Runoff Samples Research Articles

First Flush Stormwater Runoff in Urban Catchments: A Bibliometric and Comprehensive Review

First flush is a phenomenon in stormwater runoff that has been considered a topic of great interest in the field of nonpoint source pollution. Despite several attempts to define the first flush quantitively, the specified characteristics of the phenomenon vary among sources. To address these uncertainties, a bibliometric and comprehensive review on published articles related to first flush was conducted. A corpus of 403 research articles was obtained from the Scopus database, which was then parsed using the CorText Manager for the bibliometric analysis. The study examined quantitative definitions of first flush from various sources; climate and topographic characteristics of monitoring and experimental sites where the studies on first flush were performed; the sample collection methods applied; the first flush values obtained on the studies and how it influenced the nonpoint source pollution in urban watersheds. A network map, two contingency matrices, and a Sankey diagram were created to visualize the relationship of significant keywords related to first flush, as well as their co-occurrences with journals, countries, and years. It was found that the strength of the first flush effect could vary depending on the geographical location of the site, climatic conditions, and the pollutants being analyzed. Therefore, initial rainfall monitoring, runoff sampling, and water quality testing were seen as critical steps in characterizing the first flush in urban catchments. Furthermore, the characterization of first flush was found to be significant to the selection of best management practices and design of low-impact development (LID) technologies for stormwater runoff management and nonpoint source pollution control.

The Effect of Land-Use Changes on the Amount of Heavy Metal Pollution in Urban Runoff in Tehran

Background & Aims of the Study: Urban development trends and land-use changes harm the quality of urban runoff. Heavy metals are one of the most important pollutants in urban runoff. This study aimed to investigate the amount of heavy metal pollutants (Zn, Pb, Cu, As, Hg, and Cd) in different land uses in a densely populated urban area of Tehran. Materials and Methods: Six stations were selected for urban runoff sampling in five land uses. Land uses were residential, commercial, industrial, traffic, and outdoor. A station (sixth station) with mixed land use was selected, which included the runoff of all uses. The event mean concentration (EMC) model was used to estimate this study’s heavy metal pollution load. Results: The amount of all heavy metals except Arsenic in fields with industrial use was higher than other land uses (Cu=0.292 mg/l), (Pb=0.6166 mg/l), (Zn=1.36 mg/l), (Cd=0.0114 mg/l), and (Hg=0.1332 mg/l). While the amount of Arsenic metal in the station with outdoor land use (AS=0.111 mg/l) was the highest. Conclusion: The results of this study indicate that the risk of metals on long dry days without precipitation is very high. Uncertainties related to the accumulation of pollution and various human activities can be attributed to the high amount of heavy metals in the mixed land use compared to land use alone

The Survival of Salmonella Senftenberg, Escherichia coli O157:H7, Listeria monocytogenes, Enterococcus faecalis and Clostridium sporogenes in Sandy and Clay Loam Textured Soils When Applied in Bovine Slurry or Unpasteurised Digestate and the Run-Off Rate for a Test Bacterium, Listeria innocua, When Applied to Grass in Slurry and Digestate

