Reduction of the movement and persistence of pesticides in soil through common agronomic practices

Chemosphere 85 (2011) 1375–1382

Contents lists available at SciVerse ScienceDirect

Chemosphere journal homepage: www.elsevier.com/locate/chemosphere

Reduction of the movement and persistence of pesticides in soil through common agronomic practices José Fenoll a,⇑, Encarnación Ruiz a, Pilar Flores a, Pilar Hellín a, Simón Navarro b a b

Departamento de Calidad y Garantía Alimentaria, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), C/Mayor s/n, La Alberca, 30150 Murcia, Spain Departamento de Química Agrícola, Geología y Edafología, Facultad de Química, Universidad de Murcia, Campus Universitario de Espinardo, 30100 Murcia, Spain

a r t i c l e

i n f o

Article history: Received 27 May 2011 Received in revised form 27 July 2011 Accepted 29 July 2011 Available online 27 August 2011 Keywords: Groundwater pollution Organic amendment Pesticide movement Solar heating Soil decontamination

a b s t r a c t Laboratory and field studies were conducted in order to determine the leaching potential of eight pesticides commonly used during pepper cultivation by use of disturbed soil columns and field lysimeters, respectively. Two soils with different organic matter content (soils A and B) were used. Additionally, soil B was amended with compost (sheep manure). The tested compounds were cypermethrin, chlorpyrifosmethyl, bifenthrin, chlorpyrifos, cyfluthrin, endosulfan, malathion and tolclofos-methyl. In soil B (lower organic matter content), only endosulfan sulphate, malathion and tolclofos-methyl were found in leachates. For the soil A (higher organic matter content) and amended soil B, pesticide residues were not found in the leachates. In addition, this paper reports on the use of common agronomic practices (solarization and biosolarization) to enhance degradation of these pesticides from polluted soil A. The results showed that both solarization and biosolarization enhanced the degradation rates of endosulfan, bifenthrin and tolclofos-methyl compared with the control. Most of the studied pesticides showed similar behavior under solarization and biosolarization conditions. However, chlorpyrifos was degraded to a greater extent in the solarization than in biosolarization treatment. The results obtained point to the interest in the use of organic amendment in reducing the pollution of groundwater by pesticide drainage and in the use of solarization and biosolarization in reducing the persistence of pesticides in soil. Ó 2011 Elsevier Ltd. All rights reserved.

1. Introduction Groundwater contamination by nitrate, heavy metals, pesticides and other contaminants is an environmental and public health concern throughout the world. In particular, leaching of pesticides into the groundwater from agricultural practices is receiving increasing attention in European countries because groundwater represents about 98% of the available fresh water of our planet. Thus, the European Directive 98/83/EC concerning water used for human consumption establishes maximum concentrations for pesticides and their related products in drinking waters to safeguard people from harmful effects. In the leaching process, soil properties (total organic carbon content, pH, texture, mineralogy and structure), land use and management (pesticide application rate and timing, tillage), climate, subsoil and vadose zone characteristics, groundwater, and pesticide properties play a decisive role (Barbash et al., 2001; Si et al., 2006; Gilliom et al., 2007). In general, the mobility of pesticides and therefore their risk of leaching have been correlated with a weak adsorption on the soil matrix quantified in terms of small KOC values (Arias-Estevez et al., 2008). Generally, pesticides with KOC 6 1000 are potentially ⇑ Corresponding author. Tel.: +34 968366798; fax: +34 968366792. E-mail address: [email protected] (J. Fenoll). 0045-6535/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2011.07.063

leacher compounds although pesticides with KOC P 1000 have been find in groundwater and drainage water at several locations worldwide (Elliott et al., 2000; Vereecken, 2005). Soil amendment with animal manures or crop residues is a common soil management practice followed in agriculture. This practice contributes to increase soil organic matter and nutrient contents and also helps to solve environmental and economic problems related to the disposal of these waste materials. The retention and mobility of a pesticide in soil is determined by the extent and strength of sorption reactions, which are governed by the chemical and physical properties of the soils and pesticides involved (Spark and Swift, 2002). Several authors have investigated the effect of enhanced organic matter on the transport of pesticides (Dao, 1991; Guo et al., 1993; Sanchez-Camazano et al., 1996; Cox et al., 1997). In general, addition of organic matter, including soluble and insoluble fractions, increases the adsorption of pesticides and decreases their subsequent mobility in the soil profile (Worrall et al., 2001; Briceño et al., 2007). Moreover, the addition of organic amendment (OA) to soil normally results in an increase in the microbiological activity. As a consequence, OA enhances pesticide biodegradation in polluted soils (Felsot and Dzantor, 1995; Johnson et al., 1997). On the other hand, dissolved organic matter (DOM) is incorporated through OA. The complexation of pesticides with DOM lead to enhanced aqueous solubility, decreased

1376

J. Fenoll et al. / Chemosphere 85 (2011) 1375–1382

sorption, and enhanced transport of these compounds (Huang and Lee, 2001). This effect of DOM on sorption and subsequent transport will be dependent on the nature of the pesticide, soil and DOM, as well as the competition between pesticide–soil, pesticide–DOM, and DOM–soil interactions (Marschner et al., 2005; Cox et al., 2007). Solarization and biosolarization (combination of solarization and biofumigation) are two soil disinfection techniques, alternative to methyl bromide, currently used in the province of Murcia (southeast Spain) for growing vegetables in greenhouses (Ros et al., 2008). Solarization is based on solar heating of the soil by mulching with transparent polyethylene during the hot season (Katan and DeVay, 1991) and biofumigation is based on the use of gasses resulting from the decomposition of organic matter (De Leon et al., 2001; Matthiessen and Kirkegaard, 2006). These methods have produced good results, especially in low-input and organic farming systems, for the control of soil-borne pests and diseases, mostly as pre-planting soil treatments (Bello et al., 1999). In addition, soil solarization (Rubin and Benjamin, 1983; Avidov et al., 1985; Yarden et al., 1989; Navarro et al., 2009) and soil biosolarization (Fenoll et al., 2010a,b, 2011b; Flores et al., 2008) have been proposed in the recent years as methods to accelerate the degradation and natural attenuation of pesticide residues in soils. The first aim of the present research work was to study the mobility of eight pesticides (cypermethrin, chlorpyrifos-methyl, bifenthrin, chlorpyrifos, cyfluthrin, endosulfan, malathion and tolclofos-methyl), commonly used for pepper cultivation, in soils with different organic matter content. The second objective was to study the effect of solarization and biosolarization on the rate of loss of these pesticides.

