[Effects of Nitrogen Addition on Soil Organic Carbon and Its Fractions in Karst Farmland and Forest Ecosystems of China Based on Meta-analysis].

In recent decades, with the intensification of human activities, atmospheric nitrogen （N） deposition has been increasing. N deposition affects carbon （C） cycling in terrestrial ecosystems, especially in fragile karst ecosystems. Karst ecosystems are considered to be an important C pool. To evaluate the impact of N deposition on soil organic C （SOC） and its fractions in karst ecosystems of China, we collected and collated 14 English literature published through the end of March 2023, yielding a total of 460 sets of experimental data. The meta-analysis examined the effect of N addition levels [low N: ≤50 kg·ï¼ˆhm2·a）-1, medium N: 50-100 kg·ï¼ˆhm2·a）-1, and high N: >100 kg·ï¼ˆhm2·a）-1, in terms of N] on SOC and its fractions [particular organic C （POC）, readily oxidized organic C （ROC）, microbial biomass C （MBC）, and dissolved organic C （DOC）]. The results showed that N addition levels significantly affected the responses of farmland and forest soil SOC and their active fractions to N addition. Specifically, low and high N additions significantly increased SOC concentration in farmland ecosystems, whereas medium N addition significantly increased SOC concentration in forest ecosystems. In addition, soil active C fraction concentrations increased under high N addition in farmland ecosystems and under low and medium N addition in forest ecosystems. Without considering the level of N addition, N addition significantly enhanced soil organic matter （SOM） mineralization in both farmland and forest ecosystems and increased the SOC concentration in farmland ecosystems but not forest ecosystems. The responses of different active C fractions to N addition were diverse. In farmland ecosystems, the POC and ROC concentrations increased, but DOC did not change with N addition. In forest ecosystems, the DOC and POC concentrations increased, but there was no significant effect on MBC. Moreover, the response ratios （RR） of SOC and its fractions in different ecosystems to N addition were influenced by different environmental factors. In farmland ecosystems, the response ratio of SOC was related to the annual average temperature and soil pH. The response ratio of DOC was affected by the annual average temperature, mean annual precipitation, and N addition rate. The POC response ratio was related to the N addition rate. In forest ecosystems, the effects of N addition on the SOC response ratio were significantly altered by the annual average temperature, mean annual precipitation, and soil pH. However, the response ratios of DOC, POC, and MBC were not affected by the annual average temperature, mean annual precipitation, soil pH, and N addition rate. Consequently, these findings indicate that N addition could enhance soil SOC concentration and promote soil C sequestration in farmland and forest ecosystems in karst regions, but this effect relies on the level of N addition. This provides a scientific basis for predicting the soil C sink function in karst ecosystems under climate change scenarios.

[Impact of Size on Environmental Behavior of Metal Oxide Nanoparticles].

With the rapid development of nanotechnology, the environmental behavior and ecological effect of nanoparticles (NPs) are receiving more and more attention. As an important environmental component, metal oxide NPs occur widely in nature, such as in water bodies, air, soils, and sediments. They have a large surface area and high surface activity, allowing them to control and affect the speciation, migration, transformation, and bioavailability of some contaminants and nutrients in the environment. The nano-size is a unique property of nanoparticles. The size of particles regulates and determines the structure and physicochemical properties of nano-oxides, which greatly affects interfacial reactions with the relevant elements and environmental geochemical behaviors. The effects of NPs size on the environmental geochemical behaviors, such as adsorption, (reductive) dissolution, (catalytic) oxidation, aggregation and transport, are briefly summarized, and the mechanism of the size effect is discussed. Finally, hot spots for future research of metal oxide nanoparticles related to size effects in the environment are proposed.

Meta-analysis of nonsteroidal anti-inflammatory drug use and risk of atrial fibrillation.

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. The goal of the present study was to quantify the association between use of nonsteroidal anti-inflammatory drugs (NSAIDs) and risk of AF incidence. MEDLINE and EMBASE were searched for studies that reported risk of AF associated with nonaspirin NSAID use. Combined relative risk (RR) estimates and 95% confidence intervals (CIs) were calculated using the random-effects model. Stratified meta-analyses were used to discern which patients were at the highest risk of AF due to NSAID use. Five studies were identified that met the inclusion criteria, 3 of which additionally reported specifically on the association between selective NSAIDs and risk of AF. Overall, NSAID use was associated with a 12% increased risk for AF incidence (RR 1.12, 95% CI 1.06 to 1.18). The association was found to be apparent among new users (RR 1.53, 95% CI 1.37 to 1.70). The increased risk of AF might be explained by the occurrence of chronic heart failure and kidney disease. In addition, use of selective NSAIDs was still related to an increased risk of AF (RR 1.24, 95% CI 1.18 to 1.30). Sensitivity analyses found results to be robust. In conclusion, use of nonaspirin NSAIDs was associated with an increased risk of incident AF. The association was found to be apparent for new users, with a 53% increase in risk. These findings suggest that AF needs to be added to the cardiovascular risks to be considered when prescribing NSAIDs.

[Sorption and desorption characteristics of different structures of organic phosphorus onto aluminum (oxyhydr) oxides].

The sorption and desorption characteristics of four kinds of organic phosphorus with different molecular structures (glycerophosphate (GP), glucose-6-phosphate (G6P), adenosine triphosphate (ATP), and myo-inositol hexakisphosphate (IHP)) on three kinds of aluminum (oxyhydr)oxides (amorphous Al(OH)3, boehmite, and alpha-Al2O3) were studied. The underlying mechanisms were also illustrated. Results showed that the maximum sorption amounts of OP onto Al (oxyhydr)oxides, on a per gram dry weight basis, decreased as following: amorphous Al(OH)3 > boehmite > alpha-Al2O3. This mainly related to the mineral crystallinity and surface heterogeneity. With the exception of sorption of IHP on amorphous Al (OH)3, the maximum sorption density decreased with increasing molecular weight (MW) of OP, following the order: GP > G6P > ATP > IHP. However, the sorption amount of IHP on amorphous Al (OH)3 was much higher than those of other OP, due to the transformation of surface complexes of IHP to surface precipitation and thus enhancing the sorption. The sorption kinetics results showed that sorption of OP underwent the first onset rapid sorption, i. e. a certain amount of sorption occurred within an onset extremely short period, and a following long and slow sorption process. Amorphous Al (OH)3 had the greatest onset rapid sorption density, and the onset rapid sorption density of OP on Al (oxyhydr) oxides decreased with increasing MW. Desorption capacities of OP by KCl and citrate solutions related to the surface affinity between OP and boehmite. Initial desorption percentages by KCl decreased in the order: G6P (10.53%) > GP(6.91%) > ATP (3.06%) > IHP (0.8%). The maximum desorption percentages of OP by citrate were 4-5 times greater than those by KCl. During resorption process of P by KCl, the maximum desorption rate achieved after a fast desorption in a few hours, followed by diffusion-resorption during which the desorption percentage gradually decreased. Specially, both diffusion-resorption and surface precipitation promoted the resorption of IHP on mineral surface. Conclusively, the strong specific sorption of OP occurs on the surface of Al (oxyhydr) oxides, and molecular structure and size of OP as well as the crystallinity and crystal structure of minerals are the key factors affecting the interfacial reactions and environmental behaviors of OP.