Effects of extracellular polymeric substances on aerobic granulation in sequencing batch reactors

The effects of extracellular polymeric substances on aerobic granulation in sequencing batch reactors were investigated by evaluating the content and compositions of extracellular polymeric substances, and the relationship between extracellular polymeric substances composition and surface properties of glucose-fed aerobic granules. The results showed that extracellular polymeric substances could affect surface properties of cells, such as surface charge and hydrophobicity, enhance polymeric interaction and promote aerobic granulation. Moreover, extracellular polymeric substances were produced mainly in the exponential phase, and served as carbon and energy source in starvation phase during granulation process, thus regulating the growth of bacteria in the interior and exterior of granules, and maintaining the integrality of granules.     

An inventory of N(2)O emissions from agriculture in China using precipitation-rectified emission factor and background emission

Fertilized agricultural soils are a major anthropogenic source of atmospheric N₂O. A credible national inventory of agricultural N₂O emission would benefit its global strength estimate. We compiled a worldwide database of N₂O emissions from fertilized fields that were consecutively measured for more than or close to one year. Both nitrogen input (N) and precipitation (P) were found to be largely responsible for temporal and spatial variabilities in annual N₂O fluxes (N₂O–N). Thus, we established an empirical model (N₂O–N = 1.49 P + 0.0186 P · N), in which both emission factor and background emission for N₂O were rectified by precipitation. In this model, annual N₂O emission consists of a background emission of 1.49 P and a fertilizer-induced emission of 0.0186 P · N. We used this model to develop a spatial inventory at the 10 × 10 km scale of direct N₂O emissions from agriculture in China. N₂O emissions from rice paddies were separately quantified using a cropping-specific emission factor. Annual fertilizer-induced N₂O emissions amounted to 198.89 Gg N₂O–N in 1997, consisting of 18.50 Gg N₂O–N from rice paddies and 180.39 Gg N₂O–N from fertilized uplands. Annual background emissions and total emissions of N₂O from agriculture were estimated to be 92.78 Gg N₂O–N and 291.67 Gg N₂O–N, respectively. The annual direct N₂O emission accounted for 0.92% of the applied N with an uncertainty of 29%. The highest N₂O fluxes occurred in East China as compared with the least fluxes in West China.     

淮南矿业集团建设环境友好企业的探索

介绍淮南矿业集团近年来创建环境友好企业的基本做法,通过在积极推进市矿统筹,建设生态和谐矿区;构建循环经济产业链,促进资源综合利用;强化环保全过程管理,落实污染防治及减排等方面的有效工作,促进了经济建设与区域环境协调发展。     

Prenatal diagnosis and management of twin pregnancies complicated by a co-existing molar pregnancy

Recent advances in ultrasound and molecular genetics have increased our understanding and hence enhanced the perinatal management of complete and partial hydatidiform mole. By contrast, the management of a twin pregnancy combining a normal pregnancy with a normal fetus and a complete hydatidiform mole (CHM) remains complex and controversial due to conflicting data from different parts of the world. The aim of this review is to analyse the international literature on twin pregnancies that include a mole, present the complications and outcome of pregnancy and to discuss the perinatal management. Management is complicated and women should be counselled about the maternal and fetal complications, and the pregnancy monitored carefully by a perinatal team with experience in high-risk obstetrics and access to neonatal care. The data reviewed here suggest that a woman who decides to continue with the pregnancy including a CHM must be aware that, overall, she only has a one in four chance of live birth and in around 35% of cases she will develop persistent trophoblastic disease (PTD) after delivery. In ongoing pregnancies, there will be, in at least 20% of the cases, an early onset of pre-eclampsia (PET) and a 29% risk of fetal loss due to late miscarriage, intrauterine death and neonatal death. Maternal serum human chorionic gonadotrophin (MShCG) could be useful in predicting outcome in twin pregnancy combining normal pregnancy and CHM, but this needs to be investigated prospectively. Copyright © 2005 John Wiley & Sons, Ltd.     

对产业生态系统规模经济特征的研究

由于废物和副产品成为主要生产原料，产业生态系统在规模经济性方面表现出了与传统产业系统的不同。本文分析了影响产业生态系统规模经济性的5大因素：废料作为原材料的主要来源；以可更新能源替代化石能源；经济活动主体之间大量的物质交流；与周围环境在物质输入输出上保持平衡；信息不对称明显阻碍废物和回收市场的动作。这些因素导致了产业生态系统与传统产业系统在边际成本上的差异，即边际成本并不是随着规模的增加而降低的。论文指出，产业生态系统具有适度规模经济特征，在生产聚焦和生活聚居上表现出小规模化的趋势，表现为相对较小的空间分布和相对局限的生产规模。这样的规模对于处理分散的、高熵值的资源和能源与集约化生产和消费模式之间的矛盾有相当的灵活性。论文最后对进一步开展研究的方向和内容提出了建议。     

Multiple Effects of Energy Issues and Countermeasures： A Case of Shandong Province

Energy is now becoming the bottleneck of urban and regional development. The paper takes Shandong Province, one of the most energy consuming provinces in China, as an example, uses quantity methods such as SPSS （Stastics Package for Social Science） cluster sampling and regression analysis, and applies quantity analysis, to analyze the situation of energy issues in Shandong province. The conflicts between the quick industrialization and increasing extensive economic development, between urban population and energy consuming per head, between the infinite energy consuming desire and the low level of managing system, and between the unstable world energy supply and the limited energy storage in China are the main factors of energy crisis in Shandong, which not only results in energy shortage, but also becomes the barrier of economic and social development. In order to ensure sufficient energy supply for Shandong province in the 21 st century, we should take countermeasures, such as changing the economic development model, pursuing a multiple and high quality energy strategy, improving the intensive urbanization strategy, and building a scientific energy system.     

粉煤灰负载壳聚糖对磷吸附的热力学研究

以粉煤灰负载壳聚糖作为吸附剂,在静态吸附条件下,研究了其对磷的吸附行为,并对吸附过程的热力学进行了分析。结果表明,吸附平衡数据都能够较好地符合Langmuir和Freundlich吸附等温方程,但Langmuir方程能够更好地描述吸附等温线。在20～35℃范围内,磷在粉煤灰负载壳聚糖上的吸附是一个吸热过程,反应的吉布斯自由能变小,同时伴随着熵值的增加,吸附焓变为44.36 kJ/mol。     

Organochlorine pesticides and polychlorinated biphenyls in Tibetan forest soil: profile distribution and processes

Tibetan forests are located in the southeastern Tibetan Plateau, where the climate is dominated by the Indian monsoon. Due to the affinity to pollution sources and high organic carbon stocks, the fate of persistent organic pollutants in the Tibetan forests should be given more attention. In this study, seven soil profiles were investigated to obtain the vertical distribution of the organochlorine pesticides and polychlorinated biphenyls (PCBs) in the Tibetan forest soil. The results indicate that the DDTs are highly stable in the soil, with limited volatilization and leaching, while the more volatile PCBs were found in the deeper mineral layer, which means that they can translocate through the organic layer and move farther downward into the deep soil. The air-to-ground fluxes (estimated by the age of the organic layer) of the DDTs are one magnitude higher than those reported in a study on the Alps, suggesting the higher accumulation of DDTs by the Tibetan forest.