2. Materials and methods 2.1. Chemicals Pesticide analytical standards (P98%) were obtained from Dr. Ehrenstorfer GmbH (Augsburg, Germany). The main physical– chemical properties of the active ingredients are shown in Table 1. Experimental values of octanol/water partition coefficient (KOW), soil/organic partition coefficient (KOC), aqueous solubility (SW), aqueous hydrolysis, and Groundwater Ubiquity Score (GUS) index were taken from The Pesticide Properties DataBase (PPDB, 2011). Pesticide grade dichloromethane, ethyl acetate, cyclohexane and n-hexane were supplied by Scharlau (Barcelona, Spain). Stocks solutions (1000 lg mL1) of each pesticide standard were prepared in ethyl acetate/cyclohexane (1/1, v/v), protected from light and stored at 5 °C. A pesticide intermediate standard solution was prepared by dilution in the same solvent to obtain a concentration of 10 lg mL1. Several standard solutions, with concentrations of 0.05–2 lg mL1, were injected to obtain the linearity

of detector response and the detection limits of the pesticides studied. The correlation coefficient was found to be >0.99 in all cases. 2.2. Leaching study 2.2.1. Soil and amendments for the leaching experiment The soils chosen for this study were two clay loam soils from the Campo de Cartagena (south-eastern Spain). Soil samples were collected from the surface (top 20 cm), air-dried, and passed through 2 mm sieve. Characteristics of the soils were as follows: Soil A: sand 37%, silt 30%, clay 33%, organic matter 1.59%, pH 7.86. Soil B: sand 37%, silt 33%, clay 30%, organic matter 0.22%, pH 8.71. For leaching experiment under laboratory conditions, an ecological compost (sheep manure) was used [pH = 7.1 (1/1, w/v), electrical conductivity 2.84 dS m1 (1/1, w/v), organic matter 91.0%]. Composting of manure was carried out in piles with periodical turning (indore method) over a period of 4 months. After composting, the compost was left untouched in static piles for 3 months to complete the maturation process. 2.2.2. Downward movement of the pesticides through the soil columns The experiment was performed according to the OECD guidelines (OECD, 2007). Downward movement of the pesticides was studied in polyvinyl chloride (PVC) columns of 40 cm (length)  4 cm (i.d.). There were three sets of columns: (i) soil A (200 g), (ii) soil B (200 g), and (iii) soil B (160 g) mixed with the compost (40 g). The top 3 cm of the columns were filled with sea sand and the bottom 3 cm with sea sand plus nylon mesh with an effective pore diameter of 60 lm to minimizing the dead-end volume and prevent losses of soil during the experiment. Before the application of the compound, columns (three replications at room temperature, avoiding direct light) were conditioned with 0.01 M CaCl2 in distilled water to their maximal water holding capacity and then allowed to drain for 24 h. The pore volume (PV) of the packed columns was estimated by the weight difference of water-saturated columns versus dry columns. The calculated PVs (mL) of the soil columns after saturation were 95.3 ± 4.3 (soil A), 66.0 ± 3.1 (soil B) and 86.2 ± 2.8 (soil B + compost). Following this, 2.5 mL of a methanol/water solution (10 + 90, v/v) containing 50 lg of each compound (equivalent to 200 g Ha1) were added to the top of each column. Twenty-four hours after pesticide application, the compounds were leached by adding 800 mL of 0.01 M CaCl2 during 16 d with a peristaltic pump. CaCl2 instead of water was used in order to minimize soil mineral balance disruption. 2.2.3. Leaching of pesticides at field conditions Leaching study of pesticides in field was studied in eight lysimeters (3.5 m  4 m  1 m depth) from an experimental greenhouse located in Torre-Pacheco (Murcia, Spain). There were two sets of lysimeters: (i) soil A and (ii) soil B. Soil lysimeter treatment

Table 1 Physical–chemical characteristics of the pesticides used in this study.

a b c

Active ingredient

Molecular formula

Molecular weight

Log KOW

SWa

Aqueous hydrolysisb

Soil sorption log KOC

GUS indexc

Chlorpyrifos-methyl Tolclofos-methyl Malathion Chlorpyrifos Endosulfan (a + b) Bifenthrin Cyfluthrin Cypermethrin

C7H7Cl3NO3PS C9H11Cl2O3PS C10H19O6PS2 C9H11Cl3NO3PS C9H6Cl6O3S C23H22ClF3O2 C22H18Cl2FNO3 C22H19Cl2NO3

322.5 301.1 330.4 350.9 406.9 422.9 434.3 416.3

4.0 4.6 2.8 4.7 4.7 5.4 6.0 5.3

2.7 0.7 148 1.1 0.3 0.001 0.007 0.009

21 97 6 26 20 Stable 215 179

3.7 3.6 2.3 3.9 4.1 3.0 4.8 4.9

0.2 0.3 1.3 0.2 0.1 1.9 1.2 1.7

Water solubility (mg L1). DT50 (d) at 20 °C and pH = 7. Groundwater Ubiquity Score (GUS) index. Leachability in parentheses: (L, low; M, medium; H, high).

