Explore the vast range of titles available.

An improved method for accurate and precise determination of metal to calcium ratio in mass limited calcium carbonate samples has been developed. We used an Agilent®5800 ICP‐OES for major element (Na/Mg/Sr to Ca) and an Agilent®8900 ICP‐QQQ‐MS for minor and trace element (Li/B/Na/Mg/Al/Mn/Fe/Zn/Sr/Cd/Ba/U to Ca) ratio determination. We report a long‐term precision of ≤1% (1σ) by repeat analysis, spread over ≥6 analytical sessions, of multiple external standards that spanned a large range of concentration. We quasi‐quantitatively eliminated potential matrix effect from high [Ca] by concentration matching samples and standards (∆[Ca] ≤ ±5%) during both ICP‐OES and ICP‐QQQ‐MS sessions. The ICP‐OES analyses were done on 200 μl of sample at 60 ppm [Ca], consuming ∼30 μg of CaCO3 per analysis. Whereas trace element analyses by ICP‐QQQ‐MS required ∼150 μl of sample at 20 ppm [Ca], consuming ∼7.5 µg of CaCO3 per analysis. Thus, the present method allows for high precision determination of TE/Ca in <40 μg of CaCO3. We present a comprehensive approach for optimization of ICP‐OES sensitivity and stability to select elemental (Ca/Na/Mg/Sr) wavelengths with minimal interferences, high sensitivity and linearity. For choice of Ca lines, we focused on the minimization of self‐matrix effect. For the ICP‐MS method, we improved reproducibility and precision by lowering [Ca] of analyte and preconditioning of cones. Furthermore, the present method allows for precise B/Ca determination sans the use of HF matrix. In summary, we present an easily adoptable method based on readily available instrumentation for determining element‐to‐calcium ratios that is suitable for analyzing mass‐limited carbonate samples. Key Points We present a user‐friendly approach for determining trace element to calcium ratios using readily accessible and easy to use instrumentation This method requires an extremely small sample size, <40 μg of CaCO3, for determining trace elemental ratios with an excellent limit of detection Our method is characterized by better than 1% accuracy and precision during determination of TE/Ca using both ICP‐OES and ICP‐QQQ‐MS

The influence of sodium fluoride (NaF) on calcium metabolism was examined in nibbler fish (marine teleosts). Two days after the administration of NaF (5 μg/g of body weight) (around 10 −4  M in fish), we showed that plasma calcium levels significantly decreased in NaF-treated nibbler fish. In addition, we detected fluoride in the treated scales by use of a scanning electron microscope with an energy-dispersive X-ray microanalysis, indicating that NaF directly affects their scales. Therefore, the influence of NaF on osteoblasts and osteoclasts in the scales was examined. In the scales of NaF-injected nibbler fish, tartrate-resistant acid phosphatase (TRAP) (osteoclastic marker enzyme) decreased, although alkaline phosphatase (osteoblastic marker enzyme) was activated. To confirm the effect of NaF on osteoclasts, furthermore, the mRNA expressions of osteoclastic markers (matrix metalloproteinase-9 and TRAP) were decreased significantly 2 days after incubation. In barred knifejaws, plasma calcium levels decreased as they did in nibbler fish. Therefore, NaF functions in both osteoblasts and osteoclasts and then influences calcium metabolism in marine fish. In the marine environment, high levels of fluoride (1.2–1.5 mg F − /l) (around 10 −5 –10 −4  M) are present in seawater. It is probable that teleosts living in seawater efficiently use fluoride to regulate their blood calcium levels.

