中国典型农田土壤有机碳密度的空间分异及影响因素

农田土壤有机碳密度（SOCD）是衡量土壤肥力和土壤质量的重要指标.为理解我国农田SOCD空间分异特征及其影响因素,基于中国生态系统研究网络19个典型农田生态站2005~2015年SOCD的监测数据,利用地理探测器方法,分析了农田SOCD空间分异的影响因素.结果表明,我国不同站点农田SOCD平均值变化范围为0.83~4.97 kg·m^-2,并呈现出湿润季风区高于干旱半干旱地区的空间分异特征.在不同土地利用方式下,水稻田SOCD明显高于其他类型的农田,并且其表现出显著增加的趋势（P<0.05）,增加速率为0.13 kg·（m²·a）^-1.土壤理化性状和降水量是影响农田SOCD空间分布的重要因素,特别是土壤碱解氮含量对农田SOCD空间分布影响最大,且它分别与纬度、土壤类型、降水量及土壤pH等因素交互后影响力显著增强,本研究结果对我国农田温室气体减排增汇提供重要的科学依据.     

用膜结构参数模型评价溶解性有机物分子量分布对超滤膜污染的影响研究

研究了不同预处理对原水分子量分布的改变和对膜透水通量的影响,用膜污染的结构参数模型,评价了分子量分布对平均孔径和膜孔密度的影响。结果表明:(1)经过不同的预处理后,原水的分子量分布有所改变,混凝对大分子量有机物去除率较高,PAC吸附对小分子量有机物去除率较高,臭氧PAC联用预处理使大分子量有机物和小分子量有机物均有所去除。(2)分子量分布对膜通量影响较大。(3)通过试验并应用膜结构参数模型,评价了分子量分布对膜平均孔径和膜孔密度的影响,表明小分子量有机物易引起孔内吸附,大分子量有机物容易在膜面附着。     

Predicting a ‘tree change’ in Australia's tropical savannas: Combining different types of models to understand complex ecosystem behaviour

In this study, key ecological modelling limitations of a process-based simulation model and a Bayesian network were reduced by combining the two approaches. We demonstrate the combined modelling approach with a case study investigating increases in woody vegetation density in northern Australia's tropical savannas. We found that by utilising the strengths of a simulation model and a Bayesian network we could both forecast future change in woody vegetation density and diagnose the reasons for current vegetation states. The local conditions of climate, soil characteristics and the starting population of trees were found to be more important in explaining the likelihood of change in woody vegetation density compared to management practices such as grazing pressure and fire regimes. We conclude that combining the strengths of a process and BN model allowed us to produce a simple model that utilised the ability of the process model to simulate ecosystem processes in detail and over long time periods, and the ability of the BN to capture uncertainty in ecosystem response and to conduct scenario, sensitivity and diagnostic analysis. The overall result was a model that has the potential to provide land managers with a better understanding of the behaviour of a complex ecosystem than simply utilising either modelling approach in isolation.     

不同耕作方式对土壤性质与玉米生长的影响研究

通过种植前对土壤进行不同耕作处理试验,探讨不同耕作方式和耕作深度（30 cm,35 cm,45 cm）对土壤理化性状及玉米（Zea mays L）根系生长的影响。结果表明,三种耕作方式对土壤容重、土壤含水量、土壤微生物总量、玉米根系生长的影响表现为：深松耕作〉传统耕作〉免耕。其中,深松耕作对表层土壤（0～25 cm）容重降低作用大于深层土壤（25～45 cm）;对增加土壤含水量、增加土壤微生物总量、促进玉米根系生长方面的作用,深层土壤大于表层土壤;从不同耕作深度进行比较,深松45 cm〉深松35 cm〉深松30 cm〉传统耕作,即耕作越深,对土壤物理性状和作物根系生长影响越大。不同耕作处理间玉米产量无显著性差异。综合研究区的土壤性质、作物生长、自然环境等因素,雨养农区可采用免耕—深松的循环耕作模式,改良土壤性质,提高经济效益。     

广州绿地土壤理化特性及其相关性

以广州市荔湾区城市绿地为起点往东北延伸至从化流溪河自然保护区,建立长100km、宽10km的绿地土壤样带以研究广州市绿地土壤理化性状及土壤因子间的相关性。研究结果表明,广州绿地土壤容重平均值为（1.31±0.20）g·cm^-3,属偏紧范围;自然含水量为112.14～402.33g·kg^-1;总孔隙度均值（44.10%±4.84%）,属过紧实（45.3%～41.5%）。土壤pH值为2.21～7.82,变幅较广;有机质属丰富偏下水平（30～40g·kg^-1）;有效磷、有效钙和重金属的变化范围也较广。土壤砂粒质量分数与绝大多数土壤物理因子呈极显著负相关（P〈0.01）,土壤pH值与重金属总铬、总镉、总铅、有效铜、有效钙和有效钾等呈极显著正相关（P〈0.01）。研究结果为科学使用和保护城市绿地土壤提供依据。     