(L) (L) (L) (L) (L) (L) (L) (L)

1377

J. Fenoll et al. / Chemosphere 85 (2011) 1375–1382

was applied with a sprayer (Matabi) with an adjustable nozzle size of 1 mm using the following commercial formulation: Rizolex (50% tolclofos-methyl), Clortrin (2% of cypermethrin and 20% of chlorpyrifos-methyl), Talstar (10% bifenthrin), Dursban (48% chlorpyrifos), Baytroid (5% cyfluthrin), Arasulfan (35% endosulfan) and Afrathion (50% malathion). The soil lysimeter was irrigated every 3 d by three dripper lines (45 min per day and 50 L per lysimeter). One application (0.5 L of solution per lysimeter) was carried out on May 7th, 2008, at the doses recommended by the manufacturers (40 kg ha1 for tolclofos-methyl, 200 mL h L1 for cypermethrin and chlorpyrifos-methyl, 60 mL h L1 for bifenthrin, 170 mL h L1 for chlorpyrifos, 70 mL h L1 for cyfluthrin, 225 mL h L1 for endosulfan and 250 mL h L1 for malathion). Water samples were collected during 180 d. 2.3. Soil remediation study The assay was carried out during the summer season (August– October 2008) in a greenhouse situated in Torre-Pacheco (Murcia, Spain). 17-L pots were filled with clay–loam soil (33% clay, 30% silt, 37% sand) with a pH of 7.86 and 1.59% organic matter content (soil A). Treatments consisted of a control (C), in which soils were not exposed to any disinfection technique, and the application of solarization (S) and biosolarization (BS). Twenty-five pots were used per treatment distributed in a completely randomized design (CRD). For the S treatments, the top of the pots were covered with a low-density polyethylene film (LDPE) (Sotrafa, 50 lm thick, low density), with a headspace between the film and the soil. For the BS treatments, manure was applied to the pots at a rate of 400 g pot1 (according to the rate recommended for the adequate control of soilborne fungi) and then thoroughly mixed with the soil. Then, soils plus manure were covered with LDPE, similarly to the pots in the S treatment. In all the pots, soil or manure plus soil, weighed 8 kg so that the pots were of a uniform mass. The organic matter used for biofumigation was a mixture of sheep and chicken manures [pH = 8.46 (1/10, w/v), electrical conductivity 10.2 dS m1 (1/10, w/v), organic matter 63.1%]. Afterwards, all the pots (C, S and BS) were spiked with the pesticides of interest using above commercial formulations. For this, 25 mL of a solution containing 8 mg of each compound (except for cypermethrin, 0.8 mg of compound) were applied to each pot, before irrigating to field capacity. Five pots per treatment were sampled periodically up to 90 d after the beginning of the treatments, for which the whole soil of each pot was air-dried, passed through a 2 mm sieve and homogenized. 2.4. Analytical determinations An Agilent (Waldbronn, Germany) HP 6890 gas chromatograph equipped with a 5973N mass spectrometer and automatic split– splitless injector Agilent 7683 was operated in electron impact ionization mode with an ionizing energy of 70 eV, scanning from m/z 50 to 500 at 3.21 s per scan. The ion source temperature was 230 °C, and the quadrupole temperature was 150 °C. The electron multiplier voltage (EM voltage) was maintained at 1300 V, and a solvent delay of 4.5 min was employed. An HP-5MSI fused silica capillary column (30 m  0.25 mm i.d.) and 0.25 lm film thickness, supplied by Agilent Technologies, was employed. The column temperature was maintained at 70 °C for 2 min and then programmed at 25 °C min1 to 150 °C, increased to 200 °C at a rate of 3 °C min1, followed by a final ramp to 280 °C at a rate of 8 °C min1, and held for 10 min. One microliter of samples was injected in splitless mode. Analysis was performed with selected ion monitoring (SIM) mode using primary and secondary ions. The target and qualifier abundances were determined by injection of individual pesticide standards under the same chromatographic

conditions using full scan with the mass/charge ratio ranging from m/z 50 to 500. Pesticides were confirmed by their retention times, the identification of target and qualifier ions, and the determination of qualifier-to-target ratios (Table 2). Retention times had to be within 0.1 min of the expected time, and qualifier-to-target ratios had to be within a 10% range for positive confirmation. The concentration of each compound was determined by comparing the peak areas in the sample to those found for mixtures of pesticide standards of known concentration. 2.5. Pesticide analysis The leachates were quantitatively collected (50 mL d1) at the bottom of the columns, filtered through nylon membrane filter (0.45 lm) and extracted with 40 mL of n-hexane-dichloromethane 1:1 mixture solvent. At the end of the experiment, the columns were opened and the soil separated in two segments of approximately 10 cm each one. Dried soil samples (5 g) were extracted with 30 mL of acetonitrile/water (2/1) by sonication. After, 20 mL of dichloromethane were added and then centrifuged for 10 min at 1900g. Recoveries from soil and water ranged from 86% to 115% and limits of quantification (LOQ, signal-to noise ratio 10) varied from 0.9 to 11 lg kg1 and 0.02 to 0.2 lg L1 in soil and water, respectively. Determination of pesticide residues in leachates and soil extracts was accomplished in both cases by GC/MS. 2.6. Model used for pesticide dissipation in soil Among several models that have been used to describe pesticide degradation in soil, the first-order model is the most widely used (Zimdahl et al., 1994). However, the dissipation of pesticides in the surface soil sometimes better fits a biphasic kinetics, in which each phase consists of a single-exponential decrease (Henriksen et al., 2004), according to the equation Rt ¼ a  ekt þ b  ekt 1 2 , where Rt is the concentration of residue in soil and k1 and k2 are the dissipation rate constants of each phase. In this equation, the sum of the two constants, a and b, is approximately equal to R0 (concentration of residue in soil at time zero) and expresses the quantitative partition between the two compartments. 2.7. Statistical analysis The curve fitting were obtained using SigmaPlot version 12 statistical software (Systat, Software Inc., San Jose, CA). Main effect Table 2 Retention times (RT, min), target (T), qualifier ions (Q1, Q2 and Q3) (m/z) and abundance ratios (%) of qualifier ion/target ion (Q1/T and Q2/T)* of the tested pesticides.

