Toxicity of herbicides to cyanobacteria and phytoplankton species of the San Francisco Estuary and Sacramento-San Joaquin River Delta, California, USA.

The herbicides glyphosate, imazamox and fluridone are herbicides, with low toxicity towards fish and invertebrates, which are applied to waterways to control invasive aquatic weeds. However, the effects of these herbicides on natural isolates of phytoplankton and cyanobacteria are unknown. Three species of microalgae found in the San Francisco Estuary (SFE)/Sacramento-San Joaquin River Delta (Delta) (Microcystis aeruginosa, Chlamydomonas debaryana, and Thalassiosira pseudonana) were exposed to the three herbicides at a range of concentrations in 96-well plates for 5-8 days. All three algal species were the most sensitive to fluridone, with IC50 of 46.9, 21, and 109 µg L-1 for M. aeruginosa, T. pseudonana and C. debaryana, respectively. Imazamox inhibited M. aeruginosa and T. pseudonana growth at 3.6 × 104 µg L-1 or higher, and inhibited C. debaryana growth at 1.0 × 105 µg L-1 or higher. Glyphosate inhibited growth in all species at ca. 7.0 × 104 µg L-1 or higher. Fluridone was the only herbicide that inhibited the microalgae at environmentally relevant concentrations in this study and susceptibility to the herbicide depended on the species. Thus, the application of fluridone may affect cyanobacteria and phytoplankton community composition in water bodies where it is applied.

Alteration in DNA structure, molecular responses and Na+ -K+ -ATPase activities in the gill of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) in response to sub-lethal verapamil.

The ecotoxicological consequences of residues from pharmaceutical drugs on aquatic biota have necessitated the development of sensitive and reliable techniques to assess the impact of these xenobiotics on aquatic organisms. This study investigated the alteration in DNA structure, molecular responses and the activities of Na+ -K+ -ATPase and antioxidant enzymes in the gill of Nile tilapia, Oreochromis niloticus, exposed to long-term effects at the concentrations (0.14, 0.28 and 0.57mgL-1) of verapamil in static renewal system for 15, 30, 45 and 60 days. Evaluation of DNA structure, using single cell gel electrophoresis, revealed certain degree of DNA damages in the gill in a time and concentration-dependent relationship. Transcription of mRNA of superoxide dismutase (sod), catalase (cat) and heat shock protein (hsp70) genes in the gill of the fish showed the genes were up-regulated. Na+-K+-ATPase activity was inhibited in a concentration and time dependent manner. The indices of oxidative stress biomarkers (lipid peroxidation and carbonyl protein) as well as superoxide dismutase, glutathione peroxidase, glutathione-S-transferase were elevated in the treated fish in comparison to the control. Further, the level of reduced glutathione and catalase activity were inhibited at 0.28mgL-1 after day 30. Long-term exposure to sub-lethal concentration of verapamil can cause DNA damages, molecular effects and oxidative stress in O. niloticus. The biomarkers analysed can be used as early warning signals in environmental biomonitoring and assessment of drug contamination in aquatic ecosystem.

Correction to: Escherichia coli persistence kinetics in dairy manure at moderate, mesophilic, and thermophilic temperatures under aerobic and anaerobic environments.

Escherichia coli persistence kinetics in dairy manure at moderate, mesophilic, and thermophilic temperatures.

Assessment of mutagenic, hematological and oxidative stress biomarkers in liver of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) in response to sublethal verapamil exposure.

The influx of pharmaceutical drugs and their metabolites have been reported to cause negative impact on aquatic biota. In this study, effects of long-term exposure of verapamil on mutagenic, hematological parameters and activities of the oxidative enzymes of Nile tilapia, Oreochromis niloticus were investigated for 60 days exposure at the concentrations of 0.29, 0.58 and 1.15 mg L-1 in the fish liver. The exposure resulted in significantly high (p < 0.05) micronuclei induction of peripheral blood cells at the peak on day 30 at 1.15 mg L-1. Compared with the control, there was significant increase (p < 0.05) in white blood cell counts and red blood cell distribution width (RDW), with a reduction in hemoglobin (Hb), red blood cell counts (RBCs), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) level as the concentration of the drug increased. The indices of oxidative stress biomarkers (lipid peroxidation and carbonyl protein) showed elevated level, depicting a positive correlation with both time and concentration. More so, the activity of energy-related parameter (Na+ -K+- ATPase) in the tissue was significantly inhibited (p < 0.05) at the end of 60 days exposure period. Further, the activity of catalase (CAT) was inhibited while reduced glutathione (GSH) level was decreased in the liver tissue. There was increase in the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) after 30 days at 0.29 mg L-1. The study demonstrated that prolonged exposure to verapamil at sublethal concentration can result in mutagenic effects and oxidative dysfunctions in O. niloticus.

