Herbicides In Ground Water Research Articles

Enhanced degradation of herbicides in groundwater using sulfur-containing reductants and spinel zinc ferrite activated persulfate

A challenge to successfully implementing an injection-based remedial treatment in aquifers is to ensure that the oxidative reaction is efficient and lasts long enough to contact the contaminated plume. Our objective was to determine the efficacy of zinc ferrite nanocomposites (ZnFe2O4) and sulfur-containing reductants (SCR) (i.e., dithionite; DTN and bisulfite; BS) to co-activate persulfate (S2O82−; PS) and treat herbicide-contaminated water. We also evaluated the ecotoxicity of the treated water. While both SCRs delivered excellent PS activation in a 1:0.4 ratio (PS:SCR), the reaction was relatively short-lived. By including ZnFe2O4 in the PS/BS or PS/DTN activations, herbicide degradation rates dramatically increased by factors of 2.5 to 11.3. This was due to the SO4− and OH reactive radical species that formed. Radical scavenging experiments and ZnFe2O4 XPS spectra results revealed that SO4− was the dominant reactive species that originated from S(IV)/PS activation in solution and from the Fe(II)/PS activation that occurred on the ZnFe2O4 surface. Based on liquid chromatography mass spectrometry (LC–MS), atrazine and alachlor degradation pathways are proposed that involve both dehydration and hydroxylation. In 1-D column experiments, five different treatment scenarios were run using 14C-labeled and unlabeled atrazine, and 3H2O to quantify changes in breakthrough curves. Our results confirmed that ZnFe2O4 successfully prolonged the PS oxidative treatment despite the SCR being completely dissociated. Toxicity testing showed treated 14C-atrazine was more biodegradable than the parent compound in soil microcosms. Post-treatment water (25 %, v/v) also had less impact on both Zea Mays L. and Vigna radiata L. seedling growth, but more impact on root anatomies, while ≤4 % of the treated water started to exert cytotoxicity (<80 % viability) on ELT3 cell lines. Overall, the findings confirm that ZnFe2O4/SCR/PS reaction is efficient and relatively longer lasting in treating herbicide-contaminated groundwater.

Herbicide Residues in Water Resources: A Scoping Review

Several recent studies have focused on leaching pesticides from agricultural soils into surface and groundwater resources during irrigation. As a result, information about herbicide residues in water was necessary for conserving related resources. This study provided an overview of monitoring herbicides in water resources worldwide. In this scoping review, five databases were searched for publications (1990 to April 2021), including Scopus, PubMed/Medline, Cochrane library, Embase, and Web of Science. Among the 394 identified articles, 17 papers were selected for inclusion. Most of these studies have been conducted in regions with low herbicide concentrations, including Spain, Greece, Canada, Brazil, Hungary, Malawi, Portugal, Lesotho, Germany, Serbia, and the USA. The high-level alachlor, metolachlor, atrazine, metribuzin, and simazine herbicides in groundwater were detected in Portugal (0.4-13μg/L). An overview of studies demonstrated that herbicides are widely used in water resources, and surface waters are more contaminated than groundwaters.

