Peculiarities of the eutrophication of the Amur Bay (Japan Sea) by Razdolnaya River

Abstract

<jats:p>Data on dissolved organic concentration (DOC) and concentration of nutrients (phosphorus, silicon, and nitrogen of ammonium, nitrite and nitrate) in the Razdolnaya/Suifen River water are presented. The samples were collected fortnightly, as a rule, during more than a year (2013–2014). The nutrients concentration decreased and DOC and humic substances concentration increased with the river run-off increasing. In conditions of monsoon climate, the nutrients discharge from the Razdolnaya/Suifen into the Amur Bay had great pulsations that promoted sometimes producing of «excessive» phytoplankton biomass in the bay and provided a background for hypoxia at the bottom. Natural terrestrial fluxes of nutrients and DOC into the bay are much higher than these substances supply with waste waters of Vladivostok City. Interannual variability of the nutrients and dissolved organics fluxes into the Amur Bay is traced. Tendency to their increasing is supposed since 2003 because of the Razdolnaya/Suifen River annual discharge increasing observed by Hydrometeorological Agency in 2003–2017.</jats:p>

Acidification and Deoxygenation of the Northwestern Japan/East Sea

“…During the survey, severe hypoxia was found in the bottom waters [18]. There are nutrient and discharge data available for the Razdolnaya and Tumannaya Rivers [15,19] (Primorskiy Administration of Russian Hydrometeorological Service (https://gmvo.skniivh.ru/index.php?id1/41 (Data were accessed on 1 July 2018). These data made it possible to assess the temporal trend of annual nutrient fluxes into Amursky Bay and the JES in 2003-2017. In the open sea, since 1999, quite intensive fieldwork has been completed through international collaboration, including more than 20 cruises undertaking hydrochemical surveys of the northwestern part of the JES in different seasons.…”

“…variability in the pHin situ of the bottom waters of Amursky Bay caused by eutrophication (Figure 5b). Daily nutrient fluxes, Ji, were estimated from the available concentrations of nutrients in the river waters, Ci [15,19], and available water discharges, R Q , of the Razdolnaya River using the following equation:…”

“…All statistical tests were performed using the statistical software Microsoft Excel, Moscow, Russia. A regres- Daily nutrient fluxes, J i , were estimated from the available concentrations of nutrients in the river waters, C i [15,19], and available water discharges, Q R , of the Razdolnaya River using the following equation:…”