Microbial pathogen quality criteria of rendered products.

The North American rendering industry processes approximately 24 million metric tons (Mt) of raw materials and produces more than 8 million Mt of rendered products. More than 85 % of rendered products produced annually in the USA are used for producing animal feed. Pathogen contamination in rendered products is an important and topical issue. Although elevated temperatures (115-140 °C) for 40-90 min during the standard rendering processes are mathematically sufficient to completely destroy commonly found pathogens, the presence of pathogens in rendered products has nevertheless been reported. Increased concern over the risk of microbial contamination in rendered products may require additional safeguards for producing pathogen-free rendered products. This study provides an overview of rendered products, existing microbial pathogen quality criteria of rendered products (MPQCR), limitations, and the scope of improving the MPQCR.

Assessing the impacts of temperature and storage on Escherichia coli, Salmonella, and L. monocytogenes decay in dairy manure.

Elevated levels of animal waste-borne pathogen in ambient water is a serious human health issue. Mitigating influx of pathogens from animal waste such as dairy manure to soil and water requires improving our existing knowledge of pathogen reductions in dairy manure treatment methods. This study was conducted to enhance the  understanding of human pathogen decay in liquid dairy manure in anaerobic (AN) and limited aerobic (LA) storage conditions. The decay of three pathogens (Escherichia coli, Salmonella spp., and Listeria monocytogenes) was assessed in bench-scale batch reactors fed with liquid slurry. A series of temperatures (30, 35, 42, and 50 °C) conditions were tested to determine the impacts of temperature on Escherichia coli, Salmonella, and L. monocytogenes decay in AN and LA conditions. Results showed prolonged survival of E. coli compared to Salmonella and L. monocytogenes in both LA and AN environments. Variations in survival among pathogens with temperature and environmental conditions (i.e., LA and AN) indicated the necessity of developing improved dairy manure waste treatment methods for controlling animal waste-borne pathogens. The results of this study will help in improving the current understanding of human pathogen decay in dairy manure for making informed decisions of animal manure treatment by stakeholders.

Escherichia coli persistence kinetics in dairy manure at moderate, mesophilic, and thermophilic temperatures under aerobic and anaerobic environments.

To assess Escherichia coli (E. coli) persistence in dairy manure, bench scale experiments were conducted under aerobic and anaerobic environments. The changes in E. coli levels in dairy manure were assessed at moderate (25 °C), mesophilic (37 °C), and thermophilic (52.5 °C) temperatures. The inactivation of E. coli at moderate, mesophilic, and thermophilic temperatures were described by linear regression equations. Subsequently, double-exponential kinetic models were developed to describe the E. coli decay curves under aerobic and anaerobic environments. The kinetics models were used to estimate E. coli log reductions at various temperatures. Results showed that the double-exponential kinetic models performed well while calculating E. coli reductions in dairy manure over the incubation period. In addition, we evaluated digestate to compare the changes in total solids and volatile solids, total organic carbon, total nitrogen, pH, and oxygen reduction potential levels in aerobic and anaerobic conditions under various temperatures. We anticipate that the results presented here will be useful for enhancing the understanding of pathogen reduction in anaerobic and aerobic processes during dairy manure treatment.

A neighborhood statistics model for predicting stream pathogen indicator levels.

