Biochar from rice residues was investigated as a low cost material to remediate heavy metals and female sex hormones in wastewater. Therefore, the biomass including rice husk and rice straw were used in the production of biochar at 340, 400 and 500 °C. In this study, continuous flow adsorption columns packed with rice derived biochars were used to evaluate the removal efficiency of six heavy metals and three hormones at different operating conditions. Then effluent samples were collected and analyzed for each type of biochar. Besides, the spent biochars were examined by thermogravimetric analysis and surface morphology to assess the weight loss for biochar. Results showed that the adsorption potential of biochar was significantly influenced by the hydraulic retention time, type of biochar and carbonization temperature. Rice straw derived biochar had a higher adsorption capacity and lower ash content compared to rice husk biochar. At flow rate of 1mL/min, sorption capacity of heavy metals indicated the order Fe > Pb > Cu > Cd > Zn > Cr. Additionally, after seven hours of continuous flow in rice straw derived biochar at 500 °C, the concentrations of 17-ß estradiol, estrone, and progesterone were decreased by 78, 75 and 99%, respectively. Therefore, rice straw derived biochar could be a feasible renewable tool for wastewater remediation.

Increasingly a source of water for irrigation, wastewater (WW) poses risks to crops due to potential contaminants. It can harbor metals and organic contaminants known to impact harmfully on human and environmental health. Nanoparticles (NPs) detected in wastewater raises questions about their possible interactions with cocontaminants, and their effects on soil-water systems (e.g., WW-irrigated agriculture). Titanium dioxide nanoparticles (TiO2 NPs), commonly found in industrial and consumer products and observed in wastewater, could potentially influence the mobility of soil contaminants and metal uptake by crops. Accordingly, we conducted a two-year (2017 and 2018) field lysimeter study to investigate the impacts of titanium dioxide nanoparticles on the mobility of metals (Cd, Cr, Cu, Fe, Pb and Zn) and their uptake by potato plants (Solanum tuberosum L. cv. 'Russet Burbank'). The potatoes, grown in sandy soil under controlled conditions, were irrigated with synthetic wastewater (WW), or with wastewater + titanium dioxide nanoparticles (WW+TiO2 NPs). At harvest, the potato tubers, plant parts and soil samples were analyzed for their metal concentrations. The presence of 1 mg L- 1 TiO2 NPs in the irrigation wastewater significantly reduced the uptake of cadmium, copper and zinc by the potato flesh, skin and roots in both treatment years (p <= 0.05), but did not significantly change the uptake of chromium, lead and iron into any plant parts. We conclude therefore that titanium dioxide nanoparticles in the wastewater appeared to reduce the bioavailability of cadmium, copper and zinc in the soil.

Increased food production, required for a growing population, would place additional stress on freshwater resources. Since agriculture is the largest freshwater consumer, supplementation of irrigation water with wastewater could be beneficial. However, wastewater contains contaminants such as heavy metals, which can adversely affect plant growth. Thus, it is necessary to develop techniques to minimize this adverse impact of wastewater irrigation. The objective of this study was to determine the effect of super absorbent polymer (SAP), as well as a mixture of SAP and plantain peel biochar as soil amendments, on growth and yield of wastewater (WW) irrigated potatoes (Solanum tuberosum L.) and spinach (Spinacia oleracea L.). The proposed amendments are known to adsorb these contaminants and reduce their uptake by plants, thus promoting plant growth and yield. In the mixed amendment, gasified biochar (GBC) was used for potatoes, whereas pyrolyzed biochar (PBC) was used for spinach plants. In 2015 and 2016, potatoes were grown in sandy soil filled lysimeters, with treatments: SAP+WW, SAP+GBC+WW, WW (no amendment, wastewater irrigation) and FW (no amendment, freshwater irrigation). In 2016, spinach plants were grown in different lysimeters with treatments SAP+WW, SAP+PBC+WW, WW and FW. The amendments were incorporated in soil at the rate of 1% (w/w) for both the plants. Plants were irrigated with laboratory prepared, highly contaminated synthetic wastewater, and were harvested at maturity. Observations on yield and plant health parameters, viz. photosynthetic activity, stomatal conductance, normalized difference vegetative index (NDVI), relative chlorophyll content index (RCCI), leaf temperature and root structure were recorded. Results indicated that irrigating potato and spinach plants with the wastewater, had no adverse effects on yield and growth of the plants. Potato tuber yield was the lowest with treatment SAP+GBC+WW during both years, and no significant differences were found in yield amongst other treatments. Spinach yield in SAP+PBC+WW treatment was significantly higher than that in other treatments (p<0.05). No significant effect of treatments on the plant growth parameters was observed. The study indicates that the proposed amendments can be used to promote growth and yield of crops grown with contaminated wastewater, however, the effect of these amendments are dependent on the type of crop.

