Hydrogeochemical characteristics of classical karst regions in Slovenia

MIAO Ying; ZHANG Cheng; Mitja Prelovsek; XIAO Qiong

doi:10.11932/karst20250305

Abstract：Groundwater plays an important role in supplying drinking water,as well as supporting industrial and agricultural activities worldwide,especially in karst regions.Due to the unique spatial distribution of soil and water resources in these areas-where soil lies above and water below-groundwater is particularly vulnerable to water quality degradation and flood-related environmental issues.Slovenia is an important country along the Belt and Road route and is also recognized as the birthplace of karst research.Karst groundwater serves as a vital resource for both the livelihoods and agricultural production in the karst regions of Slovenia.Covering more than half of the country's territory,these karst regions are characterized by vast land and sparse population,making karst groundwater one of the most critical natural resources for its national economic development.The main environmental problems in Slovenia include water security,imbalanced spatial and temporal distribution of water resources,and flooding.Hence,it is of great significance to investigate the situation of karst groundwater in Slovenia. Under the exemplary role of the Belt and Road Initiative,this study is supported by the China-Slovenia Belt and Road Joint Laboratory Project on Karst Geology(currently in preparation)within BRI framework.It involves field investigations and sampling conducted in collaboration with the Karst Institute of Slovenia.The objectives are to elucidate the processes and patterns of the Dinaric karstification and its cycles of carbon,water and calcium,analyze the formation and distribution background of this karst system,and compare it with the subtropical karst system in China.The findings are expected to be applicable to other karst regions along the Belt and Road route,enhancing China's understanding to key resource and environmental challenges in these areas.This study will provide background information on geology,geomorphology,resources,and environment to national authorities for formulating subsequent development strategies,thereby contributing to national diplomacy concerning the environment and resources. In this study,karst geological investigations and sampling were carried out in the Postojna karst basin in Slovenia,obtaining hydrochemical and isotopic data of karst groundwater in this country.Preliminarily analysis and research are currently underway.The results show as follows. (1)The quality of karst groundwater in Slovenia is excellent,with groundwater remaining in its natural state.Parameters such as water temperature,pH,conductivity,and concentrations of anion and cation remain stable within fixed ranges throughout the year.Fluctuations,when they occur,are mostly affected by natural environment variations rather than human activities. (2)Comparative analysis with hydrochemical data from the Lijiang Basin in the karst areas of southwest China reveals that the hydrochemical types in karst areas are predominately controlled by water-rock interactions,with negligible influence from other factors. (3)Analysis of hydrogen and oxygen isotopic characteristics of groundwater shows that atmospheric precipitation serves as the primary recharge source for karst groundwater in the study area.Influenced by weathering and leaching processes in carbonate aquifers and other types of rock,groundwater exhibits typical HCO3--Ca2+type. (4)The concentrations of common pollutants,such as nitrate,are far below the safety limit for drinking water quality set by the World Health Organization.The primary sources of these contaminants are soil nitrogen derived from natural processes.During the dry season,groundwater at some sampling sites exhibits contamination from domestic sewage and livestock manure.