Comprehensive Water Quality Assessment

The air temperature, water temperature and conductivity were measured on-site using a portable EC/TDS TEMP Waterproof Combo Meter (C-100, HM Digital Inc., Culver City, CA, USA). The pH was measured using a portable Eutech pH700 meter (Thermo Fisher Scientific Inc., Waltham, MA, USA). One hundred ml of water sample in triplicate was filtered using glass fiber filters (Millipore, St. Louis, MO, USA); Chlorophyll a (Chl a) was extracted using 90% acetone and measured by spectrophotometry following the method of American Public Health Association (APHA, 2005 ). The samples for nutrient analysis were stored at −20°C soon after arrival to the lab and the parameters such as total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NO₃-N), nitrite nitrogen (NO₂-N), ammonium nitrogen (NH₄-N), phosphate (PO₄-P), and total organic carbon (TOC) were measured as reported in our earlier studies (Vadde et al., 2018 (link); Yuan et al., 2019 (link)). All the values of physico-chemical parameters were compared to the class III water quality standards set by the Chinese Ministry of Environmental Protection (now called as Ministry of Ecology and Environment, People’s Republic of China) (MEP, 2002 ) and correlated with the results of ARGs.