Total Dissolved Nitrogen and Ammonia Data for the East River Watershed, Colorado (2015-2022)

This data package contains mean values for total dissolved nitrogen (TDN) and ammonia concentrations for water samples taken from the East River Watershed in Colorado. The East River is part of the Watershed Function Scientific Focus Area (WFSFA) located in the Upper Colorado River Basin, United States. TDN was analyzed using a Shimadzu Total Nitrogen Module (TNM-1) combined with the TOC-VCSH analyzer (Shimadzu Corporation, Japan). TNM-1 is a non-specific measurement of total nitrogen (TN). All nitrogen species in samples are combusted to nitrogen monoxide and nitrogen dioxide, then reacted with ozone to form an excited state of nitrogen dioxide. Upon returning to ground state, light energy is emitted. Then, TDN is measured using a chemiluminescence detector. Ammonia was determined using a Lachat's QuikChem 8500 Series 2 Flow Injection Analysis System (LACHAT Instruments, QuckChem 8500 series 2, Automated Ion Analyzer, Loveland, Colorado). When ammonia in water samples is heated (60 degrees C) with salicylate and hypochlorite in an alkaline phosphate buffer, an emerald green color is produced which is proportional to the ammonia concentration. The color is intensified by the addition of nitroprusside. Ethylenediaminetetraacetic acid (EDTA) is added to the buffer to prevent the interference of metal ions (Ca, Mg, and Fe etc.). Ammonia-N is then determined by LACHAT flow injection and a colorimetric assay at an absorbance wavelength 660 nm. (Reference: LACHAT Instruments: QuickChem Method 90-107-06-3-A, Determination of Ammonia by Flow Injection Analysis (High Throughput, Salicylate Method/DCIC) (Multi Matrix method). Written by Lynn Egan (Application group), February 08, 2011.) All files are labeled by location and variable, and data reported are the mean values upon replicate measurements. All samples were analyzed under a rigorous quality assurance and quality control (QA/QC) process as detailed in the methods. This data package contains (1) a zip file (tdn_ammonia_data_2015-2022.zip) containing a total of 224 data files of ammonia and TDN data from across the Lawrence Berkeley National Laboratory (LBNL) Watershed Function Scientific Focus Area (SFA) which is reported in .csv files per location; (2) a file-level metadata (flmd.csv) file that lists each file contained in the dataset with associated metadata; and (3) a data dictionary (dd.csv) file that contains terms/column_headers used throughout the files along with a definition, units, and data type. Update 10/07/2020: Updated the data files to remove times from the timestamps, so that only dates remain. The data values have not changed. Update 4/11/2021: Added Determination of Method Detection Limits (MDLs) for DIC, NPOC and TDN Analyses and Determination of Method Detection Limit for Ammonia and the Interferences by LACHAT Flow Injection Analysis documents, which can be accessed as PDFs or with Microsoft Word.Update on 6/10/2022: versioned updates to this dataset was made along with these changes: (1) updated total dissolved nitrogen and ammonia data for all locations up to 2021-12-31, (2) removal of units from column headers in datafiles, (3) added row underneath headers to contain units of variables, (4) restructure of units to comply with CSV reporting format requirements, (5) added -9999 for empty numerical cells, and (6) the addition of the file-level metadata (flmd.csv) and data dictionary (dd.csv) were added to comply with the File-Level Metadata Reporting Format. Update on 2022-09-09: Updates were made to reporting format specific files (file-level metadata and data dictionary) to correct swapped file names, add additional details on metadata descriptions on both files, add a header_row column to enable parsing, and add version number and date to file names (v2_20220909_flmd.csv and v2_20220909_dd.csv). Update on 2022-12-20: Updates were made to both the data files and reporting format specific files. Units were listed incorrectly, but have been fixed to reflect correct units (ug/L). File level metadata (flmd) and data dictionary (dd) files were updated to reflect the updated versions of these files. Available data was added up until 2022-06-01.

