Physiological and biochemical responses of Microcystis aeruginosa to phosphine (PH3) under elevated CO2

Phosphine (PH₃) is an important factor driving the outbreak of cyanobacterial blooms that produce toxic microcystin threating human health. To clarify the physiological and biochemical responses of cyanobacteria to PH₃ under elevated CO₂ concentration, Microcystis aeruginosa was used in the coupling treatment of 1000 ppmv CO₂ and PH₃ at different concentrations respectively. The chlorophyll a (Chl-a), carotenoid, net photosynthetic rate and total protein of M. aeruginosa exhibited evidently increasing tendency under the coupling treatment of 1000 ppmv CO₂ and PH₃ at different concentrations (7.51 × 10^?3, 2.48 × 10^?2, 7.51 × 10^?2 mg/L). The coupling treatments resulted in the higher concentrations of Chl-a and carotenoid of M. aeruginosa, compared to those in the control and the treatment with CO₂ alone, and their enhancement increased with the increase in PH₃ concentrations. The total antioxidant capacity (T-AOC) in the coupling treatment with CO₂ and PH₃ of 2.48 × 10^?2 mg/L and 7.51 × 10^?3 mg/L showed increasing tendency, compared to the treatment with PH₃ alone. Additionally, the coupling treatment with 1000 ppmv CO₂ and PH₃ also altered the pH and DO level in the culture medium. In this regard, the coupling treatment with CO₂ and PH₃ at an appropriate concentration can enhance the resistance of M. aeruginosa to PH₃ toxicity and is beneficial to the reproduction of M. aeruginosa, presumably resulting in potential for the outbreak of cyanobacteria bloom. Given the concern about global warming and the increase in atmospheric CO₂ level, our research laid a foundation for the scientific understanding of the correlation between PH₃ and cyanobacteria blooms.     

Characterization of precipitation in the background of atmospheric pollutants reduction in Guilin: Temporal variation and source apportionment

Rainfall samples were collected from three observation sites in Guilin from 2013 to 2017, and the chemical composition characteristics of precipitation and the contribution made by different ion sources were analyzed when atmospheric pollutants levels were reduced. The results showed that acid gas emissions and atmospheric pollutant concentrations continued to decline during the study period. However, the change in the volume-weighted mean pH at the three sites suggested that acid rain pollution was not alleviated and began to deteriorate after 2015. The continuing downward trend for alkaline neutralizing ions (Ca²⁺, NH₄⁺) in precipitation indicated that the reduction in alkaline neutralizing substances in the atmosphere was an important factor that led to the deterioration in acid rain across Guilin. The principal component analysis and spearman correlation analysis indicated five sources of ions in precipitation. Quantitative assessment of these five sources indicated that fossil fuel combustion contributed the most ions concentration in precipitation at the three sites, followed by agriculture, terrestrial (crustal) sources, marine sources, and biomass burning. Long-distance airflow might affect the acidity, the electrical conductivity (EC), and ion concentrations in precipitation across Guilin. The airflow trajectory from the west and southeast directions corresponded to higher acidity and ion concentrations. According to the current air pollution control strategy planned by Guilin, reducing atmospheric coarse particles and NH₃ at the same time may potentially lead to further deteriorations in acid rain contents. Therefore, Guilin needs to develop more reasonable pollution prevention measures that synergistically control atmospheric pollutants and acid rain pollution.     

温度对湖泊沉积物中沉水植物残体厌氧分解的影响

淡水湖泊水生植物残体的腐烂分解过程为沉积物中的异养微生物提供了重要的碳源,但是目前关于温度对沉水植物残体有机质分解的影响研究还不够深入.本研究通过室内微宇宙模拟实验,研究了4℃和25℃时马来眼子菜残体在沉积物中厌氧分解特征及其主要的微生物代谢途径.结果表明,温度对马来眼子菜残体的分解影响显著,25℃实验组沉积物中总有机碳（TOC）和纤维素去除率显著高于4℃实验组.25℃实验组沉积物初始腐殖质占TOC比例为18.23%±1.47%,90 d后达到约46%,这说明微生物对马来眼子菜残体的分解促进了沉积物腐质化.此外,温度升高促进了纤维素降解细菌（如拟杆菌门,Bacteroidetes）的生长繁殖,且硫酸盐还原细菌（如GOUTA19、脱硫球菌属（Desulfocuccus）、LCP-6、HB118）和铁还原细菌（如地杆菌属,Geobacter）是沉积物中主要的优势菌种.在25℃条件下,微生物硫酸盐还原、铁还原和产甲烷作用占马来眼子菜残体厌氧代谢的比例分别达到37.3%、27.8%和10.3%.综上所述,本研究表明温度升高促进了沉积物中马来眼子菜残体的厌氧分解,且微生物硫酸盐还原、铁还原和产甲烷过程在其厌氧分解过程中发挥了重要作用.     