Because elevated levels of water-borne Escherichia coli in streams are a leading cause of water quality impairments in the U.S., water-quality managers need tools for predicting aqueous E. coli levels. Presently, E. coli levels may be predicted using complex mechanistic models that have a high degree of unchecked uncertainty or simpler statistical models. To assess spatio-temporal patterns of instream E. coli levels, herein we measured E. coli, a pathogen indicator, at 16 sites (at four different times) within the Squaw Creek watershed, Iowa, and subsequently, the Markov Random Field model was exploited to develop a neighborhood statistics model for predicting instream E. coli levels. Two observed covariates, local water temperature (degrees Celsius) and mean cross-sectional depth (meters), were used as inputs to the model. Predictions of E. coli levels in the water column were compared with independent observational data collected from 16 in-stream locations. The results revealed that spatio-temporal averages of predicted and observed E. coli levels were extremely close. Approximately 66 % of individual predicted E. coli concentrations were within a factor of 2 of the observed values. In only one event, the difference between prediction and observation was beyond one order of magnitude. The mean of all predicted values at 16 locations was approximately 1 % higher than the mean of the observed values. The approach presented here will be useful while assessing instream contaminations such as pathogen/pathogen indicator levels at the watershed scale.

Microbial diversity in dairy manure environment under liquid-solid separation systems.

In dairy manure, a wide array of microorganisms, including many pathogens, survive and grow under suitable conditions. This microbial community offers a tremendous opportunity for studying animal health, the transport of microbes into the soil, air, and water, and consequential impacts on public health. The aim of this study was to assess the impacts of manure management practices on the microbial community of manure. The key novelty of this work is to identify the impacts of various stages of manure management on microbes living in dairy manure. In general, the majority of dairy farms in California use a flush system to manage dairy manure, which involves liquid-solid separations. To separate liquid and solid in manure, Multi-stage Alternate Dairy Effluent Management Systems (ADEMS) that use mechanical separation systems (MSS) or weeping wall separation systems (WWSS) are used. Thus, this study was conducted to understand how these manure management systems affect the microbial community. We studied the microbial communities in the WWSS and MSS separation systems, as well as in the four stages of the ADEMS. The 16S rRNA gene from the extracted genomic DNA of dairy manure was amplified using the NovoSeq Illumina next-generation sequencing platform. The sequencing data were used to perform the analysis of similarity (ANOSIM) and multi-response permutation procedure (MRRP) statistical tests, and the results showed that microbial communities among WWSS and MSS were significantly different (p < 0.05). These findings have significant practical implications for the design and implementation of manure management practices in dairy farms.

A novel scalable polycationic melamine sponge-based filtration matrix for continuous ultrafast adsorption of anionic pollutants.

Effective capturing of anionic pollutants from wastewater under industrial operating conditions, which requires high processing flux and fast adsorption rate remains a challenge. Here, a commercially available melamine sponge (MS) with reticulated 3D macroporous structures was covalently modified with positively charged moieties using a single step functionalization under mild conditions. The developed novel polycationic melamine sponge (MS+) was formed by a nucleophilic addition reaction between glycidyltrimethylammonium chloride (GMTA) and MS, followed by a self-propagation of GMTA. The produced MS+ possessed strong electrostatic interactions with different anions such as Rose Bengal (RB) and phosphates (P) under a wide pH range (3-11). The MS+ exhibited promoted static adsorption efficiencies of 400 mg g-1 (P) and 600 mg g-1 (RB), within 5 min and 60 s, respectively. Furthermore, the MS+ showed high stability and recyclability for up to 15 cycles of uses, and the recycling process was environmentally friendly by using 1 M NaCl as a releasing solution. Benefiting from fast flow through the macroporous MS+ and highly positive charged skeleton, the MS+ was applied for rapid dynamic enrichment process of P from real manure wastewater with an enrichment factor of 4.4. Utilization of the MS+ as the substrate brings additional advantages such as low cost, availability, and flexibility to fit into existing filtration devices. The developed MS+ could be expanded for enrichments of other anionic species from various polluted water sources.

Physico-chemical assessment of on-farm bioconversion of organic waste in dairy farms in context to sustainability and circular bioeconomy.

