太湖流域非点源污染负荷估算系统的设计与应用

非点源污染是太湖流域水环境污染的主要来源,定量研究太湖流域非点源污染负荷,可为非点源污染的预报与防治提供决策依据.传统非点源污染负荷研究中GIS与非点源污染模型松散式结合的方式存在数据管理与转换工作量大的问题,尝试采用嵌合模式设计和开发太湖流域非点源污染负荷估算系统.介绍了系统的结构与功能,分析了系统主要功能模块-SCS模型、USLE模型和非点源污染负荷模型的实现流程.基于该系统进行了无锡市2005年非点源污染TN负荷的估算,结果显示其负荷总量为8 014.43 t.农业生产和生活污水的排放是该区非点源污染的主要来源.系统的应用表明其简化了模型计算的复杂过程,结果能够较客观地反映研究区域的非点源污染状况及其与土地利用的关系,具有较强的实用性.     

近55年渭河流域气温演变规律分析

利用渭河流域16个气象站点1954-2008年近55a气象资料,采用线性回归、Mann-Kendall检验、Pettitt及Morlet小波分析等方法,对渭河流域年及各季节平均气温的变化趋势、突变特征和周期性等演变规律进行分析.结果表明,(1)在95％的置信区间下,渭河流域年及各季节平均气温均表现为显著上升趋势,其中冬季气温上升最显著.(2)多年平均气温空间分布存在不均衡性,年平均气温以西安站为中心向外呈辐射递减.(3)年及各季平均气温存在明显的突变点,1993年为该流域大的气温转折年.(4)流域气温变化存在多个特征时间尺度,其中年平均气温具有3、7、23和55a左右的主周期,以55a左右周期相位变化最显著.除夏季外,其余季节与年平均气温相位变化时间尺度大体一致.研究成果可为分析渭河流域气候变化及其未来气候预测提供参考.     

黄河中上游流域水沙变异关系模型研究

[目的] 开展黄河流域水沙变异关系模型研究,为流域水沙变化研究提供理论支持。[方法] 从黄河中上游流域水沙变异影响因素分析入手,推导出以微分为基础的水沙变异关系模型。[结果] 模型通过黄土高原和黄河中上游流域7个测站控制流域输沙率和流量变异变量的模拟检验,获得了7个流域输沙率和水流变异模拟平均有效性系数为0.860和0.887,平均相对误差分别为14.8%和6.7%。[结论] 从水流变异、泥沙变异模拟精度和各因素变异贡献比例3个层面检验了模型,初步证明了模型结构的合理性和模拟实际泥沙变异具有的高有效性。     

Short-term microbial responses to soluble inorganic P input in a tropical lowland rain forest in Amazonia

In non-flooded lowland rain forests with low soil phosphorus (P) in parts of Amazonia, P cycling largely occurs via leaf litter recycling by arbuscular mycorrhizal (AM) fungal symbionts. Occasional high input of P into these ecosystems occurs during drought years with increased litterfall. As the length and frequency of drought events are projected to increase in the region, a single-dose nutrient addition experiment was carried out to test how this would impact P cycling. An application rate of 4 kg P ha^-1 was used, which corresponds to twice the amount of litter-derived P in an average year. It was hypothesized that i) the added mineral P would be immobilized by soil microorganisms, leading to measurable increase in soil microbial biomass carbon (C) and P and ii) AM colonization rate would be reduced by the pulse in mineral P available for plant uptake. The results did not support either of our hypotheses. The addition of P did not have an effect on AM root colonization, nor was P immobilized by soil microbiota during the experimental period. The lack of a difference between the control and treatment at our study site could be attributed to the relatively low one-off dose of P applied that did not change either the colonization rate of roots by AM fungi or the amount of soil available labile P. To obtain a mechanistic understanding of the availability, capture, and use of P by plant-symbiont associations in tropical rain forest ecosystems, further integrated studies of the soil-plant system combining long-term nutrient manipulations, modeling, and experimental approaches are required.     

Major discoveries on the dermal skeleton of fossil and Recent polypteriforms: a review

Following the discovery of the first living polypterid, Polypterus bichir, in 1802, almost two centuries later we now know of 15 living species (including four subspecies), 14 belonging to the genus Polypterus and one to the genus Erpetoichthys (Calamoichthys) all inhabiting intertropical Africa. The polypterid fossil record was for a long time reduced to some scarce, disarticulated bones, mainly scales, found in various African deposits covering a wider area than the actual geographical distribution. With the discovery, on one hand, of polypterid scales, vertebrae, dermal bones of the cranium and dorsal spiny rays in South America and, on the other hand, of scales and numerous dorsal spiny rays in Niger and Sudan, and two articulated fossils in Morocco, the story of the polypteriforms has revealed some of its mysteries. The discovery of isopedine between dentine and bony basal plate in the scales of living and fossil polypterid species is considered a synapomorphy of the group, and has been an important aid in discriminating polypterid scales from other ganoid scales. A review of the main findings during the last 20 years is presented.     