电子废弃物资源化技术现状

随着电子废弃物数量的日益增加和对电子废弃物资源化利用要求的提高,电子废弃物经历了由堆存到资源化利用的发展过程.目前电子废弃物资源化技术主要包括物理处理法、化学处理法和热处理法等方法,实现电子废弃物的资源化.     

我国环境管理中经济手段的应用现状和发展对策

市场经济条件下,在环境管理中采用经济手段的重要作用日显突出,分析目前环境管理经济手段在我国的应用现状以及存在的问题,提出我国实施环境经济手段应具备的条件和应用发展对策。     

规划环境影响评价的发展机遇与挑战

《环境影响评价法》的出台，为我国规划环境影响评价提供了新的发展机遇，同时也对传统项目环境影响评价和规划环境影响评价的发展提出了严峻的挑战。为促进《环境影响、平价法》的实施，笔者认为充分认识项目环境影响评价的局限性，加强规划环境影响评价的理论创新研究和实践，是当前应着手准备解决的问题。本文在分析传统环境影响评价局限性的基础上，研究了规划环境影响评价的发展机遇和挑战，以期能对国内规划环境影响评价工作的开展提供一些参考。     

二维时变的积云化学模式

将一组化学模式和二维时变云模式相结合,研究了随同云和雨的发展,云水和雨水中pH值和[SO_4~(2-)]的演变情况以及SO_2,NH_3,尘,O_3和H_2O_2等大气污染物的净化过程.     

有机化合物水中溶解度的测定与估算

本文介绍用摇瓶法、产生柱法和动态联柱高效液相色谱法等方法测定有机化合物在水中溶解度的研究方法,同时给出了某些农药、硝基多环芳烃和氯苯类化合物的水中溶解度的实验数值.     

Development of a PCR strategy for thraustochytrid identification based on 18S rDNA sequence

The identification and characterization of the thraustochytrids, an emerging economically and biotechnologically important group of marine heterotrophic protists, is usually based on morphological characters. In this research we used molecular markers to identify thraustochytrids. We designed three sets of primers based on the 18S rDNA sequence alignment of known strains and employed a PCR (polymerase chain reaction) strategy to identify unknown thraustochytrid isolates. DNA from 26 thraustochytrids (three isolated from primary cell cultures of the tunicate Botryllus schlosseri and 23 from a coral holding aquarium) were amplified by these primers, revealing 21 isolates with three bands each, which were assigned to two groups according to PCR fragment sizes. Taxonomic characterizations were deduced by comparing with GenBank data. Four isolates were further studied by sequencing their 18S rDNA. Sequence alignments and phylogenetic analysis revealed that isolates from the coral aquarium (7-5 and 8-7) were highly similar to each other and 95.0-97.0% similar to Thraustochytrium multirudimentale and Schizochytrium minutum. Isolates from the tunicate primary cell cultures (BS1 and BS2) were also closely related to each other and 84.3-86.0% similar to labyrinthulid quahog parasite and Thraustochytrium pachydermum. AFLP (amplified fragment-length polymorphism) analysis revealed 2.5-3.6% differences within the genomic DNA of each group, showing that each isolate is different, although isolates within each group may belong to the same species, in spite of differences found in the general morphology.     

生长温度对盾叶薯蓣POD活性等生理特性的影响

研究了15℃、20℃、25℃、30℃和35℃五个不同温度条件下盾叶薯蓣一些生理参数的变化.结果显示,盾叶薯蓣叶片的POD活性和MDA含量的变化呈V字形,其中在25℃时处于最低点;可溶性蛋白含量的变化呈M字形,可溶糖含量的变化呈W字形.在15℃、20℃、30℃和35℃下, 5d内,随着时间的延长,MDA含量增加,POD活性、可溶性蛋白和可溶性糖的含量下降;在25℃下,盾叶薯蓣的POD活性以及MDA、可溶性蛋白和可溶性糖的含量变化较小,相对稳定,所以25℃是最为适宜的生长温度. 图1表1参20