木本植物休眠的诱导因子及其细胞内Ca2+水平的调节作用

本研究揭示 ,越冬木本植物在夏秋转变过程中对光周期变化十分敏感 .在北纬 4 5°的明尼苏达州圣保罗地区 ,当日照变短 72min时 (2 0 0 0年 8月 8日 ) ,桑树顶芽细胞质浆和细胞核内即出现Ca2 流入 ,而在夏天长日照时期 (7月上、中旬 )很少有Ca2 存在的细胞质和细胞核 .12d后 (8月 2 0日 ) ,观测到桑树和杨树芽已经开始进入生理休眠 .从 9月上旬到 11月中旬 ,细胞质和细胞核内的Ca2 浓度显著升高 ,11月中旬达到高峰 .与此同时 ,芽的生理休眠深度也迅速增加 ,并于 11月达到高峰 ,4 2d培养也不见萌芽迹象 .到 12月中旬 (12月 2 0日 ) ,细胞核和细胞质中的Ca2 浓度又恢复到夏季观察到的低水平 ,显示早先进入细胞质和细胞核中的Ca2 已经被排出 .此后 ,在 12月下旬 (2 5日 ) ,检测到生理休眠的终结 .室外补充光照实验进一步证明 ,只有日照缩短才会引发植物进入自然生理休眠 ;保持日照长度不变 ,晚夏时期的自然温度降低 ,不能诱导植株停止生长和进入休眠 .这些结果表明 ,越冬木本植物在晚夏到冬季的生理休眠发展过程中 ,日照缩短引起的核和质内Ca2 的流入不仅起着传递日照变短信号的作用 ,导致生理休眠的起始 ;而且 ,高水平的核 /质Ca2 浓度还起着发展和保持深度生理休眠的作用 .图版 1图 1表 2参     

Indigenous Uses, Population Density, and Conservation of Threatened Medicinal Plants in Protected Areas of the Indian Himalayas

Abstract:  For 10 years I monitored the population density of threatened medicinal plant species in seven protected areas in the Indian Himalayas. I also documented the indigenous uses of threatened medicinal plants through interviews with 138 herbal healers (83 Tibetan healers and 55 Ayurvedic healers) residing in the buffer zone villages of these protected areas. To assess the population status of threatened medicinal plant species, I sampled the 10 major habitat types in the protected areas. In all, I found 60 threatened medicinal plant species during the study period, of which 54 species occurred in the sampling plots. Twenty-two percent of threatened medicinal plant species were critically endangered, 16% were endangered, and 27% were vulnerable. Thirty-two threatened medicinal plant species were endemic to the Himalayan region. The density of threatened medicinal plant species varied with protected areas. The Valley of Flowers protected area had the highest number of threatened medicinal plant species. The "moist" habitat type was richest in these species among all 10 habitat types sampled. Arnebia euchroma (Royle ex Benth.) Johnston and Ephedra gerardiana Wall. ex Stapf. were the most common threatened medicinal plant species. The indigenous groups of healers used these threatened species in curing about 45 different ailments. Based on my findings, I believe that to ensure the long-term sustainability of threatened medicinal plants, medicinal-plant conservation areas should be established.     

The Influence of Mycorrhiza on Uranium and Phosphorus Uptake by Barley Plants from a Field-contaminated Soil (7 pp)

