Important progress on the use of isotope techniques and methods in catchment hydrology

The use of isotope techniques and methods in catchment hydrology in the last 50 years has generated two major types of progress: (1) Assessment of the temporal variations of the major stocks and flows of water in catchments, from which the estimation of wa-ter residence times is introduced in this paper. (2) Assessment of catchment hydrologic processes, in which the interactions be-tween different waters, hydrographical separation, and bio-geochemical process are described by using isotopes tracers. Future progress on isotope techniques and methods in hydrology is toward the understanding of the hydrological process in large river basins. Much potential also waits realization in terms of how isotope information may be used to calibrate and test distributed rainfall-runoff models and regarding aid in the quantification of sustainable water resources management.

Application of transition metal isotope tracers in global change research

High-precision isotope composition determinations using multicollector, magnetic-sector induc- tively coupled plasma mass spectrometry (MC-ICPMS) have recently revealed that some transition metal isotopes such as those of Mo, Fe, Cu, Zn etc. can be used as biogeochemical tracers in global change research. The Mo isotope system may be useful in paleoredox investigations indicating that δ97/95Mo in seawater may co-vary with changes in the relative proportions of anoxic and oxic sedimentation in the ocean, and that this variation may be recorded inδ97/95Mo of anoxic sediments. The Mo continental flux into the oceans and the global Mo isotope budget can be estimated fromδ97/95Mo values. The Fe isotope composition in seawater is an important issue because Fe plays a controlling role in biological productivity in the oceans and its abundance in seawater may have substantial effect on climate changes. Iron isotope fractionations could result from bio- and abio-processes and have about 0.1% variation (δ56/54Fe), so Fe isotopes considered alone cannot be used to distinguish the products of abiotic and biotic Fe processing in geological records. Cu and Zn isotopes are also used as biogeochemical tracers, but the researches are relatively less. This review mainly focuses on the methods for preparation, purification and determination of new isotope tracer samples, and on isotope applications in marine environmental changes.

Isotope hydrogeochemical models for assessing the hydrological processes in a part of the largest continental flood basalts province of India

Continental Flood Basalts(CFB)occupy one fourth of the world’s land area.Hence,it is important to discern the hydrological processes in this complex hydrogeological setup for the sustainable water resources development.A model assisted isotope,geochemical,geospatial and geophysical study was conducted to understand the monsoonal characteristics,recharge processes,renewability and geochemical evolution in one of the largest continental flood basalt provinces of India.HYSPLIT modelling and stable isotopes were used to assess the monsoonal characteristics.Rayleigh distillation model were used to understand the climatic conditions at the time of groundwater recharge.Lumped parameter models(LPM)were employed to quantify the mean transit time(MTT)of groundwater.Statistical and geochemical models were adopted to understand the geochemical evolution along the groundwater flow path.A geophysical model was used to understand the geometry of the aquifer.The back trajectory analysis confirms the isotopic finding that precipitation in this region is caused by orographic uplifting of air masses originating from the Arabian Sea.Stable isotopic data of groundwater showed its meteoric origin and two recharge processes were discerned;(i)quick and direct recharge by precipitation through fractured and weathered basalt,(ii)low infiltration through the clayey black cotton soil and subjected to evaporation prior to the recharge.Tritium data showed that the groundwater is a renewable source and have shorter transit times(from present day to<30 years).The hydrogeochemical study indicated multiple sources/processes such as:the minerals dissolution,silicate weathering,ion exchange,anthropogenic influences etc.control the chemistry of the groundwater.Based on the geo-electrical resistivity survey,the potential zones(weathered and fractured)were delineated for the groundwater development.Thus,the study highlights the usefulness of model assisted isotopic hydrogeochemical techniques for understanding the recharge and geochemical processes in a basaltic aquifer system.

