扬尘污染防治理论初探

针对扬尘污染问题,进行了扬尘污染防治理论探讨,明确了扬尘的概念和特点;提出相对起尘量的概念,定量地分析了城市不同类型下垫面对扬尘污染的影响;建立了城市下垫面生态等级的划分方法;提出通过提高生态域等级及制定道路积尘量限定标准这两类措施来治理扬尘污染;建立了这两类扬尘污染防治措施的环境效益评估方法体系。     

氮沉降下西南亚高山针叶林生长的养分限制特征

长期氮(N)沉降及其诱导的N、磷(P)养分平衡性对森林生长与生产力的生态反馈效应已成为当前森林生态学研究的前沿与热点,但目前大多研究主要基于已有文献数据整合分析,而缺乏野外原位系统性研究与试验证据.以西南亚高山两种典型人工针叶林——云杉(Picea asperata)林和华山松(Pinus armandii)林为对象,...     

极限定义的新理解

针对“极限”概念提出了一些见解,并从理论上描述和给出了“极限”的精确定义,从该定义出发,更有助正确理解和掌握“极限”的内在含义。     

沈阳市区域噪声现状分析与管理措施探讨

统计了2001至2005年沈阳市区域噪声、功能区噪声、噪声源单位状况,找出目前沈阳市噪声污染最严重的噪声来源。针对噪声管理存在的问题提出更加合理的噪声管理办法。     

短程硝化反硝化生物脱氮的实现途径

短程硝化反硝化是近年来开发的一项新的生物脱氮技术,它具有节约曝气量、节省有机碳源和减少污泥产量等优点,实现短程硝化反硝化生物脱氮技术的关键就是将硝化控制在亚硝酸阶段,阻止亚硝酸盐的进一步氧化。简要介绍了短程硝化反硝化生物脱氮技术的原理和技术特点,通过对短程硝化反硝化影响因素的分析来介绍其实现途径,阐述了温度控制途径、溶解氧控制途径、pH值控制途径、投加抑制剂途径、泥龄控制途径以及纯种分离与固定化技术途径的控制机理及其局限性,并提出了今后的研究方向。     

Interactive effects of nitrogen deposition and fire on plant and soil chemistry in an alpine heathland

The response of alpine heathland vegetation and soil chemistry to N additions of 0, 10, 20 and 50 kg N ha⁻¹ year⁻¹ in combination with simulated accidental fire (+/−) was monitored over a 5-year period. N addition caused rapid and significant increases in plant tissue N content and N:P and N:K of Calluna vulgaris, suggesting increasing phosphorus and potassium limitation of growth. Soil C:N declined significantly with N addition, indicating N saturation and increasing likelihood of N leakage. Fire further decreased soil C:N and reduced potential for sequestration of additional N. This study shows that alpine heathlands, which occupy the headwaters of many rivers, have limited potential to retain deposited N and may rapidly become N saturated, leaking N into downstream communities and surface waters.     

Effects of phosphorus and nitrogen limitation on PHA production in activated sludge

The e ects of phosphorus and nitrogen limitation on polyhydroxyalkanoate (PHA) production and accumulation by activated sludge biomass with acetate as a carbon source were investigated. Pre-selected influent carbon-phosphorus (C:P, W/W) of 100, 160, 250, 500 and 750, and carbon-nitrogen (C:N, W/W) of 20, 60, 100, 125 and 180 were applied in the phosphorus limitation experiments and the nitrogen limitation experiments, respectively. The maximum PHA accumulation up to 59% of the cell dry weight with a PHA productivity of 1.61 mg PHA/mg COD consumed was observed at the C:N 125 in the nitrogen limitation experiment. This value was much higher than that obtained in previous studies with a normal substrate feeding. The study showed that activated sludge biomass would produce more polyhydroxybutyrate than polyhydroxyvalerate under the stress of nutrient limitation, especially under phosphorus limitation conditions. The experimental result also indicated that both phosphorus and nitrogen limitation may cause sludge bulking.     

