淹水过程不同土层磷的释放研究

采用土槽模拟实验研究了淹水土壤不同土层磷释放特征及影响因素。实验结果表明:淹水土壤不同土层磷释放呈锯齿状交替变化,但释放量有很大差异,中层释放量最低,上和下层释放量较高,最大磷浓度分别为0.0336mg/L和0.0517mg/L;而不同土层溶液中的亚铁和总铁量正好与之相反,中层铁释放量最大,上层次之,下层最低,且中层释铁量明显高于上层和下层;不同土层溶液随淹水时间pH趋于中性,Eh降低,其中中层溶液Eh下降的幅度大;淹水土壤溶液中各种不同形态铁的氧化物,如因水解和氧化形成的水铁矿以及蓝铁矿在一定程度上影响了土壤磷的释放;同时淹水增加了磷的扩散,地下水有一定量的磷累积。     

Effect of bioethanol and thermal barrier coating on the performance of dual fuel engine operating on Honge oil methyl ester (HOME) and producer gas induction

Alternative fuels have numerous advantages compared to fossil fuels as they are renewable, biodegradable; provide energy security and foreign exchange saving besides addressing environmental concerns and socio-economic issues as well. Renewable fuels can be used predominantly as fuel for both transportation and power generation applications. Improved engine performance with reduced engine exhaust emissions is a major research objective in engine development. Today, the use of biomass derived producer gas is more relevant for addressing rural power generation and is a promising technique for controlling both nitric oxide (NO_x) and soot emission levels. In view of this, exhaustive experiments on the use of Honge oil methyl ester (HOME)–Producer gas in a dual fuel engine have been carried out with an intension of improving its fuel efficiency. This paper mainly presents results on a single cylinder four stroke direct injection diesel engine operated in dual fuel mode using HOME–Producer gas combination with and without bio-ethanol addition and thermal barrier coating (TBC). Further, the results were compared with diesel–producer gas mode of operation. Experimental investigation on dual fuel operation using HOME+5% bioethanol (BE5)–Producer gas operation with TBC showed 12.35% increased brake thermal efficiency with decreased hydrocarbon and carbon monoxide emissions and increased NO_x emission levels compared to HOME–Producer gas mode of operation.     

Opportunities and challenges for development of urbanization in Western China

Urban and rural dual structure in Western China is obvious.The economic development of the central cities is relatively quick while that of the rural areas is lagging behind.The speeding up of urbanization contributes to the intensively uncoordinated development of urban and rural areas.Besides,the eco-fragile environment,shortage of available water resources,adverse geographic location,and relatively backward social economy restrict the development of urbanization in Western China.However,Western China also has the advantages of backwardness.This paper analyzes the present situation and development trend of urbanization in Western China.The results show that Western China has basically formed a development pattern with"industry promotes agriculture and urban leads to village".Therefore,combined with the present situation of Western China,this paper describes and analyzes the opportunities and challenges that may appear in the process of urbanization in Western China,puts forward the development pattern in which urban and rural areas can gain mutual support and co-development,and provides related recommendations.     

Multi-objective Programming and Social Welfare Analysis of Rural–urban Land Conversion Decision-making

Abstract

Rural–urban land conversion is an inevitable phenomenon in urbanization and industrialization. And the decision-making issue about this conversion is multi-objective because the social decision maker (the whole of central government and local authority) has to integrate the requirements of different interest groups (rural collective economic organizations, peasants, urban land users and the ones affected indirectly) and harmonize the sub-objects (economic, social and ecological outcomes) of this land allocation process. This paper established a multi-objective programming model for rural–urban land conversion decision-making and made some social welfare analysis correspondingly. Result shows that the general object of rural–urban land conversion decision-making is to reach the optimal level of social welfare in a certain state of resources allocation, while the preference of social decision makers and the value judgment of interest groups are two crucial factors which determine the realization of the rural–urban land conversion decision-making objects.     

The spatial-temporal differentiation of green land use in Beijing–Tianjin–Hebei urban agglomeration

ABSTRACT

As the space carrier of the construction of ecological civilization, land’s green and efficient utilization is an important guarantee for realizing national sustainable development. Based on traditional land evaluation, this paper scientifically defines the green land use, puts land as one of the production factors, and brings energy consumption, environmental pollution, etc. into the input-output system to measure the green land utilization efficiency of the urban construction land of Beijing-Tianjin-Hebei Urban Agglomeration from 2006 to 2016. The study shows that the overall efficiency variation of the urban agglomeration is related with the land and environment policies. Efficiency of 2016 is higher than that of 2006, and energy and environment are the principal factors affecting the green land use. The efficiency of each city is positively correlated with its economic development, negatively correlated with the construction land expansion. Efficiency gaps in different cities are expanding. There is positive correlation with overall weak space between cities, and the partial spatial agglomeration phenomenon appears. Therefore, the green land use efficiency could be improved by improving land utilization efficiency, coordinating economic growth of construction land utilization with environmental protection and taking feasible ways to transregional renovation of the stock ecological land utilization, etc.     

