The authors thank Drs. Bobby J. Presley, Robert Tayloy, Paul Boothe, Mr. Bryan Brattin, and Mr. Mike Metcalf for their assistance during the laborious field sampling and lab work for the practical development and application of "clean techniques".

1.取样准备<ol><li>取样<ol><li>采样器组合<ol><li> 4米长的氟化乙烯丙烯（FEP）管（ID0.635厘米，外径0.95厘米或类似的）连接到1.5米耐化学性的硅树脂泵浦管（外径0.635厘米）。 </li><li>插入聚丙烯Y连接到泵送管和50厘米泵送管连接到一个出口，和一个0.45μm的胶囊型过滤器（由一20厘米泵送管）到另一个。 </li><li>组装在一个干净的房间（工作台）的管路它们清洗后（见下文），并在组装存储在聚乙烯袋两层。 </li></ol></li><li>取样器清洗<ol><li>填充（由1.5米泵送管附着到蠕动泵）的管组与实验室洗涤剂溶液并浸泡24小时。冲洗管道用去离子水集，然后用10％（V / V）盐酸（试剂级）填写并浸泡48小时。 </li><li>彻底冲洗管道，用去离子W设置亚特几次，并储存在塑料袋组合。通过将它们浸泡在50％（体积/体积）HNO 3（试剂级）溶液24小时清洁的Y连接器和短抽管。 </li></ol></li><li>胶囊过滤器<ol><li>通过首先用去离子水冲洗他们48小时浸泡步骤，然后用10％（体积/体积）HCl溶液清洗胶囊型过滤器。 </li><li>酸浸泡后，冲洗用去离子水的过滤器和加入1毫升21％（重量）的NH 4 OH（副煮沸）溶液到每个滤波器以中和酸。 </li><li>密封个别滤波器30厘米清洁泵浦管的环连接在聚乙烯拉链袋的入口和出口，并存储。 </li></ol></li></ol></li><li>样品容器<ol><li>用聚乙烯（PE，1000毫升）和FEP（500毫升和1000毫升）瓶的微量金属容器的决心。 <ol><li>通过首先将它们浸泡在洗涤剂（1％），然后在50％（体积/体积）HNO 3清洗瓶（试剂级）和10％（V / V）盐酸（试剂级）为24，48和24小时的解决方案，分别和冲洗与两个浸泡步骤之间的去离子水的瓶子。 </li><li>最终盐酸浸泡后，彻底用去离子水（DIW）冲洗瓶和干燥在一个干净的房间或类100洁净工作台的瓶（用帽密封）。 </li><li>聚乙烯袋拉链和双包他们聚乙烯袋运输密封清洗瓶。 </li></ol></li><li>干净的玻璃瓶溶解有机碳（DOC）测定<ol><li>浸泡琥珀色硼硅玻璃瓶（40毫升），对溶解有机碳（DOC）的分析，10％盐酸48小时。冲洗用去离子水清洗玻璃瓶，并在480℃下燃烧它们在使用前2小时。单独密封瓶拉链聚乙烯袋运输。 </li></ol></li></ol></li></ol> 2.抽样<ol><li>水样采集<ol><li>牛浦Ñ​​到达在取样点，上外袋标记样品识别号码，并保持瓶在其原始袋。 </li><li>在河岸或在船上，有一个人打开与采样袋和4米FEP管连接到一个3米聚丙烯极（清洗）。延长杆从银行尽可能远并保持FEP管泵被接通之前运行河水的表面下约为30厘米的入口。 </li><li>有另一个人的抽水管连接到蠕动泵（取样泵具有内部电池）的泵头。启动泵和排水（下游侧）的总采样体积的至少3倍。戴上无粉手套，打开瓶子和瓶盖的袋子，开始填充样品瓶。 <ol><li>可替代地，如果另一个人是可用的，具有第三人负责打开内袋和样品盖，并保持该排出样品进b中的采样管的ottle。 </li></ol></li><li>收集在一个125毫升的塑料瓶在场电导率，温度和pH的测量未过滤样品。 </li><li>收集未过滤的样品（500毫升或1,000毫升的微粒样品收集）的第一（通过出口未经过滤器），然后用塑料夹具迫使水去通过囊式过滤器来收集已过滤的水样关闭出口（1 -L溶解微量金属测定）。 </li><li>过滤收集样品（通过与过滤器出口）的40毫升的琥珀色玻璃瓶DOC和EDTA的测量。 </li><li>在近似500ml /分至1000毫升/分的流速收集水样。当压力开始建立（根据过滤器"规范）更换囊式过滤器。