Food crops irrigated with wastewater can uptake heavy metals, causing serious health ailments in humans. Use of a polyacrylamide superabsorbent polymer hydrogel and the same hydrogel mixed with pyrolyzed plantain peel biochar as soil amendments are proposed to reduce heavy metal uptake by wastewater-irrigated spinach (Spinacia oleracea L.) plants. A sorption test was carried out to establish the ability of these treatments to bind the heavy metals. In a lysimeter field experiment, the amendments were mixed in the top 0.10 m of soil (1% w/w) and spinach plants were grown using synthetic wastewater irrigation. After each irrigation, soil samples were obtained at different depths (0, 0.10, 0.30, and 0.60 m from the surface) for heavy metal analysis. Spinach leaves, root, and stem samples were obtained at the harvest for metal analysis. Sorption test results showed that the hydrogel-biochar amended soil adsorbed 0.80, 0.46, and 0.44 mg g-1 of cadmium, copper, and zinc, respectively, from a 0.5 mM multi-metal solution; the hydrogel treatment adsorbed 0.59, 0.41, and 0.24 mg g-1 of the metals, respectively. These amounts were at least 90% more than those adsorbed by the non-amended soil. In terms of the total metal uptake by spinach leaves, the hydrogel-biochar mix treatment performed better than the hydrogel treatment; it reduced the total uptake by 48%, whereas the hydrogel treatment was only able to reduce it by 15% when compared to the control that exhibited a total metal load of 1028 mg kg- 1. Both treatments were able to significantly (p < 0.05) reduce copper uptake in plant stems, and exhibited the potential to reduce chromium, copper, and iron uptake by spinach leaves.

Heavy metal uptake by food crops and the potential for groundwater contamination are of major concern in areas where untreated wastewater is used for irrigation. To minimize heavy metal uptake by wastewater irrigated food crops and to minimize its transport to deeper soil layers, the use of polyacrylamide super absorbent polymer (SAP) and SAP-gasified plantain peel biochar mix (SAP+GBC), as soil amendments, is proposed in this study. A sorption test was conducted to determine the ability of the treatments to adsorb heavy metals (Cd, Cr, Cu, Fe, Pb and Zn). Field experiment was conducted by growing synthetic wastewater irrigated potato plants (Solanum tuberosum L.) in lysimeters packed with sandy soil, contaminated with heavy metals. Prior to conducting the study, heavy metals Cd, Cr, Cu, Fe, Pb and Zn were present in top 0.10 m of lysimeter soil within ranges of 15.6–23.9, 23.3–27.6, 30.3–62.2, 11538.6–10847.7, 64.9–131.3 and 38.7–46.8 mg kg−1, respectively. Irrigation occurred eight times, at an interval of 10 days, based on the crop water requirement. After every irrigation, soil samples were collected from different depths (surface, 0.10, 0.30 and 0.60 m) for heavy metal analysis. Upon maturity, potato tubers, plant root, stems, leaf, tuber flesh and tuber peel tissues were sampled separately for heavy metal analysis. Soil samples, collected at the end of the experiment, were also subjected to pH and cation exchange capacity (CEC) analysis. Compared to the control, treatment SAP+GBC was able to retain significantly higher amounts of Cd, Cr and Fe in topsoil (0–0.10 m depth; p<0.05), whereas, the SAP treatment retained significantly higher amounts of Cd, Cu, Fe and Zn in topsoil (p<0.05). Both hydrogel based treatments (SAP and SAP+GBC) were able to significantly (p<0.10) reduce Cd uptake in tuber flesh (1.98 and 1.54 mg kg−1, respectively) and peel tissue (20.75 and 23.89 mg kg−1, respectively), as compared to the control (2.63 mg kg−1 in flesh and 43.87 mg kg−1 in peel). Concentrations of Zn in tuber flesh tissue for both, SAP (8.30 mg kg−1) and SAP+GBC (8.65 mg kg−1) treatments were found to be significantly (p<0.05) lower than that of the control (15.28 mg kg−1), indicating the effectiveness of the treatments in reducing Zn uptake by potato tubers. Treatment SAP+GBC was also able to significantly (p<0.05) reduce Pb uptake in tuber flesh (0.05 mg kg−1) and peel tissue (1.64 mg kg−1), as compared to control (0.09 mg kg−1 in flesh and 4.99 mg kg−1 in peel). Overall, it was found that tuber peels had significantly higher levels of heavy metals, as compared to tuber flesh. The present study indicates that the hydrogel based amendments have the potential to reduce the uptake of Cd, Pb and Zn metals, by wastewater irrigated potato tubers grown on sandy soils.

