Geochemistry of the Springfield Plateau aquifer of the Ozark Plateaus Province in Arkansas,Kansas, Missouri and Oklahoma,USA

Geochemical data indicate that the Springfield Plateau aquifer, a carbonate aquifer of the Ozark Plateaus Province in central USA, has two distinct hydrochemical zones. Within each hydrochemical zone, water from springs is geochemically and isotopically different than water from wells. Geochemical data indicate that spring water generally interacts less with the surrounding rock and has a shorter residence time, probably as a result of flowing along discrete fractures and solution openings, than water from wells. Water type throughout most of the aquifer was calcium bicarbonate, indicating that carbonate‐rock dissolution is the primary geochemical process occurring in the aquifer. Concentrations of calcium, bicarbonate, dissolved oxygen and tritium indicate that most ground water in the aquifer recharged rapidly and is relatively young (less than 40 years). In general, field‐measured properties, concentrations of many chemical constituents, and calcite saturation indices were greater in samples from the northern part of the aquifer (hydrochemical zone A) than in samples from the southern part of the aquifer (hydrochemical zone B). Factors affecting differences in the geochemical composition of ground water between the two zones are difficult to identify, but could be related to differences in chert content and possibly primary porosity, solubility of the limestone, and amount and type of cementation between zone A than in zone B. In addition, specific conductance, pH, alkalinity, concentrations of many chemical constituents and calcite saturation indices were greater in samples from wells than in samples from springs in each hydrochemical zone. In contrast, concentrations of dissolved oxygen, nitrite plus nitrate, and chloride generally were greater in samples from springs than in samples from wells. Water from springs generally flows rapidly through large conduits with minimum water–rock interactions. Water from wells flow through small fractures, which restrict flow and increase water–rock interactions. As a result, springs tend to be more susceptible to surface contamination than wells. The results of this study have important implications for the geochemical and hydrogeological processes of similar carbonate aquifers in other geographical locations. Copyright © 2000 John Wiley & Sons, Ltd.     

Annual estimates of water and solute export from 42 tributaries to the Yukon River

Annual export of 11 major and trace solutes for the Yukon River is found to be accurately determined based on summing 42 tributary contributions. These findings provide the first published estimates of tributary specific distribution of solutes within the Yukon River basin. First, we show that annual discharge of the Yukon River can be computed by summing calculated annual discharges from 42 tributaries. Annual discharge for the tributaries is calculated from the basin area and average annual precipitation over that area using a previously published regional regression equation. Based on tributary inputs, we estimate an average annual discharge for the Yukon River of 210 km³ year^–1. This value is within 1% of the average measured annual discharge at the U.S. Geological Survey gaging station near the river terminus at Pilot Station, AK, for water years 2001 through 2005. Next, annual loads for 11 solutes are determined by combining annual discharge with point measurements of solute concentrations in tributary river water. Based on the sum of solutes in tributary water, we find that the Yukon River discharges approximately 33 million metric tons of dissolved solids each year at Pilot Station. Discharged solutes are dominated by cations calcium and magnesium (5.65 × 10⁹ and 1.42 × 10⁹ g year^–1) and anions bicarbonate and sulphate (17.3 × 10⁹ and 5.40 × 10⁹ g year^–1). These loads compare well with loads calculated independently at the three continuous gaging stations along the Yukon River. These findings show how annual solute yields vary throughout a major subarctic river basin and that accurate estimates of total river export can be determined from calculated tributary contributions. Copyright © 2011. This article is a U.S. Government work and is in the public domain in the USA.     

宁阳县蒋集镇彩山小流域水土保持技术研究

该文分析研究了彩山小流域的区域坡度和土壤特性,并根据区内土壤性质划分出4个小区域,即：自然坡度在20°～25°内为V1区,15°～20°内为V2区,10°～15°内为V3区,5°～10°内为V4区,分别反映了不同的土壤等级及土壤抗冲能力。同时,也研究出了一个系统化、理论化的科学依据i=V（10/3）/5B,并对所有砂石山区水土保持治理工作具有借鉴性和实用性。     

海温异常对东亚夏季风影响机理的研究进展

利用湖北省梅雨监测资料、国家气候中心新百项指数和NCEP/NCAR环流资料,分析了2020年湖北梅雨异常特征及其成因。结果表明：（1）2020年湖北梅雨持续时间异常长,为54 d,仅次于1996年;梅雨量异常多、强度强、雨日率大,均为1961年以来第1位。（2）高空西风急流、副热带高压、夏季风系统的冬夏调整季节性进程早,是造成湖北入梅早的主要原因。西风急流和副热带高压在7月下旬北跳,较常年时间偏晚,导致了出梅晚。入梅早、出梅晚,梅雨持续时间异常长。（3）在前冬El Niño事件、春夏热带印度洋海温偏暖和北大西洋三极子负位相的共同影响下,欧亚中高纬经向环流发展,冷空气活跃,副热带高压强且位置稳定,西侧水汽输送强,冷暖气流在长江中下游交汇,造成湖北省梅雨量异常偏多。

