自然条件下植物叶片CO2同化率昼夜变化的生理生态特性

本文利用二氧化碳分析仪及开放式叶室，分别于旱、温季节在野外观测１３种乔木树种的叶片ＣＯ２同化速率的全天变化，分析各种植物白天净光合速率曲线类型的特点和夜间呼吸与气温的回归关系．结果：７月份植物白天光合时间相对较长，中午，植物光合曲线的午休现象表现不一，曲线特征取决于种的生物特性及环境因子．在气温较高的范围内（２５～３０℃）夜间阔叶树种的呼吸与气温呈负相关，但在１月份却不明显，针叶树种的夜间呼吸无论在高温、潮湿的７月份还是低温、干旱的１月份都不与温度呈现线性关系．     

美国水质交易政策及其在上海的应用分析

水质交易政策被认为是美国在改善水质方面既经济又可靠的方法。介绍了美国水质交易政策的概念和实施。分析了水质交易所必备的环境，经济和技术要素，及其可获得的经济，环境和社会效益。对排污交易政策在上海市的应用进行了分析。指出上海在排污交易方面具有多年的积累，可以借鉴美国在水质交易方面的实践经验，全面实施点源和非点源交易，采用以市场为基础的经济刺激政策来解决由城市和农田径流产生的水污染问题。     

羟基聚合氯化铝铁溶液的形态分布特征

采用改进的Ａｌ＝Ｆｅ－Ｆｅｒｒｏｎ逐时络合比色法定量研究了ＨＰＡＦＣ的形态分布，结合酸解聚实验和酸反一实验结果，综述了其形态分布特征，在碱化度Ｂ为１．０～２．０内，ｎＡｌ／ｎＦｅ＝９：１时，单体和二聚体（Ａｌ＋Ｆｅ）达２０％～６０％，ｎＡｌ／ｎＦｅ＝５：５时达３０％～５０％，ｎＡｌ／ｎＦｅ＝９：１时，中间多在络合物（Ａｌ／ｎＦｅ＝５：５时达５％～２０％，ｎＡｌ／ｎＦｅ＝９：１时，溶胶（Ａｌ＋Ｆｅ）     

Property rights integrity,tenure security and forestland rental market participation: Evidence from Jiangxi Province,China

The decentralization of property rights is the focus of the forest tenure reforms in several developing countries. In China, it was achieved by the launch of a new round of collective forest tenure reform beginning in 2003, which provided farmers with more integrated and secure forestland rights. Drawing on household data collected in Jiangxi province in 2011 and 2013, this paper examines the impacts of households’ recognition of property rights and improved tenure security on forestland rental activities. Our empirical results show that households with higher perceptions of more complete use rights and mortgage rights have a lower probability and intensity of renting‐in land, while households with lower expectations of future forestland redistribution or expropriation are more likely to rent in forestland and more of it. These results imply that the development of a forestland rental market leading to better forest management requires an integrated forestland management approach consisting of decentralization of property rights and village governance. In particular, the central government may further clarify the rights and obligations affiliated to forestland ownership, contractual rights, and management rights; while the village collective may shift from direct intervention in the integrity and security of forestland rights to the supervision and protection of decentralized forestland rights to increase efficiency from the decentralization of property rights.     

Managed grassland alters soil N dynamics and N2O emissions in temperate steppe

Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen(N) dynamics and nitrous oxide(N_2O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N_2O emissions by field experiments in Hulunber in northern China. Soil(0–10 cm), nitrate(NO_3~-),ammonium(NH_4~+), and microbial N were measured in plots in a temperate steppe(Leymus chinensis grassland) and two managed grasslands(Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M.sativa or B. inermis grasslands decreased concentrations of NO_3~–-N, but did not change NH_4~–N . Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M.sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa(i.e., a legume grass) increased N_2O emissions by 26.2%, while the conversion to the B. inermis(i.e., a non-legume grass) reduced N_2O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO?3~-+–N and NH_4~–N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N_2O emissions.     