The effect of plantain peel biochar on the uptake of six heavy metals (Cd, Cr, Cu, Fe, Pb and Zn) in spinach (Spinacia oleracea L.) irrigated with untreated wastewater was investigated in nine outdoor lysimeters (0.45 m diameter × 1.0 m height) arranged in a completely randomised design with three replicates. The lysimeters were packed with sandy soil (bulk density 1.35 Mg m−3) and brought to field capacity 1 day before starting the experiment. Biochar (1% w/w) was mixed in the top 0.10 m of soil under biochar amendment. Spinach were planted in each lysimeter, irrigated (every 10 days for 4 times in total), harvested (harvest 1 and harvest 2) and analysed for the heavy metals. Spinach leaves accumulated more heavy metals than the roots and stems. Biochar amendment did not affect the translocation of heavy metals (Cd, Cu, Cr, Fe and Pb) to spinach leaves, possibly due to competition with other compounds in the soil solution. However, the biochar amendment improved CEC and increased the pH of soils which resulted in a 42% reduction of translocation of Zn in spinach leaves. Assuming daily spinach consumption of 200 g per person, Zn in spinach grown in soil amended with biochar would be below the provisional maximum tolerable daily intake limit for adults (20 mg) as prescribed by WHO/FAO/IAEA. Consumption of spinach grown with wastewater in soil without biochar amendment may not be safe because of Zn toxicity. Likewise, the concentration of Cd, above CODEX permissible levels in the spinach leaves and eleven times higher in wastewater than freshwater irrigation, raises a concern for consumers in developing countries where untreated wastewater is often used for irrigation.

HighlightsAmending soil with SAP+BC and SAP reduced Cd, Cu, and Zn uptake into potato tubers.SAP+BC treatment led to greater Cd and Zn retention in topsoil.Acrylamide monomers were not detected in potatoes grown in SAP-amended soil.Potato peels accumulated higher concentrations of heavy metals than tuber flesh.Abstract. Agriculture is the largest consumer of freshwater; therefore, use of alternate sources for irrigation, such as wastewater, could alleviate increasing stress on freshwater resources. However, wastewater may contain contaminants such as heavy metals (Cd, Cr, Cu, Fe, Pb, and Zn), which could be taken up by food crops and/or contaminate groundwater. To reduce the mobility of heavy metals in soil and deter their uptake by potatoes ( L.) irrigated with synthetic wastewater, polyacrylamide superabsorbent polymer (SAP) and a mixture of SAP and plantain peel biochar (SAP+BC) were tested as soil amendments. The experiment was performed in field lysimeters packed with sandy soil. SAP was incorporated into the soil layer from 0.15 to 0.25 m below the surface and BC was mixed into the top 0.10 m of soil, both at an application rate of 1% (w/w). Leachate and composite soil samples from different depths, collected after each irrigation event, were analyzed for heavy metals. Upon harvest, different plant parts were subjected to heavy metal analysis. Compared to the untreated control, the SAP+BC treatment led to significantly greater (p < 0.05) retention of Cd and Zn in the topsoil while significantly reducing (p < 0.05) Cd, Cu, and Zn uptake into potato tuber flesh tissue and Cd uptake into tuber peels. The SAP treatment also significantly reduced (p < 0.05) Cd uptake in the tuber as compared to the control. Acrylamide monomers were not detected in tuber flesh and peel samples for all treatments, indicating possible safe use of SAP and BC in soils to reduce heavy metal leaching and uptake by plants. Keywords: Biochar, Heavy metals, Hydrogels, Lysimeter, Plant uptake, Superabsorbent polymers, Wastewater.

