铁对四尾栅藻生长的影响

采用实验室模拟培养的方法,分别测定了初始Fe3 摩尔浓度为0、10、100、1 000、10 000、30 000 nmol/L时的四尾栅藻生物量、叶绿素a浓度,同时利用扫描电镜观察了初始Fe3 摩尔浓度为0、10 000、30 000 nmol/L时的四尾栅藻细胞的表面结构.结果表明,初始Fe3 摩尔浓度在0、10 nmol/L时,四尾栅藻的生长受到抑制;初始Fe3 摩尔浓度超过10 000 nmol/L时,四尾栅藻生长受到的促进作用仍存在,但不显著;初始Fe3 摩尔浓度增加至30 000 nmol/L时,四尾栅藻生长未受到抑制;四尾栅藻叶绿素a浓度随时间的变化与四尾栅藻生长曲线相似,随初始Fe3 浓度的增加而增加;不同初始Fe3 浓度对四尾栅藻细胞表面结构影响不明显.     

The effects of 2,4-D herbicide and organophosphorus insecticides on growth, photosynthesis, and chlorophyll a synthesis of Chlamydomonas reinhardtii (mt +)

The effects of the herbicide (2,4-D) and six organophosphorus insecticides (Diazinon, Dimethoate, Fenitrothion, Malathion, Phenthoate and Quinalphos) on growth, photosynthesis and chlorophyll a synthesis of the fresh water green alga Chlamydomonas reinhardtii (mt +) were studied. At low concentrations (1 and 5 ppm), the herbicide and all six orgnophosphorus insecticides stimulated photosynthesis of the alga. The stimulating effects on algal growth and chlorophyll a synthesis were only observed in the presence of low concentration (1 ppm) of 2,4-D and Fenitrothion, Growth, photosynthesis and chlorophyll a synthesis of the alga were inhibited in the presence of high concentrations (10, 20 and 40 ppm) of the herbicide and all the six organophosphorus insecticides. Results also indicated that the toxicities of these organophosphorus insecticides on the tested alga were dependent on their chemical structures.     

Effects of copper, chromium and nickel on growth, photosynthesis and chlorophyll a synthesis of Chlorella pyrenoidosa 251

Individual and combined effects of three heavy metals; namely, copper, chromium and nickel, on growth, photosynthesis and chlorophyll a synthesis of the unicellular green alga, Chlorella pyrenoidosa 251, were determined. Within the concentration range of 0.1 to 1.0 mg litre(-1) of the three heavy metals tested on growth, photosynthesis and chlorophyll a synthesis of the alga, the order of toxicity of the three heavy metals was copper > chromium > nickel. The presence of one of the three heavy metals interacted synergistically with the other two heavy metals in various bimetallic combinations on growth, photosynthesis and chlorophyll a synthesis of the alga.     

Effects of nozzle types and 2,4-D formulations on spray deposition

The objective of this study was to evaluate the effects of nozzle types and 2,4-D formulations on spray deposition on different targets. Two field experiments were carried out in a completely randomized design, and treatments were arranged in a factorial scheme. Species in experiment 1 were Sumatran fleabane (Conyza sumatrensis) and Brazil pusley (Richardia brasiliensis) and in experiment 2 were soybeans (Glycine max) and Benghal dayflower (Commelina benghalensis). For both experiments, the first factor corresponded to spray nozzles with different settings (AD 110.015 – 61 and 105 L ha^?1; AD 015-D – 75 and 146 L ha^?1; XR 110.0202 – 200 L ha^?1; and ADIA-D 110.02 – 208 L ha^?1) and the second factor consisted of two formulations of 2,4-D (amine and choline). The formulation of 2,4-D choline has contained Colex-D? Technology. Similar or higher spray deposition was observed on the leaves and artificial targets when using 2,4-D choline as compared to the 2,4-D amine formulation, and these differences in deposition were more evident for nozzles applying lower spray volumes. Deposition was more affected by nozzle type when amine formulation was used, compared to choline formulation.     