Evaluation of Erythrocyte Iron Incorporation in Beijing Prepubertal Children Using a Single Stable Isotope Tracer Method

Objective To analyze the rate of erythrocyte iron incorporation and provided guidance for the iron nutrition for prepubertal children.Methods Fifty-seven prepubertal children of Beijing were involved in this study and each subject was orally administered 3 mg of 57 Fe twice daily to obtain a total of 30 mg 57 Fe after a 5-d period. The stable isotope ratios in RBCs were determined in 14 th day, 28 th day, 60 th day, and 90 th day. The erythrocyte incorporation rate in children was calculated using the stable isotope ratios, blood volume and body iron mass.Results The percentage of erythrocyte 57 Fe incorporation increased starting 14 th day, reached a peak at 60 d(boys: 19.67% ± 0.56%, girls: 21.33% ± 0.59%) and then decreased. The erythrocyte incorporation rates of 57 Fe obtained for girls in 60 th day was significantly higher than those obtained for boys(P < 0.0001).Conclusions The oral administration of 57 Fe to children can be used to obtain erythrocyte iron incorporation within 90 d. Prepubertal girls should begin to increase the intake of iron and further studies should pay more attention to the iron status in prepubertal children.

Application of Cadmium Isotope Tracer Technique

Cadmium(Cd)is a strong carcinogenic heavy metal element.Because of its physical,chemical and toxicological characteristics,Cd environmental geochemical research has been concerned,and Cd detection technology is becoming more and more perfect.Cd isotope is one of the hotspots of non-traditional isotope research in recent years.One-way fractionation takes place in its evolution process,which makes the region or process significantly different and contains the information of its evolution environment and process,and Cd isotope tracer technique has been successfully applied to the study of the genesis of lead-zinc deposits,lunar soil and meteorites,marine environment and heavy metal pollution,and has become an important means to the analysis of the sources of Cd pollution.The determination technology of Cd and Cd isotope and its application were reviewed,and the future research points of Cd isotope technology were prospected.

Application of Isotope Tracer Technique in Source Apportionment of Heavy Metal Pollution in Soil

The formation of heavy metal pollution in soil is closely related to human production and life. In order to effectively control heavy metal pollution and repair damaged soil,the pollution source should be known and judged first. Based on the preliminary analysis of major sources of soil heavy metal pollution in soil,combined with relevant literatures on heavy metal pollution source of soil or sediment at home and abroad in recent years,application progress of isotope tracer technique,especially lead isotope tracer technique,in the study of heavy metal pollution sources in soils and sediments were reviewed. The key points of future isotope tracer technology in the field of heavy metal pollution source apportionment were prospected.

Estimation of Iron Physiological Requirement in Chinese Children using Single Stable Isotope Tracer Technique

Objective This study is to obtain precise data on iron physiological requirements in Chinese children using single stable isotope tracertechnique.Methods Thirty boys(10.6±0.2 years)and 27 girls(10.4±0.2 years)were received oral 6 mg ^(57)Fe each day for 5 consecutive days.Venous blood samples were subsequently drawn to examine the change of total iron concentration and ^(57)Fe abundance at day 0,14,28,60,90,180,360,450,540,630,720.The iron physiological requirement was calculated by iron loss combined with iron circulation rate once ^(57)Fe abundance stabilized in human body.Results The iron physiological requirement was significantly lower in boys than those values in girls(16.88±7.12 vs.18.40±8.81μg/kg per day,P<0.05).Correspondingly,the values were calculated as 722.46±8.43μg/day for boys and 708.40±7.55μg/day for girls,respectively.Considering nearly 10%iron absorption rate,the estimated average iron physiological requirement was 6.0 mg/day in boys and 6.2 mg/day in girls.Conclusion This study indicate that iron physiological requirement could require more daily iron intake in girls as compare with the values in boys having the same body weight.These findings would be facilitate to the new revised dietary reference intakes.

Hydrological processes in the Aksu River source region during the intense ablation period based on water chemistry and isotopes

Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an essential inland river enriched by substantial meltwater contributions,plays a pivotal role in the economic,ecological,and social development of the region.Based on 231 water samples collected during the period of intense glacial ablation in 2023,this study conducted a comprehensive analysis of the hydrochemical and stable isotopic characteristics of the Little Kurgan glacial basin in the Aksu River source region.A Piper diagram classified the hydrochemical type of the river water as Calcium-Bicarbonate.Analysis based on a Gibbs diagram indicated that rock weathering is the predominant factor affecting the hydrochemical properties within the studied basin.Through application of principal component analysis and end-member mixing analysis,it was determined that the glacier meltwater contribution to runoff was 67%,61%,and 55%in July,August,and September,respectively.The findings of this study reveal that glacier meltwater is the principal component of the river water,and highlight the critical impact of alterations in glacier ablation on the hydrological cycle within the Aksu River source region,which is vitally important for sustainable water resource management.