对于每种类型的样品，收集额外采样，以及野外空白，在选定的位置，作为质量控制等分。 </li><li>放置在干冰上，并存储我在40毫升的玻璃瓶n中的冰柜，并在冰柜聚乙烯瓶。 </li></ol></li><li>悬浮颗粒物收集（SPM） <ol><li>收集0.4微米聚碳酸酯（PC）膜过滤器的SPM（酸洗涤和预称重）通过真空过滤，用塑料过滤漏斗和容器。 </li><li>冷冻干燥膜过滤器在实验室中产生SPM浓度和微粒的微量金属测定粒子提供样品。 </li></ol></li></ol> 3.样品预处理（溶解的痕量金属） <ol><li>溶解微量金属测定，加入2毫升浓子煮沸HNO 3（每1升样品）到采样瓶。转让溶解微量金属样品（酸化）到FEP瓶。交替，样品可以直接收集到的FEP瓶。紫外线照射在FEP瓶样品24小时（8 15瓦的紫外线灯）。 </li></ol> 4.富集及处理痕量金属分析<ol><l我&gt;树脂富集<ol><li>权衡2克阳离子交换树脂的成小（10-30毫升容量）塑料杯中，并添加2N的HNO 3溶液少量放入杯中。倒入树脂成一个10毫升容量层析柱。通过用5毫升2N的HNO 3洗涤柱清洁树脂（子煮）两次，并用高纯度水（HPW）3次冲洗。 </li><li>加入10 mL 1M的NH 4 OH（分煮）入列到树脂转化为NH 4 +型。 </li></ol></li><li>缓冲溶液（1M乙酸铵） <ol><li>在大约800毫升HPW添加57毫升冰醋酸（亚煮沸）。加〜60毫升氢氧化铵（21％，分煮沸）中，用乙酸混合。调节最终pH至5.5和最终体积至1000毫升</li></ol></li><li>富集过程（溶解微量金属） <ol><li>通过加入30ml的1M ACET铵调节酸化，紫外线照射样品至5.5±0.3的pH值吃缓冲溶液和一些（〜2.8毫升） 的 NH 4 OH（子煮沸）插入采样。 </li><li>将样品瓶〜30厘米挤满了阳离子交换树脂（第4.1节）列上，并用〜60厘米FEP管色谱帽和连接器（母鲁尔）连接样品瓶富集列。 </li><li>控制在3-5毫升/分钟使用2路活塞的流速，列上方连接。允许样品通过该富集列。后，将样品都通过了列，断开列管和帽。 </li><li>用2×5毫升HPW和4×5毫升1M乙酸铵（pH为5.5）和2×5毫升HPW分开来自其它痕量金属主要阳离子的对待的列。 </li><li>放置只是列低于30毫升酸洗涤聚乙烯瓶并用7×1毫升2当量的HNO 3洗涤柱（子煮沸）进入PE瓶中。 </li><li>通过获得重量确定2 N HNO 3流出物（〜8.0毫升）的体积十二次2 N HNO 3流出物的比重。 </li></ol></li><li>悬浮颗粒物消化<ol><li>冷冻干燥过滤器的PC与SPM样品和干燥后秤重。处的SPM的样品，使用过滤器，进入预称重氟烷氧基烷烃（PFA）容器（60毫升容量），并添加3ml浓HNO 3的进入血管。 </li><li>收紧血管2.5公斤米恒定转矩，并在130℃下12小时在常规烘箱消化。冷却后，打开容器，并加2ml HF进入血管。 </li><li>收紧血管2.5公斤米恒定转矩，并在130℃下12小时在常规烘箱消化。冷却后，打开容器并增加16台毫升4.5％硼酸溶液放入容器。 </li><li>收紧血管2.5公斤米恒定转矩，并在130℃下在常规烘箱消化12小时。称重各容器，并确定每个消化溶液的比重产生最终的消化量。 </li><li>计算每个从过滤器的最终体积和重量SPM的消化稀释因子（最终消化体积样品重量上过滤分）。 </li></ol></li></ol> 5.样品分析<ol><li>微量金属<ol><li>测定痕量金属（镉，钴，铜，铁，锰，镍，铅和锌）的浓度在预浓缩溶解的样品和火焰原子吸收光谱法，石墨炉原子吸收光谱微粒的解决方案，和/或电感耦合等离子体质谱仪。 </li><li>由感应耦合等离子体 - 原子发射光谱法确定主要离子浓度和一些痕量金属，以富集之前绘制的子样品和悬浮颗粒物消化，英寸</li></ol></li><li>辅助参数<ol><li>确定样品的温度，pH值，盐度和电导率在外地，使用便携设备。 </li><li>确定溶解或加尼奇碳（DOC）的浓度通过总有机碳分析仪，基于由红外光谱21与二氧化碳检测湿式氧化。确定由高性能液相色谱法（使用的SPD-M10AV Diodearray检测器），按照既定的程序22,23总的EDTA浓度。 </li></ol></li></ol>

