Selected Whole-Rock and Sediment Geochemistry Reanalysis Data Additions to the Alaska Geochemical DataBase (AGDB) from Archived Samples, Alaska

This data release contains elemental concentration data from the reanalysis of 13,930 archived stream-sediment sample and associated stream sediment reference material and 968 archived rock samples and associated rock reference material. All archived material was from samples that were collected in Alaska. Samples were retrieved from the USGS Mineral Program's sample archive in Denver, CO. Sample processing consisted of splitting the appropriate aliquot for the requested analyses. Sample splitting was performed in the USGS Mineral Program's sample prep facilities. 13,800 samples were analyzed using a multi-element analytical method involving decomposition of the sample by sodium peroxide and elemental analysis by inductively coupled plasma-optical emission spectroscopy (ICP-AES) or inductively coupled plasma-mass spectroscopy (ICP-MS) depending on the element. A suffix AES_ST or MS_ST is used in column headers to indicate analysis by this method. Additionally, some samples were also analyzed by one of two other multi-element methods. 4864 samples were analyzed by a multi-element method in which a mixture of nitric acid (HNO3) and hydrochloric acid (HCl) was used to decompose the sample. This digestion method it commonly referred to as an Aqua Regia (AR) digestion and is considered a less aggressive digestion than a sinter digestion. Elemental analyzed was by ICP-MS. A suffix MS_AR_P column headers indicates analysis by this method. 118 samples were analyzed by a multi-element method using a mixture of hydrochloric, nitric, perchloric, and hydrofluoric acids to decompose the sample. Elemental analysis was done by ICP-AES or ICP-MS depending on the element. The suffix AES_HF or MS_HF indicates analysis by this mix-acid method. 130 stream sediment samples were analyzed only for the mercury. For these samples mercury concentrations were determined by cold-vapor atomic absorption spectrometry following sample digestion by a mixture of sulfuric and nitric acids, and dilute potassium permanganate and potassium persulfate. The suffix AA_CV indicates analysis by this method. All rock samples (968) were analyzed by the method using the sodium peroxide sample digestion described above. As with the stream sediment samples a suffix AES_ST or MS_ST is used in column headers in the rock sample dataset to indicate analysis by this method. 490 rock samples were also analyzed by the aqua-regia method. A suffix MS_AR_P column headers indicates analysis by this method. 478 samples were analyzed by a multi-element method in which the sample is decomposed using a lithium metaborate fusion and analysis by ICP-AES. A suffix AES_Fuse indicates analysis by this method. All analyses were performed between 2019 to 2023 by AGAT laboratories. AGAT was the USGS contract laboratory during the period of analysis.

本次发布的数据包含13930份存档河流沉积物样品及其配套沉积物标准物质、968份存档岩石样品及其配套岩石标准物质的再分析元素浓度数据。所有存档样品均采自阿拉斯加州，从位于科罗拉多州丹佛市的美国地质调查局（USGS）矿产项目样品库中调取。

样品处理流程为：根据分析需求分取对应试样，分样操作在美国地质调查局矿产项目样品制备实验室完成。其中13800份样品采用多元素分析方法检测：先通过过氧化钠对样品进行消解，再根据待测元素类型，分别采用电感耦合等离子体光发射光谱法（ICP-AES）或电感耦合等离子体质谱法（ICP-MS）进行元素分析，列标题中以后缀AES_ST或MS_ST标注该类分析方法。

另有部分样品采用另外两种多元素分析方法之一完成检测：4864份样品采用王水（Aqua Regia, AR）消解法——即以硝酸（HNO₃）与盐酸（HCl）混合溶液进行样品消解，该消解方式相较于烧结消解法更为温和——随后通过ICP-MS完成元素分析，列标题中以后缀MS_AR_P标注该类分析方法。118份样品采用盐酸、硝酸、高氯酸与氢氟酸组成的混合酸体系进行样品消解，再根据待测元素类型采用ICP-AES或ICP-MS完成元素分析，列标题中以后缀AES_HF或MS_HF标注该混合酸消解方法。

另有130份河流沉积物样品仅针对汞元素开展检测：此类样品经硫酸与硝酸混合溶液消解后，采用冷蒸气原子吸收光谱法测定汞浓度，列标题中以后缀AA_CV标注该分析方法。

全部968份岩石样品均采用前述过氧化钠消解方法完成分析，岩石样品数据集的列标题同样以AES_ST或MS_ST后缀标注该类分析方法。其中490份岩石样品额外采用王水消解法检测，列标题以MS_AR_P标注；另有478份岩石样品采用偏硼酸锂熔融法进行样品分解，随后通过ICP-AES完成分析，列标题以AES_Fuse标注该类分析方法。

所有分析工作均于2019年至2023年间由AGAT实验室完成，该实验室为分析期间美国地质调查局的合同合作实验室。