This study investigated the survival of Salmonella Senftenberg, Escherichia coli O157:H7, Listeria monocytogenes, Enterococcus faecalis and Clostridium sporogenes in sandy and clay loam textured soils when applied in bovine slurry or unpasteurised digestate, using laboratory based inoculation studies. The run-off rate for a test bacterium, Listeria innocua, when applied to grass in slurry and digestate, was also examined using field studies. Bovine slurry and digestate were inoculated with the target bacteria to a final concentration of 106 log10 cfu/g or spores/g, thoroughly mixed into soil samples and incubated at 4°C or 14°C. Samples were removed periodically and the surviving cells enumerated using AOAC or equivalent methods. The loss of viability/culturability phase followed first order kinetics and T90 values ranged from 11.9 to 166.7 d at 4°C and from 6.0 to 156 d at 14°C. With the exception of E. coli O157:H7 and E. faecalis in sandy loam textured soil at 14°C (T90 values were significantly (P < 0.05) higher in slurry) the type of soil texture or application material (slurry or digestate) did not affect survival rates. In the field study, 12 grass covered micro-plots were prepared. L. innocua was applied in digestate and bovine slurry and rainfall was simulated at a target rate of ~11 mm per plot per h−1. Rainfall simulation (30 min) took place after 24, 48 h, 14 d and 30 d. Run-off samples were tested for the L. innocua strain using Brilliance Listeria agar supplemented with streptomycin sulphate (1,000 μg/ml) at 37°C for 48 h, as were soil samples after 30, 58, 86 and 112 d. Significantly (P < 0.05) lower counts were obtained in the run-off from digestate after 1, 2 and 30 d as compared to slurry. It was concluded that the type of organic fertiliser does not affect the bacterial survival rates in sandy and clay soils, with the exception of E. coli O157:H7 and E. faecalis in sandy loam textured soil at 14°C. Furthermore, bacteria may be retained better in the soil-digestate matrices during rainfall although additional research is required to further validate and provide the scientific basis for this observation.

Field study on loss of tetracycline antibiotics from manure-applied soil and their risk assessment in regional water environment of Guangzhou, China

Tetracycline antibiotics (TCs) introduced into agricultural fields via manure application tend to accumulate in soils and further reach water environments via surface runoff and leachate, posing potential risks to regional water environment. This study investigated the loss of tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC) in surface runoff and leachate samples collected from a vegetable farmland with manure application in Guangzhou, South China. A risk assessment method was constructed for evaluating the ecological and health risks of manure-associated antibiotics released from soil into water environment. The results showed that the concentrations of three TCs in surface runoff, 30-cm leachate, and 60-cm leachate after the first rainfall event were 2.79–35.97, 1.71–18.44, and 0.4–2.66 μg/L, respectively, which all decreased with sampling depth and the time after rainfall events. Up to 0.13% of TCs were transported into the surface water through surface runoff, while less than 0.01% of TCs were transported into the groundwater through leachate at 60 cm. OTC had a higher total mass percentage (0.13%) into surface water via runoff than CTC (0.11%) and TC (0.07%) likely due to its smallest Kd value and largest input mass. Based on loss percentages, their predicted environmental concentrations (PEC) ranged from 4.87 (TC) to 16.91 (OTC) ng/L in regional surface water and 1.42 (TC) to 5.20 (CTC) ng/L in regional groundwater. The risk assessment based on PEC results suggested non-negligible health risk (HQ > 1.0 × 10−6) and low ecological risk (RQ < 0.1) in both regional surface water and groundwater, drawing concerns on the potential hazards of TCs released from manure-amended soil into water environments.

Prairie strips' effect on transport of antimicrobial resistance indicators in poultry litter.

Poultry litter is a valuable nutrient resource for agricultural production but is also a potential source for introducing antibiotic resistance genes (ARGs) and litter-associated bacteria (LAB) to the environment. Prairie strips have been demonstrated as an effective conservation practice to improve environmental quality in agroecosystems. This research aims to assess prairie strips' potential for reducing the transport of LAB and ARGs in runoff after litter application. Plot-scale rainfall simulations were performed using a replicated block design, with soil and surface runoff samples taken during the rainfall event. Microbial taxa and ARGs were characterized in the litter, soil, and water samples. In plots with litter application, LAB and ARGs were mainly detected in runoff, with very low detection in soils. Detection of ARGs in runoff, irrespective of strip installations, is consistent with previous observations of litter as a source of antimicrobial resistance (AMR) risks. The effectiveness of prairie strips to remove LAB and ARGs varied. In two of the three prairie strip plots, fewer AMR indicators were detected relative to control plots, suggesting that the prairie strips can potentially reduce these risks. In one plot, which was also associated with increased flow rate, we observed increased AMR indicators despite the installation of a prairie strip. Our observations highlight the need to prioritize understanding of soil properties even within the same site. Although we show that prairie strips can potentially reduce AMR risks, further research is needed to better understand the influence of rainfall timing, soil, and litter characteristics.