The Belt and Road Initiative and the 2030 Agenda for Sustainable Development: seeking linkages for global environmental governance

ABSTRACT

Global environmental cooperation serves as an important part in the Chinese ideal of building a Community with a Shared Future for all Human Beings. The report of 19th CPC National Congress indicates that China is committed to proactive mitigation under the Paris Agreement and further participating in global environmental governance under the 2030 Agenda for Sustainable Development, and both of which are largely integrated to the Belt and Road Initiative (BRI). BRI are also closely linked with South–South environmental and climate cooperation proposed by China from previous UN summits. Based on shared ideas, intersected agendas, and compatible governance approaches, BRI and the 2030 Agenda for Sustainable Development grow increasingly relevant and they might form synergies based on increasingly interactive relations. In sum, seeking and intensifying the linkages between BRI and 2030 sustainable development goals (SDGs) could address global environmental governance deficits and enhance cooperation among nations.     

上覆水营养盐浓度对底泥氮磷释放的影响

采用校园水体底泥进行上覆水营养盐浓度对底泥释放量之间的关系研究。结果表明,在本实验条件下,上覆水水质影响底泥氮、磷的释放,尤其显著影响氮、磷的初期释放;上覆水氮、磷的浓度越小,底泥氮、磷的释放量越大;上覆水氮、磷的浓度超过一定值,会抑制底泥氮、磷的释放。     

不同水体沉积物中磷的形态分析

磷是生态系统中必不可少的营养元素,其含量与水体的营养程度密切相关,过剩的磷会导致水体富营养化,使生态平衡遭到破坏.就不同水体沉积物中磷的形态进行了分类综述,归纳总结了不同水体沉积物中磷的形态以及分布特征,并且进一步概述了影响沉积物中磷向水体释放的因素.     

丹江口水库氮磷内源释放对比

利用柱状沉积物采样器在丹江口水库采集不同点位原位柱状沉积物,通过静态培养释放实验及间隙水分子扩散模型两种方法获取沉积物-水界面N和P释放速率,分析水体N和P释放特征.结果表明,不同采样点N和P界面交换速率差异显著.静态培养条件下,5个点位NH_4~+-N和PO_4~(3-)-P释放速率分别为13. 07～24. 88 mg·(m~2·d)~(-1)和3. 06～6. 02 mg·(m~2·d)~(-1);分子扩散模型条件下,5个点位NH_4~+-N和PO_4~(3-)-P释放速率分别为2. 67～7. 25 mg·(m~2·d)~(-1)和0. 04～0. 18 mg·(m~2·d)~(-1). N和P释放速率总体呈北高南低的趋势,支流N和P最低释放速率分别是主库区最高释放速率的1. 48和1. 57倍.两种方法均表明郭家山支流N和P的释放速率最高,具有较大内源N和P释放风险.比较两种方法发现,利用Fick定律计算出的界面N和P释放速率明显小于柱样模拟方法得出的结果,N和P的R/F值分别为3. 43～4. 98和29. 67～72. 88,这表明用分子扩散模型法进行内源释放速率估算时,偏离真实情况较大,而原柱样静态模拟实验则较贴近真实情况.     

Evaluating the success of functional restoration after reintroduction of a lost avian pollinator

Conservation translocation is a common method for species recovery, for which one increasingly frequent objective is restoring lost ecological functions to promote ecosystem recovery. However, few conservation translocation programs explicitly state or monitor function as an objective, limiting the ability to test assumptions, learn from past efforts, and improve management. We evaluated whether translocations of hihi (Notiomystis cincta), a threatened New Zealand passerine, achieved their implicit objective of restoring lost pollination function. Through a pollinator-exclusion experiment, we quantified, with log response ratios (lnR), the effects of birds on fruit set and seed quality in hangehange (Geniostoma ligustrifolium), a native flowering shrub. We isolated the contributions of hihi by making comparisons across sites with and without hihi. Birds improved fruit set more at sites without hihi (lnR = 1.27) than sites with hihi (lnR = 0.50), suggesting other avian pollinators compensated for and even exceeded hihi contributions to fruit set. Although birds improved seed germination only at hihi sites (lnR = 0.22–0.41), plants at sites without hihi had germination rates similar to hihi sites because they produced 26% more filled seeds, regardless of pollination condition. Therefore, although our results showed hihi improved seed quality, they also highlighted the complexity of ecological functions. When an important species is lost, ecosystems may be able to achieve similar function through different means. Our results underscore the importance of stating and monitoring the ecological benefits of conservation translocations when functional restoration is a motivation to ensure these programs are achieving their objectives.