Pesticide risk assessment: A study on inhalation and dermal exposure to 2,4-D and paraquat among Malaysian paddy farmers

A cross-section analytical study was conducted to evaluate the risk of pesticide exposure to those applying the Class II pesticides 2,4-D and paraquat in the paddy-growing areas of Kerian, Perak, Malaysia. It investigated the influence of weather on exposure as well as documented health problems commonly related to pesticide exposure. Potential inhalation and dermal exposure for 140 paddy farmers (handlers of pesticides) were assessed. Results showed that while temperature and humidity affected exposure, windspeed had the strongest impact on pesticide exposure via inhalation. However, the degree of exposure to both herbicides via inhalation was below the permissible exposure limits set by United States National Institute of Occupational Safety and Health (NIOSH). Dermal Exposure Assessment Method (DREAM) readings showed that dermal exposure with manual spraying ranged from moderate to high. With motorized sprayers, however, the level of dermal exposure ranged from low to moderate. Dermal exposure was significantly negatively correlated with the usage of protective clothing. Various types of deleterious health effects were detected among users of manual knapsack sprayers. Long-term spraying activities were positively correlated with increasing levels of the gamma-glutamyl transpeptidase (GGT) liver enzyme. The type of spraying equipment, usage of proper protective clothing and adherence to correct spraying practices were found to be the most important factors influencing the degree of pesticide exposure among those applying pesticides.     

Pesticide risk assessment: A study on inhalation and dermal exposure to 2,4-D and paraquat among Malaysian paddy farmers

A cross-section analytical study was conducted to evaluate the risk of pesticide exposure to those applying the Class II pesticides 2,4-D and paraquat in the paddy-growing areas of Kerian, Perak, Malaysia. It investigated the influence of weather on exposure as well as documented health problems commonly related to pesticide exposure. Potential inhalation and dermal exposure for 140 paddy farmers (handlers of pesticides) were assessed. Results showed that while temperature and humidity affected exposure, windspeed had the strongest impact on pesticide exposure via inhalation. However, the degree of exposure to both herbicides via inhalation was below the permissible exposure limits set by United States National Institute of Occupational Safety and Health (NIOSH). Dermal Exposure Assessment Method (DREAM) readings showed that dermal exposure with manual spraying ranged from moderate to high. With motorized sprayers, however, the level of dermal exposure ranged from low to moderate. Dermal exposure was significantly negatively correlated with the usage of protective clothing. Various types of deleterious health effects were detected among users of manual knapsack sprayers. Long-term spraying activities were positively correlated with increasing levels of the gamma-glutamyl transpeptidase (GGT) liver enzyme. The type of spraying equipment, usage of proper protective clothing and adherence to correct spraying practices were found to be the most important factors influencing the degree of pesticide exposure among those applying pesticides.     

The effects of crude and fuel oils on the growth, chlorophyll 'a' content and dry matter production of a green alga Scenedesmus quadricauda (Turp.) bréb

The growth of Scenedesmus quadricauda algae in a batch culture was examined in the presence of crude oil and fuel oil, added to the cultivation medium in the form of a water-soluble fraction (WSF), water extract (WE) and oil-water dispersion (OWD). On applying various concentrations of oils, a decrease in the number of cells, dry matter and chlorophyll 'a' production, with respect to the cell population, was observed. The extent of this decrease depended on the kind and concentration of the soluble and dispersed hydrocarbon fractions and on the proportions in which these occurred in the culture medium. On the other hand, the water extracts of both oils stimulated dry mass and chlorophyll 'a' content with respect to a single cell. This effect was accompanied by increased size of the algal cells. The WSF, WE and OWD of fuel oil, prepared from 200, 50 and 1 cm(3) of oil per dm(3) of BBM medium, respectively, had a similar inhibitory effect, which points to the dominant role of oil dispersion in the reduction of algal growth. Chemical analysis of the water extracts of fuel oil revealed the presence of 35 hydrocarbons of various kinds, mainly n-alkanes and polycyclic aromatic hydrocarbons.     

