Enhanced Weathering and Erosion of a Cohesive Shore Platform Following the Experimental Removal of Mussels

The organisms inhabiting intertidal platforms can affect their weathering and erosion rates. Research on biotic influences on platform integrity has traditionally emphasized the role of bioeroders (i.e., organisms that scrap or bore into platforms via mechanical and chemical means). Yet, recent studies illustrate that covers of sessile organisms on the surfaces of intertidal platforms can have bioprotective effects by reducing the efficacy of physical weathering and erosion agents. Eroding cliffs fronted by cohesive shore platforms are a pervasive feature along the continental Argentinean coastline (37–52°S). In this study, we investigated how mussel (Brachidontes rodriguezii) cover mediates weathering and erosion of a cohesive, consolidated silt platform at Playa Copacabana (5 km north of Miramar, Buenos Aires Province; 38° 14′ S, 57° 46′ W). By means of mussel removal experiments, we found that mussel cover attenuates variations in platform surface temperatures, enhances moisture retention during low tide, reduces rates of salt crystallization within the pores of the platform material, and attenuates hydrodynamic forcing on the platform surface. Mussel removal also led to a 10% decrease in surface hardness and a 2-mm reduction in platform height after 5 months. Collectively, our findings indicate that mussel beds limit substrate breakdown via heating-cooling, wetting-drying, and salt crystallization and provide some of the first experimental field evidence for the direct impacts of biotic cover on platform erosion. As intertidal platforms protect the cliffs behind from the hydraulic impact of waves, which may be enhanced with future sea-level rise, we posit that the protection of platforms by mussels indirectly moderates coastline retreat, especially on soft cohesive shores.

Studying the removal of CO2 on stratified ZnO prepared by hydro

In this study, ZnO was synthesized by the simple hydrothermal method. The physicochemical properties of the materials were characterized by SEM, XRD, N adsorption/desorption isotherm methods. The CO2 removal experiments were conducted using the thermogravimetric method (TGA). The material has a stratified structure, with a surface area of 24.4 m2/g and a pore volume of 0.280 cm3/g. The influences of temperature, ZnO morphology, and feed gas composition were studied. Besides, the durability and applicability of the material were evaluated through repeated regeneration.

Optimization of Process Parameters and Kinetics Analysis of Cd Removal in ZnSO4 Production

In order to optimize the process parameters of Cd removal in the ZnSO4 production process and study the mechanism of Cd removal reaction, the response surface methodology was used to arrange Cd removal experiments and analyze the optimal production conditions, and the mechanism of Cd removal was studied using kinetics. The results show that the optimal process conditions for Cd removal are as follows: reaction temperature 55 °C, reaction time 13.43 min, and the zinc powder dosage should be 2.14 times that of Cd; the main effects of the three variables from large to small are zinc powder dosage, reaction temperature and reaction time; Cd removal is a second-order reaction, and the activation energy of the reaction is 29.6986 kJ/mol, so the reaction conforms to the diffusion control mechanism.

Secondary seed removal in a degraded forest habitat in Madagascar

Forest restoration is a prime goal within the 2021–2030 UN “Decade of Ecosystem Resoration”. As part of these activities, natural regeneration has to be promoted for biological as well as for economic reasons. For this, the processes of seed dispersal, seed predation and germination have to be understood in the original as well as in degraded vegetation formations. We used seed removal experiments to assess post-dispersal processes that influence recruitment along a gradient of forest degradation in Madagascar analyzing seeds of three animal dispersed tree species. The percentage of seeds consumed or dispersed, declined from forest (28.6%) to degraded forest (17.2%) to savanna (10.8%). Only three out of 1080 seeds were cached and remained intact during the 14-day experiment. All three seeds were cached in the forest habitat and none in the degraded forest and savanna. The low percentage of seeds removed may be due to the lack of endemic rodents caching seeds, as only introduced rats were recorded in the area. The species-poor fauna of potential secondary seed dispersers of the region and especially in the degraded areas might represent an obstacle for diverse regeneration in degraded regions of Madagascar.