碳酸盐生物壳体的周期性生长纹层是记录气候环境变化的天然材料。随着原位微区测试技术的快速发展，高分辨率的同位素和化学元素组成的快速分析显著推动了古气候环境变化及生物地球化学研究。应用激光剥蚀等离子体质谱仪（LA-ICP-MS）对南黄海现代牡蛎Crassostrea gigas壳体韧带部的元素组成进行原位微区测试，利用内标元素43Ca进行元素比值的校正，探讨了牡蛎壳中化学元素特征及其环境意义。研究的长牡蛎壳体中Mg/Ca、Sr/Ca、Na/Ca比值具有显著的季节性周期变化。环境水体物理化学性质的变化对壳体生长速率影响较大，壳中白垩质方解石和叶片方解石生长层分别对应较高和较低的环境温度，白垩方解石层具有较高的Mg/Ca、Sr/Ca和较低的Na/Ca比值。Mg/Ca比值可指示牡蛎壳体生长环境水体温度，利用前人Mg/Ca比值公式计算可以恢复与器测资料相符的近岸海水温度结果。本研究对应用LA-ICP-MS分析技术开展高分辨率的生物壳体元素组成和环境示踪研究具有借鉴意义。

2018年8月山东北部弥河流域受台风暴雨影响发生洪涝灾害，通过对洪水淹没区考察，选择弥河及其支流丹河下游新鲜洪水沉积保存完好的地点，获取两根沉积物浅钻MH1、DH2(长度分别为21.5、21 cm，下段为现代土壤)，对沉积岩芯进行X射线荧光光谱(XRF)元素连续扫描，结合粒度指标和其他研究成果，探讨现代洪水沉积物元素特征及其在古洪水事件识别中的指示意义。结果显示，Al、Ti、Si、Ca、Fe等元素具有相似的波动特征，相互之间正相关关系显著，信号强度在细粒洪水沉积层出现峰值；Rb元素信号强度与粒度相关性弱，在钻孔中的变化较为稳定，仅在沉积界面处有所降低，可能与岩芯裂隙造成的实验偏差有关；Sr、Zr两种元素显著正相关，且信号强度在洪水沉积层较低。Zr/Rb和Rb/Sr分析结果表明，两者均受控于粒度特征，风化淋溶作用对其影响有待进一步研究，其中Zr/Rb与粒度呈现较强的正相关性，Rb/Sr则与粒度负相关关系显著，且在其他区域洪水地层研究中具有一致结论。Zr/Rb峰值和Rb/Sr谷值对应黏土质洪水沉积，Zr/Rb谷值和Rb/Sr峰值对应粒度粗组分高值的粉砂质洪水沉积，可在古洪水沉积识别中作为参照指标。本研究结果将为利用XRF技术识别古洪水沉积提供有力参考。

为探究江西井冈蜜柚种植区果园土壤肥力现状及区域分布特征，在江西省井冈蜜柚110个主产果园采集表土层（0~20cm）、亚表土层（20~40 cm）和底土层（40~60 cm）土壤，运用ArcGIS技术、相关性分析和主成分分析，对土壤pH、有机质及养分含量等12项土壤肥力指标进行系统分析。结果表明：果园表层土壤pH值为4.00~7.38，土壤有机质和碱解氮、有效磷、速效钾、有效锌、交换性镁含量分别为7.85~32.71 g·kg-1和45.50~318.50、1.99~146.11、26.96~306.08、0.36~16.47、15.00~219.63 mg·kg-1；有效铜和交换性钙含量分别低于7.91 mg·kg-1和658.88 mg·kg-1；果园土壤肥力指标含量随土壤深度增加而降低；总体上，种植区表层土壤pH分布呈中部高四周低的格局，有效磷含量与之相反，有机质含量西部高东部低，微量元素含量南部低北部高。相关性分析表明，表层土壤pH与交换性镁含量呈显著正相关，交换性镁含量与交换性钙、有效锌、全磷、速效钾含量均呈显著正相关。主成分分析表明，土壤交换性钙、交换性镁、碱解氮和有效锌含量是种植区土壤肥力变异的主要控制因素。研究表明，江西井冈蜜柚种植区果园土壤各土层间肥力和区域分布均存在较大差异，改良土壤以及补充养分含量有利于提升土壤肥力。This study aims to explore the current situation of the regional distribution and fertility of soil in Jinggang pomelo planting area in Jiangxi Province. The topsoil(0~20 cm),subtopsoil(20~40 cm)and subsoil(40~60 cm)were collected from 110 main orchards of Jinggang pomelo in Jiangxi Province. The study carried out a systematic analysis of 12 soil fertility indexes including soil pH,organic matter and nutrient content using the ArcGIS technolog

