Overview
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:
| Drain/site | EC (dS m-1) | SAR ((mmol L-1)1/2) | RSC (me L-1) | TDS (me L-1) | Zn (mg L-1) | Mn (mg L-1) | Fe (mg L-1) | Pb | Cd |
|---|---|---|---|---|---|---|---|---|---|
| Ganda Nala | 3.85 | 10.7 | 19.4 | 2464 | 0.3 | 0.3 | 0.3 | Nd | Nd |
| Bawachak Drain | 5.4 | 18.5 | 27.5 | 3388 | 0.3 | 0.4 | 0.3 | Nd | Nd |
| Achakhera Drain | 4.8 | 15.4 | 24.6 | 3100 | 0.1 | 0.3 | 0.4 | Nd | Nd |
| Permissible limit printed by source | 1.5 | 10 | 2 | 1200 | 2.0 | 0.2 | 5.0 | not printed | not printed |
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:
| Treatment | Parameter | 1st cutting after 45 days | 2nd cutting after 90 days |
|---|---|---|---|
| Control | Number of leaves per plant | 7.0 +/- 0.289 | 8.0 +/- 0.85 |
| Control | Plant biomass (g/plant) | 2.01 +/- 0.16 | 9.03 +/- 0.45 |
| Control | Dry weight (g/plant) | 0.14 +/- 0.013 | 0.55 +/- 0.054 |
| Control | Leaf surface area (cm3) | 39.35 +/- 1.42 | 154 +/- 1.47 |
| 150 mg L-1 Mn | Number of leaves per plant | 6.0 +/- 0.25 (-14%) | 7.0 +/- 0.25 (-13%) |
| 150 mg L-1 Mn | Plant biomass (g/plant) | 3.55 +/- 0.25 (+77%) | 12.28 +/- 1.28 (+36%) |
| 150 mg L-1 Mn | Dry weight (g/plant) | 0.25 +/- 0.022 (+78%) | 0.61 +/- 0.021 (+11%) |
| 150 mg L-1 Mn | Leaf surface area (cm3) | 67.43 +/- 1.20 (+71%) | 175 +/- 1.08 (+14%) |
| 350 mg L-1 Mn | Number of leaves per plant | 4.0 +/- 0.25 (-43%) | 6.0 +/- 0.25 (-25%) |
| 350 mg L-1 Mn | Plant biomass (g/plant) | 4.16 + 0.16 (+107%) | 13.44 +/- 0.44 (+49%) |
| 350 mg L-1 Mn | Dry weight (g/plant) | 0.31 +/- 0.012 (+121%) | 0.87 +/- 0.036 (+58%) |
| 350 mg L-1 Mn | Leaf surface area (cm3) | 72.8 +/- 1.45 (+85%) | 191 +/- 1.55 (+24%) |
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, lead (Pb), and cadmium (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.
Related evidence
- Irrigation water and soil amendments as anthropogenic inputs to cropland
- Soil-to-plant transfer of heavy metals
- Spinach
- Spinach
- Manganese
- Lead
- Cadmium
Update history
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