Assessing Seasonal Flow Dynamics at a Lagoon Saltwater–Freshwater Interface Using a Dual Tracer Approach

Study region: Eastern shore of Ringkøbing Fjord, a coastal lagoon at the west coast of Denmark Study focus: A dual tracer approach based on salinity and δ18O is used to assess seasonal dynamics at the saltwater-freshwater interface of a coastal lagoon. At the site, salinity is prone to vary on a sub-seasonal or daily frequency due to riverine freshwater inputs to the lagoon. In contrast, δ18O compositions of end-members only vary seasonally. New hydrological insights: The dual tracer approach shows to be valuable in coastal settings where end-member concentrations vary substantially over the seasons and hence, an unambiguous end-member definition does not exist. Calculated mixing fractions using only salinity, deviated from the dual tracer approach on average by 18%, but were as high as 97%. Although, these differences decrease to 6% on average when using only δ18O, our study strongly suggests their simultaneous application. Moreover, we found that seawater intrusion occurs during the summer when salinity in the lagoon is high and fresh submarine groundwater discharge (SGD) is low. This process reverses during the winter (wet season) when SGD increases by a factor of 2–3, due to the recession of the saltwater wedge from land. Our findings show that in absence of waves and tides, density-driven dynamics, and particularly the terrestrial freshwater fluxes, create a major impact on saltwater wedge dynamics

Inventory of long and short term future needs of food chain users for future functions of internet

vokKVIKA

Flexible planar supercapacitors by straightforward filtration and laser processing steps

Abstract There is ever increasing demand for flexible energy storage devices due to the development of wearable electronics and other small electronic devices. The electrode flexibility is best provided by a special set of nanomaterials, but the required methodology typically consists of multiple steps and are designed just for the specific materials. Here, a facile and scalable method of making flexible and mechanically robust planar supercapacitors with interdigital electrode structure made of commercial carbon nanomaterials and silver nanowires is presented. The capacitor structure is achieved with vacuum filtration through a micropatterned contact mask and finished with simple laser processing steps. A maximum specific capacitance of 4 F cm−3 was measured with cyclic voltammetry at scan rate of 5 mV s−1. The reliability and charge transfer properties of devices were further investigated with galvanostatic charge-discharge measurements and electrochemical impedance spectroscopy, respectively. Furthermore, mechanical bending tests confirmed the devices have excellent mechanical integrity, and the deformations have no adverse effects on the electrochemical charge-discharge behavior and stability

Control of Viscosity of Cementitious Materials Using Waste Limestone Powder

Ultra high performance cementitious materials possess high solid volume fraction by a decreased water-to-binder ratio. The use of a high-range water reducing admixture allowed us to obtain the initial fluidity of ultra-high performance cementitious materials, but its poor workability and significant loss of fluidity remained. Incorporating a high volume of supplementary cementitious materials reportedly weakens workability because they reduce the plastic viscosity of a mix. Hence, in this research, waste limestone powder was tested to evaluate its effect on the rheological properties of cement paste. The results give new insight on controlling the fluidity and plastic viscosity when preparing the mix for ultra-high performance concrete