The environmental effectiveness of plantain peel biochar in the second season of its application to soil was studied using outdoor lysimeters (0.45 m diameter x 1.0 m height) packed with sandy soil, cultivated with potatoes (Solanum tuberosum) and irrigated with wastewater. Biochar (1% w/w) was amended in the soil one-time in the first season. For two seasons, the biochar improved the soil properties, immobilized the heavy metals in the soil, and reduced their uptake by the crop. The CEC of the biochar-amended soil (WW + B) for example, as compared to the unamended treatment (WW-B), was significantly higher (p<0.05; >65%) for both seasons due to higher pH which controls the availability of cations in soils, influencing their CECs. The soil sampled in the second season showed accumulation of all the heavy metals in the topsoil, while only Zn, Pb and Fe moved to the 0.1 m depth. The Fourier transform infra-red spectra of the soil and soil-biochar mix were similar and suggested that oxygen-containing functional groups were partly responsible for binding the heavy metals. The heavy metals translocated to all the potato parts (flesh, peel, root, stem and leaves). The concentrations of the heavy metals in potato parts under freshwater were lower than those under wastewater irrigated condition. After the second season of being in the soil, biochar significantly reduced (p < 0.05) the concentrations of Cd, Cu, Cr, Pb and Zn in the edible flesh suggesting that biochar immobilized wastewater-laden heavy metals in soil and reduced their uptake in potatoes for at least two seasons.

This study investigated the effects of biochar, produced from plantain peel, on the yield of potatoes ( Solanum tuberosum L.) irrigated with wastewater in two consecutive seasons. Potatoes were grown in 2015 and 2016 in nine lysimeters (1.0 m × 0.45 m), packed with sandy soil to a bulk density of 1.35 Mg m −3 . The lysimeters were arranged in a completely randomized design with three replicates. The treatments were (i) wastewater with biochar, (ii) wastewater without biochar, and (iii) freshwater without biochar. The soil with biochar treatments was amended in 2015 with an application rate of 1% (w/w) on the top 0.1 m of soil. After 33 days of planting, the potatoes were irrigated 8 times, on a 10-day irrigation interval, with freshwater or wastewater that was synthesized to represent a typical wastewater in developing countries. Plant health parameters (e.g., photosynthetic rate) were measured. After 120 days of planting, the potato tubers were harvested; the fresh weight was measured and the tubers were counted. The plant health parameters (e.g., photosynthesis rate) varied with time but were not affected by biochar amendment. Also, the total fresh tuber weights as well as the total number of tubers were similar in all treatments although the biochar showed a significant positive effect ( p < 0.05) on the pH and the cation exchange capacity of the soil. Thus, it was concluded that application of the plantain peel biochar as soil amendment showed no significant effect on the yield of potatoes irrigated with wastewater.

In many developing countries water scarcity has led to the use of wastewater, often untreated, to irrigate a range of crops, including tuber crops such as potatoes (Solanum tuberosum L.). Untreated wastewater contains a wide range of contaminants, including heavy metals, which can find their way into the edible part of the crop, thereby posing a risk to human health. An experiment was undertaken to elucidate the fate and transport of six water-borne heavy metals (Cd, Cr, Cu, Fe, Pb and Zn), applied through irrigation water to a potato (cv. Russet Burbank) crop grown on sandy soil, having either received no biochar amendment or having top 0.10 m of soil amended with 1% (w/w) plantain peel biochar. A non-amended control, irrigated with tap water, along with the two contaminated water treatments were replicated three times in a completely randomized design carried out on nine outdoor PVC lysimeters of 1.0 m height and 0.45 m diameter. The potatoes were planted, irrigated at 10-day intervals, and leachate then collected. Soil samples collected two days after each irrigation showed that all heavy metals accumulated in the surface soil; Fe, Pb and Zn were detected at 0.1 m depth, while only Fe was detected at 0.3 m depth. Heavy metals were not detected in the leachate. Tested individually, all portions of the potato plant (tuber flesh, peel, leaf, stem and root) bore heavy metals. Biochar-amended soil significantly reduced only Cd and Zn concentrations in tuber flesh (69% and 33%, respectively) and peel compared to the non-amended wastewater control (p < 0.05). Heavy metal concentrations were significantly lower in the tuber flesh than in the peel, suggesting that when consuming potatoes grown under wastewater irrigation, the peel poses a higher health risk than the flesh.