Variables that Affect Agricultural Chemicals in Groundwater in Nebraska

Agricultural chemicals from nonpoint sources in groundwater are present in the major provinces of the High Plains aquifer in Nebraska. Nitrate and triazine-herbicide concentrations in groundwater were assessed to establish preliminary relations between these constituents and selected hydrogeologic, climatic, and land-use variables. Also, macropore flow paths were measured in an attempt to delineate their contribution to non-point source pollution from the study areas. Water from 82 wells in six study areas was analyzed for nitrate; water from 57 of the 82 wells was analyzed for triazine herbicides. Twenty-one independent variables were identified that could potentially affect chemical concentrations in groundwater. Data for 9 of 21 independent variables suspected of affecting concentrations of nitrate and triazine herbicides in groundwater were collected from the well sites. The nine variables and their measured ranges were hydraulic gradient, 0.0006–0.0053; hydraulic conductivity, 1.5–45.4 m (5–149 ft) per day; specific discharge, 0.004–0.091 m (0.0128–0.2998 ft) per day; depth to water, 0.91–76 m (3–250 ft); well depth, 12–168 m (40–550 ft); annual precipitation, 30–100 cm (12.0–39.3 in.); soil permeability, 1.9–23 cm (0.76–9.0 in.); irrigation-well density, 0–8 irrigation wells per 2.59 km2 (1 square mile); and annual nitrogen fertilizer use, 0–118 kg (0–260 lb) of nitrogen per acre. Macropore flow is listed in percent, average per study area based on determinations from dye studies. In this instance, macropore flow is used to also entail preferential flow paths. Nitrate concentrations ranged from 0.1 to 45 mgL−1. Triazine-herbicide concentrations were detected in samples from five of the six study areas in concentrations ranging from 0.1 to 2.3 μL−1. Analysis indicated that there were significant differences in nitrate concentrations (averages—at 95 % confidence level using Kendall Test) among the six study areas; no significant differences in triazine-herbicide concentrations were found. Concentrations of nitrate and triazine herbicide were determined (using contingency-table analysis), to be significantly larger in more intensively irrigated areas compared to less intensively irrigated areas. Preliminary correlations with the independent variables and nitrate concentrations indicated significant relations at the 95 % confidence level with variables hydraulic conductivity, well depth, and irrigation well density. Correlations with triazine-herbicide concentrations indicated significant relations with hydraulic conductivity, specific discharge, well depth, annual precipitation, and irrigation well density, as well as nitrate concentrations. Simple multiple-regression technique indicated that well depth and density and fertilizer use explained about 51 % of the variation in nitrate concentrations. Specific discharge and well depth explained about 60 % of the variation in triazine-herbicide concentrations. Macropore flow paths and specific discharge explained 84 % of the total variation in triazine-herbicide concentrations. The use of trade names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.

Leaching of Three Sulfonylurea Herbicides during Sprinkler Irrigation

Sulfonylurea herbicides are widely applied on the Canadian prairies to control weeds in a variety of crops. Several sulfonylurea herbicides are mobile in soil, and there is concern about their possible movement to ground water. This study was performed to assess the susceptibility of three sulfonylurea herbicides commonly used in prairie crop production to leach under a worst-case scenario. Thifensulfuron-methyl, tribenuron-methyl, and rimsulfuron were applied to a 9-ha tile-drained field, and then approximately 300 mm of irrigation water were applied over a 2-wk period using a center pivot. The commencement of tile-drain flow corresponded to the rise of the water table above tile-drain depth, and peak flow rates corresponded to the greatest depths of ground water above the tile drains. The volume of irrigation water intercepted by the tile drains in each quadrant was determined by site hydrology and represented <10% of the irrigation water applied. Concentrations of thifensulfuron-methyl, tribenuron-methyl, and rimsulfuron in the tile-drain effluent ranged (analysis by liquid chromatography/tandem mass spectrometry) from 2.0 to 248 ng L(-1), not detected (nd) to 55 ng L(-1), and nd to 497 ng L(-1), respectively. Total herbicide transport from the root zone in each quadrant was estimated at <0.5% of the amount of each sulfonylurea herbicide applied. Thifensulfuron-methyl was the only herbicide detected in ground water, with concentrations ranging from 1.2 to 2.5 ng L(-1). With the frequency and amount of rainfall typically encountered in the prairie region of Canada, detectable concentrations (>1 ng L(-1)) of these sulfonylurea herbicides in ground water would be unlikely.

Coupled‐column liquid chromatography combined with postcolumn photochemical derivatization and fluorescence detection for the determination of herbicides in groundwater

This study examines the application of coupled-column LC-photochemically induced fluorimetry-fluorescence detection (LC-LC-PIF-FD), demonstrating its potential for the quantitative and selective detection of six herbicides, including propanil and the phenylureas monuron, monolinuron, chlorotoluron, diuron and neburon in groundwater samples. An AQUASIL C18 50 x 4.6 mm(2) id column coupled to an AQUASIL C18 150 x 4.6 mm(2) id column for analyte clean-up and determination were used, respectively. A simple SPE with Cl8 cartridges was carried out, yielding average recoveries between 80 and 112% (n = 6) with RSDs between 0.5 and 9%. The LODs ranged from 0.0083 to 0.0833 microg/L in the groundwater samples.

