Hydrochemistry of the hyporheic zone in salmon spawning gravels: a preliminary assessment in a degraded agricultural stream

Hydrochemical changes were monitored in a simulated, sea run salmon redd in a small agricultural stream in northeast Scotland following the 1998–1999 spawning season. Immediately after redd construction, the hydrochemical characteristics of hyporheic water, at depths of 0.1 m and 0.3 m, were very similar to stream water. These apparently well‐mixed waters were alkaline, well‐oxygenated and enriched in nutrients. In the weeks and months following redd construction, clear and statistically significant differences in the chemistry of stream and hyporheic waters were observed. Typically, hyporheic water had lower concentrations of dissolved oxygen (mean 7.35 mg L^?1 at 0.3 m depth) than stream waters (mean=11.26 mg L^?1). Alkalinity, calcium, sulphate and conductivity levels tended to be higher in hyporheic waters, with concentrations increasing with depth. These data implied an increasing influence of groundwater with depth in the hyporheic zone following redd construction; an inference supported by subsequent hydraulic head measurements, which revealed an upwards groundwater flux in the stream bed. However, groundwater–surface water interactions were dynamic and complex: road salts eluted into the stream during periods of snowmelt simulated tracer experiments that implied that a reversed hydraulic gradient may occur at high flows with deeper streamwater penetration and mixing in the hyporheic zone. High flows also result in the mobilization of fine sediments from the stream bed which subsequently infiltrated into spawning gravels. These appear to cause ‘capping’ of redds and probably reduce the hydraulic conductivity of the redd matrix. Infiltrating sediments also contain a small, but probably important organic component, the decomposition of which may contribute to oxygen consumption and nutrient mineralization in the hyporheic zone. Copyright © 2001 John Wiley & Sons, Ltd.     

佳木斯市区地下水水化学系统的探讨

众所周知，在地下水资源的评价、开发、管理中，系统方法被广泛运用。但都是单纯的地下水数量系统的模拟，而对地下水水化学系统的分析，却无人研究。以佳木斯市区为例，对此进行了探讨。     

塔城盆地北区承压地下水化学特征及其形成机制

基于2015年8月在研究区采集的81个地下水化学和同位素数据,分析了塔城盆地北区承压水化学类型分布特征,并结合研究区水文地质条件,采用背景比拟法、Gibbs图、氘盈余模型、离子比值法、氯碱指数及钠吸附比等水化学分析方法,分析了地下水化学形成作用及其演化机制。结果表明:承压含水层普遍赋存水质较好的淡水,水化学类型以HCO_3-Ca型(Ca·Mg型、Ca·Na型)水为主。随地下水径流方向,承压水TDS及水化学类型呈较好的水平分带规律,即从承压水的上游区,沿区域地下水流向,地下水TDS逐渐升高,水化学类型由HCO_3-Ca型水,演化为SO_4·HCO_3~-Ca·Na型和SO_4~-Ca·Na型水。承压水化学特征,主要受水岩作用控制,蒸发作用对其影响有限,而且基本未受人类活动影响。整体上,在上游区,承压水化学组成主要受碳酸盐矿物和正向阳离子交替吸附作用的影响,而在中、下游区主要受石膏溶解影响。在个别径流路径上,正向阳离子交替吸附作用对地下水化学组成的影响超过矿物溶滤作用。     

格尔木河水化学特征及成因

为探究格尔木河水化学沿程变化情况,于2019年7—8月在该区采集33组水样进行测试分析,采用Piper三线图解法和Gibbs图解法,分析了格尔木河从源头至入湖口的水化学特征、形成原因以及主要离子来源。结果表明:格尔木河水体沿程水化学呈现由HCO₃-Ca-Mg型到HCO₃-Cl-Na-Ca-Mg型再到HCO₃-Cl-Na-Mg-Ca型的演变特征,到溢出带北侧Cl^-和Na⁺逐步占主导地位;水化学类型的主要形成原因为溶滤作用和蒸发浓缩作用;主要离子来源为石盐、碳酸盐以及硫酸盐等的风化溶解。     

内蒙古河套平原水体同位素及水化学特征

运用环境同位素和水化学技术,结合现场调查和室内分析,分析了河套平原不同类型水体氢、氧同位素和水化学特征,讨论了不同水体受蒸发浓缩和人类活动的影响,并利用氢、氧同位素示踪地下水的补给来源。结果表明：河套平原大气降水线斜率小于全球大气降水线斜率,不同水体的氘过量参数小于包头地区大气降水线和全球大气降水线,反映水体的蒸发作用导致氢、氧同位素的富集;河水、湖水以及地下水的氢、氧同位素组成变化差异明显,而且从湖水到河水再到地下水,氢、氧同位素组成有逐渐贫化的趋势;不同水体的水化学类型明显不同,河水主要为HCO3-Ca型,地下水主要为HCO3-Na、HCO3-Ca以及Cl-Na型,湖水为SO4-Mg和Cl-Na型;地下水与河水的氢、氧同位素组成和各离子质量浓度的相关性差,湖水的氢、氧同位素组成与K＋、Ca2＋、Mg2＋、Na＋、Cl-、SO42＋质量浓度,pH值,电导率以及矿化度则存在显著的相关性;河套平原南侧与西部地区地下水主要靠黄河水补给,北侧主要受降水和山前流水的侧向补给,而东部靠近乌梁素海地区的地下水氢、氧同位素组成和矿化度偏高,可能受湖水的影响较大。     

Hydrochemistry and baseline values of major and trace elements in tropical surface waters of the Terengganu River (Malaysia)

Hydrochemistry of 27 elements and 8 anions in tropical surface waters of the Terengganu River (Malaysia) was investigated. Dissolved elemental concentrations changed significantly with distance along the flow path depending on redox and pH, often reflecting natural enrichment. High nitrate concentration is probably associated with untreated waste water input, agricultural runoff, and atmospheric input. Overall, the quality of water was found to be acceptable with the exception of a few sites. Dilution effects, water residence times and the weathering of local mineral deposits exert major control over hydrochemistry.     