The Evaporation Effect on the Isotopes in the Yellow River Water

Based on the isotope analysis result of water samples in the 18 sections of the Yellow River, the variation of δ 18 O and δD have been analyzed. From near the source to the entrance to the sea, the Yellow River has a general trend that the ratios of the stable isotope increase progressively; The main factors affecting the isotopes in the river water are mixing of external water bodies,evaporation and others; In the river segment between Lanzhou and Baotou and in lower reaches, the extent of the evaporation effect on the isotope fractionation from the river water surface is limited but the evaporation from the irrigated river water and the return flow is one of the main factors affecting the isotopes in river water.

The Effect of the Sinking of Isotope Grains in Water Injection Profile Logging

In the process of oil field exploitation, radioactive isotope tracer water injection profile logging is a main method to determine the water-intake capacity of the target intervals. For those general water injection wells, whose perforated intervals are beyond the tubing shoe, the sinking speed of isotope grains is related to the density and salinity of the injection water and the tubing dimension. We studied the motion of the isotope grains in the water injection wells by both theoretical calculation and field experiment. The result shows that if the water injection quantity is over 20 m＆3/d, and the density of the isotope grains, whose diameter is 100-600 μm, is 1.06 g/cm^3, then the logging technique for this kind of water injection wells will be appropriate. Whether water injection profile logging is successful in the well, whose perforated intervals are beyond the tubing shoe, depends on the sinking speed of the tracer grains.

Characteristic analysis on oxygen isotopic tracer in the East China Sea and waters to east of the Ryukyu－gunto

Samlpes of O isotopic tracer ware collected at Sections P_3, P_(25), P_(CM-1/2-E) and P_(CM-1/2-W) in both the EastChina Sea and the area to the east Of the Ryukyu-gunto during October-November, 1991.Analytical results of the δ￣(18) O are as follows: (1) In the Kuroshio area, the δ￣(18) o isolines are almost parallel to the200 m isobath. The value of δ￣(18)O is nagative and reaches minimum on the main axis of the Kuroshio,and increases on both sides. (2) In the Taiwan Warm Current (TWC) area there is a high δ￣(18) O tongue extending to the northeast. (3)In the area near the coast, the distribution of δ￣(18)O isoline shows that the Changjiang River runoff diffuses seaward andthe land-ocean isotopic effect from the nearshore to the offshore. (4) The values of δ￣(18) O are from-1. 0 x 10￣(-3) to -0.5 x 10￣(-3) in the shelf. (5) There is a low core of δ￣(18) O value (< -1 .6 X 10￣(-3)) at the 600 m layer in the Kuroshioarea, which is quite in accord with the ekistence of a low salinity core (S 34. 30) between the 600 and 800 m layersin the same area. Finally, the correlations of the δ￣(18)O with the salinity and temperature, the upwelling and so on arediscussed.(This study was supported by the National Natural Science Foundation of China under contract No. 4907257.)Yuan Yaochu et al. The Northwest Pacific circulation and its impacts on the current near the Chinese coast, 1991-1993.

The Mesozoic Welding Process between South and North Dabie Blocks：An Evidence from Pb Isotopes of Yanshanian Granites

The Pb isotope compositions of K-feldspar in granites is paid more and more geologists'attention,due to their importance of tracer.It is a fact that South Dabie Block(SDB)and North Dabie Block(NDB)had exited since Indosinian epoch(Wang et al.,1992;Cong et al,1994;Zhai et al.,1995;Chen et al.1995;Zhang et al,1996,Wang et al,1997).However,the welding process between SDB

铅、锌、镉同位素示踪技术在沉积物重金属污染源解析中的应用:综述与展望

沉积物重金属污染防治的关键在于识别其污染源,采用铅、锌、镉多元同位素示踪技术是对其进行污染源解析的最佳手段之一。铅同位素示踪技术较为成熟且应用广泛,锌和镉同位素示踪技术作为新兴技术,在重金属污染源解析研究中可作为有力补充。本文系统概述了Pb-Zn-Cd同位素的示踪机理、组成特征及其在沉积物重金属污染溯源中的应用,提出未来研究工作的重点是采用多元同位素示踪技术,并结合沉积物形态中重金属稳定同位素的组成示踪污染源。