Effects of sulfur dioxide on growth, photosynthesis and enzyme activities of Chinese Guger-Tree seedlings

The Chinese Guger-Tree (Schima superba Gard et Champ var. superba) is an important harwood species in Taiwan where the ambient SO(2) concentration in some areas is high. Seedlings were raised in field chambers with and without SO(2) to determine whether this species is affected by this pollutant. After 4 weeks of exposure to 325 ppb of SO(2), the photosynthetic rate of seedlings decreased immediately. During the fumigation period, stem height growth was not inhibited, however, the stem diameter growth was reduced significantly. The dry weight of leaves was unchanged, while stem, root and total seedling weight were lower than those of control plants. Sulfhydryl groups in leaves increased by 75%, whereas they did not change in roots following SO(2) uptake. Superoxide dismutase in leaves did not change, however, peroxidase activity increased significantly. Results suggest that ambient SO(2) in some areas in Taiwan may affect the physiology and growth of the Chinese Guger-Tree.     

Effects of Ginkgo biloba extract on growth,photosynthesis, and photosynthesis-related gene expression in Microcystis flos-aquae

Environmental Science and Pollution Research - The inhibitory effect of plants on algae offers a new and promising alternative method for controlling harmful algal blooms. Previous studies showed...     

Carbaryl, 2,4-D, and Triclopyr adsorption in thatch-soil ecosystems

Thatch development in intensively managed turf sites may cause environmental concerns for greater sorption or leaching of applied chemicals in terrestrial ecosystems. To determine the adsorption potential of Carbaryl (1-Napthyl N-methylcarbamate), 2,4-D (2,4-dichloro-phenoxyacetic acid), and Triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) in turf ecosystems, composite thatch and underlying soil samples from three-and six-year-old stands of cool-season Southshore creeping bentgrass (Agrostis palustris Huds.) and warm-season Meyer zoysiagrass (Zoysia japonica Steud.) were collected. The samples were processed and analyzed for total organic carbon (COrg); extractable (CExt), humic (CHA) and fulvic acid (CFA); anthrone reactive nonhumic carbon (ARC) fractions; and CHA and CFA associated iron (Fe) contents. Pesticide adsorption capacity (Kf) and intensity (1/n), organic carbon partition coefficient (KOC) and Gibbs free energy change (deltaG) were calculated for thatch materials and the underlying soils using a modified batch/flow technique. Both bentgrass (BT) and zoysiagrass thatch (ZT) contained a greater concentration of CExt, CFA, CHA, and ARC than the respective soils (BS and ZS). The CExt, CFA, CHA, and ARC concentration was higher in BT compared with ZT. The BT contained a greater concentration of bound Fe in both CFA and CHA fractions than in BS, whereas ZT had more bound Fe in CHA fraction than in ZS. On average, the BT had a greater concentration of bound Fe in CExt, CFA, and CHA fractions than in the ZT. Among the pesticides, Carbaryl had higher Kf and 1/n values than 2,4-D and Triclopyr for both thatch and soil. Although the KOC and deltaG values of Carbaryl were higher in both BT and ZT than in the underlying soils, the KOC and deltaG values of 2,4-D were significantly higher in BS and ZS than in the overlying thatch materials. The 2,4-D and Triclopyr had higher leaching indices (LI) than Carbaryl for both BT and ZT materials than the respective soils. The Carbaryl, however, had a higher LI for soils than for thatch materials. Averaged across thatch materials and soils, COrg accounted for 96, 85, and 84% variations in Carbaryl, 2,4-D, and Triclopyr adsorption, respectively. Among the COrg fractions, lignin followed by CFA and CHA accounted for greater adsorption of pesticides, especially Carbaryl. The concentration of CHA and CFA bound Fe did not correlate with Kf and 1/n values of pesticides.     