Groundwater Resources and Human Impacts in a Quaternary Intramontane Basin (L'Aquila Plain,Central Italy)

Abstract

An aquifer vulnerability study was carried out in the L'Aquila Plain of Central Italy for evaluating changes in groundwater quantity and quality induced by human activities. The L'Aquila Plain, filled with Quaternary clastic deposits, is an intramontane basin encircled by karst massifs characterized by regional groundwater, which is connected with the porous multilayer aquifer of L'Aquila Plain. The study was organized into different steps: (1) geo-lithological characterization; (2) sampling of hydrogeological data and water budget evaluation; and (3) hydrochemical and microbiological monitoring of springs and wells. The latter step made it possible to identify water-rock interaction, groundwater mixing and recharge, and to recognize the different sources of groundwater pollution. The plain aquifer, mainly recharged by the surrounding carbonate massifs, shows centripetal groundwater flowpaths. The hydrochemical features show two groundwater end-members, coming from carbonate aquifers or circulating only in the plain, with intermediate mixed groundwater. The observed ground-water pollution is negligible, but it will probably increase if the strong development of the human activities continues without groundwater protection planning.     

文安县高氟地下水的分布特征及关键水化学性质分析

为进一步认清河北省文安县高氟地下水的水化学性质,在水文地质调查以及取样分析的基础上,采用水化学特征分析、多元统计分析和水化学成因分析等手段阐明文安县高氟地下水的分布特征和关键水化学性质.结果表明：文安县深层地下水氟化物含量0.56～4.19 mg/L,总体分布是中北部偏高;其关键水化学特征是pH值7.7～8.7、总碱度高于211 mg/L、总硬度低于90 mg/L,水化学类型为典型的Na-HCO3型;在文安县地下水环境条件下,总碱度、碳酸氢根以及钠离子是促进高氟地下水形成的关键水化学因素;当2.0 mg/L＜F-＜ 3.5 mg/L时,地下水中Ca2＋与F-有拮抗作用.通过氯碱指数和饱和指数分析可知,研究区域高氟地下水的形成主要是水-岩间的阳离子交换反应和氟矿物的溶解-沉淀反应.     

焦家断裂带深部地下水水化学特征及其变化规律研究

焦家断裂带位于龙（口）莱（州）断裂带的南段,为胶西北地区三大著名的金成矿带之一,分布有新城、焦家、寺庄和马塘等多个大中型金矿。为研究焦家断裂带深部水化学特征及其变化规律,选取了焦家断裂带上多个矿区的抽水试验孔的深部地下水水样13个,对这13个水样进行常规阴阳离子含量统计分析,并对焦家断裂带走向和倾向上深部地下水水化学变化规律进行分析。结果表明：焦家断裂带深部地下水水化学类型以Cl-Na型和Cl·HCO3-Ca·Na型为主,矿化度（TDS）在0.77~9.66 g/L之间,多数为微咸水和咸水,部分为淡水。焦家断裂带深部地下水的强酸大于弱酸。TDS与Cl-存在显著的线性正相关关系,与Na+、Mg2+之间存在较好的正相关关系,而与HCO3-、SO42-、Ca2+之间的相关关系不明显。对比分析表明,在焦家断裂带走向上,由南至北,Cl-、Ca2+含量和矿化度基本呈上升趋势。在焦家断裂带倾向上,由东至西,由浅部至深部,Cl-含量和矿化度呈上升趋势,且下盘含水层的Cl-浓度随深度变化较上盘含水层Cl-浓度随深度变化快。该研究成果为区域内深部地下水的合理开发利用提供了指导。     

基于水化学数据的矿山涌水水源识别:主成分分析与残差分析

涌水是矿山安全生产的重要威胁之一,掌握涌水的水源是预防这类灾害的重要依据。基于多期次的水化学监测数据,提出了利用主成分分析(PCA)和残差分析来识别涌水的水源数量和水源类型。主成分分析能够充分提取高维数据的结构信息,消除变量冗余。残差分析利用主成分分析结果,提取不同的主成分个数重构离子浓度,得出重构离子浓度和原始离子浓度之间的残差,利用残差的结构性信息来判断可能的涌水水源数量和水源类型。结果表明:随保留主成分个数的增加,重构离子浓度的精度越高,离子残差的结构性得到消除且表现出随机性。在实例应用中,通过利用5个主成分重构离子浓度消除了所有主要离子残差结构性,保证了信息的最大程度提取,因此,确定研究矿山涌水水源数量为5个; 同时,利用每个主成分对残差结构性的影响程度及离子相关性分析,确定了这5个水源类型为海水、第四系孔隙水、富钙基岩水、富镁基岩水和淡水。