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Lindane is documented by the Environmental Protection Agency (EPA) as one of the most toxic registered pesticides. Conventional detection of lindane in the environment requires manual field sampling and complex, time-consuming analytical sample handling relying on skilled labor. In this study, an electrochemical sensing system based on a modified electrode is reported. The system is capable of detecting lindane in aqueous medium in only 20 s. The surface of a conventional carbon electrode is modified with a film of conductive polymer that enables detection of lindane down to 30 nanomolar. The electrode modification procedure is simple and results in a robust sensor that can withstand intensive use. The sensitivity of the sensor is 7.18 &micro, A/&micro, M and the performance was demonstrated in the determination of lindane in spiked ground water. This suggests that the sensor is potentially capable of providing useful readings for decision makers. The rapid and sensitive quantification of lindane in aqueous medium is one step forward to new opportunities for direct, autonomous control of the pesticide level in the environment.

Bentazone is one of the most problematic pesticides polluting groundwater resources. It is on the list of pesticides that are mandatory to analyze at water work controls. The current pesticide measuring approach includes manual water sampling and time-consuming chromatographical quantification of the bentazone content at centralized laboratories. Here, we report the use of an electrochemical approach for analytical determination of bentazone that takes 10 s. The electrochemical electrodes were manually screen printed, resulting in the low-cost fabrication of the sensors. The current response was linearly proportional to the bentazone concentration with a R2 ~ 0.999. We demonstrated a sensitivity of 0.0987 μA/μM and a limit of detection of 0.034 μM, which is below the U.S. Health Advisory level. Furthermore, the sensors have proved to be reusable and stable with a drop of only 2% after 15 times reuse. The sensors have been applied to successfully quantify bentazone spiked in real groundwater and lake water. The sensing method presented here is a step towards on-site application of electrochemical detection of pesticides in water sources. Keywords: Bentazone, Sensor, Groundwater, Electrochemistry, Pesticide, Contamination

The ecotoxicity of platinum nanoparticles (PtNPs) widely used in for example automotive catalytic converters, is largely unknown. This study employs various characterization techniques and toxicity end points to investigate PtNP toxicity toward the green microalgae Pseudokirchneriella subcapitata and Chlamydomonas reinhardtii. Growth rate inhibition occurred in standard ISO tests (EC50 values of 15–200 mg Pt/L), but also in a double-vial setup, separating cells from PtNPs, thus demonstrating shading as an important artifact for PtNP toxicity. Negligible membrane damage, but substantial oxidative stress was detected at 0.1–80 mg Pt/L in both algal species using flow cytometry. PtNPs caused growth rate inhibition and oxidative stress in P. subcapitata, beyond what was accounted for by dissolved Pt, indicating NP-specific toxicity of PtNPs. Overall, P. subcapitata was found to be more sensitive toward PtNPs and higher body burdens were measured in this species, possibly due to a favored binding of Pt to the polysaccharide-rich cell wall of this algal species. This study highlights the importance of using multimethod approaches in nanoecotoxicological studies to elucidate toxicity mechanisms, influence of NP-interactions with media/organisms, and ultimately to identify artifacts and appropriate end points for NP-ecotoxicity testing.

Glyphosate (Gly) is one of the most problematic pesticides that repeatedly appears in drinking water. Continuous on-site detection of Gly in water supplies can provide an early warning in incidents of contamination, before the pesticide reaches the drinking water. Here, we report the first direct detection of Gly in tap water with electrochemical sensing. Gold working electrodes were used to detect the pesticide in spiked tap water without any supporting electrolyte, sample pretreatment or electrode modifications. Amperometric measurements were used to quantify Gly to a limit of detection of 2 &mu, M, which is below the regulation limit of permitted contamination of drinking water in the United States. The quantification of Gly was linearly proportional with the measured signal. The selectivity of this method was evaluated by applying the same technique on a Gly Metabolite, AMPA, and on another pesticide, omethoate, with a chemical structure similar to Gly. The testing revealed no interfering electrochemical activity at the potential range used for Gly detection. The simple detection of Gly presented in this work may lead to direct on-site monitoring of Gly contamination at drinking water sources.