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Método para a determinação de hexazinone e tebutiuron em água

METHOD FOR DETERMINATION OF HEXAZINONE AND TEBUTHIURON IN WATER. This work presents an alternative method for determination of the herbicides tebuthiuron and hexazinone in ground water. The extraction was made with dichloromethane and the analyses by high performance liquid chromatography (HPLC), using reversed-phase column, C-18, mobile phase methanol/water 50:50, v/v, detection and quantification at 247 nm. The following validation parameters were obtained: limit of detection of method 0.02 and 0.03 µg L -1 , limit of quantification of method 0.07 and 0.09 µg L -1 ; linear range limit of quantification of instrument – 300 µg L -1 (r 2 ≥ 0.998); recoveries from 90.3 to 108.2% and 90.3 to 101.6%; intermediary precision (%RSD) < 8 and < 6%, for hexazinone and tebuthiuron, respectively. The method showed to be efficient and reliable for determination of the herbicides in ground water.

Degradates provide insight to spatial and temporal trends of herbicides in ground water.

Since 1995, a network of municipal wells in Iowa, representing all major aquifer types (alluvial, bedrock/karst region, glacial drift, bedrock/nonkarst region), has been repeatedly sampled for a broad suite of herbicide compounds yielding one of the most comprehensive statewide databases of such compounds currently available in the United States. This dataset is ideal for documenting the insight that herbicide degradates provide to the spatial and temporal distribution of herbicides in ground water. During 2001, 86 municipal wells in Iowa were sampled and analyzed for 21 herbicide parent compounds and 24 herbicide degradates. The frequency of detection increased from 17% when only herbicide parent compounds were considered to 53% when both herbicide parents and degradates were considered. Thus, the transport of herbicide compounds to ground water is substantially underestimated when herbicide degradates are not considered. A significant difference in the results among the major aquifer types was apparent only when both herbicide parent compounds and their degradates were considered. In addition, including herbicide degradates greatly improved the statistical relation to the age of the water being sampled. When herbicide parent compounds are considered, only 40% of the wells lacking a herbicide detection could be explained by the age of the water predating herbicide use. However, when herbicide degradates were also considered, 80% of the ground water samples lacking a detection could be explained by the age of the water predating herbicide use. Finally, a temporal pattern in alachlor concentrations in ground water could only be identified when alachlor degradates were considered.

Aquifer vulnerability to pesticide pollution—combining soil, land-use and aquifer properties with molecular descriptors

This study uses an extensive survey of herbicides in groundwater across the midwest United States to predict occurrences of a range of compounds across the region from a combination of their molecular properties and the properties of the catchment of a borehole. The study covers 100 boreholes and eight pesticides. For each of the boreholes its catchment the soil, land-use and aquifer properties were characterized. Discriminating boreholes where pollution occurred from those where no pollution occurred gave a model that was 74% correct with organic carbon content, percentage sand content and depth to the water table being significant properties of the borehole catchment. Molecular topological descriptors as well as K oc, solubility and half-life were used to characterize each compound included in the study. Inclusion of molecular properties makes it possible to discriminate between occurrence and non-occurrence of each compound in each well. The best-fit model combines: organic carbon content, percentage sand content and depth to the water table with molecular descriptors representing molecular size, molecular branching and functional group composition of the herbicides.

Transport of three herbicides in ground water at Twin Lake test site, Chalk River, Ontario, Canada.