On a milk-producing dairy farm, milk production is correlated with manure production and the number of cattle, and manure is widely used as a soil fertilizer. However, excessive dairy manure production is linked with greenhouse gas emissions and water quality issues. On-farm planning of manure storage and application to enhance soil nutrients are essential in a circular economy to reduce environmental impact, where manure is not landfilled and incinerated. Instead, it creates a nutrient resource for crops and soil. Dairy manure, which is rich in nutrients, is a valuable fertilizer that contains many nutrients such as nitrogen (N), organic matter (OM), phosphorous (P), Potassium (K) and micronutrients. In this work, a pilot field research was conducted between 2016 and 2018 in various parts of California, USA (San Joaquin Valley, Sacramento Valley, Shasta Cascade, and the North Coast of California) to assess physio-chemical characteristics of solid fractions of dairy manure among various dairy farms. A total of 156 samples were collected from the gut (n = 107) and toe (n = 49) of the manure piles across California for determining total solid (TS), volatile solid (VS), temperature, moisture content and carbon-nitrogen ratio (C: N). Here, using the observations of field study and analysis, we show that C: N, OM and MC of solid fractions of dairy manure vary significantly among dairy farms. The average C: N ratio of manure (26-32) among various regions was close to an ideal C: N value of 24:1 for soil microbes to stimulate nutrient release to crops. Manure pH ranged between 7.0 and 8.0, which was close to an optimal pH range for common crops (6.0-8.0). Moreover, considering less cost and surplus availability, manure will likely continue providing a cost-effective organic fertilizer resource compared to commercial chemical fertilizers.

Stoichiometry of laser ablated brass nanoparticles in water and air.

We report on the stoichiometric analysis of laser ablated brass plasma nanoparticles (NPs) in water and ambient air. Morphological study of the deposited NPs in water showed smaller spherical NPs compared to micrometer sized spherical particles in air. The smaller particles were Zn enriched and the concentration decreased with increases in size. Photoluminescence of particles at 380 nm corresponding to ZnO showed higher concentrations of Zn with smaller sized deposited NPs, whereas the micrometer sized particles showed multiple peaks at 415 and 440 nm, which implied that there was an abundance of the Cu fraction in the NPs. Plasma plume parameters, electron temperature, electron density, and evolution of the plasma plume were studied using optical emission spectroscopy and 2-dimensional imaging of the plume. The mass ablation rate in water was observed to be greater than that in air. Higher electron density and temperature of the plasmoid in water was attributed to confinement of the plasma plume near the target surface in water.

Cationic microcrystalline cellulose - Montmorillonite composite aerogel for preconcentration of inorganic anions from dairy wastewater.

Development of efficient adsorbents to inorganic anions as a solid phase extraction (SPE) material is highly desirable for chromatographic analysis and pollution control. In this work we developed a new hybrid cationic microcrystalline cellulose aerogel composite. Cationic cetylpyridinium imbedded montmorillonite (CPC-MT) was uniformly entrapped in microcrystalline cellulose (MCC) to enhance anionic adsorption efficiency and mechanical stability. The developed CPC-MT@MCC aerogel was used as an SPE adsorbent for anions from dairy wastewater by coupling with ion-column chromatography. Further quaternized CPC-MT@MCC aerogel (CPC-MT@QMCC) showed unique low density (10.6 mg cm-3), large specific surface area (320 m2 g-1), porosity 70%, 800 mg g-1 nitrate adsorption capacity within 60 min and ease of elution in alkaline solutions. The CPC-MT@QMCC aerogel showed efficient regeneration and reuse performances for up to 10 cycles. More importantly, a dynamic binding efficiency of 710 mg g-1 highlights its excellent performance for practical applications. 96% of nitrate anion from environmental manure wastewater samples were adsorbed with 98.7% recovery. A good linear relationship was obtained in the range of 0.01-10 mg L-1 and the limits of detection was 0.5 mg L-1 using CPC-MT@QMCC aerogel as a preconcentration column. The successful synthesis of such intriguing and economic CPC-MT@QMCC aerogel may provide a promising matrix for high-performance and high efficiency chromatographic media.

Sublethal diclofenac induced oxidative stress, neurotoxicity, molecular responses and alters energy metabolism proteins in Nile tilapia, Oreochromis niloticus.