伟晶岩中不同副矿物U-Pb同位素定年和示踪的问题与应用

定年和示踪一直是伟晶岩成岩成矿过程和稀有金属富集机制研究的关键问题。副矿物不仅是伟晶岩中稀有稀土元素的重要载体,还蕴含丰富的微量元素并常常具有较高的U-Th含量,是研究伟晶岩年代学、成岩成矿过程和物质源区的“理想探针”。伟晶岩中常用的适合于U-Pb同位素定年的副矿物有锆石、铌钽铁矿、独居石、锡石、榍石、褐帘石、磷钇矿和磷灰石等。由于封闭温度、矿物学特性和不同性质流体中元素行为的差异,伟晶岩中不同副矿物的U-Pb系统常表现出复杂的年龄谱系,可能记录了伟晶岩中潜在的后期地质过程,如:自交代、后期变质与流体改造等。因此,基于前期光学显微镜、扫描电镜、冷阴极发光、激光拉曼光谱分析等矿物微观结构研究,对不同期次或世代的副矿物进行原位微区U-Pb定年及主微量元素和同位素地球化学分析,对于全面认知多期地质事件和伟晶岩成岩成矿过程演化历史,进而更准确地构建其构造-岩浆-热液-成矿作用时空框架具有重要的科学意义。

稀土稳定同位素分析方法及在风化壳淋积型稀土矿研究中的应用展望

稀土元素因其特殊的化学性质和在地球科学研究中的重要价值而受到广泛关注。随着化学纯化方法的发展和质谱测定技术的提高,国内外对稀土稳定同位素体系开展了一系列探索。近年来,逐渐发展起来的稳定Ce和Nd同位素分析方法,为表生地质过程、氧化还原环境示踪以及生态环境演变等方面的研究提供了新的手段,也将为研究稀土矿提供直接证据。本文先系统介绍了稀土元素及其同位素体系的地球化学特征,总结稀土稳定同位素分析方法的发展历程与研究现状,并对其未来可能突破的方向进行评述。在此基础上,对稀土稳定同位素在风化壳淋积型稀土矿床研究中的应用前景进行了展望,指出稀土稳定同位素地球化学手段是深入了解风化壳淋积型稀土矿床形成过程与控矿机制的良好指标,其与稀土元素地球化学指标相结合有望在稀土矿化过程与机制方面取得新的认识。

氮肥减施时期对水稻产量、氮肥利用率及氮肥去向的影响

为探明氮肥减施时期对水稻产量、氮肥利用率及氮肥去向的影响,为制定科学合理的水稻氮肥减施措施提供理论支持。于2018—2019年,在大田条件下设置5个处理:(1)不施氮肥(N0);(2)常规施肥(N1,N 225 kg/hm^(2),基肥、分蘖肥、穗肥分别为N 90、67.5、67.5 kg/hm^(2));(3)基肥减氮(N2,N 202.5 kg/hm^(2),基肥、分蘖肥、穗肥分别为N 67.5、67.5、67.5 kg/hm^(2));(4)分蘖肥减氮(N3,N 202.5 kg/hm^(2),基肥、分蘖肥、穗肥分别为N 90、45、67.5 kg/hm^(2));(5)穗肥减氮(N4,N 202.5 kg/hm^(2),基肥、分蘖肥、穗肥分别为N 90、67.5、45 kg/hm^(2))。2019年在施氮处理小区内设置^(15)N稳定同位素示踪微区试验。结果表明:与常规施肥(N1)相比,减氮10%不会降低水稻产量。然而,不同减氮时期对水稻产量有显著影响,N2处理的水稻产量较N3处理增产7.8%~9.4%。N2和N3处理较N1处理显著提高了氮肥表观利用率和氮肥偏生产力,而N1和N4处理间氮肥表观利用率无显著差异。与N4处理相比,N1和N2处理均显著增加了植株对^(15)N肥料的吸收量。各处理^(15)N肥料利用率为26.0%~30.1%,其中N2处理显著高于N4处理。^(15)N肥料主要残留在0~20 cm土层中,其约占^(15)N肥料总残留量的90%。基肥减氮(N2)可以提高水稻^(15)N肥料利用率和残留率,降低氮肥损失率。因此,减少施氮量应减少基肥中的氮肥用量,不仅可以保证水稻产量,而且还能提高氮肥利用率,减少氮肥损失。

