High Concentration Scenario Research Articles

Membrane fouling analysis of air-gap membrane distillation (AGMD) for recovery of water and removal of antibiotics from a model wastewater containing antibiotics and humic acid

The study investigates the efficiency of air-gap membrane distillation (AGMD) in water recovery and antibiotics removal from wastewater, focusing on high-concentration scenarios. Experimental findings reveal enhanced membrane performance with increasing the feed temperature, resulting in vapor permeate fluxes of up to 5 kg/m2.h at higher temperatures. Despite experiencing flux reduction caused by fouling from humic acid (HA) in the feed antibiotics solution, the antibiotics consistently maintain near-complete rejection rates (>99%) over 48 h. The foulant on the membrane surface was illustrated by SEM imaging. To know the temperature polarization and the fouling resistance, mathematical modeling was used, and it validates experimental results, elucidating temperature polarization effects and mass transfer coefficients. An increase in feed flow rates reduced thermal boundary layers, enhancing heat flux. Higher temperatures reduced HA fouling resistance. Therefore, AGMD proves effective in water recovery and antibiotics removal, with mathematical models aiding fouling understanding for future research and detailed computational fluid dynamics (CFD) models.

3D ultra-micropore organic polymers with fixed group and thieno[3,2-b]thiophene to enhance adsorption and separation of Xe/Kr

The reduction of environmental pollution and the exploration of economic values require the efficient separation and purification of xenon (Xe) and krypton (Kr) from radioactive gases generated during nuclear fission processes. To address this issue, we have synthesized three thieno[3,2-b]thiophene-based porous organic polymers (POP-ch-ET, POP-ch-SP and POP-ch-ME) via high yield C–H direct arylation reaction, all of which exhibited excellent thermal and acid-base stability. Notably, the three-dimensional (3D) structures of POP-ch-SP and POP-ch-ME allowed higher Xe capacity compared to the two-dimensional (2D) structure of POP-ch-ET. Density functional theory (DFT) calculations confirmed that thieno[3,2-b]thiophene moieties contributed to a more negative adsorption energy for Xe than benzene. Among them, POP-ch-SP with fixed group showed superior Xe capacity (2.37 mmol/g) at 298 K and 1.0 bar and the highest ideal adsorption solution theory (IAST) selectivity (11.5). This superior performance is attributed to its 3D ultra-micropore structure, which enables closer proximity between aromatic rings, thereby enhancing Xe interaction. The DFT calculation further revealed that the adsorption energy of Xe in POP-ch-SP was more negative compared to other POPs, indicating a stronger interaction. In addition, POP-ch-SP exhibited the largest ΔQst (14.2 kJ/mol) between Xe and Kr, highlighting a marked affinity difference. In dynamic breakthrough experiments, POP-ch-SP demonstrated robust Xe/Kr separation efficiency under both low (400 ppm Xe and 40 ppm Kr in dry air) and high concentration scenarios (Xe/Kr, v/v, 20/80), underscoring its promising potential for practical applications in radioactive gas management.

Complex resistivity spectrum of pollutant soils with low-concentration heavy metals

Soil contamination by heavy metals occurs globally, with varying degrees of severity, especially in agricultural fields. Investigating the frequency response characteristics of different types of heavy metal pollutants through induced polarization can provide valuable evidence for surveys based on this method. Soil specimens with varying low concentrations of copper (Cu), chromium (Cr), cadmium (Cd), and lead (Pb) heavy metals were prepared for this study, and parameters including complex resistivity, amplitude-frequency, and resistivity phase were measured. Our findings reveal the following trends: Complex resistivity decreases as heavy metal concentrations increase, demonstrating significant shifts within lower concentration ranges but presenting limitations for assessing pollution in high-concentration areas. Conversely, amplitude-frequency increases with higher heavy metal concentrations, displaying excellent performance in high-concentration scenarios. The differences in complex resistivity and amplitude-frequency among different types of heavy metal pollutants are distinct. In contrast, the absolute phase decreases with rising heavy metal concentrations. The resistivity phase spectra for various heavy metal pollutants exhibit unique patterns. For example, copper-contaminated soil exhibits phase peaks in the frequency range of 8–32 Hz, whereas chromium-contaminated soil shows phase peaks at 16–64 Hz. Cadmium-contaminated soil displays phase peaks ranging from 0.25 Hz to 2 Hz, while lead-contaminated soil exhibits phase peaks within the 0.5 Hz–4 Hz range. Leveraging the frequency range corresponding to phase peaks as an identification method for heavy metal pollution types proves effective. The frequency response characteristics of induced polarization vary significantly among different types and concentrations of heavy metal pollutants, providing important foundations for the application of induced polarization method in the field of heavy metal pollution detection.

