Evaluation of a Daphnia magna renewal life‐cycle test method with diazinon

Abstract

Acute and chronic toxicity tests with diazinon (diethyl 2‐isopropyl‐6‐methyl‐4‐pyrimidinyl phosphorothionate) were conducted on Daphnia magna. The 24‐hr static LC50 was 0.86 μL.L^‐1. The sublethal effects of 0.05, 0.1, 0.5, 0.75 and 1.0 ngL^‐1 of diazinon concentrations on the survival, reproduction and growth of D. magna were monitored for 21 days. The algae Nannochloris oculata (5 x 10⁵ cellsmL^‐1) was used to feed the daphnids. The parameters used to determined the effect of the pesticide on D. magna were: mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction as well as survival was significantly reduced at diazinon concentrations of 0.10 ngL^‐1 and higher. The intrinsic rate of natural increase (r) decreased with increasing concentrations of diazinon. Growth, as measured by body length, was depressed significantly at 0.05 ngL^‐1 of diazinon and higher concentrations. The maximum acceptable toxicant concentration (MATC) was calculated. The chronic data was used to formulate an acute/chronic ratio.     

Population dynamics in Daphnia Magna as modified by chronic tetradifon stress

Abstract

Two Daphnia magna offsprings (animals from the first and third brood) whose parentals (F₀‐generation) were exposed during 21 days to different tetradifon (4‐chlorophenyl 2,4,5‐trichlophenyl sulfone) concentrations, were transferred to a pesticide free medium during 21 days (recovery period). The algae Nannochloris oculata (5x10⁵ cells/mL) was used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters and the intrinsic rate of natural increase (r) as population parameter, for F₁ generation (1st and 3rd broods). Reproduction was still reduced in F₁ (1st and 3rd broods) generation daphnids from parentals (F₀) exposed to 0.18 mg/L tetradifon and higher concentrations even after 21 days in clean water. However, survival was not significantly different (p>0.05) in those F1 offsprings from parentals pre‐exposed to the acaricide. Growth was still reduced in F1 daphnids from parentals pre‐exposed to 0.10–0.44 mg/L tetradifon. The intrinsic rate of natural increase (r) was still affected in Fl generation daphnids, specially in those from the third brood. Therefore, Fl generation D. magna offsprings from a parental generation (F0) previously exposed to the acaricide tetradifon were not able to recuperate completely when a recovery period of 21 days was allowed.     

Comparative toxicity of rac- and S-tebuconazole to Daphnia magna

Tebuconazole is a chiral triazole fungicide used as raceme in a variety of agricultural applications. Earlier studies showed that tebuconazole is toxic to many non-target aquatic organisms but relative data for tebuconazole enantiomers are lacking. Thus, goal of this study was to evaluate and compare the toxicity of rac- and S-tebuconazole with Daphnia magna at both acute and chronic levels according to Organization for Economic Cooperation and Development (OECD) guidelines 202 and 211 respectively, to provide some guidelines for optimizing chiral pesticides application and management. The exposure concentrations were 0.1, 0.5, 1, 2, 4, 8, 10 mg L^?1 for both rac- and S-tebuconazole and their 48-h EC₅₀ values to D. magna were 3.53 (3.32–3.78) and 2.74 (2.33–3.10) mg L^?1 respectively, indicating that these both are medium toxic to D. magna with no significant toxicity difference at acute level. In chronic test, <24-h old D. magna were exposed to 0.01, 0.05, 0.10, 0.20, and 0.40 mg L^?1 of rac- and S-tebuconazole with one blank and one solvent control for 21 days according to OECD guideline 211. Four developmental (molting rate, days to the 1st and 3rd brood, and body length) and five reproductive (size of the 1st and 3rd brood, number of broods, and number of neonates) parameters for each D. magna were determined. Results showed that both rac- and S-tebuconazole significantly reduced the reproduction and impacted the development of D. magna at concentrations of 0.05 mg L^?1 or higher. Furthermore, S-tebuconazole was more toxic than raceme, and the difference between effects on the same parameters induced by rac- and S-tebuconazole was statistically significant. These results demonstrated that the chronic toxicity of S-tebuconazole might be underestimated in general use, and further studies should focus more on the biological behaviors of enantiomers and not just the raceme of tebuconazole and other chiral pesticides in the environment.     

