Adsorption, leaching and phytotoxicity of some herbicides as single and mixtures to some crops

Aptamer-based biosensors for the detection of neonicotinoid insecticides in environmental samples: A systematic review

Neonicotinoids, sometimes abbreviated as neonics, represent a class of neuro-active insecticides with chemical similarities to nicotine. Neonicotinoids are the most widely adopted group of insecticides globally since their discovery in the late 1980s. Their physiochemical properties surpass those of previously established insecticides, contributing to their popularity in various sectors such as agriculture and wood treatment. The environmental impact of neonicotinoids, often overlooked, underscores the urgency to develop tools for their detection and understanding of their behavior. Conventional methods for pesticide detection have limitations. Chromatographic techniques are sensitive but expensive, generate waste, and require complex sample preparation. Bioassays lack specificity and accuracy, making them suitable as preliminary tests in conjunction with instrumental methods. Aptamer-based biosensor is recognized as an advantageous tool for neonicotinoids detection due to its rapid response, user-friendly nature, cost-effectiveness, and suitability for on-site detection. This comprehensive review represents the inaugural in-depth analysis of advancements in aptamer-based biosensors targeting neonicotinoids such as imidacloprid, thiamethoxam, clothianidin, acetamiprid, thiacloprid, nitenpyram, and dinotefuran. Additionally, the review offers valuable insights into the critical challenges requiring prompt attention for the successful transition from research to practical field applications.

The leaching behaviour of herbicides in cropping soils amended with forestry biowastes

Leaching of herbicides in cropping soils not only impacts the groundwater sources but also reduces their effect in controlling weeds. Leaching studies were carried out in two cropping soils and two forestry biowaste media, wood pulp and sawdust with two herbicides, atrazine and bromacil in a packed lysimeter with simulated rainfall. The hypothesis was that high organic matter forestry biowaste soil amendments reduce the leaching of herbicides through the soil profile. Results from the experimental setups varied due to the impact of the simulated rainfall on the surface structure of the media. Organic carbon content, pH and structure of the media were all factors which affected the leaching of the two herbicides. The hypothesis was true for wood pulp, but for sawdust, organic matter content had less bearing on the leaching of the herbicides than other over-riding factors, such as pH, that were media specific. In sawdust, its large particle size and related pore volume allowed preferential flow of herbicides. Overall, the data indicated that both forestry biowastes were retentive to herbicide leaching, but the effect was more pronounced with wood pulp than sawdust.

Irrigation with Water Contaminated by Sugarcane Pesticides and Vinasse Can Inhibit Seed Germination and Crops Initial Growth

Sugarcane crops are dependent on chemicals for maintaining plantations. Therefore, environmental consequences concern adjacent areas that can be affected by contaminants in common use, including pesticides and vinasse (i.e., a by-product from the ethanol industry). This study aimed to evaluate phytotoxicity through two plant bioassays with water from mesocosms contaminated with the herbicide 2,4-D (447.0 μg L^-1), the insecticide fipronil (63.5 μg L^-1), and sugarcane vinasse (1.3%). First, the germination test (4 d) with Eruca sativa L. assessed water samples collected three times after the contamination (2 h, 14 d, and 30 d), considering germination, shoot, and root growth. The results from this bioassay indicated higher phytotoxicity for 2,4-D as it fully inhibited the shoot and root growth even in low concentrations (0.2 μg L^-1). However, no significant effect was reported for fipronil and vinasse. Also, the 2,4-D effects drastically decreased due to an expressive concentration reduction (99.4% after 30 d in mixture with vinasse). Second, the irrigation test with Phaseolus vulgaris L. and Zea mays L. considered shoot and root growth and biomass under 21 days after plants emergence. The herbicide 2,4-D inhibited the initial growth of tested species, especially the roots (up to 45% inhibition). Furthermore, sugarcane vinasse caused harmful effects on plant growth (up to 31% inhibition). Therefore, our data showed that these contaminants could inhibit plant germination and initial growth under our tested conditions. These evaluations can endorse risk assessments and water management in sugarcane crops surrounding areas.