<ol>
	<li>Taylor, H. E., Shiller, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mississippi+River+Methods+Comparison+Study:+Implications+for+water+quality+monitoring+of+dissolved+trace+elements.">Mississippi River Methods Comparison Study: Implications for water quality monitoring of dissolved trace elements.</a> Environmental Science and Technology. 29, 1313-1317 (1995).</li><li>Windom, H. L., Byrd, J. T., Smith, R. G., Huan, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inadequacy+of+NASQAN+data+for+assessing+metal+trends+in+the+nation's+rivers.">Inadequacy of NASQAN data for assessing metal trends in the nation's rivers.</a> Environmental Science and Technology. 25 (6), 1137-1142 (1991).</li><li>Mason, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Trace Metals in Aquatic Systems. , (2013).</li><li>Wen, L. -. S., Santschi, P., Gill, G., Paternostro, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estuarine+trace+metal+distributions+in+Galveston+Bay:+importance+of+colloidal+forms+in+the+speciation+of+the+dissolved+phase.">Estuarine trace metal distributions in Galveston Bay: importance of colloidal forms in the speciation of the dissolved phase.</a> Marine Chemistry. 63, 185-212 (1999).</li><li>Wen, L. -. S., Stordal, M. C., Tang, D., Gill, G. A., Santschi, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+ultraclean+cross-flow+ultrafiltration+technique+for+the+study+of+trace+metal+phase+speciation+in+seawater.">An ultraclean cross-flow ultrafiltration technique for the study of trace metal phase speciation in seawater.</a> Marine Chemistry. 55, 129-152 (1996).</li><li>Benoit, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clean+technique+measurement+of+Pb,+Ag,+and+Cd+in+freshwater:+A+redefinition+of+metal+pollution.">Clean technique measurement of Pb, Ag, and Cd in freshwater: A redefinition of metal pollution.</a> Environmental Science and Technology. 28, 1987-1991 (1994).</li><li>Benoit, G., Hunter, K. S., Rozan, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sources+of+trace+metal+contamination+artifacts+during+collection,+handling,+and+analysis+of+freshwater.">Sources of trace metal contamination artifacts during collection, handling, and analysis of freshwater.</a> Analytical Chemistry. 69 (6), 1006-1011 (1997).</li><li>Jiann, K. -. T., Presley, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preservation+and+determination+of+trace+metal+partitioning+in+river+water+by+a+two-column+ion+exchange+method.">Preservation and determination of trace metal partitioning in river water by a two-column ion exchange method.</a> Analytical Chemistry. 74 (18), 4716-4724 (2002).</li><li>Fardy, J. J., Alfassi, Z. B., Wai, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Preconcentration Techniques for Trace Elements. , 181-210 (1992).</li><li>Pai, S. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pre-concentration+efficiency+of+Chelex-100+resin+for+heavy+metals+in+seawater.+Part+2.+Distribution+of+heavy+metals+on+a+Chelex-100+column+and+optimization+of+the+column+efficiency+by+a+plate+simulation+method.">Pre-concentration efficiency of Chelex-100 resin for heavy metals in seawater. Part 2. Distribution of heavy metals on a Chelex-100 column and optimization of the column efficiency by a plate simulation method.</a> Analytica Chimica Acta. 211, 271-280 (1988).</li><li>Pai, S. -. C., Fang, T. -. H., Chen, C. -. T. A., Jeng, K. -. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+low+contamination+Chelex-100+technique+for+shipboard+pre-concentration+of+heavy+metals+in+seawater.">A low contamination Chelex-100 technique for shipboard pre-concentration of heavy metals in seawater.</a> Marine Chemistry. 29, 295-306 (1990).</li><li>Pai, S. -. C., Whung, P. -. Y., Lai, R. -. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pre-concentration+efficiency+of+Chelex-100+resin+for+heavy+metals+in+seawater.+Part+1.+Effects+of+pH+and+salts+on+the+distribution+ratios+of+heavy+metals.">Pre-concentration efficiency of Chelex-100 resin for heavy metals in seawater. Part 1. Effects of pH and salts on the distribution ratios of heavy metals.</a> Analytica Chimica Acta. 211, 257-270 (1988).</li><li>Salbu, B., Oughton, D. H., Salbu, B., Steinnes, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Trace Elements in Natural Waters. , 41-69 (1995).</li><li>. U.S. Environmental Protection Agency. Method 1669. Sampling ambient water for trace metals at EPA Water Quality criteria levels Available from: <a target="_blank" href="https://www3.epa.gov/caddis/pdf/Metals_Sampling_EPA_method_1669.pdf">https://www3.epa.gov/caddis/pdf/Metals_Sampling_EPA_method_1669.pdf</a> (1996)</li><li>Horowitz, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Problems+associated+with+using+filtration+to+define+dissolved+trace+metal+concentrations+in+natural+water+samples.">Problems associated with using filtration to define dissolved trace metal concentrations in natural water samples.</a> Environmental Science and Technology. 30, 954-963 (1996).</li><li>Cortecci, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Geochemistry+of+trace+elements+in+surface+waters+of+the+Arno+River+Basin,+northern+Tuscany,+Italy.">Geochemistry of trace elements in surface waters of the Arno River Basin, northern Tuscany, Italy.</a> Applied Geochemistry. 24 (5), 1005-1022 (2009).</li><li>Markich, S. J., Brown, P. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relative+importance+of+natural+and+anthropogenic+influences+on+the+fresh+surface+water+chemistry+of+the+Hawkesbury-Nepean+River,+south-eastern+Australia.">Relative importance of natural and anthropogenic influences on the fresh surface water chemistry of the Hawkesbury-Nepean River, south-eastern Australia.</a> The Science of the Total Environment. 217, 201-230 (1998).</li><li>Shafer, M. M., Overdier, J. T., Hurley, J. P., Armstrong, D., Webb, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+dissolved+organic+carbon,+suspended+particles,+and+hydrology+on+the+concentration,+partitioning+and+variability+of+trace+metals+in+two+contrasting+Wisconsin+watersheds+(U.S.A.).">The influence of dissolved organic carbon, suspended particles, and hydrology on the concentration, partitioning and variability of trace metals in two contrasting Wisconsin watersheds (U.S.A.).</a> Chemical Geology. 136, 71-97 (1997).</li><li>Warren, L. A., Haack, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biogeochemical+controls+on+metal+behaviour+in+freshwater+environments.">Biogeochemical controls on metal behaviour in freshwater environments.</a> Earth-Science Reviews. 54, 261-320 (2001).</li><li>Jiann, K. -. T., Santschi, P. H., Presley, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationships+between+geochemical+parameters+(pH,+DOC,+SPM,+EDTA+Concentrations)+and+trace+metal+(Cd,+Co,+Cu,+Fe,+Mn,+Ni,+Pb,+Zn)+concentrations+in+river+waters+of+Texas+(USA).">Relationships between geochemical parameters (pH, DOC, SPM, EDTA Concentrations) and trace metal (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) concentrations in river waters of Texas (USA).</a> Aquatic Geochemistry. 19 (2), 173-193 (2013).</li><li>Peltzer, E. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+comparison+of+methods+for+the+measurement+of+dissolved+organic+carbon+in+natural+waters.">A comparison of methods for the measurement of dissolved organic carbon in natural waters.</a> Marine Chemistry. 54, 85-96 (1996).</li><li>Nowack, B., Kari, F., Hilger, S. U., Sigg, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+dissolved+and+adsorbed+EDTA+species+in+water+and+sediments+by+HPLC.">Determination of dissolved and adsorbed EDTA species in water and sediments by HPLC.</a> Analytical Chemistry. 68 (3), 561-566 (1996).</li><li>Bergers, P. J. M., de Groot, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+analysis+of+EDTA+in+water+by+HPLC.">The analysis of EDTA in water by HPLC.</a> Water Research. 28 (3), 639-642 (1994).</li></ol>