Prolongation of Compound Dry–Hot Seasons Over Europe Under Climate Change Scenarios

AbstractCompound effects of drought and heat are regarded as one of the greatest hazards in relation to climate change. We study characteristics of dry–hot seasons in Europe in an ensemble of CORDEX regional climate models (RCMs). Evaluation against the E‐OBS gridded data set for 1976–2005 showed that the RCMs were able to reproduce the spatial pattern of the dry–hot season length but the simulated seasons tended to start later and interannual variability of their length was underestimated. Bias was larger (smaller) in the case of maximum (minimum) length over the 30‐year period compared to the median length. Changes in the dry–hot seasons were then analyzed for three time slices (2006–2035, 2036–2065, and 2066–2095) and low and high greenhouse gas concentration pathways. Distinct prolongation (compared to the 1976–2005 simulated climate) was projected for 2036–2065 in the Mediterranean and Western Europe (10–30 days), regardless of the concentration pathway. The dry–hot seasons length was similar in the 2036–2065 and 2066–2095 time slices under the low concentration pathway but major extensions were found under the high concentration scenario over large parts of Europe (20–50 days). The projected spatial patterns of changes in the dry–hot seasons length depend primarily on the driving global climate model. Although the extensions are predominantly driven by increasing temperature, simulated precipitation changes modulate the resulting pattern by amplifying (reducing) the dry–hot seasons length in Southern (Northern) Europe.

Concurrent water- and foodborne exposure to microplastics leads to differential microplastic ingestion and neurotoxic effects in zebrafish

Organisms constantly ingest microplastics directly from the environment or indirectly via trophic transfer due to the pervasiveness of microplastic pollution. However, most previous studies have only focused on waterborne exposure at the individual level, while few studies have investigated the contribution of trophic transfer to the exposure in organisms. We comprehensively evaluated the differences in microplastic ingestion and toxic effects in zebrafish exposed to microplastics via two concurrent routes (waterborne and foodborne). The polyethylene microplastics (40–47 μm, 0.1–10 mg/L) concentration used here was set in a range closed to the environmentally relevant microplastic concentrations, especially considering the extreme high concentration scenarios in wastewater. The concentration of microplastics resulting from foodborne exposure (0.01±0.01 μg/mg; 0.1±0.1 particles/mg) was significantly lower than that through waterborne exposure (0.06±0.02 μg/mg; 0.8±0.3 particles/mg), suggesting the ingestion of microplastics in their tissues occurs mainly through direct environmental uptake rather than food chain transfer (though the initial microplastic concentration was 1000 folds lower). However, more sublethal impacts, including the significant abnormal hyperactive swimming behaviour (107±5% induction; p< 0.05), were observed in the foodborne group than waterborne group. Additionally, ingenuity pathway analysis predicted both exposure routes caused obvious nervous system interference but through opposite modes of action. This was further verified by the alteration of neurotransmitter biomarkers that neurotoxicity mechanisms were completely different for the two exposure routes. The neurotoxic effects of microplastics are non-negligible and can exert together through both water- and foodborne exposure routes, which deserves further attention.

