Low-Level Groundwater Atrazine in High Atrazine Usage Nebraska Counties: Likely Effects of Excessive Groundwater Abstraction

Recent studies observed a correlation between estrogen-related cancers and groundwater atrazine in eastern Nebraska counties. However, the mechanisms of human exposure to atrazine are unclear because low groundwater atrazine concentration was observed in counties with high cancer incidence despite having the highest atrazine usage. We studied groundwater atrazine fate in high atrazine usage Nebraska counties. Data were collected from Quality Assessed Agrichemical Contaminant Nebraska Groundwater, Parameter–Elevation Regressions on Independent Slopes Model (PRISM), and water use databases. Descriptive statistics and cluster analysis were performed. Domestic wells (59%) were the predominant well type. Groundwater atrazine was affected by well depth. Clusters consisting of wells with low atrazine were characterized by excessive groundwater abstraction, reduced precipitation, high population, discharge areas, and metropolitan counties. Hence, low groundwater atrazine may be due to excessive groundwater abstraction accompanied by atrazine. Human exposure to atrazine in abstracted groundwater may be higher than the estimated amount in groundwater.

Association between Aqueous Atrazine and Pediatric Cancer in Nebraska

Agrichemicals, chemicals used to maximize crop and animal production, can lead to water quality concerns when these chemicals run off into surface and groundwater after precipitation events. In Nebraska, one such chemical is atrazine, a suspected carcinogen. This study evaluated the association between atrazine in surface and groundwater, in relation to the incidence of pediatric cancer in Nebraska watersheds over 30 years (1 January 1987 to 31 December 2016). The watersheds were grouped into four categories based on the average atrazine concentration over the study period, using quantile classification. The associations between atrazine (ground/surface) and pediatric cancer after adjusting for social vulnerability index (SVI) variables, using pediatric population as offset, were compared using a generalized linear model (GLM) assuming a negative binomial distribution. The results from the GLM approach suggested positive associations between watersheds with higher atrazine concentration and a higher pediatric cancer incidence rate ratio. In this study, the associations were evaluated using atrazine measurements obtained from non-drinking water sources as a proxy measure. Further research is necessary to establish the causal relationship between atrazine and pediatric cancer.

Migration Law of Atrazine During Freezing of Water

To explore the migration law of atrazine during the freezing process, an indoor simulated freezing experiment was carried out. The distribution coefficient (K) was used to characterize the migration ability of atrazine and explore the effects of freezing thickness, freezing temperature, and initial concentration on the migration of atrazine between ice and water. The research results showed that the concentration relationship between the ice and water phases was: ice < water before freezing < water under the ice. This indicates that atrazine migrated to the water under the ice during the freezing process in our experiment. The K value decreased as the ice thickness, freezing temperature, and initial concentration increased; thus, the greater the ice thickness, the higher the freezing temperature, the greater the initial atrazine concentration, and the greater the ability of atrazine to migrate to the water under the ice. This study provides a reference for managing natural waterbodies in high-latitude and high-altitude environments during the freezing period.

Facile Method by Bentonite Treated with Heat and Acid to Enhance Pesticide Adsorption

In this work, simple conditions were applied to modify bentonite for the removal of pesticides from aqueous solution. Bentonite was modified in a single step as BA0.5 (with HCl 0.5 M) and BC500 (calcined at 500 °C) and combined steps with different sequences (BA0.5C500 and BC500A0.5). These adsorbents were characterised by XRD, XRF, FT-IR, 27Al MAS NMR, BET, NH3-TPD, TGA, HPLC, particle size analysis and zeta potential. Single-component adsorption with atrazine, diuron, 2,4-D and paraquat was used in aqueous solution at various pesticide concentrations, contact times and pH levels. It was found that the sequence of the treatment significantly affected atrazine adsorption. BC500A0.5 exhibited the highest efficiency for atrazine adsorption in a broad pH range of 3.0–9.0. Its adsorption at pH 6.0 was about 12 times greater than that of other adsorbents with an initial atrazine concentration of 50 mg L−1, which indicates BC500A0.5 specifically for the adsorption of atrazine. In addition, for the simultaneous adsorption of all four pesticides, BC500A0.5 was found to remove the maximum total amount of the pesticides, indicating that it could be used as a good multifunctional adsorbent. All modified bentonites showed similar diuron adsorption better than that of unmodified bentonite. The greatest adsorption of 2,4-D prefers BA0.5C500, occurring at pH 2–4. In the case of paraquat adsorption, all adsorbents are good at absorbing paraquat, but bentonite had the highest rate of paraquat removal, whereas BA0.5C500 was found to have the lowest, and the adsorption increased with increasing pH. Furthermore, the adsorption process on the adsorbents fits well with the Langmuir isotherm and pseudo-second-order kinetics models, as the thermodynamic parameters showed a spontaneous and endothermic process.