Quantifying spatial distribution of interrill and rill erosion in a loess at different slopes using structure from motion (SfM) photogrammetry

The spatial distribution of interrill and rill erosion is essential for unravelling soil erosion principles and the application of soil and water conservation practices. To quantify interrill and rill erosion and their spatial development, four 30-min rainfalls at 90 mm h−1 intensity were consecutively simulated on runoff plots packed with a loess at six slopes of 10°, 15°, 20°, 25°, 30° and 35°. The soil surface was measured using the structure from motion (SfM) photogrammetry upon each simulation run, and the runoff and sediment samples were collected and measured at every 10 min. Rills did not develop until the third simulation run. During the initial two runs, the lower third section was more severely eroded than the upper and middle thirds along the slope direction, yet the interrill erosion was statistically uniform from left to right. Rills tended to emerge by both sidewalls and in the lower portion in the third run. The corresponding rill erosion increased with slope from 10° to 20° and then decreased for the slopes steeper, which was consistent with the slope trend of the sediment yield directly measured. The rills expanded substantially primarily via head retreat and to a lesser extent via sideward erosion after receiving another 30-min rainfall. Rill erosion contributed 69.3% of the total erosion loss, and shifted the critical slope corresponding to the maximum loss from 20° to 25°. These findings demonstrate the significance of rill erosion not only in total soil loss but also in its relation to slope, as well as the effectiveness of SfM photogrammetry in quantifying interrill and rill erosion.

Targeted extraction of pesticide from agricultural run-off using novel molecularly imprinted polymeric pendants

As a key member of benzoylurea insecticides, lufenuron exhibits a strong potential for bioaccumulation in ecosystems. Here, we report the synthesis of a molecularly imprinted polymer (MIP) and its application for selective extraction of lufenuron from agricultural runoff samples. The morphology and thermal stability of the prepared MIP was characterized by SEM and TGA, respectively. The experimental conditions for lufenuron detection were optimized through batch binding assay and response surface methodology (RSM). The MIP showcased a two-fold enhancement in binding capacity of lufenuron (74 mg g−1) relative to non-imprinted polymer (36 mg g−1), when measured through batch binding assay. Using a RSM based on central composite design, the qe value was predicted as 73.6 mg g−1 under optimal experimental conditions (e.g., pH 8). Furthermore, the percentage recovery of lufenuron was estimated as 98.8 ± 1.8% (n = 9). The adsorption kinetics of the MIP followed the pseudo-first-order model with χ2 value of 0.004 (correlation coefficient of 0.99). The limit of detection for lufenuron using MIP-based method was 3 × 10−6 µg mL−1. There was no significant decrease in the performance of MIP against lufenuron over five successive cycles.

Temporal and Spatial Distribution Characteristics and Source Apportionment of Runoff Pollution in Langfang City

Urban runoff pollution can carry pollutants into the receiving water through scouring and leaching, causing black color and odor or eutrophication. Understanding and mastering the characteristics of runoff pollution is a prerequisite for the effective control of runoff pollution. This study aimed to comprehensively analyze the temporal and spatial distribution characteristics of runoff pollution and the correlation between pollutants in the urban area of Langfang City. Rainfall runoff samples were collected seven times by setting up 14 sampling sites within the urban area. The suspended solids (SS), chemical oxygen demand (COD), N, P, fecal E. coli, anionic surfactants, volatile phenols, and Zn, Cr6+, As, Cu, etc. were analyzed. The source and distribution of pollutants were summarized and analyzed through principal component analysis and cluster analysis. The results showed that the concentration of pollutants in runoff in Langfang City varied greatly at different times and locations. The average ρ(SS) at each point ranged from 150-500 mg·L-1, and the average concentrations of COD, N, P, and fecal E. coli all exceeded those of the surface water standard Ⅴ. The average concentration of anionic surfactants, petroleum, and volatile phenols were between those of the surface water standard Ⅰ and standard Ⅳ. The concentrations of metal pollutants were relatively low. NH4+-N had a positive correlation with total nitrogen (TN), volatile phenols, and As. COD had a certain positive correlation with TN, total phosphorus (TP), Cr6+, and As, whereas fecal E. coli had a certain negative correlation with Zn and Cu. The organic matter, P, Cu, and SS were probably derived from vehicle tires and road surfaces. All sampling sites could be roughly divided into four types according to the features of pollution:mainly commercial service areas, residential areas, larger arterial roads, and small roads between communities. The pollution of runoff in Langfang City was relatively serious, especially that of COD, N, and P. This research provides important reference values for the control and regulation of runoff pollution in urban areas and other northern cities.