Pesticides are intensively used in agriculture to increase yield in food production by protecting crops from damaging organisms or competing plants [1]. Although pesticides have helped us meet the growing food demand, the use of pesticides has led to contamination of water resources from which we obtain our drinking water[2]. Bentazone is one of the widely used pesticides for control of crop quality. The compound is highly soluble in water, very mobile in soil and has a tendency to leach from the field into groundwater and surface water. Consequently, the water resources often have bentazone concentrations above the European regulation limit of 0.1 µg/L (0.39 nM)[3]. Monitoring of bentazone in water resources is obligatory. However, due to the complexity of the manual sampling, transport of samples and the need for centralized laboratories to conduct chromatographic analyses of the water, the monitoring is only conducted a few times a year[4]. This means that high concentrations of bentazone in the water may slip in between the samplings and reach the consumers through the water taps[5]. Here we present a simple electrochemical bentazone detection technique that has the potential of being deployed directly in water wells for the continuous monitoring of the water quality. The technique is based on electrochemical measurements using electrodes shadow-printed on a capton substrate. The electrodes consist of carbon and the resulting sensors have been proven to be robust and generate stable signals for at least 25 measurements[6]. We have used the sensors to achieve the selective detection of bentazone in phosphate buffer as the supporting electrolyte. Square wave voltammetry was used to selectively identify bentazone at 0.77 V. A calibration curve for the compound was obtained in the linear range between 0.190 – 50 µM and with a limit of detection of 0.063 µM at pH 7.0. Several other relevant compounds with chemical structures close to bentazone were tested to determine the risk of signal interference. We could demonstrate that the detection method is selective to bentazone, and other similar compounds did not change the target signal. Furthermore, we have spiked lake water and groundwater with bentazone to test the method on real water samples. It was possible to selectively quantify bentazone in the respective waters, despite any unknown chemicals in the samples. The availability of portable potentiostats offer the possibility of on-site detection of bentazone in the fields[7]. The low-cost shadow-printed sensors allow single-use of the sensors for monitoring water resources. Although the method has still not reached the regulation limit, this study is a proof-of-concept showing the possibility of conducting simple, on-site determination of pesticides in water resources. References: [1] J. M. Salman, “Batch study for herbicide bentazon adsorption onto palm oil fronds activated carbon,” Int. J. Chem. Sci., vol. 10, no. 2, 2012. [2] B. Wang et al., “Development of novel ionic liquids based on bentazone,” Tetrahedron, vol. 71, no. 41, pp. 7860–7864, 2015. [3] M. C. Bruzzoniti et al., “Adsorption of bentazone herbicide onto mesoporous silica: application to environmental water purification,” Environ. Sci. Pollut. Res., vol. 23, no. 6, pp. 5399–5409, 2016. [4] N. A. Mir, M. M. Haque, A. Khan, M. Muneer, and S. Vijayalakshmi, “Photocatalytic degradation of herbicide Bentazone in aqueous suspension of TiO2: Mineralization, identification of intermediates and reaction pathways,” Environ. Technol. (United Kingdom), vol. 35, no. 4, pp. 407–415, 2014. [5] A. I. Cañero et al., “Transformation of organic wastes in soil: Effect on bentazone behaviour,” Sci. Total Environ., vol. 433, pp. 198–205, 2012. [6] F. A. Z. a. Alatraktchi et al., “Paper-based sensors for rapid detection of virulence factor produced by Pseudomonas aeruginosa,” PLoS One, vol. 13, no. 3, pp. 1–9, 2018. [7] J. S. Noori, M. Dimaki, J. Mortensen, and W. E. Svendsen, “Detection of glyphosate in drinking water: A fast and direct detection method without sample pretreatment,” Sensors (Switzerland), vol. 18, no. 9, 2018.