The authors have no conflict of interests to disclose.

在自然水域中获取可靠的微量金属数据需要样品的采集，处理，预处理和分析旨在减少污染期间强调呵护备至。跟踪中获得的天然水域重金属含量中发现，该浓度可以比以前报道的低几个数量级过去二十年来使用"清洁技术"。在水中的微量金属水质标准时，微量金属水平准确测量造成有害影响人类和高等生物更好的评估，现在更容易评估。生物利用度和在水生环境痕量金属的毒性需要在较低浓度?...

人们已经普遍认识到天然水域取得了一些微量金属的结果可能是由于从样本收集，处理和决心1,2过程中应用的技术所产生的不足，文物不准确的。真正的浓度（亚纳米到纳米范围内的地表水3）溶解的微量金属元素是要比以前发表的值低的到现在为止两个数量级。同样的情况在海洋化学凡在大洋水域中溶解的接受微量金属浓度已经超过过去40年减少了数量级左右改进取样和分析方法被引入被发现。已作出努力以改善与"清洁技术"旨在减少或消除微量金属污染的整个痕量金属分析4-8的各个阶段的发展的数据质量。对于重金属含量在环境的决心水平，富集通常需要。离子交换技术的8-12已普遍应用于有效富集。 污染可从容器的壁出现，容器中，取样器，样品处理和存储，以及样品保存和分析7,13的清洗。使用进行了最近的清洁方法，所有的研究表明，在自然水域中重金属含量一般远低于常规方法7检出限。既然承认在90年代初疑微量金属的数据，清洁方法已被纳入美国EPA（环保局）准则痕量金属检测14和美国地质调查局推行清洁方法，为他们的水质监测项目15个 。需要在所有的项目中被采用，以创造一个坚定而准确的数据基础痕量金属研究清洁方法。 <p类="jove_content"&gt;原则上，用于痕量金属测定水样应该用特殊的材料组成，具有仪器分析之前，存储和处理使用适当的容器和设备正确，适当的采样齿轮进行收集。由于悬浮颗粒物（SPM）可以进行在样本储存期的变化和改变水的成分，从水样SPM的快速分离是在水生环境痕量金属研究一种常见的做法。为在自然水域溶解痕量金属浓度的测定，过滤是必需的，并在在线过滤技术是合适的和有效的。 分布和在水生环境中，如地表水和地下水的微量金属的行为可以通过天然（ 例如 ，风化）和人为的影响（ 例如 ，废水流出物）的因素，以及其它环境条件，如重gional地质，形态，土地利用，植被，气候和16-19。然后这会导致诸如悬浮颗粒物浓度（SPM），溶解的有机碳（DOC），人为的配体（ 例如 ，乙二胺四乙酸，EDTA）的盐，氧化还原电位和pH值17-20的物理化学参数的差异。因此，准确和相关的痕量金属研究需要痕量金属分析的样品的适当的收集以及相关因素和参数的确定。

