Were springline carbonates in the Kurkur-Dungul area (Southern Egypt) deposited during glacial periods?

The tufa deposits in the Kurkur–Dungul area, southern Egypt, date from marine isotope stage (MIS) 11 to MIS 1. Springs across the region were active during glacial periods (with sea level below –50 m), reflecting changed atmospheric circulation over the Indian Ocean, as well as peak interglacial periods. During times of low sea level, reduced Indonesian throughflow promoted formation of an Indian Ocean Warm Pool, and anomalous rainfall on its western margin. We suggest Egypt lies at the intersection of westerly (“maghrebian”) and easterly (“mashriqian”) rainfall provinces, which show different timing with relation to orbital forcing and different source water regions. Tufa-growth periods are therefore not mechanistically linked to “humid periods” or “sapropel events” identified elsewhere. Stable isotope and TΔ47 data are also inconsistent with these spring systems being part of a larger system spanning northern Africa, and lack a clear interaction between northern hemisphere heating and mid-latitude rainfall. We also follow previous authors in concluding that formation of springline deposit formation was likely delayed compared to rainfall, due to aquifer flow distances. This delay is unlikely sufficient to explain why rainfall is out of phase movements of the monsoon belts, but may complicate interpretation of these records.

Role of the Hyporheic Zone in Increasing the Resilience of Mountain Streams Facing Intermittency

We investigated the impact of intermittence in previously-perennial Alpine stream reaches, targeting the role of the hyporheic zone in increasing the resilience of these aquatic systems. We selected a perennial and an intermittent site in a reach of the Po River (North-Western Italy). We installed piezometers reaching −1 m (permanent and intermittent site), and −3 m (intermittent site) and monitored three supraseasonal droughts over a period of three years. We classified the hyporheic fauna into three categories of increasing affinity to life in the hyporheic (stygoxene, stygophile, stygobite), and used communities composition, abundance, beta-diversity and functional groups: (1) to compare assemblages at the same depth but with different hydrological characteristics, as well as assemblages from two depths at the intermittent site, and (2) to assess how the connection with surface water and the direction of the vertical aquifer flow determined the faunistic assemblages. Different taxonomic groups responded differently to intermittence, the hyporheic zone acted as a refuge increasing the resilience of the system, but resilience decreased with increasing degree of affinity to hyporheic life. Disentangling the effects of intermittence on the different faunistic component in the hyporheic zone can help guiding effective protection and restoration measures of river systems with temporary reaches.

Seepage and Recharge under a Stream-aquifer Unsaturated Connection

Most widely used integrated hydrologic models use outdated descriptions of the stream-aquifer flow exchange. Understandably they do it for practical reasons to avoid computational costs in large-scale regional studies. In this article we propose a largely analytical technique that (1) describes the situation when the connection is unsaturated while avoiding a lot of numerical work and at the same time remains quite physical, (2) has the capability to describe fluctuations between saturated and unsaturated connections, and (3) can be coupled easily with the numerical groundwater model that describes what happens in the broad system of cells away from the river(s). Essentially two separate methods are compared for the purpose of selecting the most practical of the two.

Transport of Nanoplastic under groundwater aquifer flow and transport conditions

<p>In terrestrial environments soils are hypothesized sinks for plastic particles. Nonetheless, due to the existence of preferential flow paths as well as a variety of geochemical and microbiological processes, this sink may only be temporary. A vertical translocation from soils to groundwater aquifers eventually occurs along different pathways. In these conditions Nanoplastic transport characteristics are similar to colloidal transport behavior. Therby the magnitude of plastic transport is eventually governed by complex interplay between the particle with its surrounding media (particle-particle, particle-solvent, particle- porous media) masked by different hydro-geochemical and microbiological conditions. The physical entrapment of particles (straining) may be significant when the particle diameter exceeds 5% of the median grain size diameter. Below that size additional electrostatic, van der Waals or steric interaction become increasingly important.</p><p>We present a preliminary dataset on the interaction between Nano-sized Polystyrene (PS) with different surface coatings and a variety of common minerals occurring in groundwater aquifers under the presence of Natural Organic Matter (NOM). The reference aquifer material is based on the Danish subsurface structure of Quaternary and Miocene aquifer material, e.g. quartz, calcite and pyrite among others. In our study, batch scale interactions are up-scaled in column flow and transport experiments, simulating different groundwater aquifer flow conditions in the presence of selected minerals and NOM.</p><p>This aims to clarify transport behavior of plastic pollutant in the subsurface environment. Furthermore, it serves as guide in qualitatively assessing and quantifying the vulnerability of groundwater aquifers to Nanoplastic pollution.</p>

Analisis Aliran Air Bawah Permukaan Dengan Menggunakan Metode Geolistrik

Cean water is needed in a human community. The need for clean water can be taken from subsurface water through a pumping process. Efforts to get clean water that has sustainability can be done by knowing the direction of the aquifer flow. The direction of the aquifer flow can be known through subsurface modeling. This study uses the geoelectric method in modeling the subsurface layer to determine the position of the aquifer. Based on the subsurface model, the average depth of an aquifer is between 30-100 meters. The subsurface model shows the type of aquifer depressed with a clay layer as the upper and lower limits of the aquifer. The subsurface water is estimated to have a flow direction from East to West in a confined aquifer.