Interaction between herbicides applied in mixtures alters the conception of its environmental impact

Herbicide mixtures have often been used to control weeds in crops worldwide, but the behavior of these mixtures in the environment is still poorly understood. Laboratory and greenhouse tests have been conducted to study the interaction of the herbicides diuron, hexazinone, and sulfometuron-methyl which have been applied alone and in binary and ternary mixtures in the processes of sorption, desorption, half-life, and leaching in the soil. A new index of the risk of leaching of these herbicides has also been proposed. The sorption and desorption study has been carried out by the batch equilibrium method. The dissipation of the herbicides has been evaluated for 180 days to determine the half-life (t_1/2). The leaching tests have been carried out on soil columns. The herbicides isolated and in mixtures have been quantified using ultra-high performance liquid chromatography coupled to the mass spectrometer. Diuron, hexazinone, and sulfometuron-methyl in binary and ternary mixtures have less sorption capacity and greater desorption when compared to these isolated herbicides. Dissipation of diuron alone is slower, with a half-life (t_1/2) = 101 days compared to mixtures (t_1/2 between 44 and 66 days). For hexazinone and sulfometuron-methyl, the dissipation rate is lower in mixtures (t_1/2 over 26 and 16 days), with a more pronounced effect in mixtures with the presence of diuron (t_1/2 = 47 and 56 and 17 and 22 days). The binary and ternary mixtures of diuron, hexazinone, and sulfometuron-methyl promoted more significant transport in depth (with the three herbicides quantified to depth P4, P7, and P7, respectively) compared to the application of these isolated herbicides (quantified to depth P2, P4, and P5). Considering the herbicides' desorption and solubility, the new index proposed to estimate the leaching potential allowed a more rigorous assessment concerning the risk of leaching these pesticides, with hexazinone and sulfometuron-methyl presenting a higher risk of contamination of groundwater.

Pesticide residues in drinking water, their potential risk to human health and removal options

The application of pesticides in agricultural and public health sectors has resulted in substantially contaminated water resources with residues in many countries. Almost no reviews have addressed pesticide residues in drinking water globally; calculated hazard indices for adults, children, and infants; or discussed the potential health risk of pesticides to the human population. The objectives of this article were to summarize advances in research related to pesticide residues in drinking water; conduct health risk assessments by estimating the daily intake of pesticide residues consumed only from drinking water by adults, children, and infants; and summarize options for pesticide removal from water systems. Approximately 113 pesticide residues were found in drinking water samples from 31 countries worldwide. There were 61, 31, and 21 insecticide, herbicide, and fungicide residues, respectively. Four residues were in toxicity class IA, 14 residues were in toxicity class IB, 55 residues were in toxicity class II, 17 residues were in toxicity class III, and 23 residues were in toxicity class IV. The calculated hazard indices (HIs) exceeded the value of one in many cases. The lowest HI value (0.0001) for children was found in Canada, and the highest HI value (30.97) was found in Egypt, suggesting a high potential health risk to adults, children, and infants. The application of advanced oxidation processes (AOPs) showed efficient removal of many pesticide classes. The combination of adsorption followed by biodegradation was shown to be an effective and efficient purification option. In conclusion, the consumption of water contaminated with pesticide residues may pose risks to human health in exposed populations.

Effect of subdoses of sugarcane ripeners on lettuce physiology in a drift scenario

In order to understand the physiological effects of ripeners in sensitive crops, the objective of this work was to evaluate the effect of subdoses of the ripeners glyphosate, trinexapac-ethyl and sulfometuron methyl commonly used in sugarcane, in the growth of lettuce cultivar 'Lucy Brown' and 'Vanda'. To address the effects of the products in the lettuce physiology, analyses of fresh weight, dry weight, number of leaves, chlorophyll content, quantum efficiency of photosystem II, lipid peroxidation (MDA), hydrogen peroxide (H2O2), glutathione reductase (GR), guaiacol peroxidase (GPOX) were performed. We observed that among the products tested, glyphosate had minor impact on plant growth, compared to trinexapac-ethyl and sulfometuron methyl. All products induced a decrease in chlorophyll content for both cultivars. Chlorophyll A fluorescence suffered a major reduction with trinexapac-ethyl and sulfometuron methyl in 'Vanda' and no differences were observed for 'Lucy Brown'. MDA content and enzyme quantification varied by cultivar and the sugarcane ripener tested. By disturbing chlorophyll content and quantum efficiency of photosystem II, through these sugarcane ripeners did not have direct mode of action affecting photosystem II, they can cause some level of damage and activate different mechanisms and at different times, in response to stress. In this sense, it is possible to observe that reduced doses of glyphosate, trinexapac ethyl, and sulfometuron methyl affect the development of lettuce at different levels and trigger an oxidative response that was cultivar dependent.