Carbaryl, 2,4-D,and Triclopyr Adsorption in Thatch-Soil Ecosystems

Thatch development in intensively managed turf sites may cause environmental concerns for greater sorption or leaching of applied chemicals in terrestrial ecosystems. To determine the adsorption potential of Carbaryl (1-Napthyl N-methylcarbamate), 2,4-D (2,4-dichloro-phenoxyacetic acid), and Triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) in turf ecosystems, composite thatch and underlying soil samples from three- and six-year-old stands of cool-season Southshore creeping bentgrass (Agrostis palustris Huds.) and warm-season Meyer zoysiagrass (Zoysia japonica Steud.) were collected. The samples were processed and analyzed for total organic carbon (C_Org); extractable (C_Ext), humic (C_HA) and fulvic acid (C_FA); anthrone reactive nonhumic carbon (ARC) fractions; and C_HA and C_FA associated iron (Fe) contents. Pesticide adsorption capacity (K _f ) and intensity (1/n), organic carbon partition coefficient (K _OC ) and Gibbs free energy change (Δ G) were calculated for thatch materials and the underlying soils using a modified batch/flow technique. Both bentgrass (BT) and zoysiagrass thatch (ZT) contained a greater concentration of C_Ext, C_FA, C_HA, and ARC than the respective soils (BS and ZS). The C_Ext, C_FA, C_HA, and ARC concentration was higher in BT compared with ZT. The BT contained a greater concentration of bound Fe in both C_FA and C_HA fractions than in BS, whereas ZT had more bound Fe in C_HA fraction than in ZS. On average, the BT had a greater concentration of bound Fe in C_Ext, C_FA, and C_HA fractions than in the ZT. Among the pesticides, Carbaryl had higher K _f and 1/n values than 2,4-D and Triclopyr for both thatch and soil. Although the K _OC and Δ G values of Carbaryl were higher in both BT and ZT than in the underlying soils, the K _OC and Δ G values of 2,4-D were significantly higher in BS and ZS than in the overlying thatch materials. The 2,4-D and Triclopyr had higher leaching indices (LI) than Carbaryl for both BT and ZT materials than the respective soils. The Carbaryl, however, had a higher LI for soils than for thatch materials. Averaged across thatch materials and soils, C_Org accounted for 96, 85, and 84% variations in Carbaryl, 2,4-D, and Triclopyr adsorption, respectively. Among the C_Org fractions, lignin followed by C_FA and C_HA accounted for greater adsorption of pesticides, especially Carbaryl. The concentration of C_HA and C_FA bound Fe did not correlate with K _f and 1/n values of pesticides.     

Effects of sorption on biodegradation rates of 2,4-D: Improvement of Rao''s model

In the presence of sorbents, the biodegradation rates of organic compounds can be decreased or increased. Four kinds of interactions have to be considered as follows: (1) chemicals in solution reacted with bacteria in solution; (2) sorbed chemicals reacted with bacteria in solution; (3) chemicals in solution reacted with sorbed bacteria and (4) sorbed chemicals reacted with sorbed bacteria. The corresponding rate constants K can be solved in our improved model. Some special situations are discussed.

The biodegradation of 2,4-D, as an example, reacted with a pure strain (Pseudomanos sp.) which was isolated from soil polluted by 2,4-D then labeled by radioactive ³²P were performed in the presence of sediment (or soil). The results showed that 2,4-D sorbed on sediment (or soil) were available to neither bacteria in solution nor bacteria on sediment (or soil), but 2,4-D in solution can be degraded by both bacteria in solution and bacteria on sediment (or soil). Biodegradation of 2,4-D in the presence of sediment (or soil) agreed with results of Rao's model.     

Light regime, riboflavin, and pH effects on 2,4-D photodegradation in water

A laboratory study was conducted to determine the effects of light regime, riboflavin, and pH on photodegradation of 2,4-D in aqueous solution. In controlled-environment chamber experiments, riboflavin sensitized 2,4-D photolysis in a concentration-dependent manner under both attenuated UV (-UV) and enhanced UV (+UV) light regimes. The photolysis half-life of 2,4-D in solutions containing 10 mg L-1 riboflavin was 9.7 and 12.5 h when exposed to +UV and -UV, respectively, compared to no photolysis in the absence of riboflavin. In contrast, the extrapolated half-life of 2,4-D in solutions containing 2.5 mg L-1 riboflavin was 46 h under +UV and 72 h under -UV. The rate of 2,4-D photolysis in the presence of riboflavin increased under both light regimes as initial pH of the solution was decreased from 7.5 to 4.5. The half-life of 2,4-D in the presence of 10 mg L-1 riboflavin at pH 4.5 and exposed to +UV was 1.6 h. Lumichrome, a principal photoproduct of riboflavin, did not photosensitize 2,4-D. Concentrations of 2,4-dichlorophenol formed as a result of riboflavin-sensitized 2,4-D photolysis were higher under the -UV than the +UV regime. These results indicate that riboflavin concentration, solution pH, and light regime are interacting factors that may be manipulated to enhance rates of aqueous 2,4-D photolysis.     

