合肥城郊典型源头溪流不同渠道形态的氮磷滞留特征

为揭示源头溪流中深潭和曲折沟渠两种典型渠道形态的氮磷养分滞留特征,在合肥城郊二十埠河的某一级支流上,以NH4Cl和KH2PO4为添加营养盐,以NaCl为保守型示踪剂,开展现场示踪实验.在此基础上,利用OTIS模型软件、暂态存储参数和养分螺旋原理,解析深潭和曲折沟渠氮磷滞留特征.结果表明:1深潭的As值较曲折沟渠大,但其α值则较弯曲沟渠小1个数量级,而且As和α值随水文条件变化均不显著;2深潭中主渠道流动水体的NH+4-λ较其暂态存储区的NH+4-λs高2~3个数量级,曲折沟渠的NH+4-λ与NH+4-λs数值较为接近;3深潭中NH+4-Vf较SRP-Vf高1~2个数量级,而在曲折沟渠中,不仅NH+4-Vf与SRP-Vf数值较为相近,NH+4-Sw与SRP-Sw也基本相当;4深潭的NH+4-U较SRP-U高出2~3个数量级,曲折沟渠NH+4-U则较SRP-U高出1~2个数量级;5总的来说,在对NH+4和SRP滞留影响方面,深潭和曲折沟渠存在较大的差异性,且在深潭中NH+4的滞留效应显著超过SRP.     

三峡库区干支流落干期消落带土壤可转化态氮含量及分布特征

为探明三峡支流水体富营养化频发与库岸消落带土壤氮素"源-库"关系转化之间的内在关系,采用分级浸提法,分析了三峡库区长江万州段干流、苎溪河支流、密溪河支流消落带落干期土壤可转化态氮含量和分布特征.结果表明,与三峡库区万州段干流相比,支流消落带落干期土壤有机质和总氮含量较高,而阳离子交换量(CEC)和p H值较低.三峡干支流消落带土壤可转化态氮(TF-N)以OSF-N(有机态和硫化物结合态)为主,且含量上OSF-NIMOF-N(铁锰氧化物结合态氮)IEF-N(离子交换态氮)CF-N(碳酸盐结合态氮);而空间分布上,TF-N表现为:密溪河苎溪河长江干流,4种TF-N形态中IEF-N和OSF-N在干支流间无显著差异,而CF-N和IMOF-N分布与TF-N相反,是造成干支流消落带TF-N差异的主要因素.     

海州湾海洋牧场人工鱼礁投放对营养盐的影响

为了解海州湾海洋牧场人工鱼礁投放对营养盐的影响,基于2008—2015年间共24个航次水质调查资料,分析了海州湾海洋牧场鱼礁区和对照区活性磷酸盐(PO_4~(3-)-P)、活性硅酸盐(SiO_3~(2-)-Si)和溶解无机氮(DIN)的浓度、组成及营养盐结构的变化.同时,比较了鱼礁区和对照区营养盐的变化,初步分析了人工鱼礁投放量与营养盐的相关性,尝试探索人工鱼礁投放对营养盐浓度与结构的影响.结果表明,鱼礁区和对照区PO_4~(3-)-P、SiO_3~(2-)-Si浓度均呈现出秋季夏季春季的特点,且鱼礁区高于对照区.DIN在鱼礁区和对照区也呈现出同样的季节变化特点,但鱼礁区的变化幅度显著大于对照区.海洋牧场人工鱼礁的投放使鱼礁区PO_4~(3-)-P和DIN浓度增加.受热力学平衡的影响,对照区DIN浓度也出现了增加,而PO_4~(3-)-P受人工鱼礁投放的影响小.鱼礁区和对照区SiO_3~(2-)-Si受人工鱼礁投放影响均不明显.另外,海洋牧场DIN组成也发生了改变,2012年前NO_3~--N为DIN主要组成,之后为NH_4~+-N.营养盐结构分析显示,海州湾海洋牧场营养盐对浮游植物主要表现为磷限制.     