*

Pesticide

RT

T

Q1

Q2

Q3

Q1/T

Q2/T

Chlorpyrifos-methyl Tolclofos-methyl Malathion Chlorpyrifos Endosulfan (alpha isomer) Endosulfan (beta isomer) Endosulfan sulfate Bifenthrin Cyfluthrin I Cyfluthrin II Cyfluthrin III Cyfluthrin IV Cypermethrin I Cypermethrin II Cypermethrin III Cypermethrin IV

16.59 16.81 18.80 19.23 22.64 25.16 26.76 28.84 32.22 32.36 32.48 32.54 32.69 32.84 32.97 33.02

286 265 173 197 241 195 272 181 163 163 163 163 181 181 163 163

288 267 127 199 195 237 274 165 206 206 206 206 163 163 181 181

125 125 125 314 239 207 229 166 165 165 165 227 165 165 165 165

290 266 93 97 237 241 237 182 227 227 227 199 77 209 209 209

68.6 37.6 85.3 93.2 98.2 85.0 82.8 26.0 69.3 71.0 67.2 65.7 87.2 95.0 81.2 81.4

48.5 19.4 83.5 70.1 90.5 81.6 61.7 25.5 65.9 66.2 66.8 52.4 75.3 80.3 65.9 64.2

Q/T (%) ratios are the results of abundance values of the qualifier ion (Q1, Q2) divided by the abundance of the target ion (T)  100.

1378

J. Fenoll et al. / Chemosphere 85 (2011) 1375–1382

(disinfection treatment) and differences between means were analyzed statistically using the SPSS 15.0 software (SPSS Inc., Chicago, IL) package, by ANOVA and Tukey’s Multiple Range Test, respectively.

A

α− endosulfan β -endosulfan endosulfan sulphate chlorpyrifos-methyl chlorpyrifos bifenthrin cypermethrin cyfluthrin malathion tolclofos-methyl

50

40

3. Results and discussion 30

3.1. Leaching and persistence of pesticides on unamended and amended soils

10

0

B

α− endosulfan β -endosulfan endosulfan sulphate chlorpyrifos-methyl chlorpyrifos bifenthrin cypermethrin cyfluthrin malathion tolclofos-methyl

50

Amount recovered (µg)

The greater water pore volumes observed in soil A, with high organic matter content, and in soil C, with organic amendment, can be attributed to the beneficial effect of organic matter on pore size distribution by decreasing the larger pores and increasing the smaller ones. Similarly, Cox et al. (2001) showed a reduction of large conducting pores (>1 lm) upon amendment with solid sewage sludge compared to liquid amendment of the same material. These authors suggested that insoluble OM cements and aggregates together soil particles, blocking large conducting pores. As observed in Fig. 1, where the distribution in soil and leaching water of pesticides applied to soil and amended soil columns is shown, the presence and/or addition of OM drastically reduced the movement of the pesticides. The amount of retained pesticides along the soil A (higher organic matter content) ranged from 0.7% for malathion to 98% to bifenthrin, while no pesticide residues were found in leachates. In soil B (lower organic matter content), total recoveries of pesticides from soil were in the range of 0–98%, and only endosulfan sulphate, malathion and tolclofosmethyl were found in leachates (8%, 3% and 1% of the total mass fraction applied to the column). In soils A and B, only endosulfan sulfate and tolclofos-methyl were recovered from both the upper and lower soil layers. For these pesticides, the highest recoveries in soil A were achieved from the top 10 cm layer. However, in soil B, similar amounts of tolclofos-methyl were recovered from both soil fractions, while for endosulfan sulphate, 30% and 18% of its residue level was recovered from the upper and lower soil B layers, respectively. In addition, for tolclofos-methyl, no more than 2% of the added amount was recovered from the bottom soil fraction. Finally, for the soil C (soil B plus compost) pesticide residues were not found in the bottom soil fraction or in the leachates. The amount recovered from the top soil fraction ranged from 0% to 98% of the initial mass applied to the columns for malathion and cyfluthrin, respectively. The breakthrough curves (BTCs) of endosulfan sulphate, malathion and tolclofos-methyl show that leaching begins at about 6, 1 and 4 PV respectively (Fig. 2). As regards malathion, leaching ends at about 2 PV, probably due to its rapid hydrolytic degradation. At the end of the experiment, when 9 PV were leached, the shape of the curve with upward tendency for endosulfan sulfate and tolclofos-methyl indicated a certain interaction with the organic and inorganic soil colloids (Fenoll et al., 2011a). For all those pesticides which are of low polarity and water solubility (cypermethrin, chlorpyrifos-methyl, bifenthrin, chlorpyrifos, cyfluthrin, endosulfan, and tolclofos-methyl) organic matter will be the important sorbent, simply because the solvent is water and hydrophobic interactions are the driving force. However, for more polar solutes like malathion log (KOW < 3), surfaces of other materials in soils, mainly clay mineral surfaces can become important sorbents, particularly in the soils where the organic matter fraction is low. KOC values are universally used as measures of the relative potential mobility of pesticides in soils and the fugacity models describing the partitioning in soil/water/atmosphere systems (Wauchope et al., 2002). However, soil/water/pesticide systems exhibit much more complex behavior. Ideally, equilibrium sorption should be instantaneous as reported in many mathematical models describ-

20

40

30

20

10

0

C

α− endosulfan β -endosulfan endosulfan sulphate chlorpyrifos-methyl chlorpyrifos bifenthrin cypermethrin cyfluthrin malathion tolclofos-methyl

50

40

30

20

10

0 0-10

10-20

leachate

Soil depth (cm) and water Fig. 1. Distribution of pesticides applied to soil A (A), soil B (B) and soil C (C) columns. The error bars denote standard deviation.

ing leaching and sorption. Thus, leaching through the soil is reduced and the time for microbial degradation increased. However, it has been reported that non-equilibrium processes likely occur during the transport of pesticides in soils, mostly caused by intrasorbent diffusion, which results from rate-limited mass transfer of sorbate from the exterior surface of the sorbent into the interior of the sorbent matrix (Brusseau and Rao, 1989a,b). Bearing in mind the total amount found in leachates (3.8, 1.4 and 0.4 lg), endosulfan sulphate, malathion and tolclofos-methyl showed an moderate leaching potential in the used conditions. As a consequence, these compounds have a potential risk for provoking the pollution of groundwater. On the contrary, cypermethrin, chlorpyrifos-methyl, bifenthrin, chlorpyrifos, cyfluthrin and endosulfan (a + b) behaved as ‘‘non-leacher’’ pesticides. The degradation rates of malathion, chlorpyrifos and chlorpyrifos-methyl in both soils were very fast and it can be attributed to

