The Role of Reactive Iron in the Preservation of Terrestrial Organic Carbon in Estuarine Sediments

To better understand the role of reactive Fe (FeR) in the preservation of sedimentary OC (SOC) in estuarine sediments, we examined specific surface area (SSA), grain size composition, total OC (TOC), lignin phenols, FeR, FeR-associated OC (Fe-OC) and lignin phenols (Fe-lignin), and δ13C of FeR-associated OC (δ13 CFe-OC) in surface sediments of the Changjiang Estuary and adjacent shelf. An estimated 7.4 ± 3.5% of the OC was directly bound with FeR in the Changjiang Estuary and adjacent shelf. Unusually low TOC/SSA loadings and Fe-OC/Fe ratios in mobile-muds suggest that frequent physical reworking may reduce FeR binding with OC, with selective loss of marine OC. More depleted 13CFe-OC relative to 13C of TOC (13 Cbulk) in deltaic regions and mobile-muds showed that FeR was largely associated with terrestrial OC, derived from extensive riverine C and Fe inputs. A higher proportion of hematite in the mobile muds compared to the offshore samples indicated that Fe oxides are likely subjected to selective sorting and/or become mature during long-term sediment transport. When considering the percentage of Fe-OC to SOC and SOC burial rates in different marine environments (e.g., non deltaic shelf, anoxic basins, slope and deep sea), our findings suggest that about 15.6 ± 6.5% of SOC is directly bound to FeR on a global scale, which is lower than the previous estimation (~21.5%). This work further supports the notion of a “Rusty Sink” where, in this case FeR plays an important role in the preservation and potential transport of terrestrial OC in the marine environment

Research on the Relationship between Water Diversion and Water Quality of Xuanwu Lake, China

Water diversion is often used to improve water quality to reach the standard of China in the short term. However, this large amount of water diversion can not only improve the water quality, but also lead to a decline in the water quality (total phosphorus, total nitrogen) of Xuanwu Lake. Through theoretical analysis, the relationship between water quality and water diversion is established. We also found that the multiplication of the pollutant degradation coefficient (K) and the water residence time (T) is a constant (N), K⋅T=N. The water quality changed better at first, with the increase of inflow discharge, and then became worse, and the optimal water quality inflow discharge is 180,000 m3/day. By constructing two-dimensional hydrodynamic and water quality models, the optimal diversion water plan is calculated. Through model calculations, it can be seen that reducing the inflow discharge makes the water residence time longer (15.3 days changed to 23.8 days). Thereby, increasing the degradation of pollutants, and thus improving water quality. Compared with other wind directions, the southwest wind makes the water quality of Xuanwu Lake the most uniform. The concentration of water quality first became smaller and then became larger, as the wind speed increased, and eventually became constant. Implementing these results for water quality improvement in small and medium lakes will significantly reduce the cost of water diversion

Research on Water Environment Regulation of Artificial Playground Lake Interconnected Yangtze River

With the rapid development of China, water pollution is still a serious problem despite implementation of control measures. Reasonable water environment management measures are very important for improving water quality and controlling eutrophication. In this study, the coupled models of hydrodynamics, water quality, and eutrophication were used to predict artificial Playground Lake water quality in the Zhenjiang, China. Recommended “unilateral” and “bilateral” river numerical models were constructed to simulate the water quality in the Playground Lake without or with water diversion by pump, sluice and push pump. Under “unilateral” and “bilateral” river layouts, total nitrogen and total phosphorus meet the landscape water requirement through water diversion. Tourist season in spring and summer and its suitable temperature result in heavier eutrophication, while winter is lighter. Under pumping condition, water quality and eutrophication of “unilateral” river is better than “bilateral” rivers. Under sluice diversion, the central landscape lake of “unilateral river” is not smooth, and water quality and eutrophication is inferior to the “bilateral”. When the water level exceeds the flood control level (4.1 m), priority 1 is launched to discharge water from the Playground Lake. During operation of playground, when water level is less than the minimum level (3.3 m), priority 2 is turned on for pumping diversion or sluice diversion to Playground Lake. After opening the Yangtze river diversion channel sluice, priority 3 is launched for sluice diversion to the Playground Lake. When the temperature is less than 15 °C, from 15 °C to 25 °C and higher than 25 °C, the water quality can be maintained for 15 days, 10 days and 7 days, respectively. Corresponding to the conditions of different priority levels, reasonable choices of scheduling measures under different conditions to improve the water quality and control eutrophication of the Playground Lake. This article is relevant for the environmental management of the artificial Playground Lake, and similar lakes elsewhere

Effect of Different Mineralization Modes on Strengthening Calcareous Sand under Simulated Seawater Conditions

Calcareous sand, as a blow-fill or construction material, is widely used in island and reef construction projects in marine environments after treatment. When microorganism-induced mineralization is used to strengthen calcareous sand, salinity and other conditions in the marine environment will adversely affect microorganisms or their mineralization process. For this reason, the two environmental conditions created by deionized water and simulated seawater were introduced to explore their effects on the growth and urease activity of Sporosarcina pasteurii. Then, the changes in the permeability and mechanical strength of calcareous sand under different mineralization methods were compared by one-dimensional sand column tests. Finally, the reinforcement mechanism was compared and analyzed based on the results of scanning electron microscopy and X-ray diffraction tests. The results show that Sporosarcina pasteurii can induce carbonate and phosphate precipitation and mineralization to strengthen calcareous sand in simulated seawater. The mineralized products greatly reduce the permeability of calcareous sand and significantly improve the mechanical strength by wrapping calcareous sand particles, filling water seepage channels and cementing adjacent particles. The reinforcement effect of carbonate mineralization is better than that of phosphate mineralization, but phosphate mineralization has less impact on the environment during the treatment process

Preparation, characterization, and adsorption capacity of pyrophosphoric acid sustainable activated carbon from baijiu spent grains for risk factor mitigation

The increasing societal concern regarding the safety of alcoholic beverages necessitates the implementation of effective and safe intervention measures to enhance their safety. This study aims to repurpose the substantial spent grains generated during Baijiu production, which have a significant environmental impact, into sustainable activated carbon (as an adsorbent) by pyrophosphoric acid to alleviate these concerns directly. Precise optimization strategies were employed for simulated and authentic Baijiu samples to determine ideal conditions for carbon synthesis suitable for different alcoholic beverages (with fewer flavor compounds and rich in flavor compounds). Characterization via FT-IR and SEM confirmed the porous structure of the activated carbon. The adsorption experiments indicate that calcination temperature significantly influences adsorption efficiency, favoring selective adsorption of higher alcohols, acetaldehyde, and methanol, while simultaneously reducing acid adsorption. Compared to commercial activated carbon, spent grain carbon exhibited superior acid retention effects. Through sensory evaluation to determine application parameters, activated carbon can reduce acetaldehyde and higher alcohols in Baijiu by 9.67 % and 14.94 %, respectively, without compromising aroma. Thus, this research not only provides a novel recycling strategy for the significant waste generated in Baijiu production but also offers a green and sustainable assurance measure for the quality and safety of alcoholic beverages