<table border="0" cellpadding="0" cellspacing="0" width="782">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:249px;">Nitric Acid</td>
			<td style="width:216px;">Seastar Chemicals</td>
			<td style="width:129px;"></td>
			<td style="width:188px;">Baseline grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:249px;">Ammonium hydroxide</td>
			<td style="width:216px;">Seastar Chemicals</td>
			<td style="width:129px;"></td>
			<td>Baseline grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:249px;">Acetic Acid</td>
			<td style="width:216px;">Seastar Chemicals</td>
			<td style="width:129px;"></td>
			<td>Baseline grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:249px;">Nitric Acid</td>
			<td style="width:216px;">J. T. Baker</td>
			<td style="width:129px;">9601-05</td>
			<td>Reagent grade</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:249px;">Hydrochloric acid</td>
			<td style="width:216px;">J. T. Baker</td>
			<td style="width:129px;">9530-33</td>
			<td>Reagent grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Chromatographic columns</td>
			<td style="width:216px;">Bio-Rad</td>
			<td>7311550&#160;</td>
			<td>Poly-Prep</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Column stack caps</td>
			<td style="width:216px;">Bio-Rad</td>
			<td>7311555</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Cap connectors (female luers)</td>
			<td style="width:216px;">Bio-Rad</td>
			<td style="width:129px;">7318223</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">2-way stopcocks</td>
			<td style="width:216px;">Bio-Rad</td>
			<td>7328102</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Cation exchange resin</td>
			<td style="width:216px;">Bio-Rad</td>
			<td>1422832&#160;</td>
			<td>Chelex-100</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Portable sampler (sampling pump)</td>
			<td style="width:216px;">Cole Palmer</td>
			<td>EW-07571-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">FEP tube</td>
			<td style="width:216px;">Cole Palmer</td>
			<td>EW-06450-07</td>
			<td>6.4 mm I.D., 9.5 mm O.D.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Pumping tube</td>
			<td style="width:216px;">Cole Palmer</td>
			<td>EW-06424-24</td>
			<td>6.4 mm I.D. C-Flex</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">Capsule filter (0.4 mm)</td>
			<td style="width:216px;">Fisher Scientific</td>
			<td>WP4HY410F0</td>
			<td>polypropylene casing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">1 L low density polyethylene bottle</td>
			<td>NALGE NUNC INTERNATIONAL</td>
			<td>312088-0032</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:249px;">1 L (or 500 ml) FEP bottle</td>
			<td>NALGE NUNC INTERNATIONAL</td>
			<td>381600-0032</td>
			<td></td>
		</tr>
	</tbody>
</table>

clean sampling and analysis of river and estuarine waters for trace metal studies

Most of the trace metal concentrations in ambient waters obtained a few decades ago have been considered unreliable owing to the lack of contamination control. Developments of some techniques aiming to reduce trace metal contamination in the last couple of decades have resulted in concentrations reported now being orders of magnitude lower than those in the past. These low concentrations often necessitate preconcentration of water samples prior to instrumental analysis of samples. Since contamination can appear in all phases of trace metal analyses, including sample collection (and during preparation of sampling containers), storage and handling, pretreatments, and instrumental analysis, specific care needs to be taken in order to reduce contamination levels at all steps. The effort to develop and utilize "clean techniques" in trace metal studies allows scientists to investigate trace metal distributions and chemical and biological behavior in greater details. This advancement also provides the required accuracy and precision of trace metal data allowing for environmental conditions to be related to trace metal concentrations in aquatic environments.
This protocol that is presented here details needed materials for sample preparation, sample collection, sample pretreatment including preconcentration, and instrumental analysis. By reducing contamination throughout all phases mentioned above for trace metal analysis, much lower detection limits and thus accuracy can be achieved. The effectiveness of "clean techniques" is further demonstrated using low field blanks and good recoveries for standard reference material. The data quality that can be obtained thus enables the assessment of trace metal distributions and their relationships to environmental parameters.

随着时代的发展和使用的"清洁技术"，现在清楚地认识到，为了获得在室温水域准确痕量金属浓度，水样品中的微量金属的富集是一种常见的做法。虽然在自然水域中的微量金属大部分的水质标准是在低微克/ L范围内，需要较低的检测限调查在空气中的含量在水生环境的痕量金属地球化学和生物效应。 与以下使用的"清洁技术"?...

Watch this Scientific Journal Video about Clean Sampling and Analysis of River and Estuarine Waters for Trace Metal Studies at JoVE.com

Clean Sampling and Analysis of River and Estuarine Waters for Trace Metal Studies

Special care using "clean techniques" is required to properly collect and process water samples for trace metal studies in aquatic environments. A protocol for sampling, processing, and analytical procedures with the aim of obtaining reliable environmental monitoring data and results with high sensitivity for detailed trace metal studies is presented.

清洁取样和痕量金属研究河和河口水域分析

Most of the trace metal concentrations in ambient waters obtained a few decades ago have been considered unreliable owing to the lack of contamination ...

clean-sampling-analysis-river-estuarine-waters-for-trace-metal

Research

JoVE Journal

Environment

11.3K 次观看.  National Sun Yat-sen University. Special care using "clean techniques" is required to properly collect and process water samples for trace metal studies in aquatic environments. A protocol for sampling, processing, and analytical procedures with the aim of obtaining reliable environmental monitoring data and results with high sensitivity for detailed trace metal studies is presented.