核电厂厂址保护范围与要求探讨

核电厂厂址选择需要综合考虑各种自然和人为因素,一种宝贵的稀缺资源,考虑核电的长远规划,为防止由于人为因素使核电厂厂址及其周围环境条件遭到破坏,有必要采取有效的措施对核电厂厂址实施保护。核电厂厂址保护内容主要涉及核电厂安全、事故应急条件以及环境相容性等方面,保护范围可分为拟征地范围和非居住区、规划限制区、外围地带等,其中拟征地范围和非居住区是厂址保护中最为核心的区域,应当予以重点保护。通过对相关的保护范围和要求展开探讨,以期对今后核电厂厂址确定相关保护范围和要求具有一定的参考意义。     

A novel auditory working-memory vigilance task for mental fatigue assessment

An auditory working-memory vigilance task (AWVT), which involves higher mental abilities of a person, like working-memory and decision-making, in addition to vigilance, is presented for measuring human mental fatigue in this paper. A 25-h sleep deprivation study, with hourly testing by AWVT (3 min), PalmPVT (5 min) and self-report of sleepiness, is conducted on eight healthy subjects. The trend of mental fatigue level as measured by a specially proposed score, AWVT Fatigue Index (AFI), during the 25-h study shows very similar pattern to those of PalmPVT lapses and self-report sleepiness. AFI even shows closer correspondence to self-report sleepiness than PalmPVT lapses. This suggests that AWVT is able to measure performance decrement due to sleep deprivation, and it can even provide better measurement of mental fatigue than PalmPVT. AWVT shows a learning curve of less than 3 trials indicating that no skill is required in performing AWVT. Furthermore, repeat studies are done on five of the eight subjects. Pearson’s correlation analysis and other statistical exhibits suggest that AWVT has good test–retest reliability and within subject consistency, which are even better than those of PalmPVT. These results suggest that the AWVT can be used as a reliable objective measure of mental fatigue, and it can even track mental fatigue more accurately than PalmPVT in the real world where most tasks require not just a reaction time type response, but also higher mental abilities.     

Study on mechanics of crowd jam based on the cusp-catastrophe model

Some characteristics of crowd jam like the phenomena of discontinuous jumping in reality are hard to be explained by the equations governing pedestrians. The catastrophe theory can explain these characteristics. A cusp-catastrophe model is developed to analyze the mechanics of crowd jam by drawing graphs for a cusp-catastrophe model of crowd, the bifurcation set and the projection of catastrophe model. Meanwhile, the critical density and the critical velocity are derived. It is concluded that the cusp model is a more efficient predictor than the linear model or the equations governing pedestrians and is reasonably realistic for dense crowd flow scenarios.     

Variations of organochlorine pesticides and polychlorinated biphenyls in atmosphere of the Tibetan Plateau: Role of the monsoon system

Monsoon transport is an important process that influences the global transport of persistent organic pollutants. Only a few studies focused on the influence of monsoon on organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) levels in the Tibetan Plateau. In this study, 19 samples were collected in Lhasa, the capital of Tibet Autonomous Region, using a high-volume air sampler. The average concentrations of α-HCH, γ-HCH, p-p′-DDT, p-p′-DDE, o-p′-DDT, α-endosulfan, β-endosulfan and PCBs (including PCB-28, 101, and 118) were 2.3, 10.3, 3.2, 2.9, 5.8, 6.3, 2.2, and 10.6 pg m^?3, respectively. The weak correlation coefficients between lnp (natural logarithm of partial pressure) and 1/T (reciprocal temperature) were obtained for DDTs and β-endosulfan (r² values ranged from 0.13 to 0.41). However, no significant correlations were obtained for HCHs and PCBs. These results suggested that both local emission and long-range atmospheric transport (monsoon) may influence the distribution of OCPs at Lhasa. In this study, peak concentrations of DDTs, endosulfans and PCBs were found in August, when Eastern Monsoon system occurred. However, the maximum concentrations of HCHs appeared in June (Indian Monsoon is the dominant air circulation pattern). Monthly variation of OCP/PCB levels was likely associated with the different air sources of monsoon system.     

两种国标方法测定大气中二氧化硫的比较研究

国标方法中环境空气中二氧化硫的测定方法主要有甲醛吸收-副玫瑰苯胺分光光度法和四氯汞盐吸收-副玫瑰苯胺分光光度法.对国标方法中两种副玫瑰苯胺分光光度法测定环境空气中二氧化硫所用的两种吸收液(四氯汞钾、甲醛)的吸收效果及方法的准确性、精密度等条件作了比较试验.结果表明,采用甲醛溶液作吸收液与四氯汞钾溶液作吸收液相比,吸收效果、精密度和准确度更好,测定的检出限低.用甲醛溶液做吸收液,除了上述优点外,还可避免使用大量的汞盐,有利于环境保护.