A field tracer test performed under natural flow conditions at the Twin Lake test site, Chalk River Laboratories of the Atomic Energy of Canada Ltd. in Chalk River, Ontario, Canada, using tritium and three herbicides (Chlortoluron, Terbuthylazine, and Pendimethalin) was interpreted using the dispersion equation with a combined reaction model. The reaction model couples an instantaneous equilibrium reaction governed by a linear adsorption isotherm with a reversible or irreversible kinetic reaction of the first order, and decay. An improved interpretation method consists of a simultaneous fitting of theoretical concentration and mass-recovery curves to the experimental data, which leads to a more reliable determining of reaction models and improves the accuracy of fitting. Tritium served as the reference tracer to determine the flow velocity, dispersivity, and the recovery of the herbicides. Chlortoluron was slightly delayed by equilibrium exchange with strongly reduced concentration due to an irreversible kinetic reaction and/or decay. Terbuthilazine was slightly delayed by equilibrium exchange, with strongly reduced concentration due to a reversible kinetic reaction with some influence of decay. A strong equilibrium reaction and a strong reversible kinetic reaction without degradation governed the transport of Pendimethalin, reducing considerably its concentration. The results obtained show that simulations based only on Kd and decay constant, especially if these parameters are found in the laboratory, may considerably differ from those performed with reaction parameters determined in properly performed field tests. The dominant reaction types, and the values of parameters found in the study, supply useful information on the transport of the investigated herbicides in sandy aquifers under natural flow conditions.

Herbicides in ground water beneath Nebraska's Management Systems Evaluation Area.

Profiles of ground water pesticide concentrations beneath the Nebraska Management Systems Evaluation Area (MSEA) describe the effect of 20 yr of pesticide usage on ground water in the central Platte Valley of Nebraska. During the 6-yr (1991-1996) study, 14 pesticides and their transformation products were detected in 7848 ground water samples from the unconfined water table aquifer. Triazine and acetamide herbicides applied on the site and their transformation products had the highest frequencies of detection. Atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4,-diamine] concentrations decreased with depth and ground water age determined with 3H/3He dating techniques. Assuming equivalent atrazine input during the past 20 yr, the measured average changes in concentration with depth (age) suggest an estimated half-life of >10 yr. Hydrolysis of atrazine and deethylatrazine (DEA; 2-chloro-4-amino-6-isopropylamino-s-triazine) to hydroxyatrazine [6-hydroxy-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] appeared to be the major degradation route. Aqueous hydroxyatrazine concentrations are governed by sorption on the saturated sediments. Atrazine was detected in the confined Ogallala aquifer in ultra-trace concentrations (0.003 microg L(-1)); however, the possibility of introduction during reverse circulation drilling of these deep wells cannot be eliminated. In fall 1997 sampling, metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] was detected in 57% of the 230 samples. Metolachlor oxanilic acid [(2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl) amino]oxo-acetic acid] was detected in most samples. In ground water profiles, concentrations of metolachlor ethane sulfonic acid [2-[(ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino]-2-oxo-ethanesulfonic acid] exceeded those of deethylatrazine. Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] was detected in <1% of the samples; however, alachlor ethane sulfonic acid [2-[(2,6-diethylphenyl)(methoxymethyl)amino]-2-oxoethanesulfonic acid] was present in most samples (63%) and was an indicator of past alachlor use.

Herbicides in Ground Water beneath Nebraska's Management Systems Evaluation Area

Herbicides in Ground Water beneath Nebraska's Management Systems Evaluation Area

Major herbicides in ground water: results from the National Water-Quality Assessment.

To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2,227 sites (wells and springs) sampled in 20 major hydrologic basins across the USA from 1993 to 1995. Results are presented for six high-use herbicides--atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), cyanazine (2-[4-chloro-6-ethylamino-1,3,5triazin-2-yl]amino]-2-methylpropionitrile), simazine (2-chloro-4,6-bis-[ethylamino]-s-triazine), alachlor (2-chloro-N-[2,6-diethylphenyl]-N-[methoxymethyl]acetamide), acetochlor (2-chloro-N-[ethoxymethyl]-N-[2-ethyl-6-methylphenyl]acetamide), and metolachlor (2-chloro-N-[2-ethyl-6-methylphenyl]-N-[2-methoxylethyl]acetamide)--as well as for prometon (2,4-bis[isopropylamino]-6-methoxy-s-triazine), a nonagricultural herbicide detected frequently during the study. Concentrations were <1 microg L(-1) at 98% of the sites with detections, but exceeded drinking-water criteria (for atrazine) at two sites. In urban areas, frequencies of detection (at or above 0.01 microg L(-1)) of atrazine, cyanazine, simazine, alachlor, and metolachlor in shallow ground water were positively correlated with their nonagricultural use nationwide (P < 0.05). Among different agricultural areas, frequencies of detection were positively correlated with nearby agricultural use for atrazine, cyanazine, alachlor, and metolachlor, but not simazine. Multivariate analysis demonstrated that for these five herbicides, frequencies of detection beneath agricultural areas were positively correlated with their agricultural use and persistence in aerobic soil. Acetochlor, an agricultural herbicide first registered in 1994 for use in the USA, was detected in shallow ground water by 1995, consistent with previous field-scale studies indicating that some pesticides may be detected in ground water within 1 yr following application. The NAWQA results agreed closely with those from other multistate studies with similar designs.