卵圆卡盾藻香港株过氧化氢产生的影响因素研究

研究了卵圆卡盾藻香港株(Chattonella ovata,Hong Kong strain,COHK)在不同生长期、盐度和营养盐条件下的生长及过氧化氢(H2O2)的产生特点.结果表明,过氧化氢浓度峰值出现在COHK对数生长期(4～8 d),以第6 d达到最大,为2.91×10-4nmol.cell-1.在N∶P为16∶1、32∶1和64∶1的情况下,COHK生长较快,以32∶1时生长速率最快(0.58 div.d-1).COHK产生H2O2的量与藻类生长呈相反趋势,在N∶P为4∶1和8∶1的情况下,藻细胞生长率较低,但单位藻细胞H2O2浓度较高.单位藻细胞H2O2浓度在N∶P为4∶1时最大,达到1.26×10-4nmol.cell-1.COHK在盐度为20和25时生长率较高,在盐度为10、15和30时生长率较低,表明低盐和高盐条件均不利于COHK的生长.低盐度和高盐度均有利于COHK过氧化氢的产生,在盐度为10时,单位藻细胞的H2O2量最高,达到2.2×10-4nmol.cell-1;但盐度在15～25范围内,单位藻细胞H2O2量相差不大(0.7×10-4～0.9×10-4nmol.cell-1).Fe3+可显著影响COHK的生长,Fe3+浓度范围为0.2×10-8～1×10-8mol.L-1时,COHK生长率较高.缺铁条件下(Fe3+浓度为0),COHK生长率最低(0.1 div.d-1),而Fe3+浓度较高时(5×10-8mol.L-1),藻细胞生长率也有所降低.缺铁以及高铁条件下,卵圆卡盾藻的H2O2产量增加,H2O2浓度分别为0.97×10-4和0.95×10-4nmol.cell-1.     

秦岭不同海拔土壤团聚体稳定性及其与土壤酶活性的耦合关系

为探究土壤团聚体稳定性在海拔上的变化规律及其影响因子,在太白山选取3个不同海拔的0~10 cm表层土壤为对象,测定并分析其土壤团聚体分布、土壤理化性质、微生物量和胞外酶等相关因子的变化特征.结果表明：①土壤团聚体平均重量直径（MWD）在锐齿栎林、辽东栎林和红桦林这3个海拔梯度上的值分别为2.17 mm、1.83 mm和1.82 mm;几何平均直径（GMD）分别为1.66 mm、1.39 mm和1.32 mm,表明土壤团聚体稳定性随海拔的上升而减弱;②土壤团聚体稳定性在海拔上的变化主要受到了土壤胞外酶活性的影响,其中,中团聚体的乙酰氨基葡萄糖酶（NAG）和微团聚体的β-葡萄糖苷酶（BG）是主要影响因子;③微生物通过调节胞外酶的相对产量和改变元素利用效率使高海拔的N限制状况得以改善,也会影响土壤团聚体稳定性在海拔上的变化.本研究结果对于太白山森林生态系统的土壤质量评价和生态环境的保护具有重要意义.     

Effects of experimental nitrogen additions on plant diversity in tropical forests of contrasting disturbance regimes in southern China

Responses of understory plant diversity to nitrogen (N) additions were investigated in reforested forests of contrasting disturbance regimes in southern China from 2003 to 2008: disturbed forest (with harvesting of understory vegetation and litter) and rehabilitated forest (without harvesting). Experimental additions of N were administered as the following treatments: Control, 50 kg N ha⁻¹ yr⁻¹, and 100 kg N ha⁻¹ yr⁻¹. Nitrogen additions did not significantly affect understory plant richness, density, and cover in the disturbed forest. Similarly, no significant response was found for canopy closure in this forest. In the rehabilitated forest, species richness and density showed no significant response to N additions; however, understory cover decreased significantly in the N-treated plots, largely a function of a significant increase in canopy closure. Our results suggest that responses of plant diversity to N deposition may vary with different land-use history, and rehabilitated forests may be more sensitive to N deposition.