Reports have shown that residues of pharmaceuticals and their metabolites can pose toxicological threats to organisms living in aquatic ecosystem. Nile tilapia, Oreochromis niloticus, was exposed at 0.17, 0.34, and 0.68 mg L-1 of diclofenac up to 60 days in a renewal static bioassay system. Antioxidant enzymes reactions, molecular responses, activities of energy metabolism proteins, and the neurotoxic potentials of the drug in the brain and fish muscle were evaluated. Antioxidant enzyme activities such as superoxide dismutase, glutathione-S-transferase, and also fructose 1, 6 bisphosphatase and glucose-6-phosphate dehydrogenase as well as the levels of lipid peroxidation and protein carbonyl were elevated, while glutathione peroxidase, total reduced glutathione, and acetylcholinesterase in the brain and muscles of the treated groups were significantly inhibited in a dose-dependent association. Expression of superoxide dismutase (sod), catalase (cat), and heat shock proteins (hsp 70) genes in brain and muscle tissues was up-regulated. Continuous treatment with sublethal diclofenac for a long time can induce oxidative imbalance, cause neurotoxicity, and alter the expression of genes related to stress in Nile tilapia, suggesting the use of these biomarkers in monitoring the adverse effects the pharmaceuticals could cause to organisms in aquatic ecosystem for possible mitigation.

Effective tetracycline removal from liquid streams of dairy manure via hierarchical poly (vinyl alcohol-co-ethylene)/polyaniline metal complex nanofibrous membranes.

Antibiotic residues from animal wastes enter underground and surface water streams, posing high risks to public health. Novel technologies capable of removing the residues from the matrix of concern such as animal waste should be developed. This research investigates the development of nanofiber absorbent for removing tetracycline (TC) antibiotic residues from liquid streams of dairy manure produced in a typical dairy farm. Hierarchically structured nanofibrous adsorbent was developed through growing a uniform polyaniline (PAni) nanodots on poly (vinyl alcohol-co-ethylene) (EVOH) nanofiber membrane (NFM). Moreover, Cu2+ ions were chelated on the developed EVOH/PAni-Cl NFM to improve TC adsorption efficiency and selectivity. The TC adsorption capacities of EVOH/PAni-Cl-Cu2+ and EVOH/PAni-Cl) NFM were 1100 mg g-1 and 600 mg g-1 within 120 min., respectively. The NFMs adsorption efficiency was investigated using dairy wastewater. Initial TC concentrations in dairy wastewater sample varied between 20 and 50 ppm. The EVOH/PAni-Cl-Cu2+ NFM showed TC removal of 86% from dairy manure samples at 25 ppm initial TC concentration within 60 min. during batch mode treatment. Results showed that the dynamic binding efficiency of 450 mg g-1 can be achieved at an initial TC concentration of 50 ppm. Furthermore, the NFM displayed efficient chemical and physical stability even after 8 cycles of reusing without significant changes in its performance or hazardous Cu2+ leaching.

Oxidative stress biomarkers, biochemical responses and Na+ -K+ -ATPase activities in Nile tilapia, Oreochromis niloticus exposed to diclofenac.

The residues and metabolites from pharmaceuticals have been noted to cause adverse effects to both target and non-target aquatic organisms. The sublethal effects of diclofenac at 0.17, 0.34 and 0.68 mg L-1 on oxidative stress biomarkers, biochemical responses and Na+ -K+ -ATPase activities in the gill tissue of Nile tilapia, Oreochromis niloticus were investigated for 60 days. Elevated levels of some serum biochemical parameters including protein, glutamic oxalacetic transaminase, glucose, glutamic pyruvic transaminase, lactate dehydrogenase, alkaline phosphatase and also some catalysts of gluconeogenic enzymes such as glucose-6-phosphatase, fructose 1, 6 bisphosphatase in the fish liver, increase as the concentration of the diclofenac increased. The reactions of glutathione-S-transferase, catalase, lipid peroxidation, superoxide dismutase, glutathione peroxidase, carbonyl protein and reduced glutathione were elevated (p < 0.05) while the activities of Na+ -K+ -ATPase was significantly reduced (p < 0.05) in fish gill, indicating an adaptive response strategies to mitigate the impact of the drug on the exposed fish. Chronic exposure to sublethal diclofenac can induce oxidative stress and modulates serum biochemical indexes of O. niloticus, suggesting the need for close monitoring of the drug and their metabolites in aquatic environment considering the possible potential adverse effects it may cause even to non-target organisms.

Degradation of antibiotic resistance genes and mobile gene elements in dairy manure anerobic digestion.