本数据包包含取自美国科罗拉多州东河流域（East River Watershed）的水样的总溶解氮（total dissolved nitrogen, TDN）与氨浓度均值。东河隶属于美国科罗拉多河上游流域的流域功能科学重点区（Watershed Function Scientific Focus Area, WFSFA）。

总溶解氮采用日本岛津（Shimadzu Corporation）生产的总氮模块（Total Nitrogen Module, TNM-1）与TOC-VCSH总有机碳分析仪联用进行分析。TNM-1为总氮（total nitrogen, TN）的非特异性检测方法：将样品中所有形态的氮燃烧生成一氧化氮与二氧化氮，随后与臭氧反应生成激发态二氧化氮；当其返回基态时会释放光能，最终通过化学发光检测器完成总溶解氮的定量。

氨浓度采用科罗拉多州洛夫兰市LACHAT仪器公司生产的QuikChem 8500 Series 2流动注射分析系统（自动化离子分析仪）进行测定。具体原理为：在碱性磷酸盐缓冲体系中，将水样与水杨酸盐、次氯酸盐于60℃下加热反应，生成与氨浓度成正比的翠绿色络合物；添加硝普钠可增强显色效果，同时向缓冲液中加入乙二胺四乙酸（Ethylenediaminetetraacetic acid, EDTA）以消除钙、镁、铁等金属离子的干扰。最终通过LACHAT流动注射系统结合660nm波长下的比色法完成氨氮（Ammonia-N）的定量检测。[参考文献：LACHAT仪器公司：QuikChem方法90-107-06-3-A，《流动注射分析法测定氨（高通量水杨酸盐法/DCIC）（多基质方法）》，应用组Lynn Egan编写，2011年2月8日]

所有文件均按采样点位与检测变量命名，所报告的数据为重复测量后的均值。所有样品均按照本方法中详述的严格质量保证与质量控制（QA/QC）流程完成分析。

本数据包包含以下内容：(1) 压缩包tdn_ammonia_data_2015-2022.zip，内含224个按采样点位分类的CSV格式数据文件，涵盖劳伦斯伯克利国家实验室（Lawrence Berkeley National Laboratory, LBNL）流域功能科学重点区（SFA）全域的氨与总溶解氮检测数据；(2) 文件级元数据文件flmd.csv，用于列出数据集内所有文件及其关联元数据；(3) 数据字典文件dd.csv，包含所有数据文件中使用的术语/列标题，以及对应的定义、单位与数据类型。

2020年10月7日更新：对数据文件进行更新，移除时间戳中的时间信息，仅保留日期，数据数值未发生变更。
2021年4月11日更新：新增LACHAT流动注射分析法的检测方法检出限（Method Detection Limits, MDLs）测定文档，涵盖溶解无机碳（Dissolved Inorganic Carbon, DIC）、非吹扫性有机碳（Non-Purgeable Organic Carbon, NPOC）与总溶解氮（TDN）分析，以及氨检测与干扰因素测定相关内容，文档可通过PDF或Microsoft Word格式获取。
2022年6月10日更新：对本数据集进行版本化更新，具体变更如下：(1) 更新所有采样点位截至2021年12月31日的总溶解氮与氨浓度数据；(2) 移除数据文件列标题中的单位信息；(3) 在列标题下方新增一行，用于标注各变量的单位；(4) 调整单位格式，以符合CSV报告格式要求；(5) 为数值型空单元格赋值为-9999；(6) 新增文件级元数据文件flmd.csv与数据字典文件dd.csv，以符合文件级元数据报告格式规范。
2022年9月9日更新：对报告格式专用文件（文件级元数据与数据字典）进行更新，修正了互换的文件名，为两个文件的元数据描述补充更多细节，新增header_row列以支持数据解析，并在文件名中添加版本号与日期（即v2_20220909_flmd.csv与v2_20220909_dd.csv）。
2022年12月20日更新：对数据文件与报告格式专用文件均进行了更新。此前单位标注存在错误，现已修正为正确的单位（微克每升，ug/L）；更新了文件级元数据（flmd）与数据字典（dd）文件，以反映其最新版本；新增截至2022年6月1日的可用检测数据。