Abatement of pesticides residues in commercial farm soils by combined ozonation-solarization treatment.

The widespread use of pesticides against agricultural pest and diseases introduces these pollutants and their transformation products into soils. The toxicity and permanence of these substances make it necessary for the development of remediation strategies in order to mitigate contamination and to further protect consumers. This work was aimed to evaluate the applicability of ozonation-solarization technology in the degradation of pesticide residues in commercial farm soils. The trial was conducted in two exploitations devoted during decades to tomato cultivation under greenhouse and net systems. Treatments were carried out using a pipping network (both superficial and sub-superficial) that delivered ozone in gaseous state after covering the soil with gas-tight plastic film to avoid ozone leaks to atmosphere. Control soil treatments, without ozone exposure, were also conducted. After 40 days of treatment, mean degradation percentages of about 55-61% for both cultivation systems were obtained, when the reduction of these pollutants in the control soils was about 8-15%. Ozonation-solarization impact was also assessed by changes on soil physical-chemical properties. Results suggest that ozonation in combination with solarization technique could be considered as a feasible approach for the remediation of pesticide-polluted farm soils.

Variation in flavonoids in a collection of peppers (Capsicum sp.) under organic and conventional cultivation: effect of the genotype, ripening stage, and growing system.

BACKGROUND: In recent years, the acreage used for organic agriculture and the demand for organic fruit and vegetables have increased considerably. Given this scenario, landraces, such as Capsicum landraces, can provide valuable germplasm. Capsicum peppers are very interesting because of their high phenolic content, and particularly their flavonoid content, which provides a high added value. Moreover, the broad genetic diversity in local varieties expands the opportunities for adaptation to organic production and for exploiting genotype × environment interactions to select peppers with the highest phenolic content. RESULTS: In this work, the main flavonoids of peppers were exhaustively evaluated over 2 years in a wide collection of heirlooms, both unripe and fully ripe, under organic and conventional cultivation. The genotype and ripening stage contributed to a high degree to the variation in flavonoids. The growing system influenced this variation to a lesser extent. Luteolin and quercetin showed the highest contributions to total phenolic content (70% and > 20%, respectively) at both ripening stages, while myricetin, apigenin, and kaempferol showed lower contributrions. The average flavonoid content was higher in ripe fruits, and organic management significantly increased the accumulation of total flavonoids and luteolin. Positive correlations between flavonoids were found at both ripening stages, especially between main flavonoids luteolin and quercetin and between kaempferol and quercetin (ρ > 0.7). CONCLUSION: Genotype × environment interaction enabled the identification of accessions with high flavonoid content grown under organic conditions at both ripening stages, particularly total flavonoids and luteolin at the fully ripe stage. Our results reinforce the importance of a wide genetic variation and of considering different ripening stages and growing conditions for breeding high-quality peppers. © 2020 Society of Chemical Industry.

Metabolite profile of the tomato dwarf cultivar Micro-Tom and comparative response to saline and nutritional stresses with regard to a commercial cultivar.

BACKGROUND: The dwarf tomato variety Micro-Tom has been used as a plant model for studies of plant development. However, its response to environmental and agricultural factors has not been well studied. This work studies the phytochemical content of Micro-Tom tomato and its comparative response to saline and nutritional (N, K and Ca) stresses with regard to a commercial variety. RESULTS: The chromatographic profiles of Micro-Tom were similar to those of the commercial variety and the only differences appear to be the concentration of the components. In Micro-Tom, the concentrations of sugars and organic acids increased by salinity in a lesser extent than in Optima. Moreover, contrary to that observed in the commercial variety, phenolic compounds and vitamin C did not increase by salinity in the dwarf variety. However, both varieties increased similarly the concentrations of carotenoids under saline conditions. Finally, fruit yield and most primary and secondary metabolite concentrations in Micro-Tom were not affected by N, K or Ca limitation. CONCLUSIONS: The mutations leading to the dwarf phenotype did not greatly alter the metabolite profiles but studies using Micro-Tom as a plant model should consider the lower capacity for sugars and organic acids under saline conditions and the greater tolerance to nutrient limitation of the dwarf variety.

Solarization and biosolarization using organic wastes for the bioremediation of soil polluted with terbuthylazine and linuron residues.