南水北调对密云水库水位变幅带土壤磷释放量的影响

南水北调来水引起的水位上涨可能会导致密云水库水位变幅带土壤中磷的释放.过量的磷可能会引起水体富营养,因此,研究水库变幅带磷释放风险对密云水库水质安全保障具有科学指导意义.本研究采用连续浸提法测定密云水库变幅带土壤及沉积物中弱吸附态磷(NH_4ClP)、铁磷(BD-P)、铝磷(NaOH-P)及钙磷(HCl-P)等4种不同形态磷含量,探讨其分布特征;并在室内进行了磷释放模拟实验,估算了南水北调来水引起水库水位上升所致的易释放磷的释放量.结果表明,NH_4Cl-P、BD-P、NaOH-P、HCl-P广泛地分布于密云水库变幅带土壤及沉积物中.在白河、内湖及潮河3个库区,磷形态分布具有一致规律,即HCl-PNaOH-PBD-PNH_4Cl-P.因密云水库变幅带为中国典型的北方碱性土壤,变幅带无机磷主要为钙磷.NH_4Cl-P在3个库区变幅带土壤中含量相差不大,在受水动扰动力影响较小的内湖库区BD-P含量略高于其它2个库区.在3个不同库区中,潜在活性磷NH_4Cl-P和较稳定的NaOH-P在岸上和水陆交界面土壤及水下沉积物中含量相差不大,受氧化还原条件影响较大的BD-P在沉积物中的含量略高于岸上和水陆交界面土壤.磷释放模拟实验及释放量估算结果表明,水库水位上涨3 m的情况下,白河、潮河和内湖库区淹没变幅带土壤分别释放1.02、0.80、0.37 mg·m~(-2)易释放磷.白河和内湖库区变幅带被水淹没土壤中磷释放的风险可能更高,需加强防护.     

Integration of long-term fish kill data with ambient water quality monitoring data and application to water quality management

Almost half (354) of all fish kills (805) in South Carolina, USA, between 1978 and 1988 occurred in the coastal zone. These kills were analyzed for causative, spatial, and temporal associations as a distinct data set and as one integrated with ambient water quality monitoring data. Estuarine kills as a result of natural causes accounted for 42.8% followed by man-induced (35.1%) and undetermined causes (22.1%). Although general pesticide usage was responsible for 53.9% of man-induced kills, weed control activities around resorts and municipal areas accounted for slightly more kills (20.9%) than did agricultural (19.8%) or vector control (13.2%) uses. A dramatic decline in agricultural-related kills has been observed since 1986 as the integrated pest management approach was adopted by many farmers. When taken with the few kills (12.0%) resulting from wastewaters, this suggests that these two land-use activities have been successfully managed via existing programs (IPM and NPDES, respectively) to minimize their contributions to estuarine fish kills. Ambient trend monitoring data demonstrated no coastal-wide dispersion of pesticide pollution. These data confirmed the nature of fish kills to be site-specific, near-field events most closely associated with the contiguous land-use practices and intensities. Typically, fish kill data are considered as event-specific data limited to the bounds of that event only. Our analysis has shown, however, that a long-term data set, when integrated with ambient water quality data, can assist in regulatory and resource management decisions for both short- and long-term planning and protection applications.     

则木河断裂变形产物中微观粘滑与蠕滑标志的鉴别

在则木河断裂带宏观研究的基础上,结合岩石破裂实验成果,对包括1850年大震变形带在内的断裂产物进行定向原态采集、固结、制片和镜下系统观测,从复杂纷呈的变形遗迹中鉴别出微观粘滑与蠕滑标志。最后就有关问题进行了简要讨论.     

MULTICOMPONENT GEOCHEMICAL TRANSPORT MODELING USING HYDRUS-1D AND HP11

Abstract: The transport of reactive contaminants in the subsurface is generally affected by a large number of nonlinear and often interactive physical, chemical, and biological processes. Simulating these processes requires a comprehensive reactive transport code that couples the physical processes of water flow and advective-dispersive transport with a range of biogeochemical processes. Two recently developed coupled geochemical models that are both based on the HYDRUS-1D software package for variably saturated flow and transport are summarized in this paper. One model resulted from coupling HYDRUS-1D with the UNSATCHEM module. While restricted to major ion chemistry, this program enables quantitative predictions of such problems as analyzing the effects of salinity on plant growth and the amount of water and amendments required to reclaim salt-affected soil profiles. The second model, HPI, resulted from coupling HYDRUS-1D with the PHREEQC biogeochemical code. The latter program accounts for a wide range of instantaneous or kinetic chemical and biological reactions, including complexation, cation exchange, surface complexation, precipitation dissolution and/or redox reactions. The versatility of HP1 is illustrated in this paper by means of two examples: the leaching of toxic trace elements and the transport of the explosive TNT and its degradation products.     