Explaining human settlement patterns in a recreational lake district: Vilas County,Wisconsin, USA

Lakeshore development in Vilas County, northern Wisconsin (USA) is heterogeneous, ranging from lakes that are surrounded by homes and commercial establishments to lakes that have no buildings on their shorelines. Development in this recreational area has increased, and since the 1960s over half of new homes have been built on the lakeshore. We examined building density around lakes in relationship to 11 variables, including in-lake, shoreline, and social characteristics. Buildings in many parts of northern Wisconsin tend to be concentrated around shorelines; in Vilas County 61% of all medium-sized buildings (our proxy for residential development) on private land were ≤100 m of a lake. The probability of development on a lake was largely related to lake surface area, with larger, more accessible lakes showing a higher probability of development. Building density along shorelines varied with travel cost, lake surface area, presence of wetlands, and extent of public land ownership. Building density was greater on larger, more accessible lakes that were surrounded by forest (as opposed to wetlands) and public lands. Gaining a more precise understanding of human settlement patterns can help direct planning and resource protection efforts to lakes most likely to experience future development.     

Ontogenetic States,Effective Density,and Classification of Plant Populations

Uranov (1975) formulated a theory of the age structure of plant populations and, in particular, defined the index of ageness . On the basis of this theory, the concepts of the energy efficiency of plants in a certain ontogenetic state and the average efficiency of a population () are introduced. A new classification of populations with respect to the types of age structure is proposed which is based on both the and values and, accordingly, is named the delta–omega classification. The notion of effective population density is defined. This parameter takes into account different loads of plants in different ontogenetic states on the environment and is quantitatively equal to the product of the population density and . The proposed approaches and methods are illustrated by data on the distribution of age states in different plant species.     

考虑疏散安全的公共场所人员容量控制研究

利用已建立的大型公共场所人员疏散行为模型,首先针对案例超市Ⅰ,在考虑疏散安全的前提下,研究了公共场所中被疏散人员的个体差异、障碍物的数量和布局差异以及疏散出口的宽度等因素对人员容量的影响,得出了不能简单地通过计算建筑面积或营业面积与给定的人员密度的乘积来设置公共场所人员容量的结论。进一步针对案例超市Ⅱ,在假设其被疏散人员构成与案例超市Ⅰ一致的条件下,通过模拟对比两个案例超市的人员容量,验证了应用均一化的人员密度来控制不同公共场所人员容量的规定不具有普适性,公共场所人员容量的确定必须要根据具体场所的实际情况来具体分析。     

Longitudinal‐Vertical Hydrodynamic and Turbidity Simulations for Prediction of Dam Reconstruction Effects in Asian Monsoon Area1

Abstract: This research investigates possible impacts of enlarged water body according to dam reconstruction on the hydrodynamics and water quality of the reservoir using a laterally averaged, two‐dimensional hydrodynamic and transport model, CE‐QUAL‐W2. The lake was formed by the artificial dam in 1983 for agricultural water supply and is currently under consideration of reconstruction so as to expand the volume of reservoir for flood control as well as water supply in downstream areas. To calibrate and validate the model, field‐collected data were compared with model predictions for water level fluctuations and water temperature during the years of 2001 (from January to December) and 2003 (from March to November). The model results showed a good agreement with field measurements both in calibration and verification. Utilizing the model, impacts of dam reconstruction on the thermal hydrodynamics and turbid current were predicted. From the model results, dam reconstruction limited the depth of thermal stratification below 10 meter and formed steep temperature gradient between epilimnion and hypolimnion. The restricted thermal stratification persisted up to the end of September. This result indicated that thermal stratification would become stronger during summer and stay longer after dam reconstruction. In addition, the restricted thermal stratification caused vertical circulation of water mixing lower than 10 meter and isolated the upper water layer from the lower water layer which increased the volume of hypolimnetic water with low temperature. The vertical circulation near the surface also mitigated propagation of density plume within the depth of 10 m which would remain the hypolimnetic water clean.     

Water Quality in Drinking Water Reservoirs of a Megacity, Istanbul

Providing clean water at relevant quality and quantity is a challenge that regulatory authorities have to face in metropolitan cities that seem to develop at their limits of sustainability. Istanbul strives to face such a challenge for its population of over 10 million, through six surface water resources. Two approaches of classification for the reservoirs are presented, one based on current regulations and an alternative based on a more detailed classification. The results have shown that nutrient control is the primary issue, and one of the reservoirs has already exceeded the limits of being eutrophic, one is at mesotrophic conditions, and the remaining four are at the limit of being eutrophic, indicating the significance of making the correct decision and taking pertinent measures for management and control. It has been observed that the only mesotrophic resource, which also has the best general quality class, has no industry and a very low population density, whereas the one that is already eutrophic is also the one with the lowest quality class, has the highest population density, and has the greatest percentage of urban land use within its watershed.