Nicosulfuron sorption kinetics and sorption/desorption on volcanic ash-derived soils: Proposal of sorption and transport mechanisms

A comparative study of the adsorption and desorption process of selected natural Albanian clays toward methomyl and dimethoate pesticides

Natural soil components, such as clays, have recently piqued interest because of their potential as pesticide adsorbents. This research work sheds light on the possibility of the application of natural Albanian clays as adsorbents for methomyl and dimethoate pesticides from aqueous solutions. Natural Albanian clays from the regions of Brari, Currila, Dardha, and Prrenjasi were employed in the study and were characterized by granulometric analysis and powder X-ray diffraction. Each clay's adsorption capacity and desorption behavior were investigated toward the chosen pesticides. Within 48 h of contact time, methomyl and dimethoate solutions with different concentrations were evaluated at 25 °C to see how the insecticide concentration affected the adsorption & desorption processes for each natural clay type. The experimental data were fitted to Freundlich, Temkin and Dubinin-Radushkevich isotherm like functions and the results showed the best correlation on Freundlich like adsorption isotherm for almost all cases. Brari clay performed better adsorptive properties toward dimethoate, followed by Dardha, Currila and Prrenjasi clays. The dimethoate adsorbed quantities varied from 0.250 mg/g for C = 0.200 g/L to 0.822 mg/g for C = 0.500 g/L. In comparison to Dardha and Prrenjasi clays, Brari and Currila clays exhibit longer saturation times and improved methomyl retention. In the first 2 h of contact, 96.5% of methomyl and 81% of dimethoate were desorbed from Brari clay. The adsorption process was also investigated employing pseudo first-order and pseudo second-order kinetic models, with the results indicating that all clay-pesticide systems studied demonstrated second-order kinetic behavior. Based on the studied desorption process, it is possible to impregnate clays with various insecticides in agriculture and completely control the quantities of the insecticide released.

COVID-19 related antiviral drugs are less adsorbable on sediment under alkaline and high cation conditions

The COVID-19 pandemic resulted in unprecedented usage and elevated environmental concentrations of antiviral drugs. However, very limited studies have reported their sorption characteristics on environmental matrices. This study investigated the sorption of six COVID-19 related antivirals on Taihu Lake sediment with varied aqueous chemistry. Results showed that the sorption isotherms for arbidol (ABD), oseltamivir (OTV), and ritonavir (RTV) were linear, while the Freundlich model was the best-fit for ribavirin (RBV) and the Langmuir model for favipiravir (FPV) and remdesivir (RDV). Their distribution coefficient, K_d, varied between 5.051 L/kg to 248.6 L/kg with the sorption capacities ranked as FPV > RDV > ABD > RTV > OTV > RBV. Alkaline conditions (pH 9) and elevated cation strength (0.05 M to 0.1 M) decreased the sorption capacities of the sediment for these drugs. Thermodynamic analysis revealed that the spontaneous sorption of RDV, ABD, and RTV was between physisorption and chemisorption while FPV, RBV, and OTV were mainly physisorption. Functional groups related to hydrogen bonds, π - π interaction, and surface complexation were implicated in the sorption processes. These findings enhance our understanding about the environmental fate of COVID-19 related antivirals and provide basic data for predicting their distribution and risk in the environment.

Insect Epigenetic Mechanisms Facing Anthropogenic-Derived Contamination, an Overview

Currently, the human species has been recognized as the primary species responsible for Earth's biodiversity decline. Contamination by different chemical compounds, such as pesticides, is among the main causes of population decreases and species extinction. Insects are key for ecosystem maintenance; unfortunately, their populations are being drastically affected by human-derived disturbances. Pesticides, applied in agricultural and urban environments, are capable of polluting soil and water sources, reaching non-target organisms (native and introduced). Pesticides alter insect's development, physiology, and inheritance. Recently, a link between pesticide effects on insects and their epigenetic molecular mechanisms (EMMs) has been demonstrated. EMMs are capable of regulating gene expression without modifying genetic sequences, resulting in the expression of different stress responses as well as compensatory mechanisms. In this work, we review the main anthropogenic contaminants capable of affecting insect biology and of triggering EMMs. EMMs are involved in the development of several diseases in native insects affected by pesticides (e.g., anomalous teratogenic reactions). Additionally, EMMs also may allow for the survival of some species (mainly pests) under contamination-derived habitats; this may lead to biodiversity decline and further biotic homogenization. We illustrate these patterns by reviewing the effect of neonicotinoid insecticides, insect EMMs, and their ecological consequences.