Strategies for remediation of polluted soils are needed to accelerate the degradation and natural attenuation of pesticides. This study was conducted to assess the effect of solarization (S) and biosolarization (BS) during the summer season using organic wastes (composted sheep manure and sugar beet vinasse) for the bioremediation of soil containing residues of terbuthylazine and linuron. The results showed that both S and BS enhanced herbicide dissipation rates compared with the non-disinfected control, an effect which was attributed to the increased soil temperature and organic matter. Linuron showed similar behavior under S and BS conditions. However, terbuthylazine was degraded to a greater extent in the biosolarization experiment using sugar beet vinasse than in the both the solarization and biosolarization experiments using composted sheep manure treatments. The main organic intermediates detected during the degradation of terbuthylazine and linuron were identified, enabling the main steps of degradation to be proposed. The results confirm that both S and BS techniques can be considered as a remediation tools for polluted soils containing these herbicides.

Use of different organic wastes in reducing the potential leaching of propanil, isoxaben, cadusafos and pencycuron through the soil.

In this study, we examined the effect of four different organic wastes (OW)-composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)-on the potential groundwater pollution of propanil and isoxaben (herbicides), cadusafos (insecticide) and pencycuron (fungicide) under laboratory conditions. For this purpose, leaching studies were conducted using disturbed soil columns filled with a clay loam soil (Hipercalcic calcisol). The addition of organic matter (OM) drastically reduced the movement of the studied pesticides. The results obtained point to the interest in the use of agro-industrial and composted OW in reducing the groundwater pollution by pesticide drainage.

Minimization of methabenzthiazuron residues in leaching water using amended soils and photocatalytic treatment with TiO2 and ZnO.

In the present work, potential groundwater pollution by methabenzthiazuron (MTBU) and the effect of three different amendments (composted sheep manure, composted pine bark and spent coffee grounds) on its mobility were investigated under laboratory conditions. The efficiency of ZnO and TiO2 suspensions in the photocatalytic degradation of MTBU in leaching water was also investigated. The relative and cumulative breakthrough curves were obtained from disturbed soil columns. The presence and/or addition of organic matter drastically reduced the movement of the herbicide. On other hand, photocatalytic experiments showed that the addition of ZnO and TiO2 strongly enhances the degradation rate of this herbicide compared with the results of photolytic experiments under artificial light. ZnO appeared to be more effective in MTBU oxidation than TiO2. The results obtained point to the interest of using organic wastes and heterogeneous photocatalysis for reducing the pollution of groundwater by pesticide drainage.

Chemical Composition of Wild Collected and Cultivated Edible Plants (Sonchus oleraceus L. and Sonchus tenerrimus L.).

The present work investigates the nutritional and bioactive composition, as well as the organoleptic and sensory properties, of S. oleraceus and S. tenerrimus, two wild plant species traditionally used in the gastronomy of the Mediterranean area. Additionally, the effect of cultivation on leaf composition was assessed to explore their potential for large-scale production and commercialization from the point of view of possible losses or gains in quality. Both species were characterized as a good source of bioactive compounds, such as vitamins, pro-vitamins and carotenoids, with health-promoting and antioxidant properties that are highly appreciated. The sensory profile revealed a good general acceptance of S. oleraceus and S. tenerrimus, indicating that they could be included in the diet. Although the cultivation of S. oleraceus resulted in a decrease in the concentration of phenolic compounds when compared to wild-harvested plants, the opposite occurred for vitamin C. In S. tenerrimus, cultivation also increased the concentration of other compounds with important nutritional and healthy properties, such as sugars, organic acids and ß-carotene. The results of the composition, organoleptic and sensory properties of S. oleraceus and S. tenerrimus support the idea of their potential to be used as edible leafy vegetables and as promising assets for functional foods.

Influence of N doses and form on ¹5N natural abundance of pepper plants: considerations for using δ¹5N values as indicator of N source.

BACKGROUND: The aim of this study was to ascertain the effect of the N form (NO(3) (-) , NH(4) (+) and organic N) and N concentration on plant isotopic fractionation and on the contribution of the different N sources to the plant N budget, in order to evaluate the feasibility of using plant δ(15) N values for discriminating between conventional and organic crops. To this end, different N concentrations (applied as NO(3) (-) ), N forms (NO(3) (-) versus NH(4) (+) ), and increasing NO(3) (-) applications to an organic N-based fertilization regime were studied. RESULTS: When using NO(3) (-) as N source, intra-plant fractionation was significant and tended to increase when NO(3) (-) concentration increased in the root medium. However, negligible net isotopic fractionation was observed when comparing theoretical and measured plant δ(15) N values. On the other hand, when plants are fertilized with a mixture of NO(3) (-) and NH(4) (+) , differences in uptake patterns for both salts could result in variation in plant δ(15) N regarding to the expected value. Finally, the application of NO(3) (-) to plants was detected when it was combined with high levels of organic N sources, from 99:1 organic:inorganic N ratio. CONCLUSION: Under certain conditions and following some considerations concerning sampling, δ(15) N values can be considered to be a potential tool to guarantee the authenticity of organic products.