1379

Amount leached (µg)

A

0,8 tolclofos-methyl endosulfan sulfate malathion 0,6

0,4

0,2

0,0

B

5

Amount leached (µg)

J. Fenoll et al. / Chemosphere 85 (2011) 1375–1382

4

tolclofos-methyl endosulfan sulfate malathion

3

2

1

0 0

2

4

6

8

10

12

PV

0

2

4

6

8

10

12

PV

Fig. 2. Relative (A) and cumulative (B) breakthrough curves (BTCs) of ‘‘leacher’’ pesticides applied to soil B columns.

the rapid rate of hydrolysis of these compounds (Roberts and Hutson, 1999; Tomlin, 2006). Thus, in soil B, only chlorpyrifos was found in soil (6% of the total mass fraction applied to the column). As regards soil A, the amount recovered of malathion, chlorpyrifos and chlorpyrifos-methyl was lower than 2%, 7% and 24%, respectively. For tolclofos-methyl, a-endosulfan, b-endosulfan and endosulfan sulphate, the difference between initial and recovered amounts can be attributed to biochemical and hydrolytic degradation during the experiment (Roberts and Hutson, 1999; Tomlin, 2006). Finally, the pyrethroids (bifenthrin, cypermethrin and cifluthrin) were not degraded in soil during the experiment. Field studies with the same soils and using soil lisymeters (Fig. 3) corroborated the presence and absence of the studied pesticides in leaching water. Thus, no pesticide residues were found in leachates (soil A), while in soil B, only endosulfan sulphate, malathion and tolclofos-methyl were found in leachates (total amount found in leachates: 325, 60 and 19 lg). In addition, bearing in mind the final amount found in soil, all pesticides, except chlorpyrifosmethyl, were recovered from the soil A, while only bifenthrin was found in soil B (Table 3). The environmental effect of the amendment on pesticide transport is ambiguous. On the one hand, it could enhance their retention by increasing soil organic carbon content (Albarran et al., 2004). On the other hand, DOM could facilitate their transport (Li et al., 2005). As we previously demon-

400

Amount leached (µg)

tolclofos-methyl endosulfan sulfate malathion

300

200

100

0 0

500

1000

1500

2000

Water leached (L) Fig. 3. Cumulative breakthrough curves (BTCs) of ‘‘leacher’’ pesticides applied to soil B lysimeter.

strated for other pesticides (Fenoll et al., 2010a, 2011a), the higher leachability of the studied pesticides was probably due to the low organic matter content of the soil B. However, some authors have not found relation between the amount of organic matter in the different amendments and the rate of adsorption of some pesticides because the structure (specific surface, particle size, etc.) of the substrate material could largely influence the sorption rate (De Wilde et al., 2008).

3.2. Dissipation of pesticides in soil by solarization and biosolarization Bearing in mind the persistence of the studied compounds in soil A, it is interesting to study tools (solarization and biosolarization) to accelerate the dissipation of these pesticides. The biphasic model satisfactorily explained the dissipation process of the pesticides studied in non-disinfected (C), solarized (S) and biosolarized (BS) soils during the greenhouse study, with r > 0.994 in all cases (Table 4). After application, the initial soil concentration for the pesticides ranged from 0.7 to 1.0 mg kg1, except for cypermethrin, which was 0.14 mg kg1 (Fig. 4). Bifenthrin showed the lowest degradation rates of all the studied fungicides in C, S and BS soils, probably due to its high KOC value (Table 1). For bifenthrin, higher degradation rates were observed in disinfected soils (S and BS) than in the control and no significant differences between S and BS treatments were observed. As regards cypermethrin and cifluthrin degradation, no significant differences between C, S and BS treatments were observed (Table 4). As far as tolclofos-methyl methyl, malathion and chlorpyrifosmethyl are concerned, these compounds showed by far the highest dissipation rate among all the studied pesticides. For malathion and chlorpyrifos-methyl no significant differences between C, S and BS treatments were observed, probably due to the high rate of hydrolysis of these pesticides (Roberts and Hutson, 1999; Tomlin, 2006). For tolclofos-methyl, statistical analyses showed significant differences (p < 0.001) between the C treatment and disinfected soils (S and BS) but no significant differences were observed between S and BS treatments. These results can be attributed to the fast biochemical and hydrolytic degradation of this compound per se which could disguise the effect of S and BS. For chlorpyrifos, higher degradation rates were observed in C and S than in BS treatments. However, no significant differences between C and S treatments were observed (Table 4). Under control, solarization and biosolarization conditions, degradation rate was similar for alpha- and beta-endosulfan. The major metabolite (endosulfan sulphate) was detected in all the treatments. The amount of this metabolite increased during the first 30 d and afterwards, this compound degraded more slowly

1380

J. Fenoll et al. / Chemosphere 85 (2011) 1375–1382

Table 3 Pesticide concentrations in soil at the end of the leaching field experiment. Concentration found (lg g1)a Soil A depth (cm)

Chlorpyrifos-methyl Tolclofos-methyl Malathion Chlorpyrifos Endosulfan (alpha isomer) Endosulfan (beta isomer) Endosulfan sulfate Bifenthrin Cyfluthrin Cypermethrin a

Soil B depth (cm)

0–20

20–40

0–20

20–40

– 0.662 ± 0.092 0.022 ± 0.008 0.055 ± 0.018 0.013 ± 0.004 0.089 ± 0.014 0.101 ± 0.019 0.058 ± 0.010 0.041 ± 0.092 0.053 ± 0.007

– 0.381 ± 0.060 – 0.028 ± 0.008 – 0.056 ± 0005 0.077 ± 0.013 0.036 ± 0.009 – 0.024 ± 0.006

– – – – – – – 0.016 ± 0.006 – –

– – – – – – – 0.012 ± 0.005 – –

Mean of 12 determinations ± SD.

