Paraquat In Soils Research Articles

Recent advances in estimation of paraquat using various analytical techniques: A review

Agriculture, one of the ancient occupations is considered as the backbone of any civilization across the countries. Development of agriculture and its technology has constantly evolved right from its origin. To increase agricultural productivity, people have started using pesticides. In ancient times, people used organic manures, however later, they have moved to synthetic/chemical pesticides, which are hazardous as well. The synthetic pesticides are not only harmful towards human beings but also to the environment. Among the available pesticides, paraquat (PQ) is one of the common herbicides used in agriculture. Usage of this herbicide leads to several life-threatening diseases and increases mortality rate. Therefore, quick, selective, and efficient detection of PQ in soil, water, and agro-products is very much essential to prevent its hazardous effects. In this perspective, several methods have been proposed in the literature for the detection of PQ using variety of catalysts.This review provides an insight on the detection of PQ using various analytical techniques including adsorption, spectrophotometric methods, chromatographic methods, and electrochemical methods etc. Further, it focuses on the different type of catalytic materials like metal nanoparticles, carbonaceous materials, and their composites, metals, polymers, and their roles during the determination of PQ. In addition, it analyses the effectiveness of the catalyst materials in terms of sensitivity, selectivity, real time monitoring in fruit juices like potato and apple juices, water samples etc., towards the detection of PQ.

Mutual influence of copper and paraquat on their adsorption in soil

Paraquat and copper (Cu) have been commonly used and detected in soils. Therefore, it is important to understand their mobility in the environment. This study investigated the competitive effects of paraquat and Cu on their adsorption in five representative Chinese soils by performing batch adsorption equilibrium experiments and spectroscopic analysis. The adsorption of paraquat in soils varied with soil types and was positively correlated with both cationic exchange capacity and soil organic matter content. Paraquat exerted a more remarkable suppression effect on the adsorption of Cu than Cu on the adsorption of paraquat. In the presence of 0.12 and 0.19 mmol L−1 paraquat, Cu adsorption decreased by 16% and 22% in Heilongjiang soil and by 24% and 37% in Jiangxi soil, respectively. While in the presence of 0.1 and 0.2 mmol L−1 Cu, paraquat adsorption decreased by 4% and 8% in Heilongjiang soil and by 15% and 19% in Jiangxi soil. Exchange selectivity involving symmetric (Paraquat2+, Cu2+) cation exchange is the probable basis for the suppression effect. An ultraviolet-visible absorption study suggested that formation of Cu–paraquat complexes was unlikely in solution or on the soil surface. Cu K-edge X-ray absorption spectroscopy indicated that Cu in soils may have some water hydration layers as the nearest neighbors, and each Cu was coordinated with five oxygen atoms. The results greatly improve our knowledge about the molecular-scale adsorption mechanisms of paraquat and Cu in soils and will be useful to predict the behavior, transport, and fate of paraquat and Cu in agricultural soils.

Determination of Paraquat (Herbicide) Residue Level in Sandy Clay Loam Soil Using High Performance Liquid Chromatography

Pesticide is considered as the most widely used form of agricultural chemical. Pesticide residue is the remaining pesticide on or in soil after pesticide is applied on agriculture soil. Soil is a component that is crucial to life. The research purposely concerned on major effects that could be contributed from medium to unlimited application of pesticide. The soil samples were systematically collected from 5 plots and Paraquat residues concentrations were determined in dissimilar depth of soil layers. The herbicide used was Paraquat that contained Paraquat Dichloride. High Performance Liquid Chromatography (HPLC) analysis detected the peak area volumes of Paraquat in soil samples at level ranging from 0.3 to 5.9 mg/l. The concentration of Paraquat in sandy clay loam soil showed that herbicide leached downward to the depth of 15 cm. The maximum concentration of Paraquat residue was detected at 0 to15 cm of soil depth at 2.783 mg/l. In highly organic soils, adsorption is weaker and Paraquat remains herbicidally active for longer, up to 29 days in one trial on soil with 98% organic matter [1]. Oral dose, LD50 for human is equal to 40-60 mg/kg [2] while the lowest fatal dose recorded for human was 17 mg/kg, but even lower doses may be fatal for children [3].

Paraquat Adsorption, Degradation, and Remobilization in Tropical Soils of Thailand

Paraquat adsorption, degradation, and remobilization were investigated in representative tropical soils of Yom River Basin, Thailand. Adsorption of paraquat in eight soil samples using batch equilibration techniques indicated that adsorption depended on soil characteristics, including exchangeable basic cations and iron content. Multiple regression analysis indicated significant contribution of exchangeable calcium percentage (ECP), total iron content (TFe) and exchangeable sodium percentage (ESP) to paraquat sorption (Q). ESP and TFe were significant at all adsorption stages, whereas ESP was significant only at the initial stage of paraquat adsorption. Adsorption studies using two soils representing clay and sandy loam textures showed that paraquat adsorption followed the Freundlich model, exhibiting a nonlinear sorption curve. Paraquat adsorption was higher in the clay soil compared to the sandy loam soil with K f values of 787 and 18, respectively. Desorption was low with 0.04 to 0.17% and 0.80 to 5.83% desorbed in clay and sandy loam soil, respectively, indicating some hysteresis effect. Time-dependent paraquat adsorption fitted to the Elovich kinetic model indicated that diffusion was a rate-limiting process. Paraquat mobility and degradation studies conducted using both field and laboratory soil column experiments with clay soil showed low mobility of paraquat with accumulation only in the surface 0–5 cm layer under field conditions and in the 0–1 cm layer in a laboratory soil column experiment. Degradation of paraquat in soil was faster under field conditions than at ambient laboratory conditions. The degradation rate followed a first-order kinetic model with the DT50 at 36–46 days and DT90 around 119–152 days.