An Improved Configuration of Vertical-Flow Mesh Tube Filters for Seawater Pretreatment: Performance, Cleaning, and Energy Consumption

Roughing filters are types of porous media filter used in pretreatment systems where the raw water contains a large amount of suspended particles (SPs) and organic matter. Mesh tube filtration (MTF) media are roughing-filter media composed of low-density polyethylene used for SP removal during wastewater treatment. In this study, we present an improved MTF design—a porous filter bed (PFB), which exhibits superior SP removal performance compared to conventional MTF media. We then compare the applicability of MTF and PFB to both the primary pretreatment process for seawater desalination and the water reuse process. In bench-scale SP removal experiments, PFB shows removal rates of 46.7%, 68.0%, 67.6%, and 68.4% at hydraulic retention times of 15, 20, 30, and 60 min, respectively, which are better than those of MTF. The specific energy consumption (SEC) of batch dissolved air flotation (DAF) was known to range from 0.035 to 0.047 kWh/m3, whereas the SEC calculated for pilot-scale MTF and PFB is 0.027 kWh/m3 and minimum energy for influent supply, respectively. This suggests that PFB can compete with DAF as a primary pretreatment process. MTF predominantly removes SPs by sedimentation, whereas SP removal in PFB typically occurs via deposition of SPs on the mesh tube media.

Mechanistic Study of Pb2+ Removal from Aqueous Solutions Using Eggshells

This study investigates the impact of eggshell particle size and solid-to-water (s/w) ratio on lead (Pb2+) removal from aqueous solution. Collected raw eggshells were washed, crushed, and sieved into two particle sizes (<150 and 150–500 µm). Batch Pb2+ removal experiments were conducted at different s/w ratios with initial Pb2+ concentrations of up to 70 mg/L. The contribution of precipitation to Pb2+ removal was simulated by quantifying removal using eggshell water, whereas sorbed Pb2+ was quantified by acid digestion. Results indicated that eggshell particle sizes did not affect Pb2+ removal. High removal (up to 99%) of Pb2+ was achieved for low initial Pb2+ concentrations (<30 mg/L) across all s/w ratios studied. However, higher removal capacity was observed at lower s/w ratios. In addition, results confirmed that precipitation played a major role in the removal of Pb2+ by eggshells. Yet, this role decreased as the s/w ratio and initial concentration of Pb2+ increased. A predictive relationship that relates the normalized removal capacity of eggshells to the s/w ratio was developed to potentially facilitate the design of the reactor.

Queen succession conflict in the paper wasp Polistes dominula is mitigated by age-based convention

Reproduction in cooperative animal groups is often dominated by one or a few individuals, with the remaining group members relegated to nonreproductive helping roles. This reproductive skew can evolve if helpers receive fitness benefits such as potential future inheritance of the breeding position, but the mechanisms by which inheritance is determined are not well resolved. Polistes paper wasps form highly reproductively skewed groups and inheritance of the breeding position is likely to play a key role in the maintenance of this social structure, making them excellent models for the processes by which simple societies are maintained. Reproductive succession is thought to be determined via an age-based convention in some Polistes species, but there is also evidence for contest-based succession systems in which the replacement queen uses physical aggression to overpower and thereby subordinate her nestmates. Here, we provide evidence that queen succession in colonies of the European paper wasp Polistes dominula is determined via convention rather than contest, with little disruption to the colony’s social functioning. We use queen removal experiments and fine-scale behavioral analyses to confirm that age is a strong predictor of succession, and that behavioral responses to queen removal are restricted to the oldest individuals rather than being experienced equally across the group. We provide the most comprehensive and detailed experimental analysis on the dynamics of breeder succession in a cooperatively breeding invertebrate to date, thereby shedding light on the mechanisms by which animal societies are able to maintain cohesion in the face of within-group conflict.

Seed type, habitat and time of day influence post-dispersal seed removal in temperate ecosystems

Seed survival is of great importance for the performance of plant species and it is strongly affected by post-dispersal seed removal by either different animals such as granivorous species and secondary dispersers or abiotic conditions such as wind or water. The success of post-dispersal seed removal depends on seed specific traits including seed size, the presence of coats or elaiosomes, the mode of seed dispersion, and on the habitat in which seeds happen to arrive. In the present study we asked how seed traits (dehulled vs. intact; size; dispersal mode), habitat (forest vs. grassland), and time of day (night vs. day) influence post-dispersal seed removal of the four plant species Chelidonium majus, Lotus corniculatus, Tragopogon pratensis and Helianthus annuus. Seed removal experiments were performed in three regions in Hesse, Germany. The results showed different, inconsistent influences of time of day, depending on habitat and region, but consistent variation across seed types. C. majus and dehulled H. annuus seeds had the fastest removal rates. The impact of the habitat on post-dispersal seed removal was very low, only intact H. annuus seeds were removed at significantly higher rates in grasslands than in forests. Our study demonstrates consistent differences across seed types across different habitats and time: smaller seeds and those dispersed by animals had a faster removal rate. It further highlights that experimental studies need to consider seeds in their natural form to be most realistic.