Microwave synthesis and antifungal evaluations of some chalcones and their derived diaryl-cyclohexenones

Microwave irradiation (MWI) of acetophenones and substituted benzaldehydes in water resulted in a “green-chemistry” procedure for the preparation of chalcones (1-14), through base catalyzed Claisen-Schmidt condensation reaction, in good yields. Further 3,5-diaryl-6-carbethoxy-2-cyclohexen-1-ones (1a-14a) were prepared through base catalyzed cyclocondensation of above chalcones with ethylacetoacetate using MWI as the energy source and silica as support. Out of fourteen cyclohexenones, ten (1a, 4a, 5a, 6a, 7a, 9a, 10a, 11a, 12a and 13a) are reported for the first time in literature. The synthesized compounds were characterized using various spectroscopic techniques, viz. (¹H NMR and IR) and screened for their antifungal activity in vitro against Sclerotium rolfsii and Rhizoctonia solani by poisoned food technique. The compounds tested were found to be active against R. solani whereas against S. rolfsii, moderate activity was observed, as evident from LC₅₀ values. The most potent compounds against R. solani were 1-(4-Fluoro-phenyl)-3-phenyl-propenone (13) and 1,3-Diphenyl-propenone (14) having LC₅₀ values of 2.36 and 2.49 mgL^{? 1} respectively (LC₅₀ of Hexaconazole = 1.12 mgL^{? 1}) and against S. rolfsii 3-(4-Fluoro-phenyl)-5-(3-nitro-phenyl)-6-carbethoxy-2-cyclohexen-1-one (12a) was most active having LC₅₀ value of 285 mgL^{? 1}compared to Hexaconazole (LC₅₀ = 1.27 mgL^{? 1}).     

Acute and chronic toxicity of organophosphate monocrotophos to Daphnia magna

The acute and chronic toxicity of monocrotophos (MCP), the binary joint toxicity of MCP and bifenthrin (BF), and sodium dodecyl benzene sulfonate (SDBS) to Daphnia magna (D. magna) was evaluated. The 24 h-median effective concentration (24 h-EC₅₀) and 48 h-median lethal concentration (48 h-LC₅₀) of MCP towards D. magna were 161 and 388 μ g/L, respectively. In addition, the lowest-observed effective concentration (LOEC) and non-observed effective concentration (NOEC) of MCP to D. magna were 10 and 5 μ g/L, respectively. Furthermore, the chronic value (ChV) of MCP against D. magna was 7 μ g/L and the acute chronic ratio (ACR) was 55. The number of offspring per female and the intrinsic rate of natural increase (r) were identified as the parameters that were most sensitive to MCP. In addition, toxic unit (TU) analysis was employed to evaluate the joint toxicities. The calculated TU_mix values of binary equitoxic mixtures of MCP + BF and MCP + SDBS were 1.47 and 1.63, respectively, which suggests that both equitoxic mixtures exert a limited antagonistic effect. The results of this study revealed that the toxic threshold of MCP towards D. magna is higher than its reported highest residue (4 μ g/L) in the ordinary aquatic environment, and that concurrent exposure to BF or SDBS may exert a slight antagonistic effect.     

Effect of lindane on antibody response to typhoid vaccine in weanling rats

Abstract

The immunosuppressive effect of lindane was assessed in weanling rats over a period of 5 weeks. Agglutinin titres against S. typhi ‘O’ and ‘H’, S. paratyphi ‘AH’ and ‘BR’ antigens were determined following TAB vaccination in control and lindane‐fed animals. The titres attained in non‐treated controls were higher significantly than those in treated animals indicating a suppressive effect of lindane on humoral immune responses.     

An assessment of the chronic toxicity of the synthetic pyrethroid, fenvalerate, to Daphnia galeata mendotae, using life tables

The effects of chronic exposure to fenvalerate, a synthetic pyrethroid insecticide, on the cladoceran Daphnia galeata mendotae were evaluated under laboratory conditions. The daphnids were exposed for their entire life cycle to concentrations ranging from 0.005 to 0.1 microg fenvalerate litre(-1). The parameters used to determined toxicity were survival, time to first reproduction, reproductive frequency, number of young per brood, cumulative brood size, intrinsic rate of natural increase (r(m)), generation time (T) and net reproductive rate (R(0)). A concentration of 0.005 microg fenvalerate litre(-1) resulted in an increase in longevity but a decrease in production of young. Higher concentrations caused a decrease in survival. Studies of shorter duration than the complete life cycle of the organisms would not have detected toxicity at such low levels. The intrinsic rate of natural increase, r(m), was not affected by fenvalerate until concentration reached 0.05 microg litre(-1) and r(m) decreased to 0.113 from 0.238. A concentration of 0.01 microg litre(-1) caused the net reproductive rate, R(0), and the generation time, T, to decrease to 73.2 offspring per female and 17.3 days from 125.9 offspring per female and 20.3 days, respectively.     