Natural Biological Attenuation of Phenoxy Herbicides in Groundwater: Dow AgroSciences Paritutu Site, New Zealand

Groundwater beneath a manufacturing site previously used for herbicide production has been shown to contain low levels of chlorinated phenols and phenoxy herbicides. The importance of biological processes in the natural attenuation of the groundwater contaminants was examined as part of an ongoing investigation. Analysis of the groundwater chemistry indicated that the aquifer is essentially aerobic in the area of interest. Laboratory microcosm experiments demonstrated that the naturally occurring microorganisms rapidly degraded a mixture of the predominant organic contaminants under conditions that simulate those in the aquifer. The time required for 50% degradation ranged from 7 to 27 days for 2,4-dichlorophenoxyacetic acid (2,4-D) and 9 to 49 days for 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The rapid biodegradation rates were consistent with the results of microbiological analyses, which demonstrated that a substantial proportion of the culturable bacteria were capable of growth on 2,4-D as a sole carbon source. Results of gene probe assays suggested the numbers of bacteria with the potential to degrade 2,4-D were one to two orders of magnitude higher than were detected using plate counts. Computer model simulations illustrated that biodegradation would be expected to significantly contribute to the attenuation of 2,4-D and 2,4,5-T in the aquifer. On the basis of the various lines of evidence and the distances the groundwater must travel, the groundwater contaminants would be expected to naturally biodegrade to below levels of concern before the plume reaches potential environmental receptors.

Oxidation of Herbicides in Groundwater by the Fenton Process: A Realistic Alternative for O3/H2O2 Treatment?

Oxidation with O3/H2O2 and Fe2+/H2O2 are optional for the degradation of herbicides and pesticides in water. The choice of which process will be applied depends upon the degree of degradation of organic micropollutants and the process conditions related to the formation of oxidation by-products, and also on the total costs and the safety and reliability of the process. Under real conditions, atrazine and some phenylureaherbicides were oxidized with O3/H2O2. Comparable experiments under conditions of different pH, iron and DOC content were performed with Fe2+/H2O2, in order to gain information on the influence of these parameters. The oxidation results of both processes as well as the formation of bromate as one of the oxidation by-products are described. It was found that 80% of atrazine and >99% of some phenylureaherbicides could be degraded with O3/H2O2 at pH 7.8 (H2O2/O3 ratio 3.7 g/g). Under these conditions, bromate was formed up to 5 μg/1. Comparable results were obtained with Fe2+/H2O2 at a pH value of 5.5, whereas the formation of bromate was kept below 0.2 μg/L.

Stereoselective analysis of acid herbicides in natural waters by capillary electrophoresis.

A capillary electrophoretic method for the stereoselective analysis of aryloxypropionic and aryloxyphenoxypropionic acidic herbicides in ground water and river water was performed. Vancomycin and gamma-cyclodextrin were added to the background electrolyte (BGE) as chiral selectors. Water sample preconcentration was accomplished by solid-phase extraction on styrene-divinylbenzene packed cartridges (2 L of ground water and 1 L of river water). The analytical method allowed for the resolution of mecoprop, fenoprop, fluazifop and haloxyfop racemic mixtures in natural water samples spiked with enantiomer concentration levels in the range 0.1-0.13 ppb for ground water and 0.4-0.54 ppb for river water.