氮同位素分馏机制、分析测试与示踪技术及其在生态环境中的应用

【研究目的】氮(N)是地球陆地生态系统中的关键营养元素,也是引起水体富营养化的污染元素之一。随着分析测试技术的不断提高,氮稳定同位素技术已经发展成为一种常用的研究方法和分析手段,在氮的生物地球化学循环、水体富营养化和地下水污染来源识别等方面广泛应用。【研究方法】本文查阅近年来国内外生态环境领域氮稳定同位素的相关文献,综述了氮同位素分馏机制、氮同位素分析技术以及氮同位素在生态环境中应用的研究现状。【研究结果】(1)氮同位素质谱分析技术与氮同位素示踪技术目前已经建立了成熟体系。(2)硝化作用与反硝化作用是土壤氮转化循环的主要机制,生物固氮实现氮的输入,而植物或微生物产生含氮气体或矿化作用是氮输出的主要途径,并伴随着不同程度的氮同位素分馏效应。(3)氮同位素可以用来测定土壤氮素周转速率、N2O排放途径与生物固氮量、指示大气氮沉降变化、探究植物与土壤的相互作用及确定植物对氮素的吸收利用、识别农作物产地与水体、大气的氮污染来源。【结论】未来应将研究重点放在提升氮循环过程中不确定性来源的定量检测能力,确定未被发现的氮输入、积累和损失途径,完善并发展生态系统氮循环模型。

Fe-Cu-Zn-Mo同位素示踪氧化还原过程

非传统稳定同位素(Fe-Cu-Zn-Mo)理论与数据相结合提高了科研工作者对地质体系氧化还原过程的理解。本文对这一相对较新的领域进行了综述,包括与氧化还原过程相关的同位素分馏理论和实验约束、时空尺度下的氧逸度以及同位素示踪氧化还原过程。稳定同位素理论预测,Fe-Cu-Zn-Mo同位素应该对氧化还原状态的变化能够做出响应。结果表明,Fe同位素作为岩浆过程、表生过程、俯冲带流体性质"氧逸度计"应用前景广阔;Cu同位素在岩浆、热液、陆地系统可以很好地示踪氧化还原过程;Zn同位素由于络合过程分馏已经被用在许多不同环境中作为含硫/碳流体迁移的敏感示踪剂;Mo同位素作为古氧逸度计可有效重建古海洋-大气氧化还原状态。

镉锌稳定同位素地球化学及其在土壤等地质体中的危害与治理研究进展

【研究目的 】镉、锌既是重要的矿产资源,也是有害的重金属元素。随着多接收电感耦合等离子体质谱仪(MC-ICP-MS)的发展,镉、锌等非传统稳定同位素体系的建立与应用使镉、锌地球化学研究水平迈上新的高度,镉、锌同位素体系建立与应用成为国际研究热点。【研究方法 】本文通过查阅大量镉、锌同位素的相关文献,从镉、锌同位素的分析方法、分馏机制、自然界储库组成及应用领域进行了综述。【研究结果 】(1)随着镉、锌同位素分析技术的不断改进,其同位素体系正在逐步建立;(2)地球各储库中的锌同位素组成已基本查明,镉同位素组成正处于数据积累阶段;(3)镉、锌同位素分馏机制主要包括吸附沉淀、生物作用、化学作用等,目前已逐渐被应用到指示行星分异、探明成矿机制、重建古环境、示踪污染源等多种领域中;(4)在解析重金属污染源时,多种同位素的联用有助于减小不确定性。【结论 】在新型同位素分析仪器和技术的开发下,镉、锌同位素的研究拥有更大的发展空间。未来的研究重点主要包括对镉、锌同位素分馏机制、部分储库含量、应用领域进行完善。