There is a need to develop innovative techniques to effectively use water in agriculture to meet the growing demands for food. Super absorbent polymers (SAPs), or hydrogels, can absorb and retain large amounts of water against gravitational forces and release it on demand to meet plant water requirements. Being an artificially synthesized compound, it is imperative that SAPs should not introduce toxicity to the growing medium or produce. The objectives of this study were to determine whether SAPs can improve water use efficiency (WUE) and the physiological growth of cherry tomatoes (Solanum lycopersicum var. cerasiforme) without causing soil toxicity. A pot-trial experiment was carried out in 2014 at the Research Greenhouse of McGill University's Macdonald Campus (Ste-Anne-de-Bellevue, Quebec, Canada) in a completely randomized design, with three concentrations of SAP (0%, 0.1%, and 0.5%) and three irrigation intervals (daily, each alternate day, and every third day). The mean yield of the experimental cherry tomatoes was statistically significantly higher where 0.5% SAP was applied, compared to where SAP was not applied (p = 0.0056). The mean WUE was also higher where 0.5% SAP was applied when compared to where SAP was not applied (p <= 0.05). To ascertain food safety, the presence of free acrylamide monomer in tomatoes was checked. The acrylamide concentrations were below the detection limit of 5 mu g kg(-1) in all tomato samples. To assess environmental toxicity, a Microtox toxicology analysis was also conducted on the growing medium, which revealed that the SAP used in the study was not toxic. Therefore, it can be concluded that the application of SAP could increase yield and WUE of greenhouse-grown cherry tomatoes. It also appears that SAP did not introduce toxic side-effects in the soil nor in the tomatoes, as determined by Microtox acute toxicity test and acrylamide residue analysis with LC-MS.

The feasibility of using two types of biochars to reduce steroid hormone pollution from poultry and swine manure application on agricultural land was evaluated. The sorption affinity and desorption resistance of softwood and hardwood biochars were also determined for two estrogen hormones, 17β-estradiol (E2) and its primary metabolite estrone (E1). The softwood and hardwood biochars demonstrated high retention capacity for both estrogens. The effective distribution coefficient (Kdeff) of soil-softwood-derived biochar (SBS450) was significantly higher than soil-hardwood-derived biochar (SBH750), indicating the stronger sorption affinity of SBS450 for estrogens. To validate the laboratory results, a field lysimeter experiment was conducted to study the fate and transport of E2 and E1 in soil and leachate in the presence of 1% softwood-biochar (BS450) in topsoil and to compare it with soil without any amendments. The spatio-temporal distribution of both estrogens was monitored at four depths over a 46-day period. The lysimeters, in which the surface layer of soil was amended with biochar, retained significantly higher concentrations of both estrogen hormones. Although they leached through the soil and were detected in leachates, collected at 1.0 m depth, the concentrations were significantly lower in the leachate collected from biochar-amended lysimeters. The result confirmed the efficacy of biochar amendment as a remediation technique to alleviate the manure-borne hormonal pollution of groundwater.

As fresh water is a limited resource in many parts of the world, the use of wastewater for irrigation has become an important alternative. Therefore, many countries facing a water deficit, use partially treated, or even untreated, wastewater. This may increase the input of many contaminants into the environment. In the present study, we investigated the effect of using surfactant rich water in irrigation on the mobility of the most commonly-used veterinary antibiotic, monensin. Nine PVC lysimeters, 1.0m long×0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 Mg m(-3). Cattle manure, containing monensin, was applied at the surface of the lysimeters at the recommended rate of 10t/ha. Each of three aqueous Brij 35 solutions, 0, 0.5 and 5 g L(-1), was applied to the lysimeters in triplicate. Over a 90 day period, soil and leachate samples were collected and analyzed. The results of the laboratory sorption experiment showed that when the nonionic surfactant Brij 35 is present, the sorption coefficient of monensin was reduced significantly from 120.22 mL g(-1) in the aqueous medium to 112.20, 100 and 63.09 mL g(-1) with Brij35 concentrations of 0.25, 2.5 and 5 g L(-1), respectively. The lysimeter results indicated a significant downward movement of monensin at depths of 60 cm in the soil profile and leachate in the presence of the surfactant. Thus, the continuous use of poor quality water could influence the transport of monensin in agricultural soils, and consequently, pose a risk for groundwater pollution.