Impacts of a mature forestry plantation on blanket peatland runoff regime and water quality

AbstractA lack of information concerning the hydrology and hydrogeology of intact blanket bogs limits current understanding of how their alteration to mature forestry plantations impacts stream flow and associated water quality. An integrated hydrological/hydrogeological monitoring programme compared processes operating in a relatively intact blanket peat‐covered catchment with conditions encountered in an adjacent area under closed canopy plantation forestry. Groundwater monitoring revealed contrasting water level regimes and deeper summer water tables in the afforested area, with forest groundwater also having more elevated specific electrical conductance (SEC) and containing higher concentrations of dissolved organic carbon (DOC). Near‐simultaneous pairwise runoff sampling at the relatively intact catchment and afforested catchment outlets demonstrated no significant difference in DOC concentration. Conversely, water samples from the afforested catchment outlet displayed significantly greater SEC; this arose in part because of higher concentrations of dissolved calcium and magnesium, discharging via artificial drainage. Comparison of base flow runoff SEC with peat groundwater samples reflected in significant contrasts in ionic signature and greater levels of mineralisation in surface water, pointing to contributions of deeper water, derived from inorganic substrate materials. Study findings indicate that disturbance to the ground in that part of the catchment under plantation forestry has led to greater variations in stream flow and water quality for aquatic ecosystems. Comparable conditions have been observed instreams flowing through plantation forestry in similar physical settings elsewhere. Study findings suggest that plantations on deep peat can adversely affect stream ecosystems and this may impact on a water body's legal status.

Event‐based run‐off and sediment yield dynamics and controls in the subhumid headwaters of the Blue Nile, Ethiopia

AbstractLand degradation due to soil erosion presents a major challenge for sustainable development. We investigated run‐off and sediment yield (SY) dynamics in the northwestern highlands of Ethiopia. The study area included 14 zero‐order catchments with a surface area ranging from 324 to 1715 m2. V‐notch weirs produced from plastic jars were introduced as measuring alternatives that met local constraints. Run‐off (RO) depth at the weir was registered manually at 5‐min intervals during two rainy seasons in 2018 and 2019, and a total of 618 events were monitored. Rainfall was measured using tipping‐bucket rain gauges. RO samples were collected in 1‐L bottles, and suspended sediment concentration was determined. The mean event RO coefficient ranged from 3% for forests to 56% for badlands. Similarly, the mean annual SY was lowest for forests (0.8 Mg ha−1 yr−1) and highest for badlands (43.4 Mg ha−1 yr−1), with significant differences among land‐use types (14.8 Mg ha−1 yr−1 in cropland, 5.7 Mg ha−1 yr−1 in grazing land, and 2.9 Mg ha−1 yr−1 in plantations). Soil organic matter (SOM) reduced RO and SY, necessitating the consideration of agronomic and land management practices that enhance SOM. Annual SY decreased exponentially with the rock fragment cover (RFC). In fields where RFC was less than 20%, collecting rock fragments for installing stone bunds resulted in a net increase in SY. Rehabilitating badlands and enhancing SOM content in croplands can substantially reduce catchment SY and hence contribute to the sustainability of land uses in the subhumid highlands.

