title: Assessment of sampling designs to measure riverine fluxes from the Pearl River Delta, China to the South China Sea.
abstract: The Pearl River Delta (PRD), located in South China and adjacent to the South China Sea, is comprised of a complicated hydrological system; therefore, it was a great challenge to sample adequately to measure fluxes of organic and inorganic materials to the coastal ocean. In this study, several sampling designs, including five-point (the number of sampling points along the river cross-section and three samples collected at the upper, middle, and bottom parts at each vertical line), three-point (at the middle and two other profiles), one-point (at the middle profile), and single-point (upper, middle, or bottom sub-sampling point at the middle profile) methods, were assessed using total organic carbon (TOC) and suspended particulate matter (SPM) as the measurables. Statistical analysis showed that the three- and five-point designs were consistent with one another for TOC measurements (p > 0.05). The three- and one-point sampling methods also yielded similar TOC results (95% of the differences within 10%). Single-point sampling yielded considerably larger errors than the three- and one-point designs, relative to the results from the five-point design, but sampling at the middle sub-point from the middle profile of a river achieved a relatively smaller error than sampling at the upper or bottom sub-point. Comparison of the sampling frequencies of 12 times a year, four times a year, and twice a year indicated that the frequency of twice a year was sufficient to acquire representative TOC data, but larger sample size and higher sampling frequency were deemed necessary to characterize SPM.
authors: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China.
authors: Hong-Gang
authors: HG
authors: Ni
authors: Feng-Hui
authors: FH
authors: Lu
authors: Xian-Lin
authors: XL
authors: Luo
authors: Hui-Yu
authors: HY
authors: Tian
authors: Ji-Zhong
authors: JZ
authors: Wang
authors: Yu-Feng
authors: YF
authors: Guan
authors: She-Jun
authors: SJ
authors: Chen
authors: Xiao-Jun
authors: XJ
authors: Luo
authors: Eddy Y
authors: EY
authors: Zeng
mesh_terms: D002244:Carbon / Q000032:analysis; D002681:China; D004784:Environmental Monitoring / Q000379:methods*; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis*; D052638:Particulate Matter / Q000032:analysis; D045483:Rivers; D014876:Water Pollution / Q000032:analysis / Q000517:prevention & control
chemical_list: D052638:Particulate Matter; D002244:Carbon