Photocatalytic degradation of four insecticides and their main generated transformation products in soil and pepper crop irrigated with reclaimed agro-wastewater under natural sunlight.

This work is the first-ever study of the concurrence of four insecticides (chlorantraniliprole, imidacloprid, pirimicarb and thiamethoxam) and their main transformation products (TPs) in soil and pepper crop irrigated with reclaimed and non-reclaimed water under agricultural field conditions. Field experiments were conducted using different irrigation supplies: control water (CW), wastewater polluted with phytosanitary commercial products containing the studied insecticides (WW) and reclaimed wastewater after a photocatalytic processing with TiO2/Na2S2O8 at pilot plant under sunlight (RWW). Photocatalytic treatments removed most of the insecticides and their TPs generated during the photoperiod. Neither target insecticides nor their TPs were detected in pepper samples when CW and RWW were used as irrigation source, whereas the four insecticides and two TPs were detected when WW was used. In the experiment carried out with WW, all insecticides and eight TPs were detected in soil samples. The impact of using reclaimed water on the quality of pepper crop was also assessed, showing barely any significant difference.

Solar photocatalysis as strategy for on-site reclamation of agro-wastewater polluted with pesticide residues on farms using a modular facility.

One of the consequences of phytosanitary treatments applied to crops is the generation of a great volume of agro-wastewater having pesticide residues. These pollutants can be considered a serious threat to the environment and human health due to their capacity to affect distant areas remaining for a long time after their application. We have assessed the degradation of five pesticides in agro-waste water produced in two farms by the cleaning pesticide containers and phytosanitary treatment equipment used in the farms. For this purpose, a pilot facility was installed in both farms and advanced oxidation treatments were conducted using natural sunlight by means of Na2S2O8 and heterogeneous photocatalysis (TiO2/Na2S2O8). The remaining percentages obtained at the end of the experiments ranged from 5 to 90.1% for chlorantraniliprole, 5 to 82.3% for difenoconazole, 0.02 to 19.1% for metalaxyl, 1.4 to 74.4% for myclobutanil, and 0.3 to 61% for triadimenol. We observed a correlation between the higher remaining percentages and the total initial concentration of pollutant because of other commercial formulations applied in the farms. The results showed that this equipment could be used to eliminate or reduce the presence of pesticide residues in agro-waste water using an innovative facility installed in the farms and a renewable and economical source of energy (sunlight).

Appraisal of water matrix on the removal of fungicide residues by heterogeneous photocatalytic treatment using UV-LED lamp as light source.

In this study, the photocatalytic degradation of four fungicides, myclobutanil, penconazole and difenoconazole (triazole compounds) and boscalid (carboxamide), has been examined in different aqueous matrices (tap water, irrigation water and two WWPT effluents). Experiments were conducted at laboratory scale with different reagents-zinc oxide (ZnO), titanium dioxide (TiO2), sodium persulphate (Na2S2O8) and the combined systems ZnO/Na2S2O8 and TiO2/Na2S2O8-in water exposed to UV-LED irradiation. Previously, the effect of catalyst and oxidant loading on the disappearance kinetics of the different fungicides was assessed to know maximum degradation efficiency. The influence of water matrices and pesticide loading in removal effectiveness has been evaluated. It was observed a greater efficiency in processes conducted using the tandems ZnO/Na2S2O8 and TiO2/Na2S2O8 in irrigation and tap waters. Results showed that UV-LED are a suitable alternative for tackling the removal of organic pollutants in water.

Phenolic and Carotenoid Profile of Lamb's Lettuce and Improvement of the Bioactive Content by Preharvest Conditions.

This study characterizes the phenolic, carotenoid and chlorophyll profile of lamb's lettuce, a vegetable whose consumption in salads and ready-to-eat products is constantly growing. The MS/MS analysis allowed the identification of thirty-five phenolic compounds including hydroxybenzoic and hydroxycinnamic acids, flavanones, flavanols and flavanones, many of which are reported here in lamb's lettuce for the first time. Chlorogenic acid was the principal phenolic compound found (57.1% of the total phenolic concentration) followed by its isomer cis-5-caffeoylquinic. Other major phenolic compounds were also hydroxycinnamic acids (coumaroylquinic, dicaffeoylquinic and feruloylquinic acids) as well as the flavones luteolin-7-rutinoside, diosmetin-apiosylglucoside and diosmin. Regarding carotenoids, seven xanthophyll and four carotenes, among which ß-carotene and lutein were the major compounds, were detected from their UV-Vis absorption spectrum. In addition, chlorophylls a and b, their isomers and derivatives (pheophytin) were identified. Preharvest factors such as reduced fertilization levels or salinity increased some secondary metabolites, highlighting the importance of these factors on the final nutritional value of plant foods. Lamb's lettuce was seen to be a good potential source of bioactive compounds, and fertilization management might be considered a useful tool for increasing its nutritional interest.