Table 4 Kinetic parameters obtained for tested pesticides as affected by non-disinfection, solarization and biosolarization. Parameter þ b  ekt (biphasic kinetics) Rt ¼ a  ekt 1 2 TEEa

a

k1

b

k2

DT50

Chlorpyrifos-methyl Control 0.999 Solarization 0.999 Biosolarization 1.000

0.009 0.009 0.002

0.800 0.750 0.799

2.122 2.825 2.565

0.055 0.106 0.056

0.018 0.056 0.046

0.4a 0.3a 0.3a

Tolclofos-methyl Control 0.998 Solarization 0.999 Biosolarization 0.999

0.055 0.035 0.030

1.024 1.004 0.534

0.032 0.065 0.090

0.028 0.038 0.507

0.000 0.001 0.090

23a 11b 8b

Malathion Control Solarization Biosolarization

0.999 0.999 1.000

0.018 0.016 0.002

0.781 0.792 0.827

3.921 4.312 4.292

0.035 0.056 0.020

0.035 0.019 0.001

0.2a 0.2a 0.2a

Chlorpyrifos Control Solarization Biosolarization

1.000 1.000 0.994

0.002 0.005 0.053

0.433 0.495 0.366

0.141 0.113 0.019

0.288 0.227 0.378

0.028 0.023 0.019

9a 9a 36b

Endosulfan (alpha isomer) Control 0.999 0.005 Solarization 1.000 0.003 Biosolarization 0.999 0.007

0.297 0.371 0.344

0.083 0.125 0.111

0.174 0.100 0.127

0.008 0.011 0.009

15a 8b 9b

Endosulfan (beta Control Solarization Biosolarization

r

isomer) 0.999 1.000 1.000

0.002 0.001 0.002

0.137 0.246 0.179

0.125 0.103 0.119

0.159 0.050 0.118

0.016 0.014 0.017

15a 8b 10b

Bifenthrin Control Solarization Biosolarization

0.995 0.997 0.999

0.006 0.020 0.005

0.058 0.183 0.209

0.112 0.191 0.204

0.865 0.739 0.714

0.000 0.002 0.002

630000a 235b 218b

Cyfluthrin Control Solarization Biosolarization

1.000 0.998 0.999

0.005 0.040 0.016

0.733 0.661 0.423

0.079 0.105 0.144

0.179 0.251 0.488

0.005 0.011 0.018

12a 10a 13a

Cypermethrin Control Solarization Biosolarization

0.999 0.999 0.999

0.005 0.005 0.003

0.073 0.101 0.056

0.117 0.095 0.189

0.068 0.040 0.085

0.016 0.012 0.022

13a 11a 12a

a Typical error of estimate. Different letters in the ‘‘DT50’’ column indicate significant differences between means according to Tukey’s test.

than the parent. For, alpha-, beta-endosulfan and endosulfan sulphate, soil disinfection led to a higher dissipation rate compared to the control treatment but with no significant differences between both treatments (Table 4).

As reviewed by Briceño et al. (2007), the principal cause of pesticide persistence in soil is commonly the lack of favorable conditions (availability, levels of nutrient, moisture conditions, aeration level, temperature, pH, etc.) for microbial degradation. All of them differ in importance, depending of the pesticide involved. The general effect of solarization and biosolarization on the studied pesticides was to enhance the residue dissipation rate. In our case, temperature and soil moisture can be considered the most important factors. This effect can be attributed, on the one hand, to an increase in the soil temperature and, on the other, to a higher number of accumulated hours at high temperature in the disinfected soils compared with the control (Fenoll et al., 2010b). Thus, in the control treatment, the maximum temperature reached by the soil was 43 °C whereas in solarized and biosolarized soils temperature reached 57 and 59 °C, respectively. These increases in temperature favors desorption of pesticides and in consequence they are more available for microbial degradation, enhancing the action of catalytic substances. Also, pesticide degradation has been found to increase with increasing soil moisture content (Dungan et al., 2003) and several studies have shown that an increase in soil pH results in an increase in soil microbial biomass and enzymatic activities, favoring a rapid growth-linked degradation (Shing et al., 2003). However, for malathion and chlorpyrifos-methyl, no significant differences between C, S and BS treatments were observed, probably due to the high rate of hydrolysis and the high rate constant degradation of these pesticides. As regards chlorpyrifos, no significant effect of S on degradation was observed compared to C. Moreover, a negative effect of BS on chlorpyrifos degradation was observed with regard to C or S treatments. Organic matter has a high potential for bioremediation when it is used as amendment, due to the large populations of microorganisms that are generally contained within it (Gupta and Baummer, 1996). Therefore, BS might be expected to show a higher bioremediation effect than S. However, the application of organic matter to the soil may affect pesticide degradation by increasing soil pesticide adsorption (Navarro et al., 2007). This effect could mask the enhancing effect of microbial activity on pesticide degradation, and could explain why in our study, several pesticides showed similar degradation in BS than in S, such as in the case of bifenthrin, endosulfan (a + b) and tolclofos-methyl or even lower degradation in BS than in S or C treatment, in the case of chlorpyrifos. Contrary trends are reported in literature on pesticide fate, and these are largely because of the differences in soil types, pesticide characteristics, and source of amendments, considered as complications for obtain a tendency pattern and making difficult the understanding of pesticide fates (Briceño et al., 2007).

1381

J. Fenoll et al. / Chemosphere 85 (2011) 1375–1382 0.6

α−endosulfan

0.5

β−endosulfan

0.3

0.4 0.2 0.3 0.2

0.1

0.1 0.0 0.0

endosulfan sulphate

0.06

bifenthrin

1.0

0.8 0.04 0.6

0.4

0.02

0.2 0.00 0.0

cyfluthrin

Residue level (mg kg-1)

1.0

cypermethrin 0.15

0.8 0.10

0.6

0.4

0.05

0.2 0.00 0.0 1.0

chlorpyrifos-methyl

chlorpyrifos

0.8

0.8 0.6 0.6 0.4 0.4 0.2

0.2

0.0

0.0

malathion

tolclofos-methyl

0.8

1.0 0.8

0.6 0.6 0.4 0.4 0.2

0.2

0.0

0.0 0

20

40

60

80

0

20

40

60

80

Time (days) 1

Fig. 4. Dissipation curves of pesticide residues (mg kg means ± SD (n = 5).