构造运动与中国沿岸平原的地质灾害

中国海岸穿过构造沉降带和隆起带，沉降带及隆起带断陷盆地的持续下降吸引了源远流长的大河在此人海，而隆起带内入海的河流多为近源小河，从而引起河流泥沙沿岸分配的不均和海岸沉积物的差异。沉降带内每公里海岸线接受的沉积物是隆起带的数十倍，且以砂质沉积物为主．隆起带河流泥沙来量少．而且砂质沉积物占了压倒的优势．河流泥沙沿岸分配的不均决定了中国沙质和淤泥质海岸的基本类型和分布格局、沉降带和隆起带松散沉积层的厚度和结构，山此产生了中国沿岸与第四纪沉积层有关的灾害和环境问题的有规律的分布。地面沉降主要分布于沉降带内，而地下海水入侵多出现在依赖地下水的隆起带内，底辟构造、浅层天然气往往在大河三角洲构成灾害和潜在的地质灾害．沉降带和隆起带断陷盆地内的海岸低地通常是海平面上升的主要脆弱地区．此外，丰富的河流泥沙使中国海岸对全球海平面上升的响应也不相同，如海岸湿地的再生和海岸侵蚀原因的复杂性等．     

A composite medium approximation for unsaturated flow in layered sediments

Saturated-unsaturated flow in strictly layered sediments proceeds via conductors in parallel in the direction parallel to bedding, and via resistors in series in the direction perpendicular to bedding. On sufficiently small scales of space and time, flow in such media will be subject to approximate capillary equilibrium locally, which provides a basis for approximating the effective hydraulic conductivity of a composite multi-layer medium in terms of the conductivities of the individual layers. Equations for the hydraulic conductivity tensor in "composite medium approximation" (COMA) are given in a coordinate system aligned with bedding. Hydraulic conductivity parallel to bedding is generally larger than in the perpendicular direction. The anisotropy depends on the spread of the conductivity distribution, and tends to increase for dryer conditions. The COMA model was implemented in a multi-phase flow simulator and tested by comparison with high-resolution simulations in which all layering heterogeneity is resolved explicitly. Under favorable conditions, COMA is found to accurately represent sub-grid scale flow and transport processes, providing a practical method for simulating field-scale flow and transport in layered media. The approximation improves when layers are thinner, and when flow rates are smaller.     

Human impacts on the stream-groundwater exchange zone

Active exchanges of water and dissolved material between the stream and groundwater in many porous sand- and gravel-bed rivers create a dynamic ecotone called the hyporheic zone. Because it lies between two heavily exploited freshwater resources—rivers and groundwater—the hyporheic zone is vulnerable to impacts coming to it through both of these habitats. This review focuses on the direct and indirect effects of human activity on ecosystem functions of the hyporheic zone. River regulation, mining, agriculture, urban, and industrial activities all have the potential to impair interstitial bacterial and invertebrate biota and disrupt the hydrological connections between the hyporheic zone and stream, groundwater, riparian, and floodplain ecosystems. Until recently, our scientific ignorance of hyporheic processes has perhaps excused the inclusion of this ecotone in river management policy. However, this no longer is the case as we become increasingly aware of the central role that the hyporheic zone plays in the maintenance of water quality and as a habitat and refuge for fauna. To fully understand the impacts of human activity on the hyporheic zone, river managers need to work with scientists to conduct long-term studies over large stretches of river. River rehabilitation and protection strategies need to prevent the degradation of linkages between the hyporheic zone and surrounding habitats while ensuring that it remains isolated from toxicants. Strategies that prevent anthropogenic restriction of exchanges may include the periodic release of environmental flows to flush silt and reoxygenate sediments, maintenance of riparian buffers, effective land use practices, and suitable groundwater and surface water extraction policies.