37 research outputs found
Potential impacts of agrochemicals associated with fugitive particulate matter originating from beef cattle feed yards on native cavity-nesting bees
No full textOver the past decade it has become apparent that veterinary pharmaceuticals are aerially transported beyond beef cattle feed yard boundaries via fugitive particulate matter (PM). However, relatively little is known about the potential transport of insecticides associated with PM beyond feed yard boundaries even though they are used more heavily on a concentration basis than veterinary pharmaceuticals. In order to characterize pesticides associated with fugitive PM, and potential exposure to local pollinators, PM was collected each month from March until October and analyzed for commonly used pesticides on feed yards and row crop agriculture. The most commonly quantified insecticides in PM were then used in a 96 hour contact toxicity test on Blue orchard mason bees (Osmia lignaria) to determine toxicity to a model native pollinator. Wildflowers and co-located bees were also collected near feed yards across three field seasons to better determine agrochemical residues associated with fugitive PM on the local environment and subsequent risk to pollinators. Further, in an effort to understand the potential impacts these agrochemicals (emanating from feed yards) have on local pollinator populations, cavity nesting reed bundles were deployed near feed yards across two field seasons.
Agrochemicals were frequently detected in feed yard PM, with the most commonly identified being pyrethroids, macrocyclic lactones, and neonicotinoids. It was determined that there are enough insecticides in PM (on a per mass basis) generated across all feed yards in the United States of America to potentially kill > 1 billion bees every day. Insecticides in PM are also highly toxic to O. lignaria with neonicotinoid LD50 values < 26 ng/bee, macrocyclic lactones values < 33 ng/bee, and pyrethroid values < 290 ng/bee. Approximately one-third of wildflowers collected near feed yards contained agrochemicals at concentrations that pose elevated risks to O. lignaria and other pollinators foraging on them. Nest bundles placed near feed yards were colonized primarily by wasp species (93%), while nest bundles placed at reference sites were dominated by bee species (71%). Additionally, agrochemicals were frequently detected in all reed matrices from nest bundles deployed at feed yard sites, and at potentially lethal concentrations. Data collected throughout this dissertation suggests that highly toxic agrochemicals are aerially transported beyond feed yard boundaries, landing on local flora and fauna, and potentially impacting cavity nesting insects and other pollinators in the region.Embargo status: Restricted until 06/2026. To request the author grant access, click on the PDF link to the left
Trophic-Level Interactive Effects of Stoichiometric Nutrient Modulation and Heavy Metal Exposure in Algae and Daphnia
No full textThe freshwater ecosystems including lakes, streams, and rivers are constantly being faced with stressors that may impair the structure and function of the ecosystems. There are various anthropogenic activities that alter the levels of essential mineral elements including phosphorus (P) and nitrogen (N) while also introducing other contaminant (e.g. heavy metals) that are toxic to aquatic organisms. Furthermore, this may impair food quality and/or quality available for keystone species and other organisms up the food chain. There are currently very limited data on ecological risk assessment (ERA) studies that couple both dietary quality (or nutrient stoichiometry) and mixed contaminant exposure (e.g. heavy metals). While there are various assessments involving single metal exposures in aquatic systems that do not consider the interactive effects of mineral elements on toxicological endpoints, toxicities of contaminant mixtures are difficult to assess. Hence, several laboratory-derived assessment endpoints derived from single contaminant exposure under single media nutrient condition may be less predictive of the influence of media and/or dietary nutrients stoichiometry on the toxicity outcomes during an ERA, in setting realistic limits for contaminant exposure. Hypotheses for toxicological effects of media-dietary metals include alterations in growth and productivity of freshwater algae, a primary producer occupying the first trophic level, as well as survival, growth, reproduction, physiology, and behavior of zooplanktonic crustacean, a grazer occupying the second trophic level, under varying stoichiometric (P- and N-based) conditions.