Vulnerability of the biota in riverine and seasonally flooded habitats to damming of Amazonian rivers

1. The extent and intensity of impacts of multiple new dams in the Amazon basin on specific biological groups are potentially large, but still uncertain and need to be better understood.
2. It is known that river disruption and regulation by dams may affect sediment supplies, river channel migration, floodplain dynamics, and, as a major adverse consequence, are likely to decrease or even suppress ecological connectivity among populations of aquatic organisms and organisms dependent upon seasonally flooded environments.
3. This article complements our previous results by assessing the relationships between dams, our Dam Environmental Vulnerability Index (DEVI), and the biotic environments threatened by the effects of dams. Because of the cartographic representation of DEVI, it is a useful tool to compare the potential hydrophysical impacts of proposed dams in the Amazon basin with the spatial distribution of biological diversity. As the impact of Amazonian dams on the biota of both rivers and periodically flooded riparian environments is severe, DEVIs from different Amazonian tributary basins are contrasted with patterns of diversity and distribution of fish, flooded forest trees and bird species.
4. There is a consistent relationship between higher DEVI values and the patterns of higher species richness and endemism in all three biological groups. An assessment of vulnerability at the scale of tributary basins, the assessment of biodiversity patterns related to DEVI, and the analysis of teleconnections at basin scale, demonstrate that recent construction of dams is affecting the biota of the Amazon basin.
5. The evidence presented here predicts that, if currently planned dams are built without considering the balance between energy production and environmental conservation, their cumulative effects will increase drastically and represent a major threat to Amazonian biodiversity.

     

漓江流域土地利用变化及与旅游发展关系研究

以典型旅游目的地漓江流域为对象,基于1973-2016年Landsat遥感影像,解译获取土地利用数据,借助RS、GIS技术,运用动态度、转移矩阵等方法,分析土地利用变化时空特征,进而探讨其与旅游发展的关系。结果表明,1973-2016年漓江流域林地、建设用地和未利用地持续增加,耕地快速减少,水域小幅下降,草地先减后增;不同时期各土地利用类型单一动态度中,建设用地增加最快,2001-2016年具有最大的综合动态度;建设用地与游客人数和旅游总收入呈显著正相关,耕地、水域与游客人数和旅游总收入呈显著负相关;土地利用变化与旅游产业呈现较强相关性,1973-2001年漓江流域旅游产业体量小,土地利用变化的主要影响因素为大面积种植结构调整和城乡建设活动,2001-2016年旅游业发展为地区主导产业,土地利用变化主要受林果种植、景区景点开发、旅游设施建设以及阳朔、兴安等地的旅游城镇化影响。研究结果可为漓江流域土地管理和旅游资源合理利用提供科学依据。     

北之江流域生态文化旅游模式研究

在详细分析广西北之江流域生态文化旅游资源状况的前提下,提出了北之江流域生态文化旅游的综合线路,并进行了具体的项目策划,以期为北之江流域生态文化旅游资源的综合开发提供参考。     

基于PSR模型的艾比湖流域生态安全评价研究

基于压力-状态-响应(PSR)概念模型,结合层次分析法并采用综合评价模型对艾比湖流域生态安全进行综合评价。研究结果表明:(1)在13项评价指标中,影响流域生态安全的主导因素为森林覆盖率、草地面积和水土流失治理面积,其所占权重均在0.1以上;(2)自2000—2010年以来,艾比湖流域生态安全指数由0.230 9增加至0.755 6,流域生态环境呈现良性发展趋势,生态安全状况有所好转。当地政府通过提高森林覆盖率、增加草地面积以及治理水土流失等措施,不断改善了该流域的自然生态环境。     

降尘对塔里木盆地香梨叶片光合特性及叶绿素含量的影响

试验对塔里木盆地生长的不同树龄香梨(Pyrus bretschneideri Rehd.cv.Fragrant pear)树的叶片在受降尘及不受降尘影响下的光合特性及叶绿素含量进行了比较分析.结果表明,香梨叶片受降尘影响后在各个生育期的净光合速率、气孔导度、胞间CO2浓度均降低.除新梢生长期外,各树龄的香梨叶片受降尘影响后蒸腾速率均下降.40年生的香梨树叶片受降尘影响后,各个生育期的叶绿素含量SPAD值均显著降低;而10年生及20年生的香梨树叶片受降尘影响后,各个生育期的叶绿素含量SPAD值均升高.