Simulation of Phosphorus Transport in Soil Under Municipal Wastewater Application Using Hydrus-1D

Today, wastewater irrigation is one of the best options to reduce the stress on limited availability of fresh water and to meet the nutrient requirements of crops. In the present study, the simulation accuracy and performance of the HYDRUS-1D model to predict phosphorus leaching have been evaluated and compared to lysimeter data. More specifically, the effects of irrigation using four types of water (wastewater, effluent, mixture of freshwater and effluent, and freshwater) on three types of soil (sandy loam, loam, and clay loam) have been investigated both experimentally and numerically. Barley was planted as a common agricultural crop. The leachates from lysimeters have been collected and sampled at the beginning, middle, and end of the growing season. These samples have then been analyzed for phosphorous. The results show that the trend of change in nutrient concentration (P) was a function of plant requirement. Maximum process of leaching occurred concurrent with minimum plant requirement. The average phosphorus leaching into the root depths turns out to be insignificant, as it amounts to only 0.65–1.65%. This reassuring result means that wastewater with high concentrations of phosphorus compounds (up to 5–10.3 PO4-P mgl−1) can just be treated through an intermittent application to the land surface. Overall, a good agreement between experimental- and numerical-model results is obtained, wherefore the model overestimates the mean phosphate leaching during the growing season of the crop slightly. On the basis of these results, soil with loamy texture was considered to be the most suitable type for irrigation with wastewater and effluent. The results of this research indicate that with a proper management program in regard to the types of soil to be used, crops to be cultivated, water quality, and timing maneuver, the negative impacts of low quality water on soil/plant/groundwater systems can be minimized

La Prospección de placeres del oro y otros minerales densos

[eng] Alluvial prospecting is the most widely used method in heavy mineral exploration. Heavy minerals are resistant to meteoric agents. Economically, the most important heavy minerals are: precious metals (gold, silver and platinum group minerals), gems (diamonds, rubies, sapphires, emeralds, etc), the tin base metal group (cassiterite), technologic metals such as titanium (ilmenite and rutile), tungsten (wolframite and scheelite), zirconium (zircon) and the rare earths. The most usual techniques used in alluvial prospecting and the different criteria employed in exploration, mineral benefit and evaluation of alluvial ore deposits known as placers are presented.[cat] La prospecció al.luvionar es un mètode excepcional per la recerca de minerals de interès econòmic, com los minerals densos d'elevada resistència física i química. Entre ells son d' interès els metalls preciosos (or, plata i platí), gemmes (diamant, rubí, zèfirs, maragdes, aigua-marina, etc.), metalls de base com l'estany (cassiterites), minerals tecnològics com el titani (ilmenites i rutils), wolfram (volframita i scheelita), zirconi (zircó), de terres rares (monacites), etc.. En aquest text, és presenten las tècniques mas usuals en Prospecció al.luvionar com la batea, així com els distints criteris a seguir per dur a termini una prospecció, un benefici i una avaluació dels seus jaciments que es coneixen com ¿placeres¿.[spa] La prospección aluvionar es un método excepcional para la búsqueda de minerales de interés económico, como los minerales densos de elevada resistencia físico-química. Entre ellos son de interés los metales preciosos (oro, plata y platinoides), gemas (diamante, rubíes, zafiros, esmeraldas, aguamarinas, etc.), metales de base como el estaño (casiteritas), minerales tecnológicos como el titanio (ilmenitas y rutilos), wólfram (volframita y scheelita), circonio (circón), de tierras raras (monacitas), etc.. En este texto, se presentan las técnicas mas usuales en prospección aluvionar como la batea, así como los distintos criterios a seguir para llevar a cabo una prospección, un beneficio y una evaluación de sus yacimientos que se conocen como ¿placeres¿