     

水源热泵井群布置方案对地下水流场影响分析

以某地下水源热泵系统工程为例,依据工程场地实际抽水-回灌试验数据,建立研究区地下水流数值模拟模型,分析该地区适宜的井群布置方案,并定量研究不同井群布置方案对地下水流场的影响范围与程度,为确定合理的井群布置方案提供技术支撑。研究表明：对于同一含水层回灌,随着抽水-回灌时间的延长,就有利于抽水-回灌能力及尽量减小对周边地下水开采的影响而言,抽水井、回灌井交叉布置,部分回灌井集中布置的方案较为合理。     

Application of Web-GIS and Geovisual Analytics to Monitoring of Seabed Evolution in South Baltic Sea Coastal Areas

Regular surveys of coastal zone seabed deliver important information about geomorphologic processes such as silting of waterways. The recent introduction of the Sentinel series of sensors has allowed for the use of satellite sensing for shallow bathymetry morphology monitoring. In this context, this article presents a dedicated Geographic Information System for Baltic Sea shallow water depth monitoring on the basis of Sentinel-2 imagery. The system employs Geovisual Analytics for differential analysis of bathymetry changes as well as monitoring the visibility of known wrecks in the coastal waters of Southern Baltic Sea. Results are verified with regard to known changes in shallow water bathymetry between 28 June 2015 and 3 March 2017.     

Size Fractionation (Dissolved, Colloidal and Particulate) of Trace Metals in the Thur River, Switzerland

The distribution of some trace metals (Cu, Zn, Ni, Co,Fe, Mn) and of DOC over a particulate (> 1 m),a colloidal (size < 0.45 m and molecular weight > 10 kD) and an ultrafiltered fraction (< 10 kD)was determined at several sites on the Thur River,Switzerland, at various times of the year. Thecomplexation of Cu by strong ligands in theultrafiltrate and in the conventional filtrate (<0.45 m) was compared using a ligand-exchange/CSV method.The <0.45 m concentrations of Cu (from anaverage of 7 nM to 24 nM), Zn (<5–23 nM), Ni (5–13 nM),Co (1.5–3 nM) and Mn (7–92 nM)increased downstream. The major part of Cu, Zn, Niand Co usually occurred in the ultrafiltratefraction at all sites, whereas Fe and Mn were mostlyin the particulate fraction, under conditions of lowsuspended matter content (< 10 mg L^-1) in theriver. The percentage of metal in the colloidalfraction, with respect to the 0.45-m filtrate,decreased in the order: Cu (median 11%) > Zn Ni(median 5–6%) > Mn Co (median < 5%). DOCalso consisted mostly of molecules in the < 10 kDrange.Cu was strongly complexed by natural organic ligandsin all filtrate and ultrafiltrate samples. A largepart of the strong Cu binding ligands consisted ofcompounds in the < 10 kD range, but colloidalligands with similar properties also occurred. Cu wasdistributed among the dissolved and the colloidalligands, roughly in proportion to organic carbon.The colloidal fraction (as defined here) did notincrease in its proportional amount downstream and wasonly of limited significance in transporting traceelements in the Thur River under low discharge conditions.     

航空电磁法在黄河口地区寻找浅层淡水的地质效果

对利用航空电磁法寻找浅层淡水的方法技术进行了探索,根据找水需要编制了保留区域场的三频标差异常图,对本区的海侵界线及海侵程度进行了研究,并在咸水区内圈定浅层淡水远景区29处,对各淡水远景区进行了分析与评价.     

北极加拿大海盆2003年和2008年上层海洋热含量的差异分析

主要利用2003年和2008年两次夏季北极科学考察的CTD数据处理了加拿大海盆上层海洋的热含量(这里上层海洋指的是200m以上的海洋),定量分析了热含量随深度的变化,并比较分析了这两年在夏季海冰融化期间热含量的垂向差异变化,以及影响热含量变化的因素,给出了上层海洋热含量在加拿大海盆的空间分布。2008年与2003年相比最显著的变化是在加拿大海盆开阔水域的增加,这将导致太阳辐射能进入海洋中的能量增加,同时海冰的大量融化带来了大量淡水,这些变化改变了上层海洋的温盐性质。海冰大量融化主要产生两个效应：一是上层海洋的普遍增暖,二是太平洋入流水体的下移。文中还分析了近年来在加拿大海盆中变化显著的次表层暖水现象,由于次表层暖水蕴含着不小的热含量,其在上层海洋热量平衡中的作用不容忽视。     

一个地下水资源系统管理模型的研究

本文以三坝灌区地下水资源的开发利用为例,介绍了一个反映地下水运动规律的综合性数学模型,并且将数值法与地下水资源系统分析的线性规划方法结合起来,提供出一个完整的模型。目的在于对地下水资源系统进行优化管理。