稀土(REY)是一组有效示踪物质源区和地质过程的元素，本研究利用X荧光光谱法(XRF)和电感耦合等离子光谱仪(ICP-MS)分析了马尔库斯-威克海山和中太平洋海山富钴结壳的主要元素和稀土元素，结合前人研究成果对比了磷酸盐化及未磷酸盐化富钴结壳的稀土特征。结果显示：磷(P)含量低的结壳具有相对低的稀土总量(∑REY)，北美页岩标准化后显示铈(Ce)正异常和钇(Y)负异常；磷酸盐化后的结壳具有相对高的∑REY，并表现出Ce正异常和显著Y正异常。磷酸盐化结壳中应存在“富稀土磷酸盐”组分，特别是对Y具有重要贡献。将磷酸盐化结壳视为磷酸盐组分和结壳组分的混合，模拟结果显示富稀土磷酸盐组分具有海山磷块岩的稀土配分模式，但是其∑REY达到普通磷块岩的10倍或以上。考虑到海洋中富钙沉积物丰富，大量PO43-不同程度地交代碳酸盐等钙质物质，容易形成贫稀土磷酸盐。而伴随结壳缓慢的成矿过程，部分磷酸盐的形成未受到碳酸盐的影响，容易形成富稀土磷酸盐。

【目的】探究不同水源磁化处理对生菜光合特性等生理生化和产量的影响。【方法】在日光温室条件下，以意大利生菜为供试对象，采用随机区组设计，设置2个因素：磁化（M）和灌溉水源（T），磁化设置未磁化处理（M0）和磁化处理（M1）2个水平，灌溉水源设置淡水（T1）、再生水（T2）、微咸水（T3）3个水平，共6个处理。通过盆栽试验研究了3种水源磁化处理对生菜净光合速率、抗氧化酶活性、矿质元素及产量等的影响。【结果】不同水源磁化处理灌溉效果有所差异。生长中期，M1T1、M1T2处理分别较M0T1、M0T2处理的净光合速率显著提高11.16%、14.73%。3种水源磁化处理灌溉的超氧化物歧化酶、过氧化物酶、过氧化氢酶活性显著提高12.77%~23.09%。M1T1、M1T2处理分别较M0T1、M0T2处理的生菜叶片氮质量分数显著提高7.71%、6.83%，生菜产量分别显著提高9.42%、10.15%，但M1T3与M0T3处理的生菜产量无显著差异。不同水源磁化处理的生菜叶片P、Ca、Mg、Na、K质量分数有不同程度的提高，水分利用效率提高5.03%~11.65%。【结论】磁化水灌溉有利于生菜光合等生理生化活动，提高产量和水分利用效率，淡水和再生水磁化效果优于微咸水。

马里亚纳弧前蛇纹岩泥火山顶部海底发育由低温碱性流体渗漏形成的自生沉积物，记录了渗漏流体特征，对俯冲带的物质循环研究有重要意义。但目前对复杂矿物组成的自生沉积物及其所指示的渗漏流体信息仍不清楚。对采自马里亚纳弧前Conical蛇纹岩泥火山的自生沉积物进行了岩石学、矿物学及主量和微量元素分析。结果表明，Conical蛇纹岩泥火山自生沉积物呈疏松多孔状，极易碎，碎块主要呈薄片状和球粒状。薄片状碎块呈白色，主要由针状文石和棱柱状方解石组成，CaO含量较高（49.3%～53.3%），MgO含量较低（2.3%～4.5%）。球粒状碎块呈黄色或白色，为无定形镁硅酸盐，MgO含量较高 （25.5%～29.1%），CaO 含量较低（0.5%～2.9%）。碳酸盐岩碎块的总稀土含量（ΣREE）为227.2～4 136.6 ng/g；无定形镁硅酸盐碎块的ΣREE为115.4～364.9 ng/g，均显示轻微重稀土富集的平坦型配分模式。自生沉积物的稀土配分模式显示，除两个稀土含量相对较高的碳酸盐岩样品外，渗漏流体的贡献高于90%，说明两类样品均形成于较强的渗漏环境，并且碳酸盐及镁硅酸盐可能分别形成于“低硅型”和“高硅型”不同的流体活跃期。