LONG-TERM VARIABILITY OF THE ION RUNOFF OF LARGE RIVERS IN THE ARCTIC ZONE OF RUSSIA

Studies of river ion runoff and its temporal variability are important. It affects coastal waters and is interrelated with climatic changes in the Arctic region. Long-term data on the chemical runoff of macrocomponents (chlorides, sulfates, hydrocarbonates, calcium and magnesium ions) at the outlet sections of large Arctic rivers in Russia - Pechora, Usa, Yenisei, Ob, Pur, Taz, Lena, Yana and Kolyma are given. The values of volumes and modules of chemical runoff were calculated on the basis of long-term (1980-2018) hydrological and hydrochemical information from the state observation system of Roshydrom-et. It is shown that the change in the absolute values of the chemical runoff is consistent with the water inflow. Greatest contribution to the ionic runoff is made by hydrocarbonates. The intra-annual change in the water inflow and the macrocomponents runoff occurs synchronously. There is a decisive role of water runoff in the formation of chemical runoff from the catchments of large Arctic rivers. Comparison of the chemical runoff modulus indicator made it possible to classify them into low, medium or high ionic runoff rivers. It was found that the maximum runoff of macrocomponents occurs from the catchment of the Usa river. It is may be due to active processes of chemical denudation and climate change.

The impact of forest fires on the rivers of the Zaigraevskiy district in the Republic of Buryatia

Forest fires significantly influence hydrological and hydrochemical regimes of rivers. Based on forest fire statistics and characteristics of river networks, areas for monitoring of river conditions were selected in the Zaigraevskiy district of the Republic of Buryatia. An inverse correlation between precipitation levels and numbers of fires was identified. During 2012, abnormal water levels and flows in the Bryanka river were related to the challenging forest fire situation in the previous year. Finally, macro- and micro-component analyses of water showed that chemical runoff into the rivers increases with pyrogenic damage to water catchment areas.

SUBSURFACE CHEMICAL DISCHARGE IN LITHUANIAN AREA

An assessment of groundwater chemical leakage under the Lithuanian hydrogeological conditions, using the classic method of hydrogeological/ hydrograph division and linking it with the chemical leakage. Subsurface chemical discharge is the amount of salts flown by the rivers due to their draining impact on the subsurface. The chemical runoff is determined by two key factors: groundwater runoff yield and total content of dissolved solids (TDS). The value of the groundwater runoff module (the yield from 1 km2) in the river basins of Lithuania ranges from 0.4 to 5.0 l/s km2. TDS values in shallow groundwater drained by the rivers range from 180 to 800 mg/l. The modules of subsurface chemical runoff in the area of Lithuania range from 3–9 to 54 t/year from 1 km2 with the highest values observed in the Baltija uplands and Dainava Plain. During the last decade, the chemical runoff has stabilised due to decline in technogenic load. If compared to the dissolved solids drained by the rivers the subsurface chemical discharge can make up 7–45%. The chemical runoff out for all area of Lithuania, as assessed by the hydrological/hydrogeological technique according to the minimum long‐term runoff and TDS content in the river water of that period, reaches 2.2 mln. t/year of mineral material, about 90% of which come from the Nemunas River basin. To restrict the influence of technogenic pollution on the results of the assessment of underground chemical runoff, only observations done upstream the pollution sources (mainly urban) have been used. The qualitative assessment of the changes in groundwater chemical discharge and flow fluctuations due to technogenic impact has been carried out by applying graphical analysis of the underground chemical runoff module. Santrauka Darbo tikslas – ivertinti požemini chemini nuoteki Lietuvos hidrogeologinemis salygomis, taikant klasikine hidrologohidrogeologine hidrografo skaidymo metodika. Požeminis cheminis nuotekis – tai drusku kiekis, nutekantis upemis del drenažinio poveikio. Chemini nuoteki lemia du pagrindiniai veiksniai – požeminio nuotekio debitas ir vandens bendroji mineralizacija. Požeminio nuotekio modulio dydis (debitas iš 1 km2) Lietuvos teritorijos upiu baseinuose kinta nuo 0,4 iki 5,0 l/s km2. I upes požemiu nutekančio gruntinio vandens bendroji mineralizacija – nuo 180 iki 800 mg/l. Požeminio cheminio nuotekio Lietuvos teritorijoje moduliai yra nuo 3–9 iki 54 t/metus iš 1 km2. Didžiausias požeminis cheminis nuotekis Baltijos aukštumose bei Dainavos lygumoje. Pastaraji dešimtmeti cheminis nuotekis stabilizavosi del sumažejusios technogenines apkrovos. Palyginti su bendru mineraliniu medžiagu kiekiu, nutekančiu upemis, požeminis cheminis nuotekis gali sudaryti 7–45 %. Visas požeminis cheminis nuotekis Lietuvos teritorijoje, ivertintas pagal minimalu daugiameti nuoteki ir to periodo upiu vandens mineralizacija, siekia 2,2 mln. t/metus mineraliniu medžiagu, kuriu apie 90 % išplukdoma iš Nemuno baseino. Technogeninio užterštumo itakai požeminio cheminio nuotekio vertinimo rezultatams riboti naudoti tik stebejimu duomenys aukščiau taršos šaltiniu (daugiausia miestu). Požeminio vandens cheminio nuotekio, kuri lemia technogeninis poveikis, pokyčiu kokybinis ivertinimas atliktas nuotekio moduliu grafoanalizes pagrindu. Резюме Целью работы было оценить подземный химический сток с использованием расчленения гидрографа рек и выноса химического материала в гидрогеологических условиях Литвы. Подземный химический сток – это количество солей, протекающих в речных водах из-за их дренажного воздействия. Химический сток зависит от двух основных факторов: дебита подземного стока и общей минерализации воды. Модуль подземного стока (дебит с 1 км2 ) речных бассейнов в пределах Литвы меняется от 0,4 до 5,0 л/с с 1 км2 . Общая минерализация грунтовых вод, притекающих в реки, составляет 180–800 мг/л. Модули подземного химического стока в пределах территории Литвы имеют значения от 3–9 до 54 т/год с 1 км2 . Наибольший подземный химический сток наблюдается на терригории Балтийских высот и Дайнавской равнины. В последнее десятилетие химический сток стал более стабильным из-за уменьшающейся техногенной нагрузки. По сравнению с общим стоком минеральных веществ в реках подземный химический сток может составляет 7–45%. Весь подземный химический сток, оцененный по минимальному многолетнему стоку и минерализации речной воды, составляет 2,2 млн. т/год минерального вещества, из которого 90% поступает из бассейна р. Нямунас. Для уменьшения техногенного воздействия на результаты расчетов использованы данные химического состава воды только с постов наблюдения, расположенных выше источников загрязнения. Оценка изменения подземного химического стока выполнена графоаналитически с использованием изменения его модуля во времени.