The important evaluation parameter in trickle irrigation is emission uniformity. There are two different methods to calculate emission uniformity; (1) field evaluation for the subunit and (2) using theoretical formulas to calculate emission uniformity during the design period. Emission uniformity is usually divided into two parts, namely, manufacturing, EUm, and hydraulics emission uniformity, EUh. The global emission uniformity is the product of these two parts. Previously, a formula was developed to predict the manufacturing emission uniformity by assuming that when the emitter is tested at a given head, emitter discharges are normally distributed around their mean. This assumption did not apply well to the tested emitters. In this research, the manufacturing part was expressed in terms of the statistical characteristics of the distribution of emitter discharges when tested at a given pressure head. The hydraulic part of emission uniformity, EUh, was expressed in terms of the hydraulic character...

Pyocyanin is a toxin produced by Pseudomonas aeruginosa. Here we describe a novel paper-based electrochemical sensor for pyocyanin detection, manufactured with a simple and inexpensive approach based on electrode printing on paper. The resulting sensors constitute an effective electrochemical method to quantify pyocyanin in bacterial cultures without the conventional time consuming pretreatment of the samples. The electrochemical properties of the paper-based sensors were evaluated by ferri/ferrocyanide as a redox mediator, and showed reliable sensing performance. The paper-based sensors readily allow for the determination of pyocyanin in bacterial cultures with high reproducibility, achieving a limit of detection of 95 nM and a sensitivity of 4.30 μA/μM in standard culture media. Compared to the similar commercial ceramic based sensors, it is a 2.3-fold enhanced performance. The simple in-house fabrication of sensors for pyocyanin quantification allows researchers to understand in vitro adaptation of P. aeruginosa infections via rapid screenings of bacterial cultures that otherwise are expensive and time-consuming.

Microbial fuel cells (MFCs) have applications possibilities for wastewater treatment, biotransformation, and biosensor, but the development of highly efficient electrode materials is critical for enhancing the power generation. Two types of electrodes modified with nanoparticles or grass-like nanostructure (termed nanograss) were used. A two-chamber MFC with plain silicium electrodes achieved a maximum power density of 0.002 mW/m 2 , while an electrode with nanograss of titanium and gold deposited on one side gave a maximum power density of 2.5 mW/m 2 . Deposition of titanium and gold on both sides of plain silicium showed a maximum power density of 86.0 mW/m 2 . Further expanding the surface area of carbon-paper electrodes with gold nanoparticles resulted in a maximum stable power density of 346.9 mW/m 2 which is 2.9 times higher than that achieved with conventional carbon-paper. These results show that fabrication of electrodes with nanograss could be an efficient way to increase the power generation.

A sediment-type photomicrobial fuel cell (PFC), based on the synergistic interaction between microalgae (Chlorella vulgaris) and electrochemically active bacteria, was developed to remove carbon and nutrients from wastewater, and produce electricity and algal biomass simultaneously. Under illumination, a stable power density of 68 ± 5 mW m−2 and a biomass of 0.56 ± 0.02 g L−1 were generated at an initial algae concentration of 3.5 g L−1. Accordingly, the removal efficiency of organic carbon, nitrogen and phosphorus was 99.6%, 87.6% and 69.8%, respectively. Mass balance analysis suggested the main removal mechanism of nitrogen and phosphorus was the algae biomass uptake (75% and 93%, respectively), while the nitrification and denitrification process contributed to a part of nitrogen removal (22%). In addition, the effect of illumination period on the performance of PFC was investigated. Except notable fluctuation of power generation, carbon and nutrients removal was not significantly affected after changing the light/dark photoperiod from 24 h/0 h to 10 h/14 h. This work represents the first successful attempt to develop an effective bacteria–algae coupled system, capable for extracting energy and removing carbon, nitrogen and phosphorus from wastewater in one-step.