Thermal Stability of Calcium Oxalates from CO2 Sequestration for Storage Purposes: An In-Situ HT-XRPD and TGA Combined Study

Calcium oxalates are naturally occurring biominerals and can be found as a byproduct of some industrial processes. Recently, a new and green method for carbon capture and sequestration in stable calcium oxalate from oxalic acid produced by carbon dioxide reduction was proposed. The reaction resulted in high-quality weddellite crystals. Assessing the stability of these weddellite crystals is crucial to forecast their reuse as solid-state reservoir of pure CO2 and CaO in a circular economy perspective or, eventually, their disposal. The thermal decomposition of weddellite obtained from the new method of carbon capture and storage was studied by coupling in-situ high-temperature X-ray powder diffraction and thermogravimetric analysis, in order to evaluate the dehydration, decarbonation, and the possible production of unwanted volatile species during heating. At low temperature (119–255 °C), structural water release was superimposed to an early CO2 feeble evolution, resulting in a water-carbon dioxide mixture that should be separated for reuse. Furthermore, the storage temperature limit must be considered bearing in mind this CO2 release low-temperature event. In the range 390–550 °C, a two-component mixture of carbon monoxide and dioxide is evolved, requiring oxidation of the former or gas separation to reuse pure gases. Finally, the last decarbonation reaction produced pure CO2 starting from 550 °C.

4081 Times Increase in Atmospheric Humidity Capture Capacity via Confinement of 2D Nanosheets in 3D Matrix

Atmospheric humidity capture is urgently needed in humidity-related process. Most of the traditional technology suffers the defects of large energy consumption, low capture capacity, etc. Here, an intelligent gel (IG), which was composed of super hygroscopic materials (SHM, for humidity detection, spontaneous capture and in-situ liquefaction), hydrophilic polymer PEG-6000 (polyethylene glycol, for humidity storage), and hydrophobic polymer PVDF (poly(vinylidene-fluoride), for fast water release), is shown. Based on such kind of integration, effective color responsive humidity detection, spontaneous humidity capture and in-situ liquefaction, under ambient conditions, have been achieved. The synergistic effects between two polymers have given birth to a 3D polymer framework that can shrink upon heating and swelling upon solvent immersion, which then act as a versatile matrix that dispersed evenly the 2D SHM into atomically scale. As a consequence, approximate 4081 times increase in working capacity than the individual SHM has been observed. Being an effective way to manipulate atmospheric humidity at the device level, the present work may open new avenue for next-generational water management systems.

Influence of nitrogen application on direct seeded rice in old and new Cauvery Delta zone of Tamil Nadu, India

Direct seeded rice is a boon to farmers where the water release from the reservoir is delayed. Nitrogen fertiliser management is one of the strategies bto rectify the nutrient-related issue in Direct seeded rice. The present study aimed to optimize the nitrogen dose for direct-seeded rice in the new and old Cauvery delta zone of Tamil Nadu. Field experiments were conducted during kuruvai and samba seasons at Tamil Nadu Rice Research Institute, Aduthurai and Agricultural research station Thanjavur representing old and new Cauvery delta regions during 2019-20 and 2020-21. Totally from eight experiments, the results of four field experiments in each location revealed the highest grain yield in the treatment T6 -application of 150 kg Nha-1 (5596kg/ha) which was statistically on par with treatment T5 -125kg N/ha (5326 kg/ha) in old delta and new delta. The higher grain yield was recorded in the T6 (5140 kg/ha), statistically on par with T5 (4550 kg/ha). The higher available nitrogen content of 312 kg/ ha,292 kg/ha was recorded for N application @ 150kg/ha, which was statistically on par with 309 kg/ha and 289 kg/ha, respectively, both the kuruvai and samba seasons for N application of 125 kg/ha. In the new CDZ, the same trend was followed as that of the old delta. Based on economics, N applied @125 kg/ha recorded a higher BC ratio for direct-seeded rice. For the benefit of farmers of both deltaic regions, the nitrogen application of 125 kg ha-1 for direct-seeded rice is recommended.