Elucidation of electrocoagulation mechanism in the removal of Blue SI dye from aqueous solution using Al-Al, Cu-Cu electrodes - A comparative study

This work presents the research on the treatment of an anthraquinone derivatives of disperse dye Blue SI from aqueous solution using aluminium for the optimization of operational parameters like pH, current density, addition of electrolyte, contact time for the color removal efficiency (CRE) and the results are compared with the performance of copper electrodes in electrocoagulation (EC). The parameters for maximum CRE was found with Al at current density 40 Am^-2, time 10 min at pH 7, and for Cu at 60 Am^-2 15 min, at pH 6 were optimized. The characterization of the treated water using HPLC, MS studies revealed intermediate compounds. From the XPS analysis of the sludge obtained, the mechanism of EC was deduced. Treated aqueous solution was studied for its phytotoxicity with Vigna radiata and ecotoxicity studies were conducted on Artemia salina to study the toxicity effect of the intermediatory products in the treated dye solution. Blue SI dye aqueous solution treated with aluminium electrodes shows no or lesser toxicity in plants as well as in ecotoxic study compared with copper electrodes.

Adsorción-desorción de diurón y ametrina en suelos de Colombia y España

Aunque en la actualidad existe una gran preocupación por la contaminación y los posibles efectos sobre la salud que genera el uso frecuente de herbicidas, los estudios ambientales en los países tropicales son escasos, especialmente en Colombia. Por tanto, en el presente trabajo se evaluó la adsorción-desorción de diurón y ametrina en un suelo de Colombia (SC) y de España (SE). Los ensayos de adsorción-desorción se realizaron con moléculas de los herbicidas marcados con 14C, empleando la técnica batch equilibrium. En ambos suelos y para ambos herbicidas hubo un buen ajuste a las isotermas de Freundlich con R2 mayores a 0,99. Para diurón, en SE (Kfa = 12,82 ± 1,23) hubo mayor poder de adsorción frente a SC (4,56 ± 0,26). Por el contrario, para la ametrina se encontró un valor de Kfa = 6,47 ± 0,25 en SC y de 3,05 ± 0,08 en SE, mostrando mayor interacción con SC en comparación con SE. Para diurón se observó un grado de histéresis mayor en SC y para ametrina en SE, mostrando que la interacción de los dos herbicidas con los componentes de cada suelo es diferente dependiendo de su constitución mineralógica y su valor de pH.  

Leaching of Diuron, Hexazinone, and Sulfometuron-methyl Applied Alone and in Mixture in Soils with Contrasting Textures

When herbicides are applied in mixture, interactions among them could potentially promote changes in herbicide behavior in the soil. Thus, application mode (isolated or in mixture) and soil texture (sandy or clayey) were investigated in the total leaching of the commercial mixture diuron + hexazinone + sulfometuron-methyl, and of each isolated compound. Experiments in soil columns also evaluated the movement of each herbicide and mixtures across soil layers. In the sandy soil, the greatest total leaching was observed with hexazinone compared to diuron and sulfometuron. Most of the applied diuron remained at the top layer of the soil, indicating that this herbicide has low soil mobility. Overall, our results show that hexazinone has greater leaching potential and mobility along the soil profile compared to diuron and sulfometuron. Our data can be used in assessing the fate of diuron, hexazinone, and sulfometuron alone or in mixture on natural ecosystems, under different soil types and application modes.