This dissertation research investigated the following: (1) toxicological effects of media treated cadmium (Cd), arsenic (As), and binary mixture (Cd/Asmix) at concentrations 0, 5, 25, 125, 625, and 3125 µg/L (for Cd and As) and 0/0, 5/5, 25/25, 125/125, 625/625, and 3125/3125 µg/L (for Cd/Asmix) on Scenedesmus acutus, and (2) toxicological effects of dietary treated Cd- (0, 18.75, 37.5, and 75 µg/L), As- (0, 625, 1250, and 2500 µg/L), and Cd/Asmix-treated (0/0, 18.75/625, 37.5/1250, and 75/2500 µg/L) on Daphnia pulex. Both exposure assessments were carried out under varied media and dietary P [low (LP), median (MP), and optimum (COMBO)] and N [low (LN), median (MN), and optimum (COMBO)] conditions. Results showed significant (p<0.05) interactive effects of media nutrients changes (P and N) and dietary metal (Cd, As, and/or Cd/Asmix) coupled with concentration-dependent inhibition of S. acutus growth and productivity. For media P modulation, the 7-d toxicity of Cd against S. acutus was 2x, 11x, and 4x that of As in LP, MP, and COMBO conditions, respectively; while the joint toxicity effects of Cd/Asmix were partial additive in LP and COMBO, and synergistic in MP media. The 7-d toxicity of Cd against S. acutus was 4.3x, 5.3x, and 1.2x that of As in low, median and optimum-N conditions, respectively; while the toxicity of Cd/Asmix showed partial additive effects in low and optimum-N, and synergistic effect in median-N.
Furthermore, acute lethal toxicity (96 h) of Cd in D. pulex was ~60x that of As, while Cd/Asmix joint toxicity was synergistic. For stoichiometric P changes, chronic toxicity (14 d) in D. pulex showed significant (p<0.05) interaction of As and P-availability on survival, reproduction and behavior (distance moved, velocity, acceleration and mobility), while Cd and P availability showed significant interactive effect on rotational behavior. For stoichiometric N changes, 14-d chronic toxicity showed significant (p<0.05) interactive effects of media N and dietary metal (As and Cd/Asmix) on D. pulex reproduction but not on behavior while survival was significantly impaired by dietary Cd, As, and Cd/Asmix. Moreover, there were significant (p<0.05) interactive effects of the stoichiometric nutrient imbalance (both P- and N-based) and metal exposures (Cd, As, and Cd/Asmix) on the growth and physiological response of D. pulex including feeding, oxygen (O2) consumption and/or heartrate. More specifically, feeding rate was significantly reduced by diets containing Cd, As, and Cd/Asmix in LP and LN media, and so is growth rate, body length, and abdominal width. Additionally, metal uptake and bioaccumulation in S. acutus and D. pulex varied with stoichiometric nutrient imbalance and metal treatments while dose-response effects of Cd, As, and Cd/Asmix in S. acutus and D. pulex were either monophasic (e.g. linear, concentration dependent) or biphasic (e.g. hormesis) under varying nutrient stoichiometry. This dissertation provides detailed empirical evidence of the interactive effects of media/dietary nutrients stoichiometry (P- and N-based) and dietary metals (Cd, As, and Cd/Asmix) exposure at environmentally relevant concentrations and higher, emphasizing the need for consideration of such interactions during ERA and in setting realistic limits for metal exposures in aquatic ecosystems
Investigation of toxic effects of agrochemicals bound to fugitive beef cattle feedyard particulate matter to critical pollinator species
No full textInsect-mediated pollination services are critical to many ecosystems around the world. Nearly 87% of angiosperms and almost a hundred cultivated food crops rely on wild or managed pollinators for reproduction or crop yield. Economic benefits of pollination services provided by animals globally are estimated up to $577 billion (USD) annually. These estimates are expected to continue rising in the future due to increasing human population and subsequent demand for food crop products. Unfortunately, between 20 – 40% of pollinator species around the globe are experiencing population decreases. The issue of pollinator decline is complex and contains a multitude of contributing factors. Chief among these are habitat loss, competition with invasive species, and exposure to toxic agrochemicals. Sensitivity to multiple classes of insecticides and parasiticides among pollinators is well documented. However, data regarding the toxic effects of agrochemicals bound to particulate matter (PM) is limited. The previously mentioned increasing human population has also driven an increase in demand for affordable, high-quality, protein-based foods, such as beef. This, in turn, has led to an increase in abundance and capacity of beef cattle feedyards in many areas of world. In the United States of America (USA), over twenty-six thousand feedyards contain over fifteen million head of cattle in a given year. Typically, feedyards are situated in arid to semi-arid environments, where precipitation is less than 510 mm per year on average. These dry, hot environments are conducive to wind-driven scouring of pen floor material (composed of cattle urine and feces), and