Study on the effect of front retaining walls on the thermal structure and outflow temperature of reservoirs

The front retaining wall (FRW) is an effective facility of selective withdrawal. Previous research has not estimated the effect of FRWs on the thermal regimes of reservoirs and outflow temperature, which are crucial to reservoir ecology. For this purpose, taking the Dongqing Reservoir as a case study, a two-dimensional hydrodynamic CE-QUAL-W2 model was configured for the typical channel-type reservoir in the southwestern Guizhou Province, to better understand the influence of FRWs on the thermal structure and outflow temperature. The simulated data from January to September 2017 showed that FRWs can change the vertical temperature distribution during the stratification period, accelerate the upper warmer water release and thus decrease the strength of thermal stratification. The stratification structure changed from a single thermocline to double thermoclines in August. An FRW resulted in an average 11.8 m increase in the thickness of the hypolimnion and a 1.2°C decrease in the thickness of the thermocline layer. An FRW increased the outflow temperature by 0.4°C and raised the withdrawal elevation by 16 m on average. The longitudinal velocity increased compared with the non-FRW condition, while the maximum velocity position moved up. In addition, FRWs can continuously obtain surface warmer water without manual operation and have low investment and good construction conditions. This study can provide an available selective withdrawal idea for reservoirs with similar hydraulic conditions.

Review planned for Fukushima waste-water release

The International Atomic Energy Agency (IAEA) is to conduct a safety review of the planned discharge of millions of tonnes of treated waste water from the Fukushima nuclear reactor into the ocean.

Twenty-Five Years of Geomorphological Evolution in the Gokurakudani Gully (Unzen Volcano): Topography, Subsurface Geophysics and Sediment Analysis

In the aftermath of pyroclastic density current-dominated eruptions, lahars are the main geomorphic agent, but at the decadal scale, different sets of processes take place in the volcanic sediment cascade. At Unzen volcano, in the Gokurakudani gully, we investigated the geomorphologic evolution and how the topographic change and the sediment change over time is controlling this transition. For this purpose, a combination of LiDAR data, aerial photography and photogrammetry, ground penetrating radar and sediment grain size analysis was done. The results show choking zones and zones of enlargement of the gully, partly controlled by pre-eruption topography, but also by the overlapping patterns of the pyroclastic flow deposits of 1990–1995. The ground penetrating radar revealed that on top of the typical lahar structure at the bottom of the gully, side wall collapses were trapping finer sandy sediments formed in a relatively low-energy deposition environment. This shows that secondary processes are taking place in the sediment transport process, on top of lahar activity, but also that these temporary dams may be a source of sudden sediment and water release, leading to lahars. Finally, the sediments from the gully walls are being preferentially oozed out of the pyroclastic flow deposit, meaning that over longer period of time, there may be a lack of fines, increasing permeability and reducing internal pore pressure needed for lahar triggering. It also poses the important question of how much of a past event one can understand from outcrops in coarse heterometric material, as the deposit structure can remain, even after losing part of its fine material.

Determination of the Environmental Flow Using the Modern Optimization Methods for Release Flow based on Game Theory

To prevent environmental risks and preserve water quality, it is necessary to determine the environmental flow of rivers. Water release from reservoirs can be used to determine the environmental flow and water quality at the downstream of a dam. In this study, considering the quantitative and qualitative objectives, water release from Dez dam was suggested as a way for preserving the environment of river. To identify the optimal release flow of Dam, an environmental zone was determined using the hydrological methods of Tennant and aquatic base flow. The Qual-2k model was used to simulate 6 quality parameters in River. The results proved its good potential for simulation of the studied quality parameters including BOD. The optimal river flow was determined by Game theory, and different qualitative and quantitative scenarios were studied using the Nash multiplying function. The results showed, with increases in qualitative and quantitative objectives of the problem, the optimal release flows are decreased and increased, respectively.

Impact of River Damming on Downstream Hydrology and Hydrochemistry: The Case of Lower Nestos River Catchment (NE. Greece)

In this paper, a series of field surveys were carried out along the Nestos River watershed (NE Greece) to assess the influence of two hydropower dams (Thissavros and Platanovrisi) upon the hydrology, hydrochemistry and nutrients stoichiometry of the river. Results showed that Nestos hydrology, downstream of the reservoirs, is entirely governed by the man-induced hydropower-driven dam retention/release policy. Dams’ operation increased the retention of dissolved inorganic nitrogen (DIN) and total suspended solids (TSS) significantly, affecting their downstream fluxes, even under water release regime. On the contrary, dams’ construction and operation did not seem to influence the downstream fluxes of dissolved inorganic phosphorus (DIP) and silica (DSi), although these elements also depended on the releasing policy. DIN retention, combined with the dependence of DIP to the water level of Thissavros, resulted in alteration of the N:P ratio at the downstream part. Almost all nutrients were stored at the bottom layer of Thissavros reservoir, especially under the summer stratification regime. Platanovrisi reservoir acts as a buffer zone between Thissavros and the Nestos downstream part. Anoxic conditions in the reservoirs favour the transformation of nitrates into ammonia and the remineralization of phosphorus from sediments, creating a degraded environment for freshwater fauna.