science Direct and Google Scholar search engines, using relevant keyword combinations for agrochemical pollution abatement with trees. More than 2000 results were found and the most relevant were selected and extensively studied, and are summarized here. From the current knowledge, it can be generally seen that tree roots in agroforestry systems are able to reduce nitrogen and phosphorus residues in soils from 20% up to 100%, have the potential to reduce pesticides leaching and runoff in considerable amounts (up to 90% for runoff), and simultaneously they provide additional benefits to the ecosystems including erosion control, improvement of soil quality and positive effects on biodiversity. [ABSTRACT FROM AUTHOR]

The removal of total phosphorus (TP) in horizontal subsurface flow constructed wetlands (HSF CW) is numerically investigated using the Freundlich linear isotherm for adsorption. For the numerical simulation, the Visual MODFLOW code family, based on the finite difference method, was used. This model is applied in the simulation of five pilot-scale HSF CWs. Influent–effluent TP concentration experimental data from these facilities were used to first calibrate this model and derive appropriate values of the distribution coefficientKdand the first-order removal coefficientλ. Then, the model was verified using the values ofλandKdfrom calibration and independent experimental data from these facilities. The calibrated model was applied to comparatively simulate differences in removal efficiency under various design and operational parameters. [ABSTRACT FROM AUTHOR]

The present study investigates the use of combined methods of optical and acoustic sensors, in collaboration with direct in situ measurements, for the calibration and validation of a model transforming acoustic backscatter intensity series into suspended particulate matter (SPM) concentration datasets. The model follows previously elaborated techniques, placing particular attention to the parameterization of the acoustic absorption index as a function of water physical properties. Results were obtained from the annual deployment (during 2007-2008) of an upward-facing acoustic Doppler current profiler (ADCP) (307 kHz), equipped with a Wave Array, and an optical backscatter sensor (OBS), at the bottom of Thassos Passage near Nestos River plume (Thracian Sea, Northern Greece). The OBS was calibrated through linear regression, using 2007 and 2012 field sampling data, exhibiting an error of 13-14 % due to chlorophyll presence. The ADCP signal was calibrated through simultaneous measurements of backscatter intensity and turbidity profiles. Harmonic analysis on the model-produced SPM concentrations explained the tidal influence on their variability, especially during the summer. Empirical orthogonal functions analysis revealed the impact of waves and wave-induced currents on SPM variability. Finally, Nestos River sediment load was found uncorrelated to the SPM change in Thassos Passage, due to the dispersal and sediment deposition near the river mouth. [ABSTRACT FROM AUTHOR]

The aim of the study is to determine environmentally friendlier construction materials for constructed wetland facilities treating wastewater. This is done by computing the environmental footprint of the facility based on the methodology of life cycle assessment (LCA). This methodology reveals the dominant aggravating processes during the construction of a constructed wetland (CW) and can help to create alternative environmentally friendlier solutions. This methodology was applied for the determination of the overall environmental profile of a hybrid CW facility. The LCA was applied first to the facility as originally designed, where reinforced concrete was used in some components. Then, alternative construction materials to reinforced concrete were used, such as earth covered with high density polyethylene (HDPE) or clay, and LCA was applied again. Earth structures were found to have reduced environmental impact compared to concrete ones, and clay was found environmentally friendlier compared to HDPE. Furthermore, estimation of the construction costs of the three scenarios indicate that the last scenario is also the least expensive. [ABSTRACT FROM AUTHOR]