The primitive model in classical density functional theory: beyond the standard mean-field approximation

The primitive model describes ions by point charges with an additional hard-core interaction. In classical density-functional theory (DFT) the mean-field electrostatic contribution can be obtained from the first order of a functional perturbation of the pair potential for an uncharged reference system of hard spheres. This mean-field electrostatic term particularly contributes at particle separations that are forbidden due to hard-core overlap. In this work we modify the mean-field contribution such that the pair potential is constant for distances smaller than the contact distance of the ions. We motivate our modification by the underlying splitting of the potential, which is similar to the splitting of the Weeks–Chandler–Andersen potential and leads to higher-order terms in the respective expansion of the functional around the reference system. The resulting formalism involves weighted densities similar to the ones found in fundamental measure theory. To test our modifications, we analyze and compare density profiles, direct and total correlation functions, and the thermodynamic consistency of the functional via a widely established sum rule and the virial pressure formula for our modified functional, for established functionals, and for data from computer simulations. We found that our modifications clearly show improvements compared to the standard mean-field functional, especially when predicting layering effects and direct correlation functions in high concentration scenarios; for the latter we also find improved consistency when calculated via different thermodynamic routes. In conclusion, we demonstrate how modifications toward higher order corrections beyond mean-field functionals can be made and how they perform, by this providing a basis for systematic future improvements in classical DFT for the description of electrostatic interactions.

Occurrence data of nickel in feed and animal exposure assessment.

Nickel (Ni) is a silvery‐white, hard, ductile metal existing in oxidation states; in biological systems, Ni2+ is the prevalent form. All analytical results used to estimate animal dietary exposure were reported as Ni', without providing information on specific chemical species. Considering the data provided by Member states, among FoodEx level 1 feed categories, the highest mean Ni levels were measured in ‘Minerals and products derived thereof’ (n = 72). High mean Ni concentrations were also observed in ‘Compound feed’ (n = 516), in particular in complementary feeds for fattening cattles, unspecified complementary feed and complementary feeds for fattening pigs. Within grains used as feed (n = 597), the highest mean Ni concentrations were measured in oats. In addition, Ni concentrations in hydrogenated vegetable oils/fats were reported by industry. Exposure to Ni in livestock and companion animals varied according to the animal species. When considering the diets with hydrogenated vegetable oils/fats based on the reported Ni concentrations, the mean exposures varied between 6.0 μg Ni/kg body weight (bw) per day in cats and 79 μg Ni/kg bw per day in laying hens and the high exposure levels varied between 11 μg Ni/kg bw per day in cats and 127 μg Ni/kg bw per day in rabbits. The mean exposure estimates considering the maximum concentration of Ni assumed from good manufacturing practice in hydrogenated vegetable oils/fats (50 mg Ni/kg) varied between 27 μg Ni/kg bw per day in cats and 255 μg Ni/kg bw per day in rabbits; for the high concentration scenarios, exposures varied between 30 μg Ni/kg bw per day and 307 μg Ni/kg bw per day in the same species. The estimated exposures to Ni are in line with the one reported in the 2015 EFSA opinion, using a worst‐case scenario. When estimating exposure with a realistic scenario, using the reported Ni concentration in hydrogenated vegetable oils/fats, the exposure of livestock and companion animals is lower (approximately from 1.5 to 6 times, depending on the species) than the 2015 assessment.

Tree radial growth is projected to decline in South Asian moist forest trees under climate change

Abstract Global climate change has been reported to affect tree growth around the world and such impacts are predicted to be intensified under future climate change particularly in the tropics. It is therefore important to study the climate-growth relationships of tropical trees to understand how they have responded to the past climate variability and to predict how they will respond to future climatic changes. We investigated tree radial growth responses to regional climatic changes in Bangladeshi moist tropical forests. We selected three species based on their distinct growth-ring boundaries and their wide distribution around the tropics. First, we simulated growth responses to climate for the past 66 years (1950–2015) based on the climate-growth relationships. Next, we projected tree-growth until the end of current century (2016–2100) under different climate change scenarios (Representative Concentration Pathways, RCP). All the three species produced statistically robust ring-width index chronologies covering the current and the past century. Climate-growth analysis revealed that temperature (monthly, annual and seasonal) significantly negatively affected tree radial growth in all three species. Precipitation prior to the current growing season negatively and current year post monsoon precipitation positively influenced radial growth. Tree radial growth was also influenced by Nino 3.4 region Sea Surface Temperature (SST) anomalies mainly through the modulation of local climate. We projected tree radial growth to be declined in all three species by 20% under high concentration scenario (RCP 8.5) followed by 11.3% and 9% under medium (RCP 6.0) and low-medium concentration scenarios (RCP 4.5). If these species show similar growth responses to climatic changes in other native ranges across the tropics, this could have severe consequences for the carbon balance of tropical forests.

