Institute of Engineering, Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, F-38000, Grenoble, France.
CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam.
Environ Sci Pollut Res Int. 2022 Jan;29(3):4076-4092. doi: 10.1007/s11356-021-15850-x. Epub 2021 Aug 16.
The spatiotemporal variation of phytoplankton and their relationship with environmental variables were analyzed in the Saigon River-a tropical river in Southern Vietnam. Two longitudinal profiles were conducted during dry and rainy season at 18 sampling sites covering more than 60 km long in the river. Besides, a bi-weekly monitoring conducted in the upstream, urban area (Ho Chi Minh City-HCMC), and downstream of Saigon River was organized from December 2016 to November 2017. The major phytoplankton were diatoms (e.g., Cyclotella cf. meneghiniana, Leptocylindrus danicus, Aulacoseira granulata), cyanobacteria (Microcystis spp., Raphidiopsis raciborskii, Pseudanabaena sp.), and euglenoids (Trachelomonas volvocina). Commonly freshwater phytoplankton species and sometimes brackish water species were dominant during the monitoring. Phytoplankton abundances in dry season were much higher than in rainy season (>100 times) which was explained by a shorter riverine water residence time and higher flushing capacity during the dry season. There was a clear separation of phytoplankton abundance between the urban area and the remaining area of Saigon River because of polluted urban emissions of HCMC. Redundancy analysis shows that the environmental variables (TOC, nitrogen, pH, salinity, Mo, Mn) were the driving factors related to the dominance of L. danicus and Cyclotella cf. meneghiniana in the upstream river and urban section of Saigon River. The dominance of cyanobacterium Microcystis spp. in the downstream of Saigon River was related to higher salinity, Mg, Cu concentrations, and lower concentrations of nutrients, Mn, Co, and Mo. The dominance of potentially toxic cyanobacteria in Saigon River possesses health risk to local residents especially upon the increasing temperature context and nutrient loading into the river in the next decades.
对越南南部西贡河——一条热带河流中的浮游植物时空变化及其与环境变量的关系进行了分析。在旱季和雨季，在河流 60 多公里长的 18 个采样点进行了两条纵向剖面测量。此外，从 2016 年 12 月至 2017 年 11 月，在西贡河的上游、市区（胡志明市）和下游组织了每两周一次的监测。主要浮游植物为硅藻（如 Cyclotella cf. meneghiniana、Leptocylindrus danicus、Aulacoseira granulata）、蓝藻（微囊藻属、Raphidiopsis raciborskii、Pseudanabaena sp.）和眼虫（Trachelomonas volvocina）。在监测期间，常见的淡水浮游植物物种有时是半咸水物种占优势。旱季浮游植物丰度比雨季高得多（高出 100 倍），这是由于旱季河流停留时间短，冲刷能力高所致。由于胡志明市的城市污染排放，市区和西贡河其余地区的浮游植物丰度有明显差异。冗余分析表明，环境变量（TOC、氮、pH、盐度、钼、锰）是与 L. danicus 和 Cyclotella cf. meneghiniana 在西贡河上游和市区占优势相关的驱动因素。下游微囊藻属在西贡河占优势与较高的盐度、Mg、Cu 浓度以及较低的营养物质 Mn、Co 和 Mo 浓度有关。在未来几十年，随着温度升高和营养物质进入河流，西贡河中潜在毒性蓝藻的优势可能对当地居民的健康构成风险。
