Irrigation water quality of Berqaber Reservoir and its implicationsfor functional food safety

Abstract

Background: Irrigation water quality is a fundamental determinant of soil health, crop productivity, and the synthesis of health-promoting bioactive compounds in functional foods. This study evaluates the hydrochemical status of the Berqaber (Joghas) Reservoir and its inflowing rivers (Aghstev and Joghas) in the Tavush region of Armenia, a strategic water resource for regional agriculture, to assess their suitability for sustainable functional crop production.

Objective: This study aims to evaluate the hydrochemical status of the Berqaber Reservoir and its inflowing rivers (Aghstev and Joghas) in northern Armenia, assess their suitability for irrigation using established water quality indices, and examine the implications of irrigation water quality for the safety, nutritional content, and bioactive compound accumulation in functional crops.

Methods: Water samples were collected in April and July 2024. Analyses included physicochemical parameters, such as pH, total dissolved solids (TDS), and major ions: calcium (Ca²⁺), magnesium (Mg²⁺), sodium (Na⁺), bicarbonate (HCO₃⁻), and chloride (Cl⁻). Heavy metals analyzed included lead (Pb), copper (Cu), zinc (Zn), manganese (Mn), and nickel (Ni). Irrigation suitability indices were calculated: Sodium Adsorption Ratio (SAR), Magnesium Hazard (MH), and Stabler’s coefficient (k). To validate irrigation safety, nitrate ion (NO₃⁻) concentrations, heavy metal accumulation, and nutritional indicators (vitamin C and starch) were assessed in irrigated potatoes, tomatoes, and eggplants.

Results: The irrigation waters exhibited a slightly alkaline reaction (pH 7.4–7.5) with low salinity (TDS 480–570 mg/L). The ionic composition was dominated by Ca²⁺, Mg²⁺, Na⁺, HCO₃⁻, and Cl⁻. SAR values (2.22–2.26) and Stabler’s coefficients (≈10) classified the water as satisfactory for irrigation with low sodicity risk (United States Salinity Laboratory (USSL C2–S1 category). MH values (48.78–49.46%) approached the 50% threshold associated with potential soil structural sensitivity. NO₃⁻ concentrations (12.4–13.0 mg/L) exceeded the Armenian regulatory limit of 10 mg/L (Class 3, Moderate Quality), yet nitrate and heavy metal concentrations in edible crop tissues remained well below Maximum Permissible Concentrations (MPC), and nutritional parameters were unaffected.

Conclusion:  The Berqaber Reservoir system provides irrigation water with low sodicity risk; however, borderline MH and elevated nitrate levels indicate moderate anthropogenic pressure. Despite this, nitrate and heavy metal concentrations in crops remain within permissible limits, ensuring their safety and functional quality. Effective institutional oversight and compliance with water quality regulations are essential to maintain long-term, sustainable, functional crop production.

Novelty of the Study: This study is the first to integrate hydrochemical assessment of irrigation water with empirical validation of functional crop safety in the Tavush agroecosystem of northern Armenia. By linking irrigation water chemistry with crop nitrate accumulation, heavy metal transfer, and nutritional quality indicators, the research establishes a comprehensive “water-to-table” evaluation framework for sustainable functional food production in mountainous agricultural systems.

Keywords: irrigation water, water quality, heavy metals, sodium adsorption ratio, nitrates, magnesium hazard, Berqaber Reservoir, functional foods, water regulation