EFFECTS OF SELECTIVE HERBICIDE, ATRAZINE ON THE RHIZOBIUM POPULATION AND NODULATION OF GROUNDNUT (ARACHIS HYPOGEAE)

Atrazine is a selective herbicide used to control weeds in farm operations. The effect of different concentrations of atrazine on Rhizobium population and nodulation in groundnut (Arachis hypogeae) was investigated using Yeast Extract Mannitol Agar (YEMA). The test crop was planted for 90 days after the soil was treated with the various concentration of atrazine. The following parameters; Rhizobium count, nodule count, plant height and germination percentage were observed. The total Rhizobium count obtained at 0% atrazine treatment has 3.0 x 108, 0.1% has 2.9 x 108, 0.5% has 2.5 x 108, 1% has 2.0 x 108, and 3% has 1.4 x 108 all in cfu/ml while the number of root nodules formed was also counted after uproot which was; 0% atrazine treated has 50 nodules, 0.1% has 50 nodules, 0.5% has 30 nodules, 1% has 23 nodules and 3% has 19 nodules. The study revealed that the higher the atrazine concentration the lower the population of Rhizobium, the numbers of root nodules increased with decrease in atrazine concentration and Plant height, root length and germination percentage was also affected adversely by increased in atrazine concentrations.

Atrazine residues in flooded and nonflooded soil and effects on soybean

Atrazine applied at planting is commonly used for weed control in corn. With global climate change causing an increase in river flooding in the United States over the past decade, producers need information to determine the best course of action in flooded fields treated with atrazine into which they wish to immediately plant soybean. Studies were designed to understand the effect of flooding on atrazine residual activity including atrazine concentration, soybean injury, and soybean yield. In 2012, soybean yield in flooded treatments was reduced by prior atrazine application. In 2014, soybean injury was <10% in all plots, and nonflooded, atrazine-treated soils had yields equal to the nontreated. Findings from this research indicated that it is possible for producers to consider replanting soybean after atrazine application, with appropriate changes to product labeling.

Atrazine removal in aqueous solutions using activated carbon from peach stone

Activated carbon is commonly used as a material for contaminant-adsorption processes in aqueous systems. However, its use is more restricted to charcoal than to coal, for the most part, in view of the fact of the higher cost (~ 40%) if the mineral is a fossil fuel which needs to be extracted from the earth by mining. For this reason, the peach stone that comes from alimentary industrial tailings can be a good choice for the separation of pollutants from aqueous suspensions and other soluble substances. The purpose of this research was the development of a low-cost filter, using stones to remove atrazine from water. Appraisal and characterization studies were performed along with batch experiments to investigate dosing effects of the activated carbon, atrazine concentration, contact time, and adsorption pH on removal procedures. From the results of the experiment, an excellent removal of the analyte in question was observed under conditions that can be considered as close as possible to the environment, such as pH = 6.5, room temperature and 10 minutes of agitation time, always choosing the best alternative with the lowest cost of energy and time. Batch system application has been recommended as versatile for utilization in seasonal problems such as pesticide contamination.

Investigating Atrazine Concentrations in the Zwischenscholle Aquifer Using MODFLOW with the HYDRUS-1D Package and MT3DMS

Simulation models that describe the flow and transport processes of pesticides in soil and groundwater are important tools to analyze how surface pesticide applications influence groundwater quality. The aim of this study is to investigate whether the slow decline and the stable spatial pattern of atrazine concentrations after its ban, which were observed in a long-term monitoring study of pesticide concentrations in the Zwischenscholle aquifer (Germany), could be explained by such model simulations. Model simulations were carried out using MODFLOW model coupled with the HYDRUS-1D package and MT3DMS. The results indicate that the spatial variability in the atrazine application rate and the volume of water entering and leaving the aquifer through lateral boundaries produced variations in the spatial distribution of atrazine in the aquifer. The simulated and observed water table levels and the average annual atrazine concentrations were found to be comparable. The long-term analysis of the simulated impact of atrazine applications in the study area shows that atrazine persisted in groundwater even 20 years after its ban at an average atrazine concentration of 0.035 µg/L. These results corroborate the findings of the previous monitoring studies.

Performance Assessment of Micropollutants Removal From Water Using Advanced Oxidation Processes

In a global climate change scenario, reliable access to clean and safe water for all remains a great worldwide challenge for the twenty first century, as one of the most ambitious targets of several Sustainable Development Goals (SDG) established in the UN Agenda 2030. The increasing presence in the urban aquatic ecosystems of priority pollutants and contaminants of emerging concerning (CECs) have brought new challenges to the existing water treatment systems (WTS) concerning with public health protection and the of drinking water sources preservation. Advanced oxidation processes (AOPs) have been widely studied because of their potential as a complementary or alternative process to conventional wastewater treatment. Several AOPs using nanomaterials as photocatalyst can be particularly effective in the degradation of many toxic micropollutants, and enhance the multifunctionality, versatility and sustainability of WTS. This work presents a synthesis of the major results obtained in several pilot and lab-scale studies aiming to assess the performance of different low-cost catalytic processes used for antibiotic and pesticide removal. For each photo-oxidation reactors, different test scenarios are defined in order to evaluate the effects of several abiotic and hydraulic parameters on process kinetics and removal efficiencies. The experimental results were very promising, because antibiotic removal efficiencies achieved the maximum value of 96% for the photo-oxidation by water columns with suspended TiO2 nanoparticles, and 98% for the photocatalytic filtration performed by a porous medium coated with TiO2. In the photoelectrocatalytic reactor, the atrazine concentration has been fully removed for reaction times between 35 and 95 minutes.