高岭土中全硫量快速测定方法

采用碳酸钠一氧化镁半熔融一氯化钡滴定法测定高岭土中的硫含量。试样用碱性熔荆半熔,熔块以水浸取,将转化为硫酸盐后的滤液,以玫瑰红酸钠为指示剂,在pH为5．5．7．0的条件下,用氯化钡标准溶液进行滴定。测定结果的RSD=2．47％（n=5）,加标回收率为95．2％-100．3％。改进后的方法已用于高岭土中全硫量的测定,结果与国标重量法相符。     

预富集柱—离子色谱法测定高纯水中痕量氟和氯

在国产离子色谱仪上加装填充有季铵型阴离子交换剂的预富集柱,所设计的流路和方法可将测定Ｆ－和Ｃｌ－的检出限分别降至０１７μｇ／Ｌ和０２７μｇ／Ｌ。测定精密度好,ＲＳＤ＜５％,方法满足反应堆堆芯冷却水中痕量Ｆ－和Ｃｌ－的检测要求。     

沉积岩中总有机碳测定的自动预处理方法

总有机碳(TOC)是衡量烃源岩有机质丰度的首要指标,实现其高效准确测定具有重要的现实意义。在TOC整体测试流程中,用稀盐酸去除无机碳的样品预处理过程目前主要采用手动法进行,存在周期长、氯化物残留等问题,成为制约整体测试效率的首要因素。学者们研究了溶样时间、溶样温度、离心洗样等对TOC测定值的影响,但尚未形成系统的预处理方法,预处理效率也未得到实质性改善。本文利用自主研制的有机碳自动预处理仪建立了两种自动预处理方法;根据国家标准 《沉积岩中总有机碳的测定》(GB/T 19145—2022)规定的预处理流程,采用多种岩性、不同TOC水平的国家标准物质和质量控制样品对这两种预处理方法进行了方法验证;并进一步分析了自动预处理方法的优势。结果表明,两种自动预处理的方法回收率总体为96.23%～102.12%,相对标准偏差为0.37%～3.23%,满足标准规定的数据准确性、重复性和再现性要求,数据质量较手动法得到进一步提升;自动预处理法的预处理时长大幅缩短至4～6h/批,提高了测试效率;氯离子活度对洗样次数的变化更为敏感,且可监测并有效降低样品中氯化物的残留量,建议作为洗样终点的定量监测指标。建立的两种自动预处理方法可替代手动法进行TOC测试的样品预处理,在保障数据质量和测试效率的前提下又可解放人力,使总有机碳的测试能力得以显著提升。     

Quantifying chloride retention and release in urban stormwater management ponds using a mass balance approach

Chloride (Cl⁻) in urban waterways largely originates from runoff containing deicing salts. Cl⁻ is retained in watersheds after deicing ends, resulting in deleterious effects on aquatic biota. Stormwater management ponds (SWMPs), designed to mitigate ‘flashy’ urban runoff response, are known to impact pollutant transport. However, there is little information on what role SWMPs play in the timing and magnitude of Cl⁻ transport over different timescales. This study quantifies the mass of Cl⁻ retained in two SWMPs over varying timescales. Both ponds are in an urbanizing watershed in south-central Ontario; one drains a commercial area, the other, a residential area. High frequency measurements of water level and specific conductivity, from which flow and Cl⁻ concentration were derived, were taken with sensors at pond inlets and outlets. For one SWMP, data were also collected upstream and downstream of the confluence of the pond outflow and the receiving creek to quantify the in-stream response to Cl⁻-laden pond outflows. The findings suggest that SWMPs likely play a role in watershed-scale Cl⁻ retention; one SWMP consistently retained Cl⁻ while the other had variable retention and release of Cl⁻. In the receiving creek, Cl⁻ concentrations downstream of the pond exceeded the acute toxicity threshold for aquatic organisms twice as often as concentrations upstream of the pond, and Cl⁻ pulses corresponded to Cl⁻ release events from the pond. The results of this study suggest that SWMPs concentrate spatially distributed salt inputs and modify the timing and magnitude of their release to receiving streams. Stream reaches that receive water inputs from SWMPs may be more vulnerable to Cl⁻ toxicity than reaches that do not receive flow via SWMPs. The results of this study will help parameterize the role of SWMPs in watershed-scale Cl⁻ transport models and geospatial models of salt vulnerable areas.     