Sorption/desorption of antibiotics, oxytetracycline (OTC), and sulfachloropyridazine (SCP) was investigated in the presence of a nonionic surfactant Brij35. Batch sorption experiments indicated that Freundlich equation fits sorption isotherms well for OTC. The sorption coefficients, K F, values were computed as 23.55 mL g−1 in the absence of Brij35 and 25.46 mL g−1 in the presence of Brij35 in the monomer form (below critical micelle concentration CMC, of 74 mg L−1). However, the K F values reduced to 12.76 mL g−1 in the presence of Brij35 at 2.5 g L−1. Therefore, irrigation with surfactant-rich water may increase the leaching potential of OTC. In the case of SCP, the K F value, in the absence of Brij35, was 19.95 mL g−1. As a result of increasing the concentration of Brij35 to 0.25 g L−1 (about 2.5 CMC), K F values first increased and reached a maximum value of 95.49 mL g−1 and then reduced to 66.06 mL g−1, at surfactant concentration of 5 g L−1. Unlike OTC, the presence of surfactant in irrigation water is likely to decrease SCP leaching. In the case of OTC, hysteresis was found at Brij35 concentrations below CMC. However, OTC desorbed readily from soil (no hysteresis) at Brij35 concentrations above CMC. In the case of SCP, no hysteresis was found in the presence of the surfactant, both below and above CMC. Further, the obtained values of the efficiency coefficient (E), reveals that Brij35 had the potential to release more OTC from the soil (E > 1) as compared to SCP (E < 1). From these results, it can be concluded that regular use of manure on agricultural soils, especially in regions where poor quality irrigation water is used, can increase OTC contamination of water resources.

In many parts of the world, river water is used for irrigation. Treated, partially treated, and even untreated water from wastewater treatment plants is discharged directly into rivers, thereby degrading the quality of the water. Consequently, irrigation water may contain surfactants which may affect the fate and transport of chemicals such as pesticides and antibiotics in agricultural soils. A field lysimeter study was undertaken to investigate the effect of the nonionic surfactant, Brij 35, on the fate and transport of an antibiotic, Oxytetracycline, commonly used in cattle farms. Nine PVC lysimeters, 1.0 m long x 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 Mg m(-3). Cattle manure, containing Oxytetracycline, was applied at the surface of the lysimeters at the recommended rate of 10 t/ha. Each of three aqueous Brij 35 solutions, 0, 0.5 and 5 g L-1 (i.e., 'good,'poor' and 'very poor' quality irrigation water) were each applied to the lysimeters in triplicate. Over a 90 day period, soil and leachate samples were collected and analyzed. Batch experiment results showed that the presence of the nonionic surfactant Brij 35 significantly reduced the sorption coefficient of OTC from 23.55 mL g(-1) in the aqueous medium to 19.49, 12.49 and 14.53 in the presence of Brij 35 at concentrations of 0.25, 2.5 and 5 g L-1, respectively. Lysimeter results indicted the significant downward movement of OTC at depths of 60 cm into soil profile and leachate in the presence of surfactant. Thus, the reuse of wastewater containing surfactants might enhance the mobility of contaminants and increase ground water pollution. (C) 2012 Elsevier Ltd. All rights reserved.

Given the water scarcity becoming endemic to a large portion of the globe, arid region irrigation has resorted to the use of treated, partially treated, or even untreated wastewaters. Such waters contain a number of pollutants, including surfactants. Applied to agricultural lands, these surfactants could affect the fate and transport of other chemicals in the soil, particularly pesticides. A field lysimeter study was undertaken to investigate the effect of nonionic surfactant, Brij35, on the in-soil fate and transport of a commonly used herbicide, metribuzin [4-amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one]. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 mg m−3. Antibiotic-free cattle manure was applied (10 mg ha−1) at the surface of the lysimeters. Metribuzin was then applied to the soil surface of all lysimeters at a rate of 1.00 kg a.i. ha−1. Each of three aqueous Brij35 solutions, 0, 0.5 and 5 mg L−1 (i.e., “good”, “poor” and “very poor” quality irrigation water) were each applied to the lysimeters in triplicate. Analysis for metribuzin residues in samples of both soil and leachate, collected over a 90-day period, showed the surfactant Brij35 to have increased the mobility of metribuzin in soil, indicating that continued use of poor quality water could influence pesticide transport in agricultural soils, and increase the risk of groundwater contamination.