Influence of paraquat, glyphosate, and cadmium on the activity of some serum enzymes and protein electrophoretic behavior (in vitro)

In vitro study for the determination of the toxicity of some pesticides (glyphospate and paraquat) and cadmium chloride (CdCl2) on the activities of serum acetylcholinesterase (AChE), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AlP), and acid phosphatase (AcP) is described. Changes in electrophoretic patterns of serum proteins were also tested. Results revealed that glyphosate was effective on all enzymes except AcP. Its IC50 values (the concentration of compound that inhibits 50% of the enzyme activity in 1 h at 37 degrees C) were 714.3, 750, 54.2, 270.8, and 71.4 mM for AChE, LDH, AST, ALT, and AlP, respectively. The inhibitory effect of paraquat varied markedly among all enzymes. The IC50 values of paraquat were 321.4 and 750 mM for AST and ALT, respectively. It had mild effect on AChE and LDH; and no effect on the activities of AlP and AcP. The effect of CdCl2 was pronounced with AChE, ALT, AlP, and AcP, and no effect on LDH and AST was found. The corresponding IC50 values were 77.7, 22.2, 33.3, and 83.3 mM for AChE, ALT, AlP, and AcP, respectively. Polyacrylamide gel electrophoretic patterns of serum proteins showed marked differences with glyphosate and CdCl2 but not with paraquat. The results suggest that the in vitro enzyme-activity test seems to have a potential for the assessment of pesticide and heavy metal toxicity.     

Fungal bioconversion of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP)

Ninety strains of fungi from the collection of our mycology laboratory were tested in Galzy and Slonimski (GS) synthetic liquid medium for their ability to degrade the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) and its by-product, 2,4-dichlorophenol (2,4-DCP) at 100 mg l(-1), each. Evolution of the amounts of each chemical in the culture media was monitored by HPLC. After 5 days of cultivation, the best results were obtained with Aspergillus penicilloides and Mortierella isabellina for 2,4-D and with Chrysosporium pannorum and Mucor genevensis for 2,4-DCP. The data collected seemed to prove, on one hand, that the strains responses varied with the taxonomic groups and the chemicals tested, and, on the other hand, that 2,4-D was less accessible to fungal degradation than 2,4-DCP. In each case, kinetics studies with the two most efficient strains revealed that there was a lag phase of 1 day before the onset of 2,4-D degradation, whereas there was none during 2,4-DCP degradation. Moreover, 2,4-DCP was detected transiently during 2,4-D degradation. Finally, M. isabellina improved its degradation potential in Tartaric Acid (TA) medium relative to GS and Malt Extract (ME) media.     

Impact of Sublethal Doses of 2,4-D,Simulating Drift,on Tomato Yield

Abstract

Tomato is considered one of the most sensitive crops regarding 2,4-D drift. In many cases, such susceptibility has led to important restrictions in the use of 2,4-D based products. Field experiments were carried out for two consecutive years in tomato, by applying sublethal doses of 2,4-D (ranging from 0.42 to 13.44 g a.i. ha^?1) directly to plants, at different stages of growth, as a simulation of eventual drifts to the crop. The range of rates was based on the assumption of a 0.0625–2.0% drift level of a 1 L ha^?1 of the most common formulated herbicides. For this crop, the range of rates between 0.42 and 13.44 g a.i ha^?1 applied at the beginning of flowering caused a linear crop reduction. On the other hand, rates ≤13.44 g a.i. ha^?1 applied after full development of fourth truss stage or latter had no effect on crop yield or development. For tomato, tolerance to 2,4-D strongly increases with plant age.     

Impact of sublethal doses of 2,4-D, simulating drift, on tomato yield

Tomato is considered one of the most sensitive crops regarding 2,4-D drift. In many cases, such susceptibility has led to important restrictions in the use of 2,4-D based products. Field experiments were carried out for two consecutive years in tomato, by applying sublethal doses of 2,4-D (ranging from 0.42 to 13.44 g a.i. ha(-1)) directly to plants, at different stages of growth, as a simulation of eventual drifts to the crop. The range of rates was based on the assumption of a 0.0625-2.0% drift level of a 1 L ha(-1) of the most common formulated herbicides. For this crop, the range of rates between 0.42 and 13.44 g a.i ha(-1) applied at the beginning of flowering caused a linear crop reduction. On the other hand, rates < or = 13.44 g a.i. ha(-1) applied after full development of fourth truss stage or latter had no effect on crop yield or development. For tomato, tolerance to 2,4-D strongly increases with plant age.     

