Nitrogen to phosphorus ratios of two understory plant species in response to nitrogen and phosphorus addition in tropical forest of southern China北大核心CSCD

The secondary tropical forests in southern China have suffered from frequent human disturbance and increasing high N deposition. In order to explore the nutrient limitation status in secondary tropical forests of South China, this 3-year field experiment of nitrogen (+N) and phosphorus (+P) addition investigated nitrogen (N) and phosphorus (P) concentrations of the aboveground tissue (leaf and branch) of two widely distributed understory native species Clerodendrum cyrtophyllum and Uvaria microcarpa in a secondary tropical forest of South China. The results showed that: 1) the N and P concentrations of the two species were significantly different (P < 0.001); N and P concentrations of different tissues in the same species were different; N&P addition greatly affected N and P concentrations in branch rather than new leaf and older leaf. 2) +N treatment had no significant effect on N or P concentrations of either species, but significantly decreased N:P ratios (P = 0.001), at the level of 9% for C. cyrtophyllum and 50% for U. microcarpa, respectively. 3) +P treatment had no significant effect on tissue N concentrations, but significantly increased plant P concentrations (P < 0.001), at 54% for C. cyrtophyllum and 88% for U. microcarpa, respectively; +P treatment significantly decreased plant N:P ratios (P < 0.001), at 28% and 60%, respectively. 4) The alterations of P concentrations of two species had significantly negative correlations with N:P alterations under +N/+P treatment (P < 0.001), suggesting that the alteration of P concentrations in plant tissue was the major driver for N:P alteration. Our results show that N and P addition would affect tissue N and P concentrations of the two species, with +P treatment having relatively greater effect on nutrient concentrations than +N treatment; the branch is more sensitive than new or older leaf in response to nutrient addition. Therefore, P availability may be the limiting factor for plant growth in the tropical forests.     

Preparation and characterization of Fe2O3-CeO2-TiO2/γ-Al2O3 catalyst for degradation dye wastewater

In order to develop a catalyst with high activity for catalytic wet oxidation （CWO） process at room temperature and atmospheric pressure, Fe2O3-CeO2-TiO2/γ-Al2O3 catalyst was prepared by consecutive impregnation method and the prepared parameters were optimized. The structure of the catalyst was characterized by BET, XRF, SEM and XPS technologies, and the actual wastewater was used to investigate the catalytic activity of Fe2O3-CeO2-TiO2/γ-Al2O3 in CWO process. The experimental results showed that the prepared catalyst exhibited good catalytic activity when the doping amount of Ti was 1.0 wt% （the weight ratio of Ti to carriers）, and the middle product, Fe2O3-CeO2-TiO2/γ-Al2O3, was calcined in 450℃ for 2 h. The CWO experiment for treating actual dye wastewater indicated that the COD, color and TOC of actual wastewater were decreased by 62.23%, 50.12% and 41.26% in 3 h, respectively, and the ratio of BOD5/COD was increased from 0.19 to 0.30.     

β-Cyclodextrin and its derivatives-enhanced solubility and biodegradation of 2-nitrobiphenyl

This paper investigated the effects of β-cyclodextrins （I3-CD） and its two derivatives, hydroxypropyl-β-cyclodextrin （HPCD） and carboxymethyl-β-cyclodextrin （CMCD）, on the solubility and biodegradation of 2-nitrophenyl by an A cinetbacter sp. Results showed that β-CD, HPCD and CMCD could not be utilized by A cinetbacter sp. as sole carbon source and none of the CDs had toxic effects on the growth of the bacteria in the experiments; all the CDs could enhance the apparent solubility and accelerate the biodegradation of 2-nitrobipheny. It showed that biodegradation-accelerating effects of CDs on 2-nitrobiphenyl were correlated with their solubility-enhancing effects. Among three CDs investigated, CMCD had the most obvious effects both on the apparent solubility and the biodegradation, followed by β-CD and HPCD.     

Impact of Carbon Storage Through Restoration of Drylands on the Global Carbon Cycle

   Using estimates of land suitable for restoration in woodlands, grasslands, and deserts, as well as estimates of the rate at which restoration can proceed, we estimate that carbon storage in these biomes can range up to 0.8 billion tons of carbon per year (Gt C/yr), for a combination of land management strategies. This corresponds to a reduction in atmospheric buildup of 0.5 Gt C/yr, which represents up to 15% of the average annual atmospheric carbon buildup in the next century, 3.5 Gt C/yr, assuming the IPCC 92d scenario. A global strategy for reducing atmospheric carbon dioxide concentration will require the implementation of multiple options. The advantage of carbon storage in restored drylands is that it comes as a side benefit to programs that are also justifiable in terms of land management.     

三峡地区农业经济监测原理与方法研究

提出了经济系统抟动监测原理，认为受扰动Ｘ作用的系统Ｓ的特征指标（监测指标）Ｏ的变化量△Ｏ分为由系统Ｓ自身发展引起的变化量△Ｏ和由扰动Ｘ的作用引起的变化量△Ｏｘ，即△Ｏ＝△Ｏ＋△Ｏｘ，监测的目的是考察由扰动Ｘ引起的指标Ｏ的变化量△Ｏｘ，提出了建立经济系统监测指标体系。针对５项原则和三峡地区农业经济指标体系。针对不同系统特点和扰动特性，提出８种监测方法。以对三峡库区秭归县水田坝乡眩坝区域柑桔产业开发对     

水泥粉尘的比电阻及其测量之二

水泥粉尘经分级，并经吸湿和吸油处理，对所得尘样分别测定比电阻，从而找出湿度等对比电阻的变化规律、分析其产生原因，为改进和合理使用电除尘器提供依据。     

石油野外作业工人体力劳动强度分级调查

据ＧＢ３８６９—８３标准对江汉油田测量、地震、钻井、井下四类野外作业３４名工人、２４个工种进行了体力劳动强度分级调查，其结果：测量作业为Ⅰ～Ⅱ级；钻井作业Ⅱ级占５／８，Ⅲ级占１／４；井下作业Ⅲ级占２／３；地震作业Ⅲ、Ⅳ级各占４／９、２／９。说明前两类基本属中等强度劳动，后两类大部分属重强度劳动。     

灰色─马尔柯夫模型在接发列车事故预测中的应用研究

应用灰色─马尔柯夫过程预测模型，对接发列车作业事故进行预先估计和推测；然后建立相应的软件包，通过定量的方法进行事故预测。以此达到了解和全面评价接发列车作业事故的未来状态和发展趋势。