Quality indices of groundwater for agricultural use in the Soconusco, Chiapas, Mexico

Abstract

In Soconusco, Chiapas, in spite of the high availability of surface water, it is resorting to the use of groundwater. Knowledge about the quality of surface or groundwater used to irrigate crops in that region is low. This paper aims to contribute to the knowledge of the quality of groundwater for agricultural use through the characterization of the spatial variability. Assuming a random spatial distribution of 45 samples which were collected in situ were determined: acidity and alkalinity (pH), electrical conductivity (EC), Total Dissolved Solids (TDS), cations and anions and trace elements; in addition to the agricultural index: Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP), Sodium Percentage (% Na), Kelly Ratio (KR), Magnesium Adsorption Ratio (MAR), Permeability Index (PI), Effective Salinity (ES), Salinity Potential (SP) and Osmotic Potential (OP). In general, SSP, % Na, KR, PI are low, there is only one anomalous point (9) with high values at W of the study area. Similarly, PS, ES, Cl, Na and SAR are low except point 16 and conversely, RSC and pH are high, except at this point located in the center of the study area. The results allow us to infer that the water in that aquifer presents no problems or sodicity toxic ions. In 27 sites sampled values above 250 µmhos/cm were found at 25°C, classified as medium to high risk of salinity, unsuitable for agricultural use. Analysis of the combined effect of the presence of sodium (SAR) and salinity (EC or TDS) shows that 27 of analyzing sites have restricted water medium at very high for use in irrigation.

Water Chemical Characteristics and Water Quality Evaluation of the River under the Ecological Water Replenishment: A Case Study in the Yongding River Basin in North China

“…At present, the sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and sodium percentage (Na %) have been widely employed globally and are effective for the evaluation of water quality in different regions. The ion concentrations are equivalent concentrations (meq/L) and the detailed calculations are as follows normalS normalA normalR = normalN normala + × false[ 2 / ( C a 2 + + M g 2 + ) false] 1 / 2 normalR normalS normalC = ( H C O 3 − + C O 3 2 − ) .25em − .25em ( C a 2 + + M g 2 + ) normalN normala .25em % = normalN normala + / ( N a + + C a 2 + + M g 2 + + <...…”

“…At present, the sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and sodium percentage (Na %) have been widely employed globally and are effective for the evaluation of water quality in different regions. The ion concentrations are equivalent concentrations (meq/L) and the detailed calculations are as follows …”

Distribution, Sources and Water Quality Evaluation of the Riverine Solutes: A Case Study in the Lancangjiang River Basin, Tibetan Plateau

“…In order to assess the suitability for irrigation and drinking purposes, the physicochemical parameters EC (electrical conductibility) and ion concentrations of the river waters are evaluated following drinking water quality guidelines (Chinese drinking water standards: GB 5749-2006 and WHO guidelines (WHO 2017)). The quality of irrigation water can affect soil quality attributes and further the crop yields [19,20,21]. The sodium hazard assessment for irrigation purpose is conducted by the calculated parameters including SAR, Na% and RSC.…”

“…The sodium hazard assessment for irrigation purpose is conducted by the calculated parameters including SAR, Na% and RSC. The detailed calculation processes are listed as Equations (8–10) [21]: SAR = Na + ×[2/(Ca 2+ +Mg 2+ )] 1/2 Na% = 100%×Na + /(Na + +K + +Ca 2+ +Mg 2+ ) RSC = (HCO 3 − + CO 3 2− ) - (Ca 2+ +Mg 2+ ) where the used ion concentrations are equivalent concentrations (meq/L). The results are shown in Table S2.…”

“…eutrophication) [16], but also threaten the daily life of local residents [17,18]. The inappropriate water with high salinity and alkalinity used for irrigation may destroy soil aggregate structure, thus reduce the grain yields [19,20,21], additionally, drinking water with deleterious or toxic matters may cause health hazards for the residents [22,23].…”