subsequent dissemination into surrounding environs. Feedyard profitability and yield necessitates the use of a variety of veterinary pharmaceuticals, growth promoters, and pesticides to facilitate rapid muscle accretion and minimize losses due to pests. Residues of these chemicals are excreted by cattle in urine and feces or sequestered by pen floor material. When this contaminated material is disturbed by cattle activity it becomes suspended in the air and can be transported beyond feedyard boundaries, taking PM-bound agrochemicals with it. Multiple agrochemicals have been detected in relatively high concentrations in fugitive beef cattle feedyard PM. Data regarding the potential toxic effects of fugitive agrochemical-laden PM may exert on local pollinators is lacking. Here I present data generated from field- and laboratory-based experiments designed to bridge this data gap. First, honeybees (Apis mellifera) and blue orchard mason bees (Osmia lignaria) were exposed, in situ to agrochemical-laden PM emanating from feedyards. Second, I developed a method by which to simulate the conditions at feedyards and expose pollinators to PM under controlled conditions in a laboratory-based circulator system. Third, this method was used to conduct toxicity testing to determine the effects of individual agrochemicals bound to PM among three pollinators (honeybees, mason bees, and painted lady butterfly larvae (Vanessa cardui)). Honeybees and mason bees placed downwind of feedyards experienced significantly higher mortality compared to bees sited upwind of the same feedyards. Pollinator mortality in these experiments was positively correlated with toxicity-weighted concentrations (TWC) of seven commonly used agrochemicals (bifenthrin, permethrin, clothianidin, imidacloprid, thiamethoxam, abamectin, and ivermectin). Testing and verification of the novel PM circulation system revealed no significant increase in pollinator mortality due to agrochemical-free PM. Results of the toxicity tests conducted using the circulator system indicated significantly elevated mortality of all three pollinator species when exposed to environmentally relevant concentrations of individual agrochemical-fortified PM. Significantly elevated mortality of pollinators exposed to individual PM-bound agrochemicals implicates agrochemicals as the major driver of mortality observed in field experiments. Pollinator mortality in the circulator toxicity tests did not reach the magnitude observed in the field experiments, indicating additive or synergistic effects of agrochemical mixtures as an important contributor to mortality. Further, mortality was lower than expected, as the circulator exposure treatments far exceeded previously published contact toxicity benchmarks, suggesting limited uptake of PM-bound agrochemicals. Particulate matter emitted from beef cattle feedyards, and the many constituent agrochemicals contained therein pose a significant threat to local pollinators
Dissipation Behavior of Fenpyroximate Residues in Black Tea and Brew
No full textFenpyroximate is an effective acaricide on several food crops. In the present study, dissipation of residue of this acaricide in black tea, tea infusion and spent tea was studied. Analysis was carried out using high performance liquid chromatography with diode array detection. The rate of dissipation was found to vary with the nature of the substrate. In tea leaves the half-life of fenpyroximate ranged from 2.20 to 4.22 days. The residue of fenpyroximate was not detectable in the tea brew
Monitoring cyanobacterial toxins in a large reservoir: Relationships with water quality parameters
No full text© 2019 Subbiah et al. cc-byCyanobacteria are widely distributed in fresh, brackish, and ocean water environments, as well as in soil and on moist surfaces. Changes in the population of cyanobacteria can be an important indicator of alterations in water quality. Metabolites produced by blooms of cyanobacteria can be harmful, so cell counts are frequently monitored to assess the potential risk from cyanobacterial toxins. A frequent uncertainty in these types of assessments is the lack of strong relationships between cell count numbers and algal toxin concentrations. In an effort to use ion concentrations and other water quality parameters to determine the existence of any relationships with cyanobacterial toxin concentrations, we monitored four cyanobacterial toxins and inorganic ions in monthly water samples from a large reservoir over a 2-year period. Toxin concentrations during the study period never exceeded safety limits. In addition, toxin concentrations at levels above the limit of quantitation were infrequent during the 2-year sampling period; non-detects were common. Microcystin-LA was the least frequently detected analyte (86 of 89 samples were ND), followed by the other microcystins (microcystin- RR, microcystin-LR). Cylindrospermopsin and saxitoxin were the most frequently detected analytes. Microcystin and anatoxin concentrations were inversely correlated with Cl-, SO-2 4 , Na+, and NH+4, and directly correlated with turbidity and total P. Cylindrospermopsin and saxitoxin concentrations in water samples were inversely correlated with MgC2 and directly correlated with water temperature. Results of our study are expected to increase the understanding of potential relationships between human activities and water quality