Spatio-temporal variations of quality of rainwater and stormwater and treatment of stormwater runoff using sand–gravel filters: case study of Delhi, India

The present study was undertaken to characterise rainwater and stormwater runoff, along with reusability potential of treated stormwater runoff in Delhi, India. The analysis of rainwater and stormwater runoff samples revealed that the acidic ions (SO42− and NO3−) in rainfall are being neutralised by alkaline species resulting in zero event of acidic rain (pH < 5.6) over Delhi. The higher level of alkaline species (Ca2+, NH4+, HCO3−, etc.) in stormwater runoff may be attributed to the alluvial nature of soil and suspended dust which is chiefly being of crustal origin in Delhi. Non-sea-salt fraction (NSSF) indicated no marine contribution towards rainwater quality. Neutralization factor (NF) validated the dominance of alkaline species (NH4+, HCO3−, K+, Ca2+, and Mg2+) over the acidic species (SO42−, NO3−, Cl− etc.), thereby resulting in near neutral pH of rainwater. Physico-chemical analysis of stormwater runoff from different locations in Delhi revealed relatively higher concentration of all the dissolved species (Ca2+, Mg2+, HCO3−, PO43−, NO3−, Cl−) along with higher level of suspended impurities and the spatial variations were observed to be regulated by land use landcover pattern. The treatment of stormwater runoff by sand–gravel filter resulted in complete removal of suspended impurities and partial removal of hardness. This study proposes additional use of a constructed wetland to remove the organic impurities, PO43−, and NO3−. Furthermore, the study concludes that the stormwater runoff in Delhi can easily be treated to the desired level of drinking water supply with additional provision of disinfection to narrow down the demand–supply gap for drinking water.

Detection of pesticide using Cu-rGO modified electrochemical sensor

The increased population of the world has intensified the demand for food, which escalates the use of pesticides in agricultural fields. The pesticides contaminate food, soil, and water bodies. The present article focuses on the detection of pesticides in runoff water from agricultural fields. In this study, a high sensitive electrochemical sensor for detection of organophosphate with the help of Cu-rGO nanocomposite. Cu-rGo was synthesized using the co-precipitation method and GO was synthesized using modified hummer’s method. The scanning Electron microscope, X-ray diffraction, and Raman spectroscopy confirmed the successful synthesis of the nanocomposite. The surface morphology of the nanocomposite was obtained from SEM analysis. Cyclic voltammetry and differential pulse voltammetry was performed using corrtest Potentiostat (CS 350) and a three-electrode setup for determination of electrochemical behavior of Cu-rGO nanocomposite and its interaction with malathion. Cu-rGO nanoparticles were deposited on the surface of a glassy carbon electrode and used as a working electrode and Ag/AgCl electrode as reference electrode and platinum wire as the counter electrode was used for detection of pesticide. Altogether, Cu-rGO modified electrode produced a very good result for the determination of pesticide in runoff water samples of agricultural fields.

Chemical evolution of runoff in Eastern Mediterranean mountainous karstic terrains

The Israeli central mountain rim was chosen to represent the transformation of rain chemical composition to runoff composition in a carbonate landscape under a Mediterranean climate. It was found that at the mostly dolomitic slopes of the Samaria Mountains the main processes shaping runoff chemistry are dissolution of dry fallout (dust) and salts that were precipitated during evaporation of water from previous small-scale runoff events. Calcium and sulfate concentrations in the runoff are defined mainly by the dissolution of dust minerals. The main input of sodium and chloride into runoff composition comes from both rain and dissolution of halite that remained from the evaporation of the previous runoff, whereas the main input of magnesium is connected to dissolution of dolomite outcrops. A combination of forward and inverse modeling by using PHREEQC software was found to be effective for studying runoff chemistry formation. Numerical simulations of runoff sample evaporation have shown that the main minerals precipitating during dry periods are calcite, anhydrite/gypsum, glauberite and halite. The high Na to Cl equivalent ratios (about 1.3 at average) may reflect two-phase dissolution of sulfates and halite in the initial stage that whereas and of glauberite in the following stage. Rainwater transformation to runoff inverse modeling was found to be consistent with the results of forward modeling, confirming these runoff chemical processes.

