Overview
This study characterized the hydrochemistry of 159 groundwater samples from District Dadu, Sindh, one of Pakistan’s most flood-prone agricultural districts, assessing fitness for drinking and irrigation. Arsenic concentrations ranged up to 500 µg/L, exceeding WHO and Pakistan National Standards for Drinking Water Quality limits (10 µg/L) at a substantial fraction of sampling sites. Fluoride co-contamination was also widespread. Total dissolved solids reached up to 22,900 mg/L, and Escherichia coli was detected in 59.7% of samples, indicating concurrent microbiological hazard. Hazard quotient analysis showed elevated non-carcinogenic health risks for arsenic and fluoride, with infants and children identified as the highest-risk subpopulations due to their lower body weight relative to intake. The sodium adsorption ratio and residual sodium carbonate indices indicated that a majority of groundwater samples are unsuitable for irrigation without treatment, raising concerns for arsenic transfer to crops grown in the district.
Key numbers
- Sample count: n = 159 groundwater samples
- Maximum As: 500 µg/L (50× WHO guideline of 10 µg/L)
- Maximum TDS: 22,900 mg/L
- E. coli detection rate: 59.7% of samples
- Analytes assessed: As, F⁻, pH, EC, TDS, major cations/anions, SAR, RSC
- Health risk subpopulations ranked highest: infants, children
- Analytical methods: ICP-MS for As; ion chromatography for fluoride; standard methods for physicochemical parameters
Methods (brief)
Cross-sectional groundwater sampling in Dadu district, 2023–2024. ICP-MS for trace elements including arsenic. Hazard quotients calculated per US EPA risk assessment methodology using body-weight-adjusted daily intake. Irrigation suitability assessed via Wilcox diagram, SAR, RSC, and Piper diagram for hydrochemical facies classification.
Implications
Certification: Not directly applicable to product concentration thresholds, but relevant to supply-chain water sourcing in regions where groundwater is used for irrigation or food processing; arsenic at 500 µg/L irrigation water transfers to crops, particularly rice in flood-irrigated paddy agriculture.
Courses: Good case study for supply-chain contamination pathways — flood-driven arsenic mobilization from alluvial geology, compounded by microbiological hazard, illustrates the multi-hazard character of water quality in South Asian agricultural districts.
App: Supports geographic risk weighting for ingredients sourced from Sindh province of Pakistan, particularly rice and wheat grown under flood irrigation.
Microbiome: Not directly addressed.
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Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| a8052bb | 2026-08-09 | major | 6 sections added; narrative text revised |