Aquatic toxicity of cartap and cypermethrin to different life stages of Daphnia magna and Oryzias latipes

Cartap and cypermethrin, which are among the most widely used pesticides in many countries, are considered safe because of their low mammalian toxicity and their low persistence in the environment. However, recent findings of endocrine-disrupting effects and developmental neurotoxicity have raised concerns about the potential ecological impacts of these pesticides. We evaluated the aquatic toxicity of cartap [S,S′-(2-dimethylaminotrimethylene) bis(thiocarbamate), unspecified hydrochloride] and cypermethrin [(RS)-alpha-cyano-3-phenoxybenzyl-(1RS,3RS,1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate], both individually and combined, on different life stages of the freshwater cladoceran Daphnia magna and a freshwater teleost, Japanese medaka (Oryzias latipes). The 96-hr Daphnia median effective concentrations (EC50s) for cartap and cypermethrin were 91.0 μ g/L and 0.00061 μ g/L, respectively. Rapid recovery of Daphnia was observed after short-term pulsed exposure to cartap and cypermethrin; there were no adverse effects on reproduction or survival 20 d after a 24 hr exposure to cartap up to 1240 μ g/L and cypermethrin up to 1.9 μ g/L. Chronic continuous exposure (for 21 d) of 7-d-old Daphnia to cypermethrin significantly reduced the intrinsic population growth rate in a concentration-dependent manner. However, because the intrinsic population growth rates were all above zero, populations did not decrease even at the highest experimental concentration of 200 ng/L. Exposure of Daphnia neonates (< 24 hr old) to cypermethrin for 21 d caused significant, sub-lethal reproduction-related problems, such as increased time to first brood, reduced brood size, and reduced total brood number, at 0.0002, 0.002, and 0.2 ng/L cypermethrin, but the intrinsic population growth rate was not significantly affected. Oryzias latipes was relatively more resistant to both pesticides. In particular, embryos appeared to be more resistant than juveniles or adults, which may be partly due to the protective role of the chorion. The incidence of larval fish deformity was significantly higher after a 96 hr exposure to as low as 250 μ g/L of cartap or 40 μ g/L of cypermethrin. The mixture of both compounds showed no synergistic toxicity. The extremely high acute-to-chronic ratio suggests that the standard acute lethal toxicity assessment might not reflect the true environmental hazards of these frequently used pesticides. Ecological hazard assessments of long-term low dose or pulsed exposures to cartap and cypermethrin may reveal more realistic consequences of these compounds in surface water.     

Toxicity identification evaluation of anaerobically treated swine slurry: A comparison between Daphnia magna and Raphanus sativus

Anaerobic digestion does not efficiently reduce ionic compounds present in swine slurry, which could present a potential risk to aquatic ecosystems (surface runoff) and terrestrial ambient (irrigation). The objective of this study was to evaluate the ecotoxicological characteristics of anaerobically treated swine slurry using acute and chronic (epicotyl elongation) toxicity tests with Daphnia magna and Raphanus sativus and identification of suspected toxic compounds using the Toxicity Identification Evaluation (TIE) method. The evaluation was performed in three phases: physicochemical characterization of the slurry; acute/chronic toxicity testing with Daphnia magna and Raphanus sativus for each fraction of the TIE (cation and anion exchange columns, activated carbon, pH modification/aeration and EDTA) and identification of suspected toxic compounds. The anaerobically treated slurry contained concentrations of ammonium of 1,072 mg L^?1, chloride of 815 mg L^?1 and metals below 1 mg L^?1 with a D. magna acute toxicity (48h-LC₅₀) of 5.3% and R. sativus acute toxicity (144h-LC₅₀) of 48.1%. Epicotyl elongation of R. sativus was inhibited at concentrations above 25% (NOEC). The cation exchange reduced the toxicity and free ammonia by more than 90% for both bio-indicators. Moreover, this condition stimulated the epicotyl growth of R. sativus between 10% and 37%. In conclusion, the main compound suspected of causing acute toxicity in D. magna and acute/chronic toxicity in R. sativus is the ammonium. The findings suggest the need the ammonium treatment prior to the agricultural reuse of swine slurry given the high risk to contaminate the aquatic environment by runoff and toxicity of sensitive plants.     