Herbicide use on railway tracks for safety reasons in Germany?

A short overview on the occurrence of herbicides in groundwater and drinking water located in the vicinity of railway travks in Germany is presented. The study has been conducted using the experience of various water supply companies and includes a literature research on the subject. It has been documented that in Germany only 1% of the total area treated with pesticides was under management of the former Deutsche Bundesbahn before 1990. The specific amount applied on the railway tracks was, however, a factor of 6 higher than that used in agriculture, although it must be borne in mind that the retaining capacity of railway tracks for pesticides is much lower. The herbicides applied ranged from 2,4-D and 2,4,5-T, triazine derivatives, e.g. atrazine and urea derivatives such as diuron. Traces of almost all of the herbicides applied could be detected in samples of groundwater and drinking water in the vicinity of railway tracks. Since 1997 only glyphosate has been used.

Determination of sulfonic acid degradates of chloroacetanilide and chloroacetamide herbicides in groundwater by LC/MS/MS.

An analytical method is presented which permits qualitative and quantitative analysis of sulfonic acid degradates of three chloroacetanilide herbicides (acetochlor, alachlor, and metolachlor) and one chloroacetamide herbicide (dimethenamid) in groundwater at trace levels with determination by LC/MS/MS. The analytes were isolated from groundwater by solid-phase extraction (SPE). The final samples were analyzed by reversed-phase HPLC with MS/MS detection utilizing a pneumatically assisted, and heat-assisted electrospray interface (TurboIonSpray). Unique precursor/production pairs were obtained in the MS/MS mode which permitted conclusive identification of each analyte, even when the analytes coeluted. Quantification was performed by generation of an external calibration curve. Excellent linearity was obtained over a calibration range from 0.25 to 10 ng injected on-column, with all linear correlation coefficients exceeding 0.999. Method performance for this analytical procedure was validated by analyzing groundwater samples fortified at levels of 0.1, 1, and 50 ppb. The average recovery at each fortification level for each analyte exceeded 89%. Excellent method precision was demonstrated with percent relative standard deviations of less than 10% for all analytes at all fortification levels.

Determination of acidic herbicides using liquid chromatography with pneumatically assisted electrospray ionization mass spectrometric and tandem mass spectrometric detection

Liquid chromatography–pneumatically assisted electrospray mass spectrometry with negative ionization has been used for the determination of acidic herbicides in ground water. Eighteen pesticides or pesticide degradation products belonging to several different groups of acidic herbicides (phenoxy acids, sulfonylureas, phenols, etc.) were covered in the study. Optimization of electrospray inlet conditions is described as well as results from investigations of the linearity of the detector response. Conditions for tandem mass spectrometry (MS–MS) detection of characteristic daughter ions formed by collision-induced dissociation (CID) of the parent ion are described and a comparison of obtainable instrument detection limits by single MS and MS–MS was made. Detection limits using MS in the selected ion monitoring (SIM) mode were generally in the order of 1 μg/l or below, whereas detection limits were three–four times higher using MS–MS detection. A principle of analysis is proposed based on single quadrupole MS as a method for quantitative determination followed by verification of positive findings by CID MS–MS. Application of the method for detecting acidic herbicides residues in a “real-world” ground water sample is demonstrated.

Rapid method for analysis of atrazine and acetanilide herbicides in groundwater by micro liquid/liquid extraction

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRapid method for analysis of atrazine and acetanilide herbicides in groundwater by micro liquid/liquid extractionThomas L. Potter, Thomas Carpenter, Raymond Putnam, Krishna Reddy, and J. Marshall ClarkCite this: J. Agric. Food Chem. 1991, 39, 12, 2184–2187Publication Date (Print):December 1, 1991Publication History Published online1 May 2002Published inissue 1 December 1991https://doi.org/10.1021/jf00012a017RIGHTS & PERMISSIONSArticle Views233Altmetric-Citations22LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (493 KB) Get e-Alerts Get e-Alerts