Stochastic generation of runoff series for multiple reservoirs based on generative adversarial networks

The implicit stochastic optimization (ISO) model is a methodology that has been extensively employed in the mid-long term optimal operation of a reservoir system. The generation of runoff series is the key technology to make up for the poor representativeness and reliability of historical runoff samples and is the premise to guarantee the accuracy of the ISO model. However, the traditional methods are not suitable for the stochastic generation of runoff series, among reservoirs with spatial–temporal correlation. In this work, the generative adversarial network called DC-WGAN is developed as a runoff generation model. DC-WGAN is based on a data-driven model and can capture the correlation of runoff series in time and space dimensions simultaneously. The proposed method is applied to the downstream Jinsha river cascade and Three Gorges cascade reservoirs in China to generate ten-day runoff series and is compared with the stochastic generation method based on Copula function. The focus of this paper is the model's performance in replicating the spatial–temporal correlation of ten-day runoff series. Results are as follows. (1) DC-WGAN has strong learning and generalization ability, which can learn the correct distribution of original runoff samples and generate runoff series similar to that from the validation set. (2) The runoff series among reservoirs with spatial–temporal correlation can be generated through DC-WGAN without assuming the probability distribution of samples in advance. (3) DC-WGAN is better than Copula function in capturing the spatial–temporal correlation, especially the moderate and weak correlation. The proposed methodology has a high practical value and application prospect for the stochastic generation of runoff series with spatial–temporal correlation.

Influence of green infrastructure objects for quality of surface runoff (on the example of green roofs in Kharkiv)

Relevance. Modern urbanization processes in Kharkiv are accompanied by an increase in anthropogenic pressure on the natural component, compaction of buildings and reduction of green areas. The concept of green infrastructure is used in many countries around the world; it is the best way to reorganize urban space into modern cities. The purpose of the article is a determination of quality changes of water runoff after passing through of green roofs in Kharkiv, Ukraine. Material and methods. A green roof is the roof of a build, partially or completely covered with vegetation and soil layer. Green roofs are divided into “intensive” and “extensive” types. In the research was studied the frequency of use of green roofs in construction and landscaping on the example of Kharkiv, was conducted an inventory of green roofs in Kharkiv. As the number of green roofs in Kharkiv is rather small, is optimal to choice the particular test sites for research. For chemical analysis, were taken samples of snow, surface runoff from the flat, and sloping green roofs and roof without greening for the content of pollutants. Chemical analysis of the samples was performed by the Laboratory of Analytical Ecological Research of V.N. Karazin Kharkiv National University. The laboratory has the attestation and certificate of ISO 10012:2005 № 01-0155/2019. The study determined the following indicators: pH, nitrites, nitrates, transparency, smell, turbidity, chlorides, general rigidity, total alkalinity, ammonia, zinc, copper, manganese, cadmium, total iron, chromium. Two types often represent green roofs in Kharkiv: parking roofs and cellars. Points of samples are located at Shevchenkivsky and Kholodnohirsky districts. Results and discussion. Results of a study of snow and runoff sampling after a green roof and a roof without landscaping show that most water quality indicators improve after water passes through green areas. Thus, at points the pH, general rigidity, alkalinity, concentration of chlorides, chromium are decrease. The green roof of the first point (parking) also reduces the concentration of nitrites, ammonia, zinc and manganese. The concentration of iron also decreases in the second point. However, there is an increase in the concentration of heavy metals in the water due to their accumulation in the substrate of the green roof. The results of the study are can be used by the Post-Soviet countries, as previously the impact of surface runoff was considered only in terms of the flow of pollutants from storm sewers to water bodies. Conclusion. The results of the study indicate that green roofs contribute to the treatment of runoff, natural replenishment of surface water bodies and groundwater and reduce the load on municipal wastewater treatment plant.

A comprehensive experimental assessment of glyphosate ecological impacts in riparian forest restoration.

