Use of groundwater and reclaimed water for agricultural irrigation: Farmers' practices and attitudes and related environmental and health risks

Dynamic interaction of antibiotic resistance between plant microbiome and organic fertilizers: sources, dissemination, and health risks

Antibiotic resistance is a global health problem driven by the irrational use of antibiotics in different areas (such as agriculture, animal farming, and human healthcare). Sub-lethal concentrations of antibiotic residues impose selective pressure on environmental, plant-associated, and human microbiome leading to the emergence of antibiotic-resistant bacteria (ARB). This review summarizes all sources of antibiotic resistance in agricultural soils (including manure, sewage sludge, wastewater, hospitals/pharmaceutical industry, and bioinoculants). The factors (such as the physicochemical properties of soil, root exudates, concentration of antibiotic exposure, and heavy metals) that facilitate the transmission of resistance in plant microbiomes are discussed. Potential solutions for effective measures and control of antibiotic resistance in the environment are also hypothesized. Manure exhibits the highest antibiotics load, followed by hospital and municipal WW. Chlortetracycline, tetracycline, and sulfadiazine have the highest concentrations in the manure. Antibiotic resistance from organic fertilizers is transmitted to the plant microbiome via horizontal gene transfer (HGT). Plant microbiomes serve as transmission routes of ARB and ARGS to humans. The ingestion of ARB leads to human health risks (such as ineffectiveness of medication, increased morbidity, and mortality).

Modelling the impacts generated by reclaimed wastewater reuse in agriculture: From literature gaps to an integrated risk assessment in a One Health perspective

The reuse of reclaimed wastewater is increasingly recognized as a viable alternative water source for irrigation. Its application, whether direct or indirect, impacts several interconnected compartments, including groundwater, surface water, soil, crops, and humans. Reclaimed wastewater provides essential resources for crops, like water and nutrients. However, it also introduces pathogens, and contaminants of emerging concern (CECs), defined as chemicals that may pose risks to human health and ecosystems but are not yet fully regulated, such as pharmaceuticals and personal care products, among others. Additionally, reclaimed wastewater may contain antibiotic-resistant bacteria (ARBs) and disinfection by-products (DBPs), all of which present potential health and environmental risks. Therefore, regulatory bodies stress the need for preventive risk assessments to ensure safe reuse. This paper critically reviews available models for assessing the impacts of reclaimed wastewater reuse in agriculture. It identifies gaps in current modelling approaches and outlines future research directions. Key areas requiring further investigation include the fate and transfer of CECs, ARBs and DBPs, and the co-occurrence of multiple risks in such interconnected systems, especially in the indirect reuse. To address these gaps, we proposed a simplified approach to integrate three types of risk associated with CECs in indirect reuse, focusing on risks posed by antibiotics and other pharmaceuticals: human health risk, environmental risk and risk from antibiotic resistance development. This approach aids in identifying the most critical endpoints within the One Health approach, supporting (i) CECs prioritization in regulations based on their critical endpoints and (ii) the adoption of CEC-specific mitigation measures.

Inhalation of ferrate-disinfected Escherichia coli caused lung injury via endotoxin-induced oxidative stress and inflammation response

Ferrate (Fe(VI)) is an environmentally friendly disinfectant that is widely used to eradicate microbes in reclaimed water. However, the potential health risks associated with inhalation of Fe(VI)-treated bacteria-laden reclaimed water remains uncertain. We aimed to explore the inhalation hazards and potential mechanisms of K2FeO4-treated Escherichia coli (E. coli, ATCC 25922). Our findings indicated that Fe(VI) disinfection induced a dose- and time-dependent E. coli inactivation, accompanied by a rapid release of the bacterial endotoxin, lipopolysaccharide (LPS). Scanning electron microscopy (SEM) observations indicate that Fe(VI)-induced endotoxin production consists of at least two stages: initial binding of endotoxin to bacteria and subsequent dissociation to release free endotoxin. Furthermore, Fe(VI) disinfection was not able to effectively eliminate pure or E. coli-derived endotoxins. The E. coli strain used in this study lacks lung infection capability, thus the inhalation of bacteria alone failed to induce severe lung injury. However, mice inhaled exposure to Fe(VI)-treated E. coli showed severe impairment of lung structure and function. Moreover, we observed an accumulation of neutrophil/macrophage recruitment, cell apoptosis, and ROS generation in the lung tissue of mice subjected to Fe(VI)-treated E. coli. RNA sequencing (RNA-seq) and PCR results revealed that genes involved with endotoxin stimuli, cell apoptosis, antioxidant defence, inflammation response, chemokines and their receptors were upregulated in response to Fe(VI)-treated E. coli. In conclusion, Fe(VI) is ineffective in eliminating endotoxins and can trigger secondary hazards owing to endotoxin release from inactivated bacteria. Aerosol exposure to Fe(VI)-treated E. coli causes considerable damage to lung tissue by inducing oxidative stress and inflammatory responses.