Agroecological Strategies to Safeguard Insect Pollinators in Biodiversity Hotspots: Chile as a Case Study

Industrial agriculture (IA) has been recognized among the main drivers of biodiversity loss, climate change, and native pollinator decline. Here we summarize the known negative effects of IA on pollinator biodiversity and illustrate these problems by considering the case of Chile, a “world biodiversity hotspot” (WBH) where food exports account for a considerable share of the economy in this country. Most of Chile’s WBH area is currently being replaced by IA at a fast pace, threatening local biodiversity. We present an agroecological strategy for sustainable food production and pollinator conservation in food-producing WBHs. In this we recognize native pollinators as internal inputs that cannot be replaced by IA technological packages and support the development of agroecological and biodiversity restorative practices to protect biodiversity. We suggest four fundamental pillars for food production change based on: (1) sharing the land, restoring and protecting; (2) ecological intensification; (3) localized knowledge, research, and technological development; and (4) territorial planning and implementation of socio-agroecological policies. This approach does not need modification of native pollination services that sustain the world with food and basic subsistence goods, but a paradigm change where the interdependency of nature and human wellbeing must be recognized for ensuring the world’s food security and sovereignty.

Study of Sorption Kinetics and Sorption-Desorption Models to Assess the Transport Mechanisms of 2,4-Dichlorophenoxyacetic Acid on Volcanic Soils

The sorption behavior of 2,4-dichlorophenoxyacetic acid (2,4-D) in the abundant agricultural volcanic ash-derived soils (VADS) is not well understood despite being widely used throughout the world, causing effects to the environment and human health. The environmental behavior and risk assessment of groundwater pollution by pesticides can be evaluated through kinetic models. This study evaluated the sorption kinetics and 2,4-D sorption-desorption in ten VADS through batch sorption experiments. Differences in the sorption extent for the fast and slow phases was observed through the IPD model where 2,4-D sorption kinetics was controlled by external mass transfer and intra organic matter diffusion in Andisols (C1 ≠ 0). We confirmed from the spectroscopic analysis that the carboxylate group directly drives the interaction of 2,4-D on Andisol soil. The MLR model showed that IEP, FeDCB, and pH×Silt are important soil descriptors in the 2,4-D sorption in VADS. The Freundlich model accurately represented sorption equilibrium data in all cases (Kf values between 1.1 and 24.1 µg1-1/n mL1/ng-1) with comparatively higher sorption capacity on Andisols, where the highest hysteresis was observed in soils that presented the highest and lowest OC content (H close to 0).

Adsorption and degradation of the herbicide nicosulfuron in a stagnic Luvisol and Vermic Umbrisol cultivated under conventional or conservation agriculture

The main goals of conservation agriculture are to enhance soil fertility and reduce soil degradation, especially through erosion. However, conservation agriculture practices can increase the risk of contamination by pesticides, mainly through vertical transfer via water flow. Better understanding of their sorption and degradation processes is thus needed in conservation agriculture as they control the amount of pesticide available for vertical transfer. The purpose of our study was to investigate the sorption and degradation processes of nicosulfuron in soil profiles (up to 90 cm deep) of a Vermic Umbrisol and a Stagnic Luvisol managed either in conventional or in conservation agriculture. Two laboratory sorption and incubation experiments were performed. Low sorption was observed regardless of the soil type, agricultural management or depth, with a maximum value of 1.3 ± 2.0 L kg^-1. By the end of the experiment (91 days), nicosulfuron mineralisation in the Vermic Umbrisol was similar for the two types of agricultural management and rather depended on soil depth (29.0 ± 2.3% in the 0-60-cm layers against 7.5 ± 1.4% in the 60-90 cm). In the Stagnic Luvisol, nicosulfuron mineralisation reached similar value in every layer of the conservation agriculture plot (26.5% ± 0.7%). On the conventional tillage plot, mineralisation decreased in the deepest layer (25-60 cm) reaching only 18.4 ± 6.9% of the applied nicosulfuron. Regardless of the soil type or agricultural management, non-extractable residue formation was identified as the main dissipation process of nicosulfuron (45.1 ± 8.5% and 50.2 ± 7.0% under conventional and conservation agriculture respectively after 91 days). In our study, nicosulfuron behaved similarly in the Vermic Umbrisol regardless of the agricultural management, whereas the risk of transfer to groundwater seemed lower in the Stagnic Luvisol under conservation agriculture.

Volatile compounds sorption during the aging of Chinese Liquor (Baijiu) using Pottery Powder

Pottery jar is the preferred storage vessel for aging baijiu, Chinese liquor, and it could sorb liquor micro-compounds. The objective of this work was to identify the sorption of liquor micro-compounds onto pottery powder, and gained insights regarding the sorption processes and mechanism. The sorption of liquor micro-compounds onto pottery powder of different sizes was studied using different kinetic models. The results showed that the sorption capacity varied among particle size of pottery powder, which also affected equilibrium time. The sorption process could be well described by the pseudo-second-order model, and the external diffusion was the rate-limiting step. Liquor volatiles in pottery powder at equilibrium were characterized, which detected alcohols, esters, acids, and furan by gas chromatography-mass spectrometry (GC-MS). These findings demonstrated pottery could not only cause subtractive changes that occur to liquor during the aging period, but also as a vector for transferring aromas sorbed when reused.