), fitted to the biphasic kinetics model, in non-disinfected (d), solarized (N) and biosolarized (j) soils. Data are

4. Conclusions This study summarizes the effect of different agronomic practices on the movement and persistence of several pesticides. As general rule, the use of compost (organic amendment) drastically

reduces the mobility of these compounds in soils with low organic matter content. The leaching reduction can be attributed to the increased sorption capability on the amended soils although other possibilities as direct degradation by the organic matter in the columns or lysimeters must be considered. On the other hand,

1382

J. Fenoll et al. / Chemosphere 85 (2011) 1375–1382

the results obtained in this work indicate the efficiency of the use of solarization and biosolarization in decreasing the persistence of some pesticides in the soil, probably as a result of the increased microbial activity by changes in temperature and soil moisture. Therefore, solarization and biosolarization can be considered as a bioremediation tool for pesticide-polluted soils. Acknowledgements The authors acknowledge financial support from Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Project RTA2005-00127-00-00), from the European Social and FEDER Funds and from Ministerio de España de Ciencia e Innovación through the Ramon and Cajal Subprogram. In addition, the authors are grateful to Inmaculada Garrido, Juana Cava and María V. Molina for technical assistance. References Albarran, A., Celis, R., Hermosin, M.C., Lopez-Pineiro, A., Cornejo, J., 2004. Behaviour of simazine in soil amended with the final residue of the olive-oil extraction process. Chemosphere 54, 717–724. Arias-Estevez, M., Lopez-Periago, E., Martinez-Carballo, E., Simal-Gandara, J., Mejuto, J.C., Garcia-Rio, L., 2008. The mobility and degradation of pesticides in soils and the pollution of groundwater resources. Agriculture Ecosystems & Environment 123, 247–260. Avidov, E., Aharonson, N., Katan, J., Rubin, B., Yarden, O., 1985. Persistence of terbutryn and atrazine in soil as affected by soil disinfestation and fungicides. Weed Science 33, 457–461. Barbash, J.E., Thelin, G.P., Kolpin, D.W., Gilliom, R.J., 2001. Major herbicides in ground water: results from the National Water-Quality Assessment. Journal of Environmental Quality 30, 831–845. Bello, A., Lopez-Perez, A., Diaz-Viruliche, L., de Leon, L., Sanz, R., Esmer, M., 1999. Local resources as methyl bromide alternatives in nematode control. Nematropica 29, 116. Briceño, G., Palma, G., Durán, N., 2007. Influence of organic amendment on the biodegradation and movement of pesticides. Critical Reviews in Environmental Science and Technology 37, 233–271. Brusseau, M.L., Rao, P.S.C., 1989a. Sorption nonideality during organic contaminant transport in porous-media. Critical Reviews in Environmental Control 19, 33– 99. Brusseau, M.L., Rao, P.S.C., 1989b. The influence of sorbate–organic matter interactions on sorption nonequilibrium. Chemosphere 18, 1691–1706. Cox, L., Celis, R., Hermosin, M.C., Becker, A., Cornejo, J., 1997. Porosity and herbicide leaching in soils amended with olive-mill wastewater. Agriculture Ecosystems & Environment 65, 151–161. Cox, L., Cecchi, A., Celis, R., Hermosin, M.C., Koskinen, W.C., Cornejo, J., 2001. Effect of exogenous carbon on movement of simazine and 2,4-D in soils. Soil Science Society of America Journal 65, 1688–1695. Cox, L., Velarde, P., Cabrera, A., Hermosin, M.C., Cornejo, J., 2007. Dissolved organic carbon interactions with sorption and leaching of diuron in organic-amended soils. European Journal of Soil Science 58, 714–721. Dao, T.H., 1991. Field decay of wheat straw and its effects on metribuzin and s-ethyl metribuzin sorption and elution from crop residues. Journal of Environmental Quality 20, 203–208. De Leon, L., Lopez-Perez, J.A., Rodriguez, A., Casanova, D., Arias, M., Bello, A., 2001. Management of Meloidogyne arenaria in protected crops of Swiss chard in Uruguay. Nematropica 31, 103–108. De Wilde, T., Mertens, J., Spanoghe, P., Ryckeboer, J., Jaeken, P., Springael, D., 2008. Sorption kinetics and its effects on retention and leaching. Chemosphere 72, 509–516. Dungan, R., Gan, J., Yates, S., 2003. Accelerated degradation of methyl isothiocyanate in soil. Water, Air and Soil Pollution 142, 299–310. Elliott, J.A., Cessna, A.J., Nicholaichuk, W., Tollefson, L.C., 2000. Leaching rates and preferential flow of selected herbicides through tilled and untilled soil. Journal of Environmental Quality 29, 1650–1656. Felsot, A.S., Dzantor, E.K., 1995. Effect of alachlor concentration and an organic amendment on soil dehydrogenase-activity and pesticide degradation rate. Environmental Toxicology and Chemistry 14, 23–28. Fenoll, J., Ruiz, E., Flores, P., Hellin, P., Navarro, S., 2010a. Leaching potential of several insecticides and fungicides through disturbed clay–loam soil columns. International Journal of Environmental Analytical Chemistry 90, 276–285. Fenoll, J., Ruiz, E., Hellin, P., Navarro, S., Flores, P., 2010b. Solarization and biosolarization enhance fungicide dissipation in the soil. Chemosphere 79, 216–220. Fenoll, J., Ruiz, E., Flores, P., Vela, N., Hellin, P., Navarro, S., 2011a. Use of farming and agro-industrial wastes as versatile barriers in reducing pesticide leaching through soil columns. Journal of Hazardous Materials 187, 206–212.