酸强度和作用方式对石栎生长与光合作用的影响

以石栎(Lithocarpus glabra)为研究对象,通过分析不同强度酸喷淋于土壤、地上部分和两者兼喷3种处理方式下的生物量、营养元素和光合作用情况,探究石栎对酸雨胁迫的响应特征。结果表明,含H2SO4和HNO3的强酸(pH=2.5)喷淋到土壤中对石栎幼苗生物量积累、氮元素吸收和光合作用均有显著促进作用;而喷淋到植株地上部分可能对石栎幼苗生物量积累、营养元素吸收和光合作用有抑制作用,但基本无显著差异;同时喷淋土壤和地上部分,促进和抑制作用可以互相抵消,对石栎幼苗生物量积累、营养元素吸收和光合作用基本无显著影响。因此,石栎对pH=2.5的强酸有很好的适应性,短期强酸雨胁迫不会对石栎产生显著影响,可以作为亚热带酸雨区森林恢复的备选树种。     

Treatment of 2,4-D, mecoprop, and dicamba using membrane bioreactor technology

Phenoxyacetic and benzoic acid herbicides are widely used agricultural, commercial, and domestic pesticides. As a result of high water solubility, mobility, and persistence, 2,4-dichlorophenoxyacetic acid (2,4-D), methylchlorophenoxypropionic acid (mecoprop), and 3,6-dichloro-2-methoxybenzoic acid (dicamba) have been detected in surface and waste waters across Canada. As current municipal wastewater treatment plants do not specifically address chronic, trace levels of contaminants like pesticides, an urgent need exists for an efficient, environmentally friendly means of breaking down these toxic herbicides. A commercially available herbicide mix, WeedEx, containing 2,4-D, mecoprop, and dicamba, was subjected to treatment using membrane bioreactor (MBR) technology. The three herbicides, in simulated wastewater with a chemical oxygen demand of 745 mg/L, were introduced to the MBR at concentrations ranging from 300 μg/L to 3.5 mg/L. Herbicides and biodegradation products were extracted from MBR effluent using solid-phase extraction followed by detection using high-performance liquid chromatography coupled with mass spectrometry. 2,4-D was reduced by more than 99.0 % within 12 days. Mecoprop and dicamba were more persistent and reduced by 69.0 and 75.4 %, respectively, after 112 days of treatment. Half-lives of 2,4-D, mecoprop and dicamba during the treatment were determined to be 1.9, 10.5, and 28.3 days, respectively. Important water quality parameters of the effluent such as dissolved oxygen, pH, ammonia, chemical oxygen demand, etc. were measured daily. MBR was demonstrated to be an environmentally friendly, compact, and efficient method for the treatment of toxic phenoxyacetic and benzoic acid herbicides.     

Spiking solvent, humidity and their impact on 2,4-D and 2,4-DCP extractability from high humic matter content soils

The 2,4-dichlorophenoxyacetic acid (2,4-D) is a hormone-like herbicide widely used in agriculture. Although its half life in soil is approximately two weeks, the thousands of tons introduced in the environment every year represent a risk for human health and the environment. Considering the toxic properties of this compound and its degradation products, it is important to assess and monitor the 2,4-D residues in agricultural soils. Furthermore, experiments of phyto/bioremediation are carried out to find economic and environmental friendly tools to restore the polluted soils. Accordingly, it is essential to accurately measure the amount of 2,4-D and its metabolites in soils. There is evidence that 2,4-D extraction from soil samples seriously depends on the physical and chemical properties of the soil, especially in those soils with high content of humic acids. The aim of this work was to assess the variables that influence the recovery and subsequent analysis of 2,4-D and its main metabolite (2,4-dichlorophenol) from those soils samples. The results showed that the recovery efficiency depends on the solvent and method used for the extraction, the amount and kind of solvent used for dissolving the herbicide and the soil water content at the moment of spiking. An optimized protocol for the extraction and quantification of 2,4-D and its main metabolite from soil samples is presented.