Sublethal Effects of Monocrotophos on Locomotor Behavior and Gill Architecture of the Mosquito Fish,Gambusia affinis

Subacute studies of monocrotophos [Dimethyl (E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] on mosquito fish, Gambusia affinis, were carried out in vivo for 24 days to assess the locomotor behavior, structural integrity of gill, and targeted enzyme acetylcholinesterase (AChE, EC: 3.1.1.7) interactions. Monocrotophos (MCP) can be rated as moderately toxic to G. affinis, with a median lethal concentration (LC₅₀) of 20.49 ± 2.45 mgL^?1. The fish exposed to sublethal concentration of LC₁₀ (7.74 mgL^?1) were under stress and altered their locomotor behavior, such as distance traveled per unit time (m min^?1) and swimming speed (cm sec^?1) with respect to the length of exposure. Inhibition in the activity of brain AChE and deformities in the primary and secondary lamellae of gill may have resulted in failure of exchange of gases. The maximum inhibition of 95% of AChE activity was observed on days 20 and 24.

Morphological aberrations in the gills were also studied during exposure to the sublethal concentration of monocrotophos for a period ranging from 8 to 24 days. The extent of damage in gill was dependent on the duration of exposure. The findings revealed that inhibition in brain AChE activity and structural alteration in gill were responsible for altering the locomotor behavior of exposed fish.     

Bioavailability to rats of 14C‐lindane residues in stored potato tubers

Abstract

Potato tubers were applied with radiolabelled lindane (U‐¹⁴C γ‐ 1,2,3,4,5,6 hexachlorocyclohexane) at three dose levels 30, 150, and 300 ppm and stored for 30, 60 and 90 days at room temperature. The data revealed that lindane penetrated into the pulp tissues through the epidermal layer. The amounts recovered in the peel were found to increase with a greater storage period up to 60 days followed by a drop at 90 days. On the other hand, there was a slight increase in radioactivity in the pulp tissue from 30 to 60 days followed by significant increase after 90 days. The incorporation of the compound in the tubers was dose independent. Methanol extraction showed binding of about 8.1% and 5.8% ofthe applied dose in peel and pulp tissues, respectively. The insecticide was found to be bioavailable when rats health hazard. It is therefore, desirable to demonstrate that the quantity of the terminal residues may be safe for the consumer. In the present investigation an attempt was made to determine the fate and bioavailability of lindane when applied to stored potato tubers.     

Effect of the pesticide lindane on the biomass of the microalgae Nannochloris oculata

This study assesses the growth of the microalgae Nannochloris oculata in the presence of lindane and the ability of N. oculata to remove lindane from media. Algal biomass increased with 0.1 and 0.5 mg L^?1 of lindane, and lindane concentrations in the media decreased. N. oculata removed 73% and 68.2% of lindane in the 0.1 and 0.5 mg L^?1 media concentrations, respectively. Algal biomass decreased to the level of the control at lindane concentrations greater than 2.5 mg L^?1, probably due to toxicity. N. oculata removed lindane from the media at concentrations lower than 1.0 mg L^?1. Thus, N. oculata may be useful for lindane bioremediation in contaminated aquatic systems.     

Fate of 14C‐lindane in a rice‐fish model ecosystem*

Abstract

A model ecosystem has been used to evaluate the impact of ¹⁴C‐lindane on rice‐fish agricultural system. The distribution of ¹⁴C‐residues among the constituents of the model ecosystem was studied over a period of 90 days. The insecticide was found to be readily absorbed by the roots and translocated to all parts of the rice plant. The peak level in the shoots (26 ppm) and roots (105 ppm) of plants was reached to within three weeks. Lindane was concentrated in fish and residues as high as 90 ppm could be detected after 30 days.

The major part of the residues present in the different constituents of the ecosystem could be extracted with hexane and proved to contain soley the parent compound. The data obtained show that lindane possesses a relatively low biodegradability in fish and in rice plant. The insecticide accumulates in fish and rice plant to considerable extent.     