Fenoll, J., Ruiz, E., Hellin, P., Martinez, C.M., Flores, P., 2011b. Rate of loss of insecticides during soil solarization and soil biosolarization. Journal of Hazardous Materials 185, 634–638. Flores, P., Lacasa, A., Fernandez, P., Hellin, P., Fenoll, J., 2008. Impact of biofumigation with solarization on degradation of pesticides and heavy metal accumulation. Journal of Environmental Science and Health Part B – Pesticides Food Contaminants and Agricultural Wastes 43, 513–518. Gilliom, R.J., Barbash, J.E., Crawford, C.G., Hamilton, P.A., Martin, J.D., Nakagaki, N., Nowell, L.H., Scott, J.C., Stackelberg, P.E., Thelin, G.P., Wolock, D.M., et al., 2007. Pesticides in streams and ground water of the United States. In: Del Re, A.A.M., XIII (Eds.), Symposium Pesticide Chemistry—Environmental Fate and Ecological Effects of Pesticides. La Goliardica Pavese s.r.l. pp. 731–742. Guo, L., Bicki, T.J., Felsot, A.S., Hinesly, T.D., 1993. Sorption and movement of alachlor in soil modified by carbon-rich wastes. Journal of Environmental Quality 22, 186–194. Gupta, G., Baummer, J., 1996. Biodegradation of atrazine in soil using poultry litter. Journal of Hazardous Materials 45, 185–192. Henriksen, T., Svensmark, B., Juhler, R.K., 2004. Degradation and sorption of metribuzin and primary metabolites in a sandy soil. Journal of Environmental Quality 33, 619–627. Huang, X.J., Lee, L.S., 2001. Effects of dissolved organic matter from animal waste effluent on chlorpyrifos sorption by soils. Journal of Environmental Quality 30, 1258–1265. Johnson, A.C., Worrall, F., White, C., Walker, A., Besien, T.J., Williams, R.J., 1997. The potential of incorporated organic matter to reduce pesticide leaching. Toxicological and Environmental Chemistry 58, 47–61. Katan, J., DeVay, J.E., 1991. Soil Solarization. CRC Press, London. Li, K., Xing, B.S., Torello, W.A., 2005. Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching. Environmental Pollution 134, 187–194. Marschner, B., Winkler, R., Jodemann, D., 2005. Factors controlling the partitioning of pyrene to dissolved organic matter extracted from different soils. European Journal of Soil Science 56, 299–306. Matthiessen, J.N., Kirkegaard, J.A., 2006. Biofumigation and enhanced biodegradation: opportunity and challenge in soilborne pest and disease management. Critical Reviews in Plant Sciences 25, 235–265. Navarro, S., Vela, N., Navarro, G., 2007. Review. An overview on the environmental behaviour of pesticide residues in soils. Spanish Journal of Agricultural Research 5, 357–375. Navarro, S., Bermejo, S., Vela, N., Hernandez, J., 2009. Rate of loss of simazine, terbuthylazine, isoproturon, and methabenzthiazuron during soil solarization. Journal of Agricultural and Food Chemistry 57, 6375–6382. OECD Organisation for Economic Cooperation and Development Guidelines for Testing of Chemicals, 2007. No. 312, Leaching in Soil Columns, Paris. The Pesticide Properties DataBase (PPDB), 2011. Agriculture & Environment Research Unit (AERU) at the University of Hertfordshire. . Roberts, T., Hutson, D., 1999. Metabolic pathways of agrochemicals. Part two. In: Roberts, T., Hutson, D. (Eds.), Insecticides and Fungicides. The Royal Society of Chemistry, Thomas Grahan House, Cambridge, England. Ros, M., Garcia, C., Hernandez, M.T., Lacasa, A., Fernandez, P., Pascual, J.A., 2008. Effects of biosolarization as methyl bromide alternative for Meloidogyne incognita control on quality of soil under pepper. Biology and Fertility of Soils 45, 37–44. Rubin, B., Benjamin, A., 1983. Solar heating of the soil-effect on weed-control and on soil-incorporated herbicides. Weed Science 31, 819–825. Sanchez-Camazano, M., Sanchez-Martin, M.J., Poveda, E., Iglesias-Jimenez, E., 1996. Study of the effect of exogenous organic matter on the mobility of pesticides in soils using soil thin-layer chromatography. Journal of Chromatography A 754, 279–284. Shing, B., Walker, A., Morgan, J., Wright, D., 2003. Effects of soil pH on the biodegradation of chlorpyrifos and isolation of a chlorpyrifos-degrading bacterium. Applied Environmental Microbiology 69, 5198–5206. Si, Y.B., Zhang, J., Wang, S.Q., Zhang, L.G., Zhou, D.M., 2006. Influence of organic amendment on the adsorption and leaching of ethametsulfuron-methyl in acidic soils in China. Geoderma 130, 66–76. Spark, K.M., Swift, R.S., 2002. Effect of soil composition and dissolved organic matter on pesticide sorption. Science of the Total Environment 298, 147–161. Tomlin, C.D.S., 2006. The Pesticide Manual, 14th ed. British Crop Protection Council, Hampshire, England. Vereecken, H., 2005. Mobility and leaching of glyphosate: a review. Pest Management Science 61, 1139–1151. Wauchope, R.D., Yeh, S., Linders, J., Kloskowski, R., Tanaka, K., Rubin, B., Katayama, A., Kördel, W., Gerstl, Z., Lane, M., Unsworth, J.B., 2002. Pesticide soil sorption parameters: theory, measurement, uses, limitations and reliability. Pest Management Science 58, 419–445. Worrall, F., Fernandez-Perez, M., Johnson, A.C., Flores-Cesperedes, F., GonzalezPradas, E., 2001. Limitations on the role of incorporated organic matter in reducing pesticide leaching. Journal of Contaminant Hydrology 49, 241– 262. Yarden, O., Gamliel, A., Aharonson, N., Katan, J., 1989. Solarization enhances dissipation of carbendazim (MBC) in soil. Soil Biology & Biochemistry 21, 857–861. Zimdahl, R.L., Cranmer, B.K., Stroup, W.W., 1994. Use of empirical equations to describe dissipation of metribuzin and pendimethalin. Weed Science 42, 241– 248.