视频: Clean Sampling and Analysis of River and Estuarine Waters for Trace Metal Studies

Integrated Field Lysimetry and Porewater Sampling for Evaluation of Chemical Mobility in Soils and Established Vegetation

Potentially toxic chemicals are routinely applied to land to meet growing demands on waste management and food production, but the fate of these chemicals is often not well understood. Here we demonstrate an integrated field lysimetry and porewater sampling method for evaluating the mobility of chemicals applied to soils and established vegetation. Lysimeters, open columns made of metal or plastic, are driven into bareground or vegetated soils. Porewater samplers, which are commercially available and use vacuum to collect percolating soil water, are installed at predetermined depths within the lysimeters. At prearranged times following chemical application to experimental plots, porewater is collected, and lysimeters, containing soil and vegetation, are exhumed. By analyzing chemical concentrations in the lysimeter soil, vegetation, and porewater, downward leaching rates, soil retention capacities, and plant uptake for the chemical of interest may be quantified. Because field lysimetry and porewater sampling are conducted under natural environmental conditions and with minimal soil disturbance, derived results project real-case scenarios and provide valuable information for chemical management. As chemicals are increasingly applied to land worldwide, the described techniques may be utilized to determine whether applied chemicals pose adverse effects to human health or the environment.

Field lysimetry and porewater sampling allow researchers to evaluate the fate of chemicals applied to soils and established vegetation. The goal of this protocol is to demonstrate how to install required instrumentation and collect samples for chemical analysis during integrated field lysimetry and porewater sampling experiments.

综合外地Lysimetry和孔隙水采样的化学活动性土壤的评价和植被成立

Potentially toxic chemicals are routinely applied to land to meet growing demands on waste management and food production, but the fate of these chemicals ...

科研

环境科学

Soil Sampling and Isolation of Entomopathogenic Nematodes (Steinernematidae, Heterorhabditidae)

Entomopathogenic nematodes (a.k.a. EPN) represent a group of soil-inhabiting nematodes that parasitize a wide range of insects. These nematodes belong to two families: Steinernematidae and Heterorhabditidae. Until now, more than 70 species have been described in the Steinernematidae and there are about 20 species in the Heterorhabditidae. The nematodes have a mutualistic partnership with Enterobacteriaceae bacteria and together they act as a potent insecticidal complex that kills a wide range of insect species.
Herein, we focus on the most common techniques considered for collecting EPN from soil. The second part of this presentation focuses on the insect-baiting technique, a widely used approach for the isolation of EPN from soil samples, and the modified White trap technique which is used for the recovery of these nematodes from infected insects. These methods and techniques are key steps for the successful establishment of EPN cultures in the laboratory and also form the basis for other bioassays that consider these nematodes as model organisms for research in other biological disciplines. The techniques shown in this presentation correspond to those performed and/or designed by members of S. P. Stock laboratory as well as those described by various authors.

Soil Sampling and Isolation of Entomopathogenic Nematodes Steinernematidae, Heterorhabditidae

Entomopathogenic nematodes are soil-inhabiting roundworms that parasitize a wide range of insects. We demonstrate sampling methods used for the isolation of these nematodes from the soil using two techniques: the insect baiting and the modified White trap, for the recovery of nematodes from soil samples and infected insect cadavers, respectively.

土壤采样及昆虫病原线虫的分离（Steine​​rnematidae，异小）

Entomopathogenic nematodes (a.k.a. EPN) represent a group of soil-inhabiting nematodes that parasitize a wide range of insects. These nematodes belong to ...

A Whole Cell Bioreporter Approach to Assess Transport and Bioavailability of Organic Contaminants in Water Unsaturated Systems

Bioavailability of contaminants is a prerequisite for their effective biodegradation in soil. The average bulk concentration of a contaminant, however, is not an appropriate measure for its availability; bioavailability rather depends on the dynamic interplay of potential mass transfer (flux) of a compound to a microbial cell and the capacity of the latter to degrade the compound. In water-unsaturated parts of the soil, mycelia have been shown to overcome bioavailability limitations by actively transporting and mobilizing organic compounds over the range of centimeters. Whereas the extent of mycelia-based transport can be quantified easily by chemical means, verification of the contaminant-bioavailability to bacterial cells requires a biological method. Addressing this constraint, we chose the PAH fluorene (FLU) as a model compound and developed a water unsaturated model microcosm linking a spatially separated FLU point source and the FLU degrading bioreporter bacterium Burkholderia sartisoli RP037-mChe by a mycelial network of Pythium ultimum. Since the bioreporter expresses eGFP in response of the PAH flux to the cell, bacterial FLU exposure and degradation could be monitored directly in the microcosms via confocal laser scanning microscopy (CLSM). CLSM and image analyses revealed a significant increase of the eGFP expression in the presence of P. ultimum compared to controls without mycelia or FLU thus indicating FLU bioavailability to bacteria after mycelia-mediated transport. CLSM results were supported by chemical analyses in identical microcosms. The developed microcosm proved suitable to investigate contaminant bioavailability and to concomitantly visualize the involved bacteria-mycelial interactions.