Background Recent studies indicated that arbuscular mycorrhizal fungi (AMF) play important roles in plant accumulation of uranium (U) from contaminated environments, but the impacts of fertilization practices on functioning of the symbiotic associations, which are crucial factors influencing plant nutrition and growth responses to mycorrhiza, have rarely been considered. Materials and Methods In a greenhouse experiment, a bald root barley mutant (brb) together with the wild type (wt) were used to test the role of root hairs and AMF in uranium (U) uptake by host plants from a U contaminated soil. Nil, 20 and 60 mg KH2PO4-P kg–1 soil were included to investigate the influences of phosphorus (P) fertilization on plant growth and accumulation of U. Results Dry matter yield of barley plants increased with increasing P additions and wt produced significantly higher dry weight than brb. Mycorrhiza markedly improved dry matter yield of both genotypes grown at nil P, whereas only brb responded positively to mycorrhiza at 20 mg P kg-1. At the highest P level, mycorrhiza resulted in growth depressions in both genotypes, except for the roots of wt. In general, plant P concentrations increased markedly with increasing P additions and in response to mycorrhiza. Mycorrhiza and P additions had no significant effects on shoot U concentrations. However, root U concentrations in both genotypes were significantly increased by mycorrhiza. On the other hand, shoot U contents increased with increasing P levels, while 20 mg P kg-1 stimulated, but 60 mg P kg-1 marginally affected the U accumulation in roots. Root length specific U uptake was moderately enhanced both by root hairs and strongly enhanced by mycorrhiza. Moreover, non-inoculated plants generally had higher shoot-root ratios of U content than the corresponding inoculated controls. Conclusion Our study shows that AMF and root hairs improves not only P acquisition but also the root uptake of U, and mycorrhiza generally decreases U translocation from plant root to shoot. Hence, mycorrhiza is of potential use in the phytostabilization of U contaminated environments. Perspectives The complex impacts of P on U accumulation by barley plants suggested that U behavior in mycorrhizosphere and translocation along the soil-fungi-plant continuum as affected by fertilization practices deserve extensive studies for optimizing the function of mycorrhizal associations for phytoremediation purposes.     

Cyanide Removal by Chinese Vegetation. Quantification of the Michaelis-Menten Kinetics (6 pp)

Background Little is known about metabolism rates of environmental chemicals by vegetation. A good model compound to study the variation of rates among plant species is cyanide. Vascular plants possess an enzyme system that detoxifies cyanide by converting it to the amino acid asparagine. Knowledge of the kinetic parameters, the half-saturation constant (Km) and the maximum metabolic capacity (vmax), is very useful for enzyme characterization and biochemical purposes. The goal of this study is to find the enzyme kinetics (KM and vmax) during cyanide metabolism in the presence of Chinese vegetation, to provide quantitative data for engineered phytoremediation, and to investigate the variation of metabolic rates of plants. Methods Detached leaves (1.0 g fresh weight) from 12 species out of 9 families were kept in glass vessels with 100 mL of aqueous solution spiked with potassium cyanide at 23°C for 28 h. Four different treatment concentrations of cyanide were used, ranging from 0.44 to 7.69 mg CN/L. The disappearance of cyanide from the aqueous solution was analyzed spectrophotometrically. Realistic values of the half-saturation constant (KM) and the maximum metabolic capacity (vmax) were estimated by a computer program using non-linear regression treatments. As a comparison, Lineweaver-Burk plots were also used to estimate the kinetic parameters. Results and Discussion The values obtained for KM and vmax varied with plant species. Using non-linear regression treatments, values of vmax and KM were found in a range between 6.68 and 21.91 mg CN/kg/h and 0.90 to 3.15 mg CN/L, respectively. The highest vmax was by Chinese elder (Sambucus chinensis), followed by upright hedge-parsley (Torilis japonica). The lowest vmax was demonstrated by the hybrid willow (Salix matssudana x alba). However, the highest KM was found in the water lily (Nymphea teragona), followed by the poplar (Populus deltoides Marsh). The lowest KM was demonstrated by corn (Zea mays L.). The values of vmax were normally distributed with a mean of 13 mg CN/kg/h. Conclusions Significant removal of cyanide from aqueous solution was observed in the presence of plant materials without phytotoxicity, even at high doses of cyanide. This gives rise to the conclusion that the Chinese plant species used in this study are all able to efficiently metabolize cyanide, although with different maximum metabolic capacities. A second conclusion is that the variation of metabolism rates between species is small. All these plants had a similar KM, indicating the same enzyme is active in all plants. Recommendations and Outlook Detoxification of cyanide with trees seems to be a feasible option for cleaning soils and water contaminated with cyanide. For phytoremediation projects, screening appropriate plant species adapted to local conditions should be seriously considered. More chemicals should be investigated to find common principles of the metabolism of environmental chemicals by plants.     