Residues of Propargite in Tea
No full textPropargite is an acaricide extensively used in India for controlling the populations of the red spider mite (RSM) infesting tea. Field experiments were conducted at two places in Tamil Nadu (India) during the dry season to determine the residues of propargite in black tea. Residues were quantified at different harvest intervals of ‘0’ (3 hr), 1st, 3rd, 5th, 7th, 10th and 14th day after acaricide application. Persistence, issipation pattern, half-life value and safe harvest interval of the acaricide in tea were calculated. Residues of propargite dissipated exponentially after application at both the locations and reached below the CODEX MRL of 5 mg/kg on the 7th day. Regression lines drawn on propargite showed that like other acaricides it followed the first order dissipation kinetics. Half-life values varied from 1.63 to 1.92 days for propargite and a safety harvest interval of 7 days is suggested for the tea crop
Socio Economic Conditions Of Construction Workers In Tamilnadu: Issues And Challenges
No full textThe present study is aimed to explore socio-economic problems of Tamilnadu women workers at construction sites in working environment and to document issues like gender bias, living conditions, vulnerability and slackness, wages, their economic status by finding out their savings, loan etc. The author concentrated only on the women workers who are working in the construction sector and how they are facing problems in the work place. Majority of the women construction workers are facing lots of problems like absence of social security, low wages, gender discrimination, unhygienic conditions at work place etc. Data was collected from 160 women workers from four areas of Tamilnadu (North, East, West, South) city. The data for this study has been collected through primary source. The primary for this study was collected with the help of the questionnaire. The secondary data was collected from the library and websites. The major findings of construction women labor facing many problems they asked government security for their jobs
Small Blubber Samples (50 mg) Sufficient for Analyses of 10 Stress and Reproductive Steroid Hormones in Gray and Fin Whales via Liquid Chromatography Mass Spectrometry
No full text© 2022 Wittmaack, Urbán Ramírez, Bernot-Simon, Martínez-Aguilar, Subbiah, Surles, Looney, Kumar, Halaska, Duignan, Knauss, Burns and Godard-Codding. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.Information on stress, reproductive fitness, and health is difficult to obtain in wild cetaceans but critical for conservation and management. The goal of this study was to develop a methodology requiring minimal blubber mass for analysis of reproductive and stress steroid hormones and, hence, suitable for cetacean biopsies. Blubber biopsies and samples were collected from free-ranging and stranded gray and fin whales. Steroid hormones were extracted from blubber samples as small as 50 mg using liquid-liquid extraction methodology developed to handle the high fat content of blubber. Samples were analyzed via liquid chromatography with tandem mass spectrometry for 10 hormones: aldosterone, androstenedione, cortisol, cortisone, corticosterone, 17β-estradiol, estrone, 17α-hydroxyprogesterone, progesterone, and testosterone. As part of the optimization, homogenization via bead beating and blade dispersion were compared, and the former found superior. To investigate optimal yet minimal tissue mass required, hormone panels were compared among paired 50, 150, and 400 mg samples, the latter two being commonly reported masses for hormone blubber analysis. Results indicated that 50 mg of blubber was suitable and sometimes superior. Additionally, significant differences in precision values were observed between species, possibly stemming from differences in blubber composition, and relevant to homogenization technique selection and calibration methods that use blubber matrix matches obtained from a species other than the study species. Based on recovery and precision values, our methodology was accurate and precise in the measurement of spiked known quantities for all 10 hormones, confirming the methodology capabilities in 50 mg blubber mass in both species. Altogether, and in our specific sample sets, all endogenous hormones, except corticosterone, were identified above the detection limit in 50 mg gray whale blubber samples while all endogenous hormones, except aldosterone, cortisone, estrone, and progesterone, were detected in 50 mg fin whale blubber samples. We present a robust methodology for the analysis of multiple reproductive and stress steroid hormones in minimal masses of cetacean blubber compatible with small biopsies. Finally, we identified statistically significant differences in corticosteroid concentrations between stranded and free ranging animals