A whole cell bioreporter assay with Burkholderia sartisoli RP037-mChe was developed to detect fractions of an organic contaminant (i.e., fluorene) available for bacterial degradation after active transport by mycelia bridging air-filled pores in a water unsaturated model system.

全细胞Bioreporter方法​​评估交通有机污染物的生物利用度和水饱和系统

Bioavailability of contaminants is a prerequisite for their effective biodegradation in soil. The average bulk concentration of a contaminant, however, is ...

Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions

We demonstrate a method for sectioning sediment cores and extracting pore waters while maintaining oxygen-free conditions. A simple, inexpensive system is built and can be transported to a temporary work space close to field sampling site(s) to facilitate rapid analysis. Cores are extruded into a portable glove bag, where they are sectioned and each 1-3 cm thick section (depending on core diameter) is sealed into 50 ml centrifuge tubes. Pore waters are separated with centrifugation outside of the glove bag and then returned to the glove bag for separation from the sediment. These extracted pore water samples can be analyzed immediately. Immediate analyses of redox sensitive species, such as sulfide, iron speciation, and arsenic speciation indicate that oxidation of pore waters is minimal; some samples show approximately 100% of the reduced species, e.g. 100% Fe(II) with no detectable Fe(III). Both sediment and pore water samples can be preserved to maintain chemical species for further analysis upon return to the laboratory.

A protocol for sectioning sediment cores and extracting pore waters under anoxic conditions in order to permit analysis of redox sensitive species in both solids and fluids is presented.

沉积物核心切片和孔隙水萃取缺氧条件下

We demonstrate a method for sectioning sediment cores and extracting pore waters while maintaining oxygen-free conditions. A simple, inexpensive system is ...

Modification and Application of a Leaf Blower-vac for Field Sampling of Arthropods

Rice fields host a large diversity of arthropods, but investigating their population dynamics and interactions is challenging. Here we describe the modification and application of a leaf blower-vac for suction sampling of arthropod populations in rice. When used in combination with an enclosure, application of this sampling device provides absolute estimates of the populations of arthropods as numbers per standardized sampling area. The sampling efficiency depends critically on the sampling duration. In a mature rice crop, a two-minute sampling in an enclosure of 0.13 m2 yields more than 90% of the arthropod population. The device also allows sampling of arthropods dwelling on the water surface or the soil in rice paddies, but it is not suitable for sampling fast flying insects, such as predatory Odonata or larger hymenopterous parasitoids. The modified blower-vac is simple to construct, and cheaper and easier to handle than traditional suction sampling devices, such as D-vac. The low cost makes the modified blower-vac also accessible to researchers in developing countries.

Assessment of arthropod abundance in crops is critical for investigating population dynamics and species interactions. Here we describe the modification and application of a leaf blower-vac for suction sampling of arthropods in rice.

修改和叶鼓风机-VAC的节肢动物领域采样中的应用

Rice fields host a large diversity of arthropods, but investigating their population dynamics and interactions is challenging. Here we describe the ...

Protocol for Microplastics Sampling on the Sea Surface and Sample Analysis

Microplastic pollution in the marine environment is a scientific topic that has received increasing attention over the last decade. The majority of scientific publications address microplastic pollution of the sea surface. The protocol below describes the methodology for sampling, sample preparation, separation and chemical identification of microplastic particles. A manta net fixed on an &#187;A frame&#171; attached to the side of the vessel was used for sampling. Microplastic particles caught in the cod end of the net were separated from samples by visual identification and use of stereomicroscopes. Particles were analyzed for their size using an image analysis program and for their chemical structure using ATR-FTIR and micro FTIR spectroscopy. The described protocol is in line with recommendations for microplastics monitoring published by the Marine Strategy Framework Directive (MSFD) Technical Subgroup on Marine Litter. This written protocol with video guide will support the work of researchers that deal with microplastics monitoring all over the world.

The protocol below describes the methodology for: microplastics sampling on the sea surface, separation of microplastic and chemical identification of particles. This protocol is in line with the recommendations for microplastics monitoring published by the MSFD Technical Subgroup on Marine Litter.

协议塑料微粒采样的海面和样品分析

Microplastic pollution in the marine environment is a scientific topic that has received increasing attention over the last decade. The majority of ...

Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.

Microplastics act as vector of potentially toxic organic contaminants with unpredictable effects. This protocol describes an alternative methodology for assessing the levels of organochlorine pesticides adsorbed on plastic pellets and identifying the polymer chemical structure. The focus is on pressurized fluid extraction and attenuated total reflectance Fourier transform infrared spectroscopy.

从塑料颗粒中提取有机氯农药和塑料类型分析

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment ...

Determination of Inorganic Arsenic in a Wide Range of Food Matrices using Hydride Generation - Atomic Absorption Spectrometry.

