Closing the phosphorus loop in England: The spatio-temporal balance of phosphorus capture from manure versus crop demand for fertiliser

Every year 90 million tonnes of housed livestock manures are produced in the UK. This is a valuable reservoir of global phosphorus (P) and a point in the cycle where it is vulnerable to being lost from the terrestrial system. Improved manure management for the effective reuse of phosphorus is vital to simultaneously tackle a major source of water pollution and reduce our dependence on imported fertilisers. This paper quantifies, for the first time, the spatial and temporal challenges of recycling the required amount of manure P from areas of livestock production to areas of crop production in eight regions of England. The analysis shows that England has a P deficit and therefore the capacity to fully utilise the manure P on arable land, but that uneven spatial distribution of livestock poses a significant challenge to closing the P loop in agriculture. Two of the eight regions were shown to have surplus manure P, with the remaining six regions having P deficits, indicating that an annual export of 4.7 thousand tonnes P (2.8 million tonnes manure) must take place from the west to the east of the country each year to balance P supply and demand. Moreover, housed manure production peaks between October and February, requiring an excess of 23.0 thousand tonnes P (15 million tonnes manure) to be stored until it can be used for crop fertilisation from March onwards. The results demonstrate the scale of the challenge in managing manure P in an agricultural system that has separated livestock production from crop production, a pattern that is echoed throughout the developed world. To overcome the spatial and temporal challenges, a logistical system is recommended that will balance the nutrient potential (nitrogen and P content and availability) and pollution potential (eutrophication, greenhouse gas emissions, particulates and nitrous oxide from transport) for cost-effective and environmentally compatible redistribution of manure P from areas of surplus to areas of deficit, when required.     

碳纳米管在环境样品前处理中的研究现状及应用进展

纳米碳管是一种新型的纳米材料,其独特的分子结构和性能引起了人们的广泛关注。本文重点评述了纳米碳管在环境样品前处理特别是在固相萃取和固相微萃取方面的研究现状与应用进展,并对纳米碳管的应用前景进行了展望。     

石化废水深度处理用臭氧催化氧化体系的研究＊

文章就臭氧催化氧化体系在石化废水处理中的作用进行了深入研究,对催化剂载体、催化剂配伍体系以及臭氧的投加方式进行了优化筛选。根据实验,多元催化掺杂体系较一元催化体系氧化效果好,CODCr的去除率可由一元催化时的20%提高到多元催化时的33%;在臭氧的投加方式上,分段投加要优于单级投加,臭氧投加分配比例为6∶3∶1时,CODCr的去除率可由单一投加时的9%提高到分级投加时的19%。     

玻璃钢管线在英买力潜山原油集输中的应用

埋地管道的腐蚀是影响油气田地面工程安全运行的重要因素之一,玻璃钢管道的非金属特性根除了腐蚀环境的形成,杜绝了管道腐蚀穿孔事件的发生,降低了污染土壤等环境问题发生的机率,塔里木油田管道服役现状、史密斯公司30a的研究结果对此做了充分的诠释。英—红外输油管道和哈森-威廉姆斯公式分别从实践和理论上展示了玻璃钢管卓越的水力特性,英买力潜山玻璃钢管线具有良好的经济和社会效益。     

套管保护液对钻井废水处理效果的影响＊

通过研究高含硫气田钻井完井后套管保护液对钻井废水处理效果的影响,可知:采用混凝/二次絮凝/吸附工艺处理不含套管保护液的钻井废水时,出水COD<150 mg/L;当套管保护液加量>0.5 mL/L时,出水中COD随套管保护液用量增加而急剧升高,远大于150 mg/L;采用混凝/吸附/微电解组合工艺处理含套管保护液的完井钻井废水,出水COD<150 mg/L,满足GB 8978-1996《污水综合排放标准》二级标准的要求。     

电磁辐射污染及防护探索

电子设备、仪器的广泛使用产生的电磁辐射已成为当今的重要污染之一。电磁辐射分为天然和人为两种,严重危害和影响着人类的生活和生产。人们要重视电磁辐射,从行政、科学技术、个人生活方面加强对电磁辐射的防范。     

