Terrestrial discharge influences microbioerosion and microbioeroder community structure in coral reefs

Microbioerosion rates and microbioeroder community structure were studied in four Kenyan protected coral-reef lagoons using shell fragments of Tridacna giant clams to determine their response to the influence of terrestrial run-off. Fourteen different microbioeroder traces from seven cyanobacteria, three green algae and four fungi species were identified. The river discharge-impacted reef and ‘pristine’ reef showed similar composition but higher microbioeroder abundance and total cyanobacteria- and chlorophyte-bioeroded areas when compared with the other study reefs. Cyanobacteria dominated during the north-east monsoon (NEM) relative to the south-east monsoon (SEM) season, with algae and cyanobacteria being major microbioeroders in the river-impacted and pristine reefs. The rate of microbioerosion varied between 4.3 g CaCO3 m^?2 y^?1 (SEM) and 134.7 g CaCO₃ m^?2 y^?1 (NEM), and was highest in the river-impacted reef (127.6 g CaCO₃ m^?2 y^?1), which was almost double that in the pristine reef (69.5 g CaCO₃ m^?2 y^?1) and the mangrove-fringed reef (56.2 g CaCO₃ m^?2 y^?1). The microbioerosion rates measured in this study may not be high enough to cause concern with regard to the health and net carbonate production of Kenya’s coral reefs. Nevertheless, predicted increases in the frequency and severity of stresses related to global climate change (e.g. increased sea surface temperature, acidification), as well as interactions with local disturbances and their influence on bioerosion, may be increasingly important in the future.     

Gas adsorption on crushed quartz and basalt

The new surfaces generated by crushing rocks and minerals adsorb gases. Different gases are adsorbed to different extents so that both the total amount and composition of the released gases are changed. This affects the interpretation of the composition of the gases obtained by vacuum crushing lunar basalts, meteorites and minerals with fluid inclusions.     

Effect of sludge pretreatment on the performance of anaerobic/ anoxic/ oxic membrane bioreactor treating domestic wastewater

In the present study, two bench-scale anaerobic/ anoxic/ oxic submerged membrane bioreactors were used to study the effect of thermochemical sludge disintegration system on the excess sludge production. Among the two membrane bioreactors, one was named experimental membrane bioreactor and another one was named as control membrane bioreactor, where a part of the mixed liquor was treated with thermo chemical and was returned back to membrane bioreactor. Thermo chemical digestion of sludge was carried out at fixed pH (11) and temperature (75 °C) for 24 % chemical oxygen demand solution. The other one was named control membrane bioreactor and was used as control. The reactors were operated at three different mixed liquor suspended solids range starting from 7500 mg/L to 15000 mg/L. Both of membrane bioreactors were operated at a flux of 17 LMH over a period of 240 days. The designed flux was increased stepwise over a period of one week. During the 240 days of reactor operation, both of membrane bioreactors maintained relatively constant transmembrane pressure. The sludge digestion had no impact on chemical oxygen demand removal efficiency of the reactor. The results based on the study indicated that the proposed process configuration has potential to reduce the excess sludge production as well as it didn’t deteriorate the treated water quality.     

近三十年长江口九段沙及其植被的演变

研究河口沙洲及其植被的演变规律对维护河势稳定、保护河口地区生态环境具有重大意义。然而在较大时空尺度上，针对河口沙洲演变与其植被变化之间的相互作用关系尚讨论不足。因此，本文通过对文献资料中九段沙区域河势演变、涉水工程、植被面积等数据的收集和总结，结合海图及遥感影像分析，归纳分析了近三十年九段沙沙体及植被的演变特征及其相关作用关系。结果显示，近三十年九段沙沙体扩张明显，特别是0m以上沙体面积增长迅速，总增长达到176.5%；而5m等深线以内沙体面积扩张相对缓慢。九段沙区域河口汊道分流比、分沙比、悬沙浓度等水文、泥沙要素变化显著。九段沙植被面积由1990年的9.1 km²扩张到了2015年的65.68 km²，其中不同植被类群的变化特征有所不同。筛选得到的与0m等深线以内沙体面积变化具有显著相关性的环境因子包括互花米草群落面积和芦苇群落面积。未筛选得到与5m 等深线以内沙体面积变化有显著相关性的环境因子。九段沙沙体的演变受到了水文、泥沙条件及河势变化的重要影响。同时，沙体的发育提供了适宜植物生长的高程及环境条件进而促进了植被面积的扩张。沙洲演变与植被演变之间的相互作用关系在不同植被和不同高程间有所差异。未来需要进行长期有效监测以系统综合分析水文过程、沙洲演变与植被变化之间的相互作用关系。