Diffusion mechanism of lindane into wood charcoal

Abstract

The wood charcoal treated by 1N HNO₃ (WCT) was used to remove toxic chlorinated pesticide lindane (y‐HCH) residue from water by the sorption process. Using a simple first order reversible kinetics constants and half time equations, the film and pore diffusion coefficients were determined. Film diffusion was found to be rate limiting step in sorbing lindane by WCT. This was further authenticated by kinetics studies at different initial sorbate concentrations, different sorbent sizes, and different agitation speeds besides interruption test. A pore diffusion model was used to fit the data of kinetics in continuously mixed batch reactors (CMBR), and the tortuosity, external resistance, and surface diffusion effects on lindane sorption by WCT were noticed. The tortuosity values of 15 to 28 were obtained for WCT‐lindane system.     

Ammonium,Nitrate and Nitrite Nitrogen and Nitrate Reductase Enzyme Activity in Groundnut (Arachis hypogaea L.) Fields After Diazinon,Imidacloprid and Lindane Treatments

Impacts of diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate), imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] and lindane (1,2,3,4,5.6-hexachlorocyclohexane) treatments on ammonium, nitrate, and nitrite nitrogen and nitrate reductase enzyme activities were determined in groundnut (Arachis hypogaea L.) field for three consecutive years (1997 to 1999). Diazinon was applied for both seed- and soil-treatments but imidacloprid and lindane were used for seed treatments only at recommended rates. Diazinon residues persisted for 60 days in both the cases. Average half-lives (t_1/2) of diazinon were found 29.3 and 34.8 days respectively in seed and soil treatments. In diazinon seed treatment, NH₄ ⁺, NO₃ ^?, and NO₂ ^? nitrogen and nitrate reductase activity were not affected. Whereas, diazinon soil treatment indicated significant increase in NH₄ ⁺-N in a 1-day sample, which continued until 90 days. Some declines in NO₃ ^?N were found from 15 to 60 days. Along with this decline, significant increases in NO₂ ^?N and nitrate reductase activity were found between 1 and 30 days. Imidacloprid and lindane persisted for 90 and 120 days with average half-lives (t_1/2) of 40.9 and 53.3 days, respectively. Within 90 days, imidacloprid residues lost by 73.17% to 82.49% while such losses for lindane residues were found 78.19% to 79.86 % within 120 days. In imidacloprid seed-treated field, stimulation of NO₃ ^?N and the decline in NH₄ ⁺NO₂ ^?-N and nitrate reductase enzyme activity were observed between 15 to 90 days. However, lindane seed treatment indicated significant increases in NH₄ ⁺-N, NO₂ ^?-N and nitrate reductase activity and some adverse effects on NO₃ ^?N between 15 and 90 days.     

Volatilization of lindane from water in soil‐free and flooded soil systems

Abstract

Volatilization of ¹⁴C‐lindane from water in planchets and under flooded soil ecosystem was investigated. Lindane disappeared faster than parathion from planchets. More rapid loss of both insecticides occurred from water than from chloroform. Loss of lindane and parathion was related to measured losses of water by evaporation. During 5‐day incubation under flooded soil conditions, disappearance of lindane was faster from open vials than from sealed vials, whereas in nonflooded soil, no volatile loss of the insecticide was evident despite water evaporation. Over 5 day incubation under flooded conditions, greater volatile loss of lindane occurred in sandy soil than in alluvial soil apparently due to greater adsorption to the soil colloids decreasing the insecticide concentration in the standing water of the laterite soil. Under identical conditions of water evaporation, lindane loss was directly proportional to its initial concentration in the water. These results suggest that considerable loss of soil applied pesticides can occur by volatilization from the standing water in flooded rice fields, particularly under tropical conditions.     