Deficit irrigation of reclaimed water relieves oat drought stress while controlling the risk of PAEs pollution in microplastics-polluted soil

Reclaimed water irrigation has emerged as a critical alternative in agricultural regions facing water scarcity. However, soil pollution with microplastics (MPs) greatly increases the exposure risk and toxic effects of reclaimed water contaminations, such as phthalate esters (PAEs). A field experiment consisting of soil column pots evaluated the feasibility of using PAEs-contaminated water to irrigate oats (Avena sativa L.) in drought seasons. Three irrigation regimens based on soil matric potential thresholds (-10 kPa, -30 kPa, -50 kPa) explored the impact of PAE-contaminated water on oat physiology and environmental pollution in soil with and without MPs contamination. The results showed that treating oats at the SMP of -30 kPa boosted shoot biomass by 3.1%-14.0% compared to the drought condition at -50 kPa, and the root biomass of oats was significantly increased. The physiological metrics of oats indicated that irrigation at -50 kPa induced drought stress and oxidative damage in oats, particularly during the milk stage. Different irrigation treatments influenced the accumulation of PAEs in plants, soil, and leachate. The ratios of leachate to irrigation water in -10 kPa treatment with and without MPs addition were 1.18% and 4.48%, respectively, which aggravated the accumulation of pollutants in deep soil layers and may cause groundwater pollution. MPs pollution in soil increased the content of PAEs in the harvested oats and reduced the transport and accumulation of PAEs in deep soil layers (20-50 cm) and leachate. The coupling of PAEs in irrigation water with soil MPs pollution may exacerbate plant damage. However, the damage can be minimized under the scheduled irrigation at -30 kPa which could balance crop yield and potential risks.

Effects of Simulated Reclaimed Water on Soil Particle Sizes and Cd Adsorption and Migration in Soils at Smelting Sites

This work studied the vertical migration characteristics of Cd in soil profiles from a zinc smelting site under the influence of simulated reclaimed water containing NaCl and Na2SO4. The isothermal adsorption curves of Cd in the soils of miscellaneous fill and weathered slate well fitted the Freundlich and Langmuir models, with R2 ranging from 0.991 to 0.998. The maximum adsorption capacity of Cd in the soils decreased significantly under the salt ion treatments with NaCl and Na2SO4. After leaching, the Cd concentrations in the leachates and Cd contents in the subsoil layers of 10-60 cm followed the order NaCl treatment > Na2SO4 treatment > CK (p < 0.05), suggesting that the salt ions promoted the vertical migration of exogenous Cd. The proportion of coarse particles (> 0.02 mm) decreased, while that of fine particles (< 0.02 mm) increased under salt ion treatments (p < 0.05). The morphological characterization indicated that salt ions accelerated the erosion and fragmentation of coarse particles to form fine particles. The use of reclaimed water to flush smelting sites may increase the risk of Cd migration with small-sized soil particles from the soil to groundwater.

Ketoprofen as an emerging contaminant: occurrence, ecotoxicity and (bio)removal

Ketoprofen, a bicyclic non-steroidal anti-inflammatory drug commonly used in human and veterinary medicine, has recently been cited as an environmental contaminant that raises concerns for ecological well-being. It poses a growing threat due to its racemic mixture, enantiomers, and transformation products, which have ecotoxicological effects on various organisms, including invertebrates, vertebrates, plants, and microorganisms. Furthermore, ketoprofen is bioaccumulated and biomagnified throughout the food chain, threatening the ecosystem function. Surprisingly, despite these concerns, ketoprofen is not currently considered a priority substance. While targeted eco-pharmacovigilance for ketoprofen has been proposed, data on ketoprofen as a pharmaceutical contaminant are limited and incomplete. This review aims to provide a comprehensive summary of the most recent findings (from 2017 to March 2023) regarding the global distribution of ketoprofen in the environment, its ecotoxicity towards aquatic animals and plants, and available removal methods. Special emphasis is placed on understanding how ketoprofen affects microorganisms that play a pivotal role in Earth's ecosystems. The review broadly covers various approaches to ketoprofen biodegradation, including whole-cell fungal and bacterial systems as well as enzyme biocatalysts. Additionally, it explores the potential of adsorption by algae and phytoremediation for removing ketoprofen. This review will be of interest to a wide range of readers, including ecologists, microbiologists, policymakers, and those concerned about pharmaceutical pollution.

Changes of Microbial Diversity in Rhizosphere of Different Cadmium-Gradients Soil under Irrigation with Reclaimed Water

Water scarcity and the uneven distribution of water resources in China have resulted in water shortages for agricultural irrigation in arid and semi-arid areas. Reclaimed water used for agricultural irrigation has become an effective solution in the context of the global water shortage. In order to improve soil productivity and solve the shortage of water resources, we carried out reclaimed water irrigation experiments on polluted soil. Compared with full irrigation treatments, the EC value of reclaimed water under deficit irrigation treatments decreased by 2.89–42.90%, and the content of organic matter increased by 6.31–12.10%. The proportion of Acidobacteria community in soils with different cadmium concentration gradients irrigated with reclaimed water ranged from 13.6% to 30.5%, its relative abundance decreased with the increase of soil cadmium concentration. In particular, the relative abundance of Pseudomonas pathogens in deficit irrigation treatments was lower than that of the full irrigation treatments. RDA analysis showed that the environmental factors that played a leading role in the change of microbial community structure were organic matter and pH. Furthermore, the metabolic function potential of the rhizosphere soil bacterial community in deficit irrigation treatments was higher than that of full irrigation treatments with reclaimed water. This study proved that reclaimed water irrigation for cadmium contaminated soil did not aggravate the pollution level and promoted the soil ecological environment with better microbial community diversity.