抗生素抗性基因在两级废水处理系统中的分布和去除

废水处理系统被认为是水环境中抗生素抗性基因(ARGs)的重要污染源.为探究ARGs在废水处理系统中的分布特征和去除情况,选取某精细化工园区内的制药废水处理系统和园区综合性废水处理系统,使用PCR和实时荧光定量PCR对不同处理单元中ARGs的存在情况和丰度变化进行研究.在两个系统进水中分别检出了10种和15种ARGs,其中以四环素类和磺胺类ARGs居多,并首次检出了dfrA13基因.进水中sulⅠ和sulⅡ基因的丰度最高,随后依次是dfrA13、tetQ、floR、tetO和tetW基因.制药废水处理系统使总ARGs浓度上升了0.21个数量级,出水汇入园区综合性废水处理系统再次处理,其对综合性废水处理系统进水中总ARGs的贡献率为5.05%.综合性废水处理系统使总ARGs浓度下降了1.03个数量级,残留ARGs同最终出水一起直接排海,对近海环境中微生物群落的潜在影响有待深入研究.     

我国火电行业NO_x排放现状及烟气脱氮技术发展

介绍了我国火电行业NOx的排放现状以及部分烟气脱氮技术的研究和应用现状,分析了脱氮技术存在的问题和发展方向。     

污水湿地处理系统中植物研究现状

文章陈述了植物在人工湿地中的作用,探讨了植物对人工湿地净化污水的影响,对人工湿地系统中植物的选择、种植与管理进行了阐述,提出了人工湿地系统研究与实践存在的问题,以期为人工湿地系统的工程设计、技术研究及运行管理提供参考。     

“烟塔合一”技术的应用现状及有关问题的探讨

介绍了国内外燃煤电厂＂烟塔合一＂技术的应用现状,阐述了＂烟塔合一＂的工艺流程及技术特点,重点进行了＂烟塔合一＂排烟方案与常规的烟囱排烟方案对环境影响的对比分析,并针对燃煤电厂＂烟塔合一＂技术在环评过程中存在的问题进行探讨。     

2种水生植物根际溶液磷素时空变异及有机酸分泌

利用根际土壤溶液的原位抽提和微量样品分析技术,比较了喜旱莲子草(Alternanthera philoxeroides)和香蒲(Typhalatifolia)2种水生植物根际土壤溶液磷素含量的时空变异和根系分泌有机酸种类及数量的差异,从植物吸收磷素、根系分泌有机酸和根际土壤pH值变化等角度探讨了植物磷素高效净化的根际调控机制.结果表明,2种水生植物的根际溶液磷素含量均明显低于非根际溶液;喜旱莲子草的根际溶液磷酸根离子质量浓度(2.53 mg.L-1)显著低于香蒲的根际溶液(5.43mg.L-1)(p<0.05),且喜旱莲子草根系对土壤溶液磷酸根的影响范围大于香蒲.与香蒲相比,喜旱莲子草分泌了较多的苹果酸(浓度27.33μmol.L-1),在活化土壤磷素、促进根系对磷素的吸收方面起了更大的作用.喜旱莲子草吸收磷素的根际效应强于香蒲.     

Insight into the safety distance of ground and underground installations in typical petrochemical plants

Petrochemical plants are continuously turning into large-size corporations, the installations of facilities show a developing trend from ground to underground because of the difference in land using rate. In this regard, the safety distance of petrochemical equipment buried in both ground and underground cases were investigated based on risk assessment. As a case study, gasoline tank and LPG tank set on the ground and underground are singled out to compare the risks involved. The research showed that the setting case of installation had a great influence on safety distance. Two cases have 80% reduction of equivalent safety distance compared with the rest of the cases. It was found that when the gasoline storage tank was placed underground alone, the PLL value decreased by 36.7%. Only LPG tank was placed underground, and the PLL decreased by 6.33%, and the gasoline and LPG storage tanks were placed underground simultaneously, the PLL value declined by 42.3%. Thus, the layout of plants could be further optimized, which can greatly improve the performances of land use efficiency and safety. In addition, this paper, the selection of embedding methods and the sensitivity of underground case to overpressure was resumed from two aspects: soil properties and burial depth. For the soil properties, it was found that the water saturated sandy soil with high air content and the low density unsaturated sandy soil had better effects on weakening overpressure. Such properties are particularly beneficial to reducing the occurrence rate of accidents. In terms of burial depth, it can be observed that as the burial depth was changed from 0.5m to 1.1m, the value of overpressure has dropped dramatically. When the burial depth was 2m, the damage to personnel and buildings has been greatly reduced beyond 2m from the explosion center.