Multiresidue analysis of pesticides in soil by high-performance liquid chromatography with tandem mass spectrometry.

An analytical multiresidue method using HPLC/MS/MS with a triple-quadrupole mass spectrometer in the multiple reaction monitoring mode for the simultaneous determination of 54 pesticides in soil has been developed. The procedure involved initial single-phase extraction of soil sample with acetonitrile by sonication, followed by liquid-liquid partitioning after addition of NaCI. The average recovery by the HPLC/MS/MS method obtained for these compounds varied from 63.2 to 113.8%, with an RSD between 1.9 and 7.1%. The method gave good linearity over the assay range of 10-500 microg/L (except famoxadone, 50-1000 microg/L); the LOD and LOQ for the pesticides varied from 0.02 to 13.2 and from 0.1 to 43.9 microg/kg, respectively. The proposed method was used to determine pesticide levels in soil samples from two experimental vineyards and two tomato greenhouses.

Solar photocatalytic reclamation of agro-waste water polluted with twelve pesticides for agricultural reuse.

This study aims to demonstrate a technically feasible alternative to remove pesticide residues from agro-waste water produced in farms from remnants in containers and treatment tanks, rinse in tanks after treatments, and cleaning of machines and equipment. For this, the photocatalyzed degradation of 12 pesticides commonly used on vegetables, vines, citrus and fruit crops was investigated in aqueous suspensions of TiO2 in tandem with Na2S2O8 at pilot plant scale under natural sunlight in Murcia (SE of Spain) during summer and winter seasons. Previously, preliminary experiments were carried out at laboratory scale using a photoreactor to optimize the photocatalyst (200 mg L-1) and oxidant (250 mg L-1) concentrations on the rate constants of the studied pesticides. The photodegradation of all pesticides can be modelled assuming a pseudo-first-order kinetics. The time needed for disappearance of 90% (DT90) of the studied pesticides, was lower than 4 h in summer in all cases with the exception of cyproconazole (4.9 h), while, cyproconazole (8.9 h), metalaxil (6.1 h) and propyzamide (7.9 h) showed DT90 higher than 6 h in winter. The reaction rate was enhanced 3-fold in summer season, which is directly correlated to the higher accumulated fluence per time received during this season (about a factor of 2.9 higher than in winter). In both cases, the higher and lower degradation rates were obtained for cyprodinil and cyproconazole, respectively. The total fluence to get a 90% reduction (H90) ranged from 4.6 to 5.2 J cm-2 (cyprodinil) to 71.5-76 J cm-2 (cyproconazole).

Reclamation of agro-wastewater polluted with pesticide residues using sunlight activated persulfate for agricultural reuse.

The removal of 17 pesticides (pymetrozine, flonicamid, imidacloprid, acetamiprid, cymoxanil, thiachloprid, spinosad, chlorantraniliprole, triadimenol, tebuconazole, fluopyram, difenoconazole, cyflufenamid, hexythiazox, spiromesifen, folpet and acrinathrin) found in agro-wastewater from washing of containers and phytosanitary treatments equipment, has been carried out using sodium persulfate (Na2S2O8) at pilot plant scale under natural sunlight. Persulfate is a strong oxidant, inexpensive and environmentally appropriate. However, this oxidant is slow in kinetics under ordinary conditions. Na2S2O8 can be activated by ultraviolet light, generating SO4- radicals, which are also a very strong oxidizing species (E0 = 2.6 V). Previously, preliminary experiments were carried out at laboratory scale using a photoreactor to optimize the Na2S2O8 (300 mg L-1) concentration on the rate constants of the found pesticides. The residual levels of the studied pesticides in agro-wastewater (900 L) were in the range 0.02-1.17 mg L-1 for acrinathrin and fluopyram, respectively. After treatment, nearly complete degradation (>97%) of the parent molecules was achieved although 13% of initial DOC was measured. No significant differences (p < 0.05) were found when comparing grown broccoli using reclaimed and unreclaimed water.

Impact of biofumigation with solarization on degradation of pesticides and heavy metal accumulation.