Deactivation of the biological activity of paraquat in the soil environment: a review of long-term environmental fate.

During the many years of paraquat usage, wide ranges of investigations of its environmental impact have been conducted. Much of this information has been published, but key, long-term field studies have not previously been presented and assessed. The purpose of this review is to bring together and appraise this information. Due to the nature of paraquat residues in soils, the major part (some 99.99%) of a paraquat application that reaches the soil within the typical Good Agricultural Practice (GAP) is strongly adsorbed to soils of a wide variety of textures. This is in equilibrium with an extremely low concentration in soil solution. However, the paraquat in soil solution is intrinsically biodegradable, being rapidly and completely mineralized by soil microorganisms. The deactivation of the biological activity of paraquat in soils, due to sorption, has been investigated thoroughly and systematically. It is recognized that the determination of total soil residues by severe extraction procedures provides no insight into the amount of paraquat biologically available in soil. Consequently, the key assay developed for this purpose, namely, the strong adsorption capacity-wheat bioassay (SAC-WB) method, has proved to be valuable for determination of the adsorption capacity relevant to paraquat for any particular soil. This method has been validated in the field with a series of long-term (>10 years) trials in different regions of the world. These trials have also shown that, following repeated applications of very high levels of paraquat in the field, residues not only reach a plateau but also subsequently decline. This demonstrates that the known biodegradation of paraquat in soil pore water plays an important role in field dissipation. The biological effects of paraquat in the field have been assessed under unrealistically high treatment regimes. These trials have demonstrated that the continued use of paraquat under GAP conditions will have no detrimental effects on either crops or soil-dwelling flora and fauna. Any such effects can occur only under extreme use conditions (above the SAC-WB), which do not arise in normal agricultural practice.

The microbial biodegradation of paraquat in soil

The microbial degradation of [14C]paraquat using cultures from two agricultural soils was investigated. The experiments were carried out in the absence of light, under aerobic conditions. Degradation was rapid, with 50% mineralisation to [14C]carbon dioxide occurring within three weeks. HPLC, capillary electrophoresis and mass spectroscopy confirmed that the majority (>85%) of the remaining radiochemical in solution was [14C]oxalic acid, and that no paraquat remained.

The microbial biodegradation of paraquat in soil

The microbial biodegradation of paraquat in soil

Apparent decomposition of paraquat in soil

Apparent decomposition of paraquat in soil

An integrated method for trifluralin, diphenamid, and paraquat in soil and runoff from agricultural land.

An integrated method for trifluralin, diphenamid, and paraquat in soil and runoff from agricultural land.

The Fate of Paraquat in Soils

Abstract An outstanding property of the bipyridylium herbicides is the rapidity with which they are inactivated in contact with soils. The initial inactivation is attributable to strong adsorption on soil colloids and, as may be expected, is governed by the nature of the soil. Subsequent degradation may be induced by ultraviolet radiation or, below the soil surface, by the activity of the microflora. The agronomic significance of these mechanisms is described by reference to recent work on paraquat.

The fate of paraquat in soils

An outstanding property of the bipyridylium herbicides is the rapidity with which they are inactivated in contact with soils. The initial inactivation is attributable to strong adsorption on soil colloids and, as may be expected, is governed by the nature of the soil. Subsequent degradation may be induced by ultraviolet radiation or, below the soil surface, by the activity of the microflora. The agronomic significance of these mechanisms is described by reference to recent work on paraquat.

THE INTERACTION OF PARAQUAT (1: 1′‐DIMETHYL 4:4′‐DIPYRIDYLIUM DICHLORIDE) WITH MINERAL SOILS

SummaryInvestigation of the adsorption of 1:1′‐dimethyl 4:4′‐dipyridylium (paraquat) dichloride by a range of soils, using a solution‐equilibration technique, has shown that the adsorption is characterized by three factors:1. Up to a limiting value, defined as the Strong Adsorption Capacity (SAC), the solution concentration of paraquat is reduced below the level of chemical detection by suspended soil: this strongly adsorbed paraquat is preferentially held against 0.1 to 2.0N solutions of ammonium ion. A range of strengths of adsorption probably exists within the strong adsorption range, but the greater part of the strongly adsorbed material is de‐activated herbicidally; this accounts for the herbicidal de‐activation of paraquat in soils.2. Removal of soil organic matter by treatment with hydrogen peroxide usually does not greatly change the SAC. Strong adsorption of paraquat is primarily a property of clay minerals, and the presence of expanding lattice minerals is of particular importance.3. For fortifications above the strong adsorption region, there is a region of weaker adsorption but the total adsorption capacities of soils at saturation are less than their cation exchange capacities for inorganic cations. Taken with the difficulty of displacement, this indicates that the adsorption of paraquat is strongly influenced by factors other than simple electrostatic interaction.