Competition with invasive grasses is one of the most important drivers of tree planting failures, especially in tropical forests. A widely disseminated weeding approach has been glyphosate spraying, the most used herbicide globally in forestry and ecosystem restoration. However, glyphosate use in restoration is highly controversial and requires further studies to elucidate its effects on restoration processes and the environment. We evaluated the use of glyphosate in riparian forest restoration and its impacts on tree planting costs, weed control efficiency, planted seedling performance, herbaceous and woody species regeneration, soil bacteria, and environmental contamination, using mowing treatments as a reference and based on a controlled experiment established in the Brazilian Atlantic Forest. Glyphosate spraying reduced by one-half and one-third the accumulated aboveground biomass of, respectively, weeds in general and of the invasive grass Urochloa decumbens compared to mowing treatments, and it reduced the cost by half. The performance of planted tree seedlings was markedly favored by glyphosate spraying compared to mowing treatments, as expressed by improved seedling height (~twice higher), crown area (~5× higher), and basal area (~5× higher); the regeneration of both native woody and ruderal herbaceous plants were also enhanced. Neither glyphosate nor its metabolite Aminomethylphosphonic acid (AMPA) residues were detected in either water runoff or soil samples, but they were found at relatively high concentrations in the runoff sediments (from 1.32 to 24.75 mg/kg for glyphosate and from 1.75 to 76.13 mg/kg for AMPA). Soil bacteria communities differed before and after glyphosate spraying in comparison to mowing plots (without glyphosate). Glyphosate spraying was far more cost effective than mowing for controlling U. decumbens and greatly improved the performance of planted tree seedlings and natural regeneration, while not leaving residues in soil and water. However, the changes in the structure of bacterial communities and high concentration of glyphosate and AMPA residues in runoff sediments highlight the need for caution when using this herbicide in riparian buffers. We present alternatives for reducing glyphosate use and minimizing its risks in tree planting initiatives.

Targeted On-Demand Screening of Pesticide Panel in Soil Runoff.

Using pesticides is a common agricultural and horticultural practice to serve as a control against weeds, fungi, and insects in plant systems. The application of these chemical agents is usually by spraying them on the crop or plant. However, this methodology is not highly directional, and so only a fraction of the pesticide actually adsorbs onto the plant, and the rest seeps through into the soil base contaminating its composition and eventually leaching into groundwater sources. Electrochemical sensors which are more practical for in situ analysis used for pesticide detection in soil runoff systems are still in dearth, while the ones published in the literature are attributed with complex sensor modification/functionalization and preprocessing of samples. Hence, in this work, we present a highly intuitive electroanalytical sensor approach toward rapid (10 min), on-demand screening of commonly used pesticides—glyphosate and atrazine—in soil runoff. The proposed sensor functions based on the affinity biosensing mechanism driven via thiol cross-linker and antibody receptors that holistically behaves as a recognition immunoassay stack that is specific and sensitive to track test pesticide analytes. Then, this developed sensor is integrated further to create a pesticide-sensing ecosystem using a front-end field-deployable smart device. The method put forward in this work is compared and validated against a standard laboratory potentiostat instrument to determine efficacy, feasibility, and robustness for a point-of-use (PoU) setting yielding LoD levels of 0.001 ng/ml for atrazine and 1 ng/ml for glyphosate. Also, the ML model integration resulted in an accurate prediction rate of ≈80% in real soil samples. Therefore, a universal pesticide screening analytical device is designed, fabricated, and tested for pesticide assessment in real soil runoff samples.

