YAKUTSK, March 2. /TASS/. Scientists found in the Yana River upper reaches in Yakutia’s north-east rare positive anomalies of the rare earth metals, recognized as man-made pollutants, leading expert of the Melnikov Permafrost Institute (the Russian Academy of Sciences’ Siberian Branch) Nikita Tananayev told TASS.
The studies in the hard-to-reach areas in the Yana’s upper reaches in Yakutia’s north-east were conducted in summer 2017. During that expedition, the hydrology scientists analyzed the water’s chemical structure, stable water isotopes and microelements, including rare earth elements (REE, a set of 17 metallic elements). The scientists completed the tests and were able to publish results and conclusions in an international magazine in early 2022 only.
"Having studied the chemical structure of the Verkhoyansk Ridge’s waters, we found rare geochemical anomalies in the upper reaches of the Dulgalakh River, a part of the Yana River," the scientist said. "We speak here about two rare earth metals - samarium and gadolinium, which demonstrate high positive anomalies that are not typical for natural conditions."
"The European Union over the recent decade has recognized both elements as significant man-made pollutants," he added.
Gadolinium is widely used in contrasts for magnetic resonance imaging, thus usually its anomalies are confined to the places of wastewater discharges from medical institutions. Samarium gets into the European natural waters with industrial effluents.
Noteworthy, the places, where the scientists sampled the waters, are hard-to-reach areas, and getting there is possible exclusively by a helicopter.
"Next to those areas there no big settlements, and the nearest settlement, Sebyan-Kuel [is located] 65 kilometers to the west," he continued. "There have never been industrial activities, though the nearby Endybalsk ore cluster, which is to the north-west, has been known and has been developed since the 18th century."
"We have confirmed that the contents of samarium in the Dulgalakh River is by three to dozens times higher than in the intensively exploited and contaminated Rhine River," the expert said, adding "the share of gadolinium is by 3-4 times higher than the element’s regular concentration in natural waters."
The accumulation of those elements in living organisms may hinder their growth and development, though any direct toxic influence requires much higher concentrations of those metals. The scientists look into three versions of the anomalies’ potential sources: atmospheric precipitation, man-made factors, and a local geochemical anomaly. "Anyway, we may learn the anomaly’s reasons only in further studies," the scientist said.
Ice thawing impact
The Yana River is formed at the confluence of the Dulgalakh and Sartang rivers. It flows into the Laptev Sea’s Yansky Bay. The river’s basin is 238,000 square kilometers. The Yana is 872 kilometers long. In terms of the basin size, the Yana River ranks fourth among Yakutia’s rivers and the 14th among Russia’s rivers. The Yana refers to rivers with the East Siberian type of water regime with elements of the Far Eastern regime in summer and autumn periods. The river receives water from snow and rain, and in summer seasons in its upper reaches it gains water from melting ice - unique natural objects in Russia’s North-East. During the studies, the scientists managed to see a certain influence of the ice on the chemical composition of water in the river.
In the continuing climate warming, huge masses of ice disappear in summer much earlier, which reflects not only higher air temperatures, but also a smaller amount of glaciation in river valleys. The scientists forecast that with the climate warming this trend will only develop. "This implies certain other changes in the watercourses’ chemical compositions, and the rivers will be absorbing deeper ground waters," he added.
The experts have proved that results of detailed chemical water tests may be used to find out exactly how water runs from the place of precipitation to the beds of big rivers.
Stressful environmental situation
Earlier, experts of the North-Eastern Federal University (NEFU) urged attention and handling of the gained ecology damage in environmentally unfriendly districts, which form the so-called Yana-Indigirka Impact Zone.
According to NEFU’s Institute of Applied Ecology of North, in the Arctic Ocean’s coastline area more than four million tonnes of industrial and construction waste have been accumulated. The Arctic nature would not be able to process this huge amount of waste even in centuries. The most devastating situations are in the Ust-Yanisky and Verkhoyansky Districts (Yakutia), where tailing dumps from the former Soviet industries remain potentially hazardous contaminating agents.
The development of placer diamond deposits has affected the Anabar River’s ecosystem, the scientists say. The experts have proven that in the diamond producing areas, fish contain higher concentrations of heavy metals. Those heavy metals flow into the Anabar, when the miners wash floodplain deposits.
Additionally, results of the institute’s studies have shown that zooplankton’s biomass in the river has shrunk by almost 19 times. The river’s spawning areas have also shrunk. Therefore, the populations of ryapushka, broad whitefish and whitefish have been endangered. At the same time, lamprey, grayling and pike are not to be found any longer in that water flow.