Population dynamics in Daphnia magna as modified by chronic tetradifon stress

Two Daphnia magna offsprings (animals from the first and third brood) whose parentals (F0-generation) were exposed during 21 days to different tetradifon (4-chlorophenyl 2,4,5-trichlophenyl sulfone) concentrations, were transferred to a pesticide free medium during 21 days (recovery period). The algae Nannochloris oculata (5 x 10(5) cells/mL) was used as food. In this recovery study, survival, growth and reproduction (mean total young per female, mean brood size, onset of reproduction and mean number broods per female) were assessed as individual parameters and the intrinsic rate of natural increase (r) as population parameter, for F1 generation (1st and 3rd broods). Reproduction was still reduced in F1 (1st and 3rd broods) generation daphnids from parentals (F0) exposed to 0.18 mg/L tetradifon and higher concentrations even after 21 days in clean water. However, survival was not significantly different (p > 0.05) in those F1 offsprings from parentals pre-exposed to the acaricide. Growth was still reduced in F1 daphnids from parentals pre-exposed to 0.10-0.44 mg/L tetradifon. The intrinsic rate of natural increase (r) was still affected in F1 generation daphnids, specially in those from the third brood. Therefore, F1 generation D. magna offsprings from a parental generation (F0) previously exposed to the acaricide tetradifon were not able to recuperate completely when a recovery period of 21 days was allowed.     

Toxicity op technical X‐factor∗ to weanling rats. II. A subacute oral study

Abstract

Eighty male weanling rats were fed dietary levels o£ Technical X‐factor (β ‐isomer free BHC, a by‐product obtained during the separation of lindane from Tech. BHC) at dosages of 10, 50, 250, 750, 1500 and 3000 ppm for 90 days. No overt signs of toxicity or mortality were observed at any of the dietary levels. However, a significant reduction in food consumption and growth was evident beyond 750 ppm. Pronounced hepatomegaly observed at 1500 and 3000 ppra was associated with histolo‐gical alterations such as cellular hypertrophy, cyto‐plasmic vacuolisation and focal necrosis. Adrenals showed cortical hypertrophy and highly vacuolated cytoplasm. Though a significant increase in the levels of SGOT was noted at 3000 ppra dosage, no appreciable changes were observed in the levels of SGPT and SLDH. Technical X‐factor appeared to possess low chronic toxicity compared to Tech. BHC as evidenced by the various parameters studied. The observed low chronic toxicity of X‐factor is probably due to the absence of β ‐isomer and altered composition of delta and alpha isomers.     

Acute and chronic ecotoxicity of carbaryl with a battery of aquatic bioassays

The ecotoxic effects of carbaryl (carbamate insecticide) were investigated with a battery of four aquatic bioassays. The nominal effective concentrations immobilizing 50% of Daphnia magna (EC50) after 24 and 48 h were 12.76 and 7.47 µg L^?1, respectively. After 21 days of exposure of D. magna, LOECs (lowest observed effect concentrations) for cumulative molts and the number of neonates per surviving adult were observed at carbaryl concentration of 0.4 µg L^?1. An increase of embryo deformities (curved or unextended shell spines) was observed at 1.8 and 3.7 µg L^?1, revealing that carbaryl could act as an endocrine disruptor in D. magna. Other bioassays of the tested battery were less sensitive: the IC50-72h and IC10-72h of the algae Pseudokirchneriella subcapitata were 5.96 and 2.87 mg L^?1, respectively. The LC50-6d of the ostracod Heterocypris incongruens was 4.84 mg L^?1. A growth inhibition of H. incongruens was registered after carbaryl exposure and the IC20-6d was 1.29 mg L^?1. Our results suggest that the daphnid test sensitivity was better than other used tests. Moreover, carbaryl has harmful and toxic effects on tested species because it acts at low concentrations on diverse life history traits of species and induce embryo deformities in crustaceans.     

Sorption and desorption of lindane by wood charcoal in fixed‐bed reactor

Abstract

Sorption and desorption of lindane (y‐HCH) by wood charcoal (WC) and wood charcoal treated by 1N HNO₃ (WCT) in fixed‐bed reactor (FBR) were investigated in this study. WCT revealed a better performance than WC, in removing lindane in FBR. The breakthrough of lindane was significantly affected by the size of WCT, flow rate to the FBR, and depth of WCT bed. The removal of lindane in the presence of mixture of other pesticides was considerably reduced. The design parameters for FBR were calculated based on the bed‐depth service time (BDST) approach. Many parameters Viz. depth of sorption zone, velocity of sorption, sorbent use rate, critical bed‐depth, bed efficiency, and service time, were determined for design of the fixed‐bed. Using the material balance principle, the characteristics of the wave‐front were evaluated and found that the wave‐front velocity is approximately equal to the sorption velocity determined from the BDST approach. Desorption studies were performed in dilute organic solvent media and they gave an excellent performance in regeneration process.