Hydrochemical data, Nyong, Cameroon.

This data set contains the data related to chemical composition of water for all monitored sites: major ion concentrations (Na+, K+, Ca2+, Mg2+, NO3−, SO42−, F−, Cl−, HCO3−, Si; µmol/L), total alkalinity (Alk; µeq/L), dissolved organic carbon (DOC; mg/L), suspended particulate matter (SPM; mg/L), electrical conductivity (EC; µS/cm), pH, water temperature (WT; °C). The timeframes available are as follows: since 1994 for the Nsimi SEW outlet and since 1998 for the large river sites (Messam, Pont So’o, Mbalmayo and Olama). Additionally, major ion concentrations are available for 6 piezometers (BFP, BFS, FRP, FSP, F1, F3) in the Nsimi SEW from 2002 to 2007 for BFP, BFS, FRP, F3 and from 2002 to 2005 for F1 and FSP.

Methods: Water samples from streams (Nsimi SEW, Awout, So’o) and river (Nyong) are collected manually with a fortnightly frequency. Each water sample is filtered (cellulose acetate membrane, pore size of 0.22-μm) on site and split into two aliquots and stored in polypropylene bottles. The first aliquot (acidified) is dedicated to the determination of major cation concentrations (Na+, K+, Ca2+, Mg2+) and the second aliquot (non-acidified) to the determination of anion concentration (NO3−, SO42−, F−, Cl−). Alkalinity (i.e. HCO3−) is obtained by acid titration and using the Gran method. Suspended Particulate Matter (SPM) concentrations are determined after the filtration of a known water volume on 0.7-µm glass-fiber membrane. Dissolved Organic Carbon (DOC) concentrations are determined using the water filtered through the glass-fiber membrane. Blanks are less than 0.1 ppm for DOC. Cation and anion concentrations and alkalinity are measured in the Laboratory of Geochemical Analysis of Water (LAGE), an analytical facility of the IRGM (Institut de Recherches Géologiques et Minières) in Yaounde, Cameroon. Silica and DOC concentrations are analyzed at GET (Géosciences Environnement Toulouse) laboratory in France. The accuracy of the sample analyses is verified by jointly analyzing certified reference waters such as PERADE20 (mostly DOC, Si), ION 915 and SUPER-05 (low concentrations), ION 96.4 (high concentrations) and Anions WS (anions, including PO4). Additionally, inter-calibration campaigns are carried out between the LAGE and the GET to ensure optimal analytical quality. They consist of the analysis of international standards and of the replication of analysis on common samples.

本数据集涵盖所有监测点位的水体化学成分相关数据，包括主要离子浓度（Na+、K+、Ca2+、Mg2+、NO3−、SO42−、F−、Cl−、HCO3−、Si；单位：μmol/L）、总碱度（Alkalinity, Alk；单位：μeq/L）、溶解性有机碳（Dissolved Organic Carbon, DOC；单位：mg/L）、悬浮颗粒物（Suspended Particulate Matter, SPM；单位：mg/L）、电导率（Electrical Conductivity, EC；单位：μS/cm）、pH值以及水温（Water Temperature, WT；单位：℃）。可用监测时段如下：Nsimi SEW排污口的监测数据始于1994年，大型河流点位（Messam、Pont So’o、Mbalmayo及Olama）的监测数据始于1998年。此外，Nsimi SEW区域内的6个测压管（BFP、BFS、FRP、FSP、F1、F3）拥有主要离子浓度数据，其中BFP、BFS、FRP、F3的监测时段为2002年至2007年，F1与FSP的监测时段为2002年至2005年。实验方法：对溪流（Nsimi SEW、Awout、So’o）及尼永河（Nyong）的水样采用人工采集方式，采样频率为每两周一次。每份水样现场经醋酸纤维素膜（孔径0.22μm）过滤后，被分为两份子样品并储存在聚丙烯瓶中。其中经酸化处理的第一份子样品用于测定主要阳离子浓度（Na+、K+、Ca2+、Mg2+），未酸化的第二份子样品用于测定阴离子浓度（NO3−、SO42−、F−、Cl−）。总碱度（即HCO3−）通过酸滴定法结合Gran法测定。悬浮颗粒物（Suspended Particulate Matter, SPM）浓度通过将已知体积的水样经0.7μm玻璃纤维膜过滤后测得。溶解性有机碳（Dissolved Organic Carbon, DOC）浓度则通过经玻璃纤维膜过滤后的水样测定，其空白值低于0.1 ppm。阳离子、阴离子浓度及总碱度的测定工作在喀麦隆雅温得的地质与矿产研究所（Institut de Recherches Géologiques et Minières, IRGM）下属的水地球化学分析实验室（Laboratory of Geochemical Analysis of Water, LAGE）完成。二氧化硅与DOC浓度的分析工作在法国图卢兹环境地球科学实验室（Géosciences Environnement Toulouse, GET）进行。样品分析的准确性通过同步分析有证标准水样进行验证，涵盖PERADE20（主要用于DOC、Si的测定）、ION 915与SUPER-05（低浓度标准）、ION 96.4（高浓度标准）以及Anions WS（阴离子类标准，含PO4）。此外，为确保最优分析质量，LAGE与GET之间开展了跨实验室校准工作，内容包括国际标准物质分析以及共用样品的重复测定。