Lab simulation of soil erosion on cultivated soil slopes with wheat straw incorporation

Sloping lands are prone to heavy soil erosion, resulting in farmland degradation in most mountainous regions. Straw incorporation can enhance resistance to erosion by improving the soil structure and reducing runoff. Laboratory-simulated rainfall experiments were conducted on silt loam soil to measure the effect of wheat straw incorporation on soil erosion and sediment delivery processes. Different wheat straw incorporation rates (WSIRs: 0, 2, 4, and 8 t ha−1), slope gradients (SGs: 10°, 15°, and 20°), and rainfall intensities (RIs: 80, 120, and 160 mm h−1) were evaluated. The results showed that the total rainfall amount was set at 100 mm. The sediment delivery processes were measured using oven-dried runoff samples collected during the specific intervals. The experimental data revealed that sediment delivery processes increased with increasing rainfall duration and decreased with increasing straw incorporation rates, respectively. Straw incorporation significantly reduced soil losses under steep slopes (20°) and during high-intensity rainfall (160 mm h−1). Compared with the control plot, the sediment concentrations, sediment delivery rates, and soil losses of slopes with straw incorporation were reduced by 52%, 62%, and 63%, respectively. The reduced sediment delivery rate and soil loss be attributed to increased soil surface roughness (exposed straw) that intercepted runoff, increased soil infiltration, and reduced flow velocity. The incorporated straw indirectly reduced sediment concentration by improving soil structure, which resulted in a smaller reduction in sediment concentration. The sediment reduction was maximized at 80 mm h−1 or 10°, while the benefits of straw incorporation on soil and water conservation were reduced with higher rainfall intensities and slope gradients. This study can serve as a basis for guiding soil and water conservation on sloping farmlands.

Cesium-137 stored on and discharged from banks of an agricultural canal in Iitate, Fukushima

This study aimed to investigate the dynamics of 137Cs around banks along an agricultural canal for paddy fields in Iitate, Fukushima, Japan. Five plots (2.4–12.6 m2) on the banks were monitored intermittently during six time periods from May 2018 to November 2019. We directly collected runoff water samples discharged from the banks followed by partitioning it into particulate and dissolved fractions and determining 137Cs in them. To investigate the source of 137Cs in the runoff water, we sequentially extracted 137Cs in various chemical forms from litter samples collected on the banks. The results showed that the discharge rates of the dissolved 137Cs per unit area from the plots were lower than those observed at the downstream of the agricultural canal, whereas more than 50% of the 137Cs discharged from the plots was in the dissolved fraction. Moreover, the results indicate that 137Cs stored in the standing plants and the litter was the primary source of the dissolved 137Cs discharged into the agricultural canal. The concentrations of the water-soluble 137Cs in the litter per plot area may have been retained by the sufficiently higher concentrations of 137Cs in litter in other chemical forms and those in the standing plants, which are the source of the litter.

Validation of a simple and robust multi-residue gas chromatography-mass spectrometry method for the analysis of polycyclic aromatic hydrocarbons, phthalates and biocides in roofing material leachate and roof runoff

A multi-residue method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs), biocides diuron (DIU), octylisothiazolinone (OIT) and mecoprop (MCPP), and phthalates bis(2-ethylhexyl) phthalate (DEHP) and diisodecyl phthalate (DIDP) in material leachate and roof runoff is presented. The method aims to keep sample pretreatment as simple as possible, not only to minimize sample contamination and sample losses, but also to have an environmental friendly and cost efficient method with low solvent consumption, in line with the principles of Green Analytical Chemistry. Solid phase extraction (SPE, C18) in combination with GC-MS was used for this purpose. A good separation and accurate detection for the majority of included analytes was obtained, resulting in overall low detection limits ranging between 0.1 ng/L and 18 µg/L in aqueous matrices. Furthermore, the addition of a surrogate standard containing three deuterated PAHs prior to SPE extraction was found to increase the method's repeatability. For the higher molecular weighted PAHs and phthalates, recovery was affected by the concentration level as higher recoveries were observed at lower spiking levels. Furthermore, also the matrix was found to affect the recovery of these higher molecular weighted components as the recoveries in roof runoff and material leachate were higher in comparison to the ones found in bidest water. Water solubility and the affinity to adsorb onto particles were hypothesized to play an important role. The multi-residue SPE-GC-MS method was found to be suitable for the quick and reliable analysis of material leachates and roof runoff samples.