库车盆地天然氯化锶矿物的发现

通过扫描电镜分析,在新疆库车盆地首次发现天然氯化锶矿物。该矿物大小为几微米至几十微米,具有形态不规则、在空气中易潮解等特征。由于颗粒太小,暂时无法测定其晶体结构参数。初步认为极度干旱气候条件下,如有锶的来源,在蒸发盐壳中可形成天然氯化锶矿物。其晶体结构参数、确切成因等还有待于进一步深入研究。     

Alkalinization and acidification of stream water with changes in atmospheric deposition in a tropical dry evergreen forest of northeastern Thailand

Field surveys on atmospheric deposition and stream water chemistry were conducted in an evergreen forest in northeastern Thailand characterized by a tropical savanna climate with distinct dry and wet seasons. Atmospheric deposition of ion constituents by throughfall and stemflow was shown to increase in the beginning and end of the wet season, reflecting the precipitation pattern. The pH and electrical conductivity of stream water increased with alkalinity and base cation concentrations due to mineralization of organic matter by the first rain and retention of anions in soil during the start of the wet season. After initial alkalinization, the pH and alkalinity declined rapidly with the highest SO₄^2? concentration displayed in the middle towards the end of the wet season. The magnitude of peaks in SO₄^2? concentration (13.5–60.6 μmol_c/L) reflects deposition during the first 2 months of the wet season (March and April) in respective years (60.8–170 mol_c/ha). Release of SO₄^2? with H⁺, which is retained in soil during the early wet season, may cause acidification later in the season. The deposition and concentration of SO₄^2? declined over 6 years. However, the pH of stream water declined with increasing concentrations of SO₄^2? and other major ions. The release of materials accumulated in the ecosystem was facilitated by the decrease in SO₄^2? concentration/deposition and increased precipitation in the middle–late wet season. The retention‐release cycle of SO₄^2? largely contributed to both seasonal and interannual variations in stream water chemistry in the tropical savanna climate studied.     

Bedrock infiltration and mountain block recharge accounting using chloride mass balance

Mountain front catchment net groundwater recharge (NR) represents the upper end of mountain block recharge (MBR) groundwater flow paths. Using environmental chloride in precipitation, streamflow and groundwater, we apply chloride mass balance (CMB) to estimate NR at multiple catchment scales within the 27 km² Dry Creek Experimental Watershed (DCEW) on the Boise Front, southwestern Idaho. The estimate for average annual precipitation partitioning to NR is approximately 14% for DCEW. In contrast, as much as 44% of annual precipitation routes to NR in ephemeral headwater catchments. NR in headwater catchments is likely routed to downgradient springs, baseflow, and MBR, while downgradient streamflow losses contribute further to MBR. A key assumption in the CMB approach is that the change in stored chloride during the study period is zero. We found that this assumption is violated in some individual years, but that a 5‐year integration period is sufficient. Copyright © 2011 John Wiley & Sons, Ltd.     

谱睿在线除氯技术检测高氯水样中的阴离子

采用戴安公司谱睿(Pre)在线样品前处理技术,使用高容量在线Ag柱和Na柱,开发出了一种柱前去除高氯基体中氯离子的在线分析方法。操作简便,且适用样品范围广;不更换Ag柱可耐受10 g/L NaCl基体,25μL连续进样400针,氯离子去除效率可保持在99%以上。系统选用高容量IonPac AS11-HC氢氧根体系阴离子交换色谱柱,在线淋洗液自动发生装置进行梯度淋洗,用抑制型电导检测。对食盐、分析纯氯化钠等不同基体进行检测,可实现样品在线除氯,并可检测其中不高于10μg/L的溴酸根、氯酸根、亚硝酸根、硝酸根和硫酸根等离子。不同离子校准曲线相关系数均在99.8%以上,加标回收率为80%~110%。该技术具有操作简单、可重复性强、方法新颖等特点,解决了以往高氯基体检测成本过高、适用范围有限、前处理操作复杂等问题。     

室温氯化铜-氯化钠溶液中铜氯络合物浓度的电化学分析

运用Tafel极化曲线和线性电势扫描法研究了常温弱酸性CuCl2-NaCl溶液中铜氯络合物体系的电化学放电机理。通过测量不同浓度配比的CuCl2-NaCl溶液的极化曲线得到各自的交换电流密度,然后根据电化学反应级数法计算直接在电极上放电的Cu(Ⅱ)-Cl络合物的配位数。并且运用线性电势扫描法进一步研究了此络合物在铂电极上的还原反应,在体系可逆的情况下计算得到其发生放电反应的离子浓度。结果表明:溶液中存在的主要络离子是[CuCl]+,在铂电极上发生电化学反应的铜络离子是[CuCl]+。铜氯络离子在铂电极上的还原反应分两步进行,其中第一步为可逆的单电子还原过程,体系中[CuCl]+和Cu的电化学反应级数均为一级;4.000 mol/L NaCl-0.100 mol/L CuCl2溶液体系中发生放电反应的[CuCl]+的浓度为0.086 mol/L。研究结果为目前学术界存在广泛分歧的Cu2+在高浓度氯离子溶液中的放电机理提供了重要的实验依据,同时对未来湿法冶金、地质和地球化学等领域中溶解态金属络合物的电化学分析具有一定的借鉴作用。