Antibiotic resistance genes (ARGs) are emerging contaminants causing serious global health concern. Interventions to address this concern include improving our understanding of methods for treating waste material of human and animal origin that are known to harbor ARGs. Anaerobic digestion is a commonly used process for treating dairy manure, and although effective in reducing ARGs, its mechanism of action is not clear. In this study, we used three ARGs to conducted a longitudinal bench scale anaerobic digestion experiment with various temperatures (28, 36, 44, and 52°C) in triplicate using fresh dairy manure for 30 days to evaluate the reduction of gene abundance. Three ARGs and two mobile genetic elements (MGEs) were studied: sulfonamide resistance gene (sulII), tetracycline resistance genes (tetW), macrolide-lincosamide-streptogramin B (MLSB) superfamily resistance genes (ermF), class 1 integrase gene (intI1), and transposase gene (tnpA). Genes were quantified by real-time quantitative PCR. Results show that the thermophilic anaerobic digestion (52°C) significantly reduced (p < 0.05) the absolute abundance of sulII (95%), intI1 (95%), tnpA (77%) and 16S rRNA gene (76%) after 30 days of digestion. A modified Collins-Selleck model was used to fit the decay curve, and results suggest that the gene reduction during the startup phase of anaerobic digestion (first 5 days) was faster than the later stage, and reductions in the first five days were more than 50% for most genes.

Modeling effects of granules on the start-up of anaerobic digestion of dairy wastewater with Langmuir and extended Freundlich equations.

The effects of granules-inocula on the start-up of anaerobic reactors treating dairy manure were studied in a batch-fed reactor. The effects of start-up period and ratio of granules to feed were analyzed. Results indicated that the effects of start-up period could be described by Langmuir model, while the Extended Freundlich model could be used to model the effects of ratio of granules to feed on cumulative biogas production. In addition, transmission electron microscopes (TEM) and scanning electron microscope analysis were conducted to elucidate the distribution of microbial population and micro-colonies in granules and manure. From the TEM micrographs analyses, the ratios the Syntrophobacter and methanogens in granule and manure were shown to be 1.57 +/- 0.42 and 0.22 +/- 0.20, respectively. These results demonstrated that granules-inocula could reduce the period required for onset of biogas by 25%.

Congenital third cranial nerve palsy with prenuclear dysinnervation involving otolithic pathways: Underpinnings of a novel congenital cranial dysinnervation disorder.

A 10-year-old boy with unilateral cryptorchidism and renal aplasia displayed features of unilateral congenital pupil sparing third cranial nerve palsy with exotropia manifesting novel dysinnervation encompassing synergistic divergence with upshoot, convergence on attempted upgaze, gaze-evoked phasic conjugate torsion, and gaze-evoked nystagmus. Congenital third nucleus/nerve hypoplasia with secondary dysinnervation is classfied as congenital cranial dysinnervation disorder (CCDD). It is speculated that miswiring between prenuclear structures, otolithic pathways, interstitial nucleus of Cajal (INC), nucleus prepositus hypoglossi, and third and sixth nerve nuclei likely resulted in this novel dysinnervation. Cryptorchidism and renal aplasia if seen may point towards an overlapping phenotype with Duane-radial ray syndrome and acro-renal-ocular/IVIC syndromes.

Sub-lethal effects of herbicides penoxsulam, imazamox, fluridone and glyphosate on Delta Smelt (Hypomesus transpacificus).

Concerns regarding non-target toxicity of new herbicides used to control invasive aquatic weeds in the San Francisco Estuary led us to compare sub-lethal toxicity of four herbicides (penoxsulam, imazamox, fluridone, and glyphosate) on an endangered fish species Delta Smelt (Hypomesus transpacificus). We measured 17ß-estradiol (E2) and glutathione (GSH) concentrations in liver, and acetylcholinesterase (AChE) activity in brain of female and male fish after 6 h of exposure to each of the four herbicides. Our results indicate that fluridone and glyphosate disrupted the E2 concentration and decreased glutathione concentration in liver, whereas penoxsulam, imazamox, and fluridone inhibited brain AChE activity. E2 concentrations were significantly increased in female and male fish exposed to 0.21 µM of fluridone and in male fish exposed to 0.46, 4.2, and 5300 µM of glyphosate. GSH concentrations decreased in males exposed to fluridone at 2.8 µM and higher, and glyphosate at 4.2 µM. AChE activity was significantly inhibited in both sexes exposed to penoxsulam, imazamox, and fluridone, and more pronounced inhibition was observed in females. The present study demonstrates the potential detrimental effects of these commonly used herbicides on Delta Smelt.