Vulnerability of forest vegetation to anthropogenic climate change in China

China has large areas of forest vegetation that are critical to biodiversity and carbon storage. It is important to assess vulnerability of forest vegetation to anthropogenic climate change in China because it may change the distributions and species compositions of forest vegetation. Based on the equilibrium assumption of forest communities across different spatial and temporal scales, we used species distribution modelling coupled with endemics–area relationship to assess the vulnerability of 204 forest communities across 16 vegetation types under different climate change scenarios in China. By mapping the vulnerability of forest vegetation to climate change, we determined that 78.9% and 61.8% of forest vegetation should be relatively stable in the low and high concentration scenarios, respectively. There were large vulnerable areas of forest vegetation under anthropogenic climate change in northeastern and southwestern China. The vegetation of subtropical mixed broadleaf evergreen and deciduous forest, cold-temperate and temperate mountains needleleaf forest, and temperate mixed needleleaf and broadleaf deciduous forest types were the most vulnerable under climate change. Furthermore, the vulnerability of forest vegetation may increase due to high greenhouse gas concentrations. Given our estimates of forest vegetation vulnerability to anthropogenic climate change, it is critical that we ensure long-term monitoring of forest vegetation responses to future climate change to assess our projections against observations. We need to better integrate projected changes of temperature and precipitation into climate-adaptive conservation strategies for forest vegetation in China.

Human and animal dietary exposure to T-2 and HT-2 toxin.

T‐2 toxin (T2) and HT‐2 (HT2) toxin are trichothecenes, which form part of the group of Fusarium mycotoxins. Food and feed samples used to estimate human dietary and animal exposure were reported either as the individual results for T2 and/or, HT2, and/or as the sum of the two. The highest concentrations were reported in oats and oat‐containing commodities. Very high levels were reported in a small number of data on specific plant‐ and herb‐based dietary supplements. In humans, the mean chronic dietary exposure to the sum of T2 and HT2 was highest in ‘Toddlers’ and ‘Infants’, with maximum upper bound (UB) estimates of 64.8 and 62.9 ng/kg body weight (bw) per day, respectively. The 95th percentile dietary exposure was highest in ‘Infants’ with a maximum UB estimate of 146 ng/kg bw per day. UB estimations were on average fourfold higher than lower bound (LB) estimations. Average acute exposure ranged from a minimum of 13.4 ng/kg bw per day, estimated in ‘Elderly’, up to a maximum of 64.7 ng/kg bw per day estimated in ‘Toddlers’. The highest 95th percentile acute dietary exposure was estimated for a dietary survey within the age class ‘Infants’ (170 ng/kg bw per day). Overall, among processed foods the main contributors were cereal flakes, fine bakery wares and, for acute exposure, also bread and rolls. In the elderly and very elderly, dietary supplements made an important contribution. Exposure to the sum of T2 and HT2 in farm and companion animals varied according to the animal species. Exposures considering mean concentration scenarios varied between 0.03–0.08 (LB–UB) μg/kg bw per day in beef cattle and 1.13–1.47 μg/kg bw per day in milking goats. For high concentration scenarios, exposures varied between 0.12–0.16 μg/kg bw per day and 2.37–2.58μg/kg bw per day in the same species. In the absence of data, potential modified form were not included.

Human and animal dietary exposure to ergot alkaloids.

