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.

Occurrence and mass loadings of n‐Alkanes in riverine runoff of the Pearl River Delta, South China: Global implications for levels and inputs

“…The sampling sites and procedures have been described in detail previously [9] and are detailed in the Supporting Information (). Therefore, only a brief description is presented here.…”

Environmental Characteristics of Polybrominated Diphenyl Ethers in Marine System, with Emphasis on Marine Organisms and Sediments

“…Since the hydrophobicity nature, PBDEs have very low water solubility [2], and only a little portion of the PBDEs exist in the water phase. Due to the lower concentrations and technical difficulty in measurement, to our knowledge, few papers have been published related with sea water [31, 32]. Here, main focuses were set on the sediment and biota matrixes.…”

Impact of anthropogenic activities on urban stream water quality: a case study in Guangzhou, China

“…Sampling was conducted on December 24, 2010, May 24, 2011, and August 28, 2011, representative of the low-, normal-, and high-flow periods, respectively, during neap tides and approximately 1 h before the intra-day low tides to avoid tidal influences (Ni et al 2008). Water was taken from 0.5 m below the air-water surface, middle of the water column, and 0.5 m above the sediment bed, with a stainless-steel submersible pump to constitute one composite sample.…”