A greenhouse study was conducted to evaluate the effect of biofumigation (with sheep and chicken manure) combined with solarization on the dissipation of pesticides (pyrifenox, DDT and dieldrin), and on soil metals accumulation. The treatments consisted of a control, and soil disinfestations by biofumigation combined with solarization (B+S) for two, four, five, six consecutive years. B+S enhanced the dissipation of pyrifenox with regard to control treatment. Significant differences were not detected among plots disinfected with B+S for consecutive years. On the other hand, B+S had no effect on the dissipation of DDT and dieldrin, probably due to the resistance of these pesticides to microbial degradation and/or high temperatures. Biofumigation is considered to be an environmentally safe practice, since no accumulation of heavy metals such as Cd, Co, Cu, Cr, Pb, Ni, or Zn was observed after the subsequent application of organic matter through the treatments.

The feasibility of using delta15N and delta13C values for discriminating between conventionally and organically fertilized pepper (Capsicum annuum L.).

A greenhouse experiment was conducted to determine the feasibility of using leaf and fruit delta15N and delta13C values to discriminate between conventionally and organically fertilized peppers, when conventional management involves the application of organic amendment for soil preparation. All of the treatments involved adding horse manure to the soil before applying different rates of synthetic N fertilizers: 0 (T1 and T2), 150 (T3), and 300 kg ha(-1) (T4). The difference between T1 and T2 was that no synthetic fertilizer had been applied to plot T1 during the 5 years prior to the experiment. Significant differences were found in the delta15N values of leaves and fruit from the plants grown under organic or mixed fertilization. The results indicate the possibility of using 15N natural abundance as an indicator of fertilization management. On the other hand, delta13C values did not contribute any additional information for discriminating between the organically and the synthetically and organically fertilized peppers.

Pesticide residue analysis of vegetables by gas chromatography with electron-capture detection.

A new and original analytical method was developed for the routine analysis of 28 multiclass pesticide residues in vegetables (green pepper, red pepper, and tomato). The extraction was performed with acetone, and the pesticides were partitioned into ethyl acetate-cyclohexane (1 + 1, v/v). Residue levels in vegetables were determined by gas chromatography (GC) with electron-capture detection. Residue identities were confirmed by GC coupled with mass spectrometry in the selected ion monitoring mode. The average recoveries in pepper and tomato obtained for all analytes studied were 67.3 and 123.1%, respectively, with relative standard deviation between 1.8 and 7.0%. The detection limit for the pesticides studied varied from 0.1 to 2.6 microg/kg. The proposed method was applied to the analysis of these compounds in vegetables grown in experimental greenhouses.

Determination of pesticide residues in lettuce by gas chromatography with electron-capture detection.

A sensitive, rapid, and simple multiresidue method for the simultaneous determination of 19 pesticides in different varieties of lettuce (Lactuca sativum) was developed. Lettuce samples were extracted by homogenization with acetone and partitioned into ethyl acetate-cyclohexane. Subsequent sample cleanup was not needed. Final determination was made by capillary gas chromatography (GC) with electron-capture detection (ECD). Confirmation analysis of pesticides was performed by GC coupled with mass spectrometry in the selected ion monitoring mode. The average recovery by the GC-ECD method obtained for these compounds varied from 66.4 to 119.2% with relative standard deviations < 7.7%. The GC-ECD method has good linearity, and the detection limit for the pesticides studied varied from 0.1 to 3.8 microg/kg. The proposed method was used to determine pesticide levels in different types of lettuce grown in soils from experimental fields.

Genotypic variability of carotenoids in traditional tomato cultivars.

Traditional varieties constitute a wide source of genetic variation that can be used per se or to obtain new cultivars with high consumer appeal and nutritional value. This work focuses on the carotenoid and chlorophyll profiles and contents of 53 traditional tomato cultivars, paying particular attention to compounds with recognized health-promoting properties. The study includes fruits with different shapes (oblate, slightly flattened, rounded, heart-shaped, long oblong and pyriform), colors (yellow, pink and red) and sizes (very small to very large). In addition, black colored tomato fruits with yellow, pink or red background color were studied. The highest concentrations of lycopene, ß-carotene, phytoene and phytofluene were found in pink and red tomatoes, while the highest concentrations of lutein, violaxanthin, neoxanthin and chlorophylls were found in fruits with a dark coloration, regardless of their background coloration. Finally, the highest concentrations of the studied compounds as a whole (except ß-carotene) were found in red- and pink-black varieties. Findings will hopefully contribute to recovering many tomato traditional varieties for use, directly in the field or as donor parents for breeding programs, to increase the nutraceutical properties of commercial varieties.