The European Food Safety Authority (EFSA) underlined in its Scientific Opinion on Arsenic in Food that in order to support a sound exposure assessment to inorganic arsenic through diet, information about distribution of arsenic species in various food types must be generated. A method, previously validated in a collaborative trial, has been applied to determine inorganic arsenic in a wide variety of food matrices, covering grains, mushrooms and food of marine origin (31 samples in total). The method is based on detection by flow injection-hydride generation-atomic absorption spectrometry of the iAs selectively extracted into chloroform after digestion of the proteins with concentrated HCl. The method is characterized by a limit of quantification of 10 &#181;g/kg dry weight, which allowed quantification of inorganic arsenic in a large amount of food matrices. Information is provided about performance scores given to results obtained with this method and which were reported by different laboratories in several proficiency tests. The percentage of satisfactory results obtained with the discussed method is higher than that of the results obtained with other analytical approaches.

The usefulness of an analytical method to determine inorganic arsenic in a wide range of food matrices is demonstrated. The method consists of selective extraction of inorganic arsenic into chloroform with a final determination by hydride generation-atomic absorption spectrometry.

用氢化物发生-原子吸收光谱法测定多种食品基质中的无机砷。

The European Food Safety Authority (EFSA) underlined in its Scientific Opinion on Arsenic in Food that in order to support a sound exposure assessment to ...

Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron (Oxy)Hydroxides, Trace Elements, and Bacteria

Fate and speciation of trace elements (TEs), such as arsenic (As) and mercury (Hg), in aquifers are closely related to physio-chemical conditions, such as redox potential (Eh) and pH, but also to microbial activities that can play a direct or indirect role on speciation and/or mobility. Indeed, some bacteria can directly oxidize As(III) to As(V) or reduce As(V) to As(III). Likewise, bacteria are strongly involved in Hg cycling, either through its methylation, forming the neurotoxin monomethyl mercury, or through its reduction to elemental Hg&#176;. The fates of both As and Hg are also strongly linked to soil or aquifer composition; indeed, As and Hg can bind to organic compounds or (oxy)hydroxides, which will influence their mobility. In turn, bacterial activities such as iron (oxy)hydroxide reduction or organic matter mineralization can indirectly influence As and Hg sequestration. The presence of sulfate/sulfide can also strongly impact these particular elements through the formation of complexes such as thio-arsenates with As or metacinnabar with Hg.
Consequently, many important questions have been raised on the fate and speciation of As and Hg in the environment and how to limit their toxicity. However, due to their reactivity towards aquifer components, it is difficult to clearly dissociate the biogeochemical processes that occur and their different impacts on the fate of these TE.
To do so, we developed an original, experimental, column setup that mimics an aquifer with As- or Hg-iron-oxide rich areas versus iron depleted areas, enabling a better understanding of TE biogeochemistry in anoxic conditions. The following protocol gives step by step instructions for the column set-up either for As or Hg, as well as an example with As under iron and sulfate reducing conditions.

Experimental Column Setup for Studying Anaerobic Biogeochemical Interactions Between Iron OxyHydroxides, Trace Elements, and Bacteria

Fate and speciation of arsenic and mercury in aquifers are closely related to physio-chemical conditions and microbial activity. Here, we present an original experimental column setup that mimics an aquifer and enables a better understanding of trace element biogeochemistry in anoxic conditions. Two examples are presented, combining geochemical and microbiological approaches.

用于研究铁 (氧) 氢氧化物、微量元素和细菌之间厌氧生物地球化学相互作用的实验柱装置

Fate and speciation of trace elements (TEs), such as arsenic (As) and mercury (Hg), in aquifers are closely related to physio-chemical conditions, such as ...

An Ultra-clean Multilayer Apparatus for Collecting Size Fractionated Marine Plankton and Suspended Particles

The distributions of many trace elements in the ocean are strongly associated with the growth, death, and re-mineralization of marine plankton and those of suspended/sinking particles. Here, we present an all plastic (Polypropylene and Polycarbonate), multi-layer filtration system for collection of suspended particulate matter (SPM) at sea. This ultra-clean sampling device has been designed and developed specifically for trace element studies. Meticulous selection of all non-metallic materials and utilization of an in-line flow-through procedure minimizes any possible metal contamination during sampling. This system has been successfully tested and tweaked for determining trace metals (e.g., Fe, Al, Mn, Cd, Cu, Ni) on particles of varying size in coastal and open ocean waters. Results from the South China Sea at the South East Asia Time-Series (SEATS) station indicate that diurnal variations and spatial distribution of plankton in the euphotic zone can be easily resolved and recognized. Chemical analysis of size-fractionated particles in surface waters of the Taiwan Strait suggests that the larger particles (&#62;153 &#181;m) were mostly biologically derived, while the smaller particles (10 - 63 &#181;m) were mostly composed of inorganic matter. Apart from Cd, the concentrations of metals (Fe, Al, Mn, Cu, Ni) decreased with increasing size.

Plankton and suspended particles play a major role in the biogeochemical cycles in the ocean. Here, we provide an ultra-clean, low stress method for the collection of various sizes of particles and plankton at sea with the capability of handling large volumes of seawater.

海洋浮游生物和悬浮颗粒的超洁净多层采集装置

The distributions of many trace elements in the ocean are strongly associated with the growth, death, and re-mineralization of marine plankton and those ...