Large eddy simulation of oxy-coal combustion in an industrial combustion test facility

Oxy-fuel combustion is considered as one of the most promising technologies for carbon capture and storage (CCS). In this study, a commercial computational fluid dynamics (CFD) code has been employed for the simulation of an air-fired coal combustion and an oxy-fired coal combustion with recycled flue gas in a 1 MW_th combustion test facility. Reynolds–averaged Navier–Stokes (RANS) solutions have been obtained for both cases. Results indicate that the CFD code with existing physical sub-models can provide a reasonable prediction for the air-fired combustion. However, the prediction for the oxy-fired case has not been as satisfactory as expected. In order to assess the impact of the turbulence treatment in CFD on the predictions, large eddy simulation (LES) has been performed for oxy-fired case and compared with the results from the RANS simulation and the available experimental data. Although the results suggest that LES can provide a more realistic prediction of the shape and the physical properties of the flame, there has not been significant improvement in the prediction of the temperature. In addition, the complexity of the problem requires more detailed experimental data for the validation of the LES. In order to improve the validity of numerical simulations for design purposes, further modelling improvements for oxy-coal combustion that are necessary for more accurate predictions are addressed. Based on this study, it is envisaged that the complexity in the oxy-coal combustion process requires more detailed analyses of the available physical sub-models.     

The reproductive ecology of the invasive ascidian, <Emphasis Type="Italic">Styela clava,</Emphasis> in Auckland Harbour,New Zealand

The ascidian Styela clava, native to the north-west Pacific, is an invasive species affecting New Zealand’s marine ecosystems, biodiversity and aquaculture operations. To provide detailed information on the reproductive biology of S. clava in New Zealand for post-border biosecurity management, long-term seasonal patterns of gametogenesis were determined from May 2006 to May 2008 in Auckland’s Waitemata Harbour (36°49′20″S, 174°45′85″E). Of particular interest was whether the critical 15°C threshold spawning temperature for reproduction observed in the Northern Hemisphere applied here to the first Southern Hemisphere study. S. clava gametogenesis followed a regular seasonal cycle with ripe gametes appearing as early as September and persisting to June; this time frame corresponds to the period when sea surface temperatures in the region first reach 15°C and with spawning occurring mainly during late summer to early autumn. From photoperiod manipulation, it was determined that spawning occurred at approximately 18:20. The extended reproductive period and a short generation time in the Waitemata Harbour provides a lengthy opportunity for S. clava to spread. Findings are discussed in relation to S. clava’s post-border management.     

杀虫单在小白菜和土壤中的残留及消解动态研究

为了解杀虫单在小白菜和土壤中的残留消解动态及最终残留状况,研究了杀虫单在小白菜和土壤中的气相色谱检测方法,并在天津、江苏两地开展了20%阿维菌素.杀虫单可湿性粉剂在小白菜和土壤中的残留消解动态和最终残留田间试验研究.结果表明,在0.02—1 mg.kg-1添加水平范围内,通过外标法定量,获得杀虫单在小白菜和土壤中的平均...     

Dispersal connectivity and reserve selection for marine conservation

Although larval dispersal is crucial for the persistence of most marine populations, dispersal connectivity between sites is rarely considered in designing marine protected area networks. In particular the role of structural characteristics (known as topology) for the network of larval dispersal routes in the conservation of metapopulations has not been addressed. To determine reserve site configurations that provide highest persistence values with respect to their connectivity characteristics, we model nine connectivity topological models derived from graph theory in a demographic metapopulation model. We identify reserve site configurations that provide the highest persistence values for each of the metapopulation connectivity models. Except for the minimally connected and fully connected populations, we observed two general ‘rules of thumb’ for optimising the mean life time for all topological models: firstly place the majority of reserves, so that they are neighbours of each other, on the sites where the number of connections between the populations is highest (hub), secondly when the reserves have occupied the majority of the vertices in the hub, then select another area of high connectivity and repeat. If there are no suitable hubs remaining then distribute the remaining reserves to isolated locations optimising contact with non-reserved sites.