Nawaz et al. 2019 - Wastewater manganese and spinach

Nawaz and colleagues tested how manganese-contaminated wastewater changed spinach growth and manganese uptake in Faisalabad, Pakistan. This is in-scope irrigation-water and soil-to-plant pathway evidence, not market spinach occurrence and not a lead paper despite the recovery filename.

Key numbers

The abstract states that sewage water used for vegetable production can contain heavy metals including manganese, cadmium, lead, and zinc. The experiment then focused on manganese by applying wastewater amended to 150 mg L-1 Mn or 350 mg L-1 Mn, with wastewater alone as the control.

Table 1 reports wastewater quality. Selected means and heavy-metal values are preserved below in the source’s units:

The results text says the Bawachak drain wastewater had Mn above the permissible limit and was used to test Mn bioavailability in spinach.

The abstract reports maximum spinach Mn concentrations of 11.13 and 12.67 mg L-1 at 350 mg L-1 Mn in wastewater for the two cuttings. The results section reports 11.13 and 13.9 mg L-1 for the same toxic treatment. Figure 1 labels the uptake axis as ppm. This internal mismatch is not reconciled here.

Table 2 reports growth parameters for two spinach cuttings:

Table 3 reports Pearson correlations. Mn concentration uptake correlated negatively with number of leaves per plant at r = -0.99 for the first cutting and r = -0.93 to -0.98 across the second-cutting comparisons printed in the table. Mn concentration correlated positively with dry weight at r = 0.95 for the first cutting and r = 0.86 to 1.00 in the second-cutting comparisons printed in the text/table.

Methods (brief)

Wastewater was collected from three Faisalabad drains: Bawachak Drain, Ganda Nala, and Achakhera Drain. Physical and chemical parameters were measured following U.S. Salinity Laboratory methods, and Zn, Mn, Fe, Pb, and Cd were analyzed with atomic absorption spectrophotometry. The pot experiment used Bawachak drain wastewater and developed two Mn toxicity levels with MnCl2: 150 mg L-1 and 350 mg L-1. Spinach was harvested after 45 and 90 days. Ground plant material was digested with HNO3 and HClO4 at a 2:1 ratio and analyzed for Mn with a Varian Spectra AA 250 plus atomic absorption spectrophotometer.

Implications

Certification: Do not use the spinach Mn values as ordinary market spinach occurrence. The experiment uses wastewater deliberately amended with high Mn concentrations.

Courses: Useful example of irrigation-water source control. The wastewater already exceeded the source’s Mn limit before the experimental Mn additions, and the toxic Mn treatment reduced leaf number while increasing Mn uptake.

App: Context only. The source can inform spinach pathway notes and irrigation-water risk questions, not finished-product scoring.

Wiki pages this source may touch

• irrigation-and-soil-amendments
• soil-to-plant-transfer
• spinach
• spinach
• manganese
• lead
• cadmium

Verification notes

Recovered from skip:not-food-occurrence under the 2026-06-10 inclusion-by-default rule. On reading, this is lane a3 irrigation-water and soil-to-plant pathway evidence because it measures wastewater metals and manganese uptake into spinach leaves.

Numbers were checked against the abstract, wastewater Table 1, growth Table 2, Pearson-correlation Table 3, results text, Figure 1 caption, and conclusion in the extracted PDF text. Units are copied as printed. Pb and Cd were not found in the wastewater table (Nd) and are not treated as spinach occurrence. The source has an internal mismatch for the second-cutting maximum Mn uptake, so both printed values are recorded rather than averaged.

Page history

The five most recent substantive edits to this page. 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.