[Short-term nitrogen deposition changes chemical composition of litter and soil organic matter in a Moso bamboo forest]. / 短期氮沉降改变毛竹林凋落物和土壤有机质化学组成.

To investigate the effects of short-term nitrogen (N) deposition on organic matter composition of litter and soil in Moso bamboo (Phyllostachys edulis) forests, we established a N-addition treatments (50 kg N·hm-2·a-1) to simulate the ambient and N deposition in a subtropical Moso bamboo forest from July 2020 to January 2022. We analyzed the organic matter composition of Moso bamboo leaf/root litter and soil by using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique. The results showed that short-term N deposition significantly increased the relative content of soil phenols by 50.9%, while significantly decreased fatty acids by 26.3%. The rela-tive content of alkanes & alkenes and lignin in leaf litter was significantly increased by 51.9% and 33.5%, respectively, while that of phenols and polysaccharides significantly decreased by 52.2% and 56.3%. In root litter, eleva-ted N significantly decreased the relative content of polycyclic aromatic hydrocarbons by 16.6%. Moreover, the relative content of fatty acids in soil organic matter was significantly positively correlated with the relative content of poly-saccharides in leaf litter. The relative content of phenols in soil organic matter was significantly positively correlated with the relative content of lignin, and negatively correlated with the relative content of polysaccharides in leaf litter. Our results demonstrated that short-term N deposition did not change the concentration of total organic carbon, total nitrogen, and C/N of the soil, leaf litter, and root litter, but significantly altered the chemical composition of organic matter. In addition, the changes in chemical composition of organic matter in soil under short-term N deposition were affected by the composition of organic matter in leaf litter.

[Occurrence, Distribution, and Ecological Risk of Antibiotics in Surface Water in the Liaohe River Basin, China].

The pollution and ecological risk characteristics of five typical antibiotics found in the surface water of the Liaohe River Basin (LRB) were analyzed and evaluated using solid-phase extraction and high-performance liquid chromatography tandem mass spectrometry. These results showed that macrolides have the highest average concentration of all antibiotics in the surface water of the LRB of 201.88 ng·L-1, followed by quinolones, trimethoprim, and sulfonamides with average concentrations of 113.40 ng·L-1, 93.93 ng·L-1, and 124.27 ng·L-1, respectively. Tetracycline demonstrated the lowest concentration at 24.37 ng·L-1. In addition, antibiotics pollution of the Daliao River is clearly identified as being higher than that of the Liaohe River, and the highest proportion of antibiotic pollution (49.1%) is found to come from human use according to a source apportionme0nt analysis. Relatively high levels of ecological risk are identified from Trimethoprim and Erythromycin-H2O concentrations, especially for cities such as Xinmin, Shenyang, and Anshan. The risk assessment indicates that surface water of the LRB faces high ecological risk and argues for greater attention to be paid to risk management and pollution controls.

[Ecological function evaluation and related management strategies of river ecosystem in Taizi River basin, North China].

By the method of index evaluation at reach scale, this paper evaluated the ecological functions of aquatic biodiversity maintenance, habitat maintenance, water quality sustainment, and hydrological support of the river system in Taizi River basin of North China. The dominant ecological functions and the total ecological function were determined after sorting and summing. All the reaches in the basin were divided into four hierarchies of ecological functions. Overall, the total ecological function showed a spatially degrading trend from the mountainous region to the plain. Based on the evaluation results of the total function and dominant functions, six ecosystem management strategies were proposed. For the reaches with the functions of aquatic biodiversity- and habitat maintenance, the primary ecological management strategies included ecological conservation, ecological maintenance, and ecological restoration; for the reaches with the functions of water quality sustainment and hydrological support, the primary strategies of ecological management included limited development, development optimization, and exploitation.