The ergot alkaloids (EAs) are mycotoxins produced by several species of fungi in the genus Claviceps. In Europe, Claviceps purpurea is the most widespread species and it commonly affects cereals such as rye, wheat, triticale, barley, millets and oats. Food and feed samples used to estimate human and animal dietary exposure were analysed for the 12 main C. purpurea EAs: ergometrine, ergosine, ergocornine, ergotamine, ergocristine, ergocryptine (α‐ and β‐isomers) and their corresponding –inine (S)‐epimers. The highest levels of EAs were reported in rye and rye‐containing commodities. In humans, mean chronic dietary exposure was highest in ‘Toddlers’ and ‘Other children’ with maximum UB estimates of 0.47 and 0.46 μg/kg bw per day, respectively. The 95th percentile exposure was highest in ‘Toddlers’ with a maximum UB estimate of 0.86 μg/kg bw per day. UB estimations were on average fourfold higher than LB estimations. Average acute exposure (MB estimations) ranged from 0.02 μg/kg bw per day in ‘Infants’ up to 0.32 μg/kg bw per day estimated in ‘Other children’. For the 95th percentile acute exposure, the highest estimate was for a dietary survey within the age class ‘Other children’ (0.98 μg/kg bw per day). Dietary exposure estimates for animals, assuming a mean concentration scenario, varied between 0.31–0.46 μg/kg bw per day in beef cattle and 6.82–8.07 μg/kg bw per day (LB–UB) in piglets, while exposure estimates assuming a high concentration scenario (95th percentile) varied between 1.43–1.45 μg/kg bw per day and 16.38–16.61 μg/kg bw per day (LB–UB) in the same species. A statistically significant linear relationship between the content of sclerotia and the levels of EAs quantified was observed in different crops (barley, oats, rye, triticale and wheat grains). However, the absence of sclerotia cannot exclude the presence of EAs as samples with no sclerotia identified showed measurable levels of EAs (‘false negatives’).

Risk hotspots for terrestrial plant invaders under climate change at the global scale

Terrestrial plant invaders (TPIs) have a large potential to threaten plant diversity under climate change. To prevent the spread of TPIs under climate change, we must identify the risk hotspots for TPIs. However, the risk hotspots for TPIs have not yet been explicitly addressed at the global scale under climate change. Here, we selected 336 TPIs from the Invasive Species Specialist Group list and used species distribution modelling and Hot Spot Analysis to map the risk hotspots of TPIs based on the terrestrial ecoregions in the current, low and high gas concentration scenarios. The risk hotspots of TPIs were mainly distributed in South America, Europe, Australia, New Zealand and northern and southern Africa. Climate change may decrease the areas of hotspots that allow for TPI expansion, but the potential distribution probabilities of TPIs may increase in the high concentration scenario. Furthermore, TPIs, particularly herbaceous and woody ones, might still expand into critical or endangered ecoregions of these risk hotspots in the current, low and high concentration scenarios. We also need to focus on the impact of TPI expansion on both vulnerable and relatively stable ecoregions due to the increasing potential distribution probabilities of TPIs in risk hotspots and should integrate climate change into the risk assessment of plant invasion in the vulnerable and relatively stable ecoregions.

Response of the Greenland and Antarctic Ice Sheets to Multi-Millennial Greenhouse Warming in the Earth System Model of Intermediate Complexity LOVECLIM

Calculations were performed with the Earth system model of intermediate complexity LOVECLIM to study the response of the Greenland and Antarctic ice sheets to sustained multi-millennial greenhouse warming. Use was made of fully dynamic 3D thermomechanical ice-sheet models bidirectionally coupled to an atmosphere and an ocean model. Two 3,000-year experiments were evaluated following forcing scenarios with atmospheric CO2 concentration increased to two and four times the pre-industrial value, and held constant thereafter. In the high concentration scenario the model shows a sustained mean annual warming of up to 10°C in both polar regions. This leads to an almost complete disintegration of the Greenland ice sheet after 3,000 years, almost entirely caused by increased surface melting. Significant volume loss of the Antarctic ice sheet takes many centuries to initiate due to the thermal inertia of the Southern Ocean but is equivalent to more than 4 m of global sea-level rise by the end of simulation period. By that time, surface conditions along the East Antarctic ice sheet margin take on characteristics of the present-day Greenland ice sheet. West Antarctic ice shelves have thinned considerably from subshelf melting and grounding lines have retreated over distances of several 100 km, especially for the Ross ice shelf. In the low concentration scenario, corresponding to a local warming of 3–4°C, polar ice-sheet melting proceeds at a much lower rate. For the first 1,200 years, the Antarctic ice sheet is even slightly larger than today on account of increased accumulation rates but contributes positively to sea-level rise after that. The Greenland ice sheet loses mass at a rate equivalent to 35 cm of global sea level rise during the first 1,000 years increasing to 150 cm during the last 1,000 years. For both scenarios, ice loss from the Antarctic ice sheet is still accelerating after 3,000 years despite a constant greenhouse gas forcing after the first 70–140 years of the simulation.