The role of storm flows in concentration of pesticides associated with particulate and dissolved fractions as a threat to aquatic ecosystems - Case study: the agricultural watershed of Save river (Southwest of France)

Measurement of the fluxes of pesticides was carried out for a year, ending in March 2009, in the Save catchment, in the vicinity of Toulouse. The hydrograph separation technique was used to evaluate the respective contribution of stormflow and baseflow in transport of 12 pesticide molecules. Transport of over 59% of pesticides and their controlling factors such as total suspended matter (TSM), particulate organic carbon (POC) and dissolved organic carbon (DOC) occurred during storm periods. Hysteresis patterns could be observed in the concentration-discharge relationships only for some molecules between rising and falling periods of the storm hydrograph. Clockwise hysteresis was noticed for low to moderately soluble pesticide molecules and for particulate fractions, which explains the role of surface runoff in pesticide displacement. In contrast, anticlockwise hysteresis was registered for soluble molecules and dissolved fractions, explaining the role of subsurface flows and soil leaching processes. The important role of TSM, POC and DOC in pesticide transport was clearly established. We also came to the conclusion that the role of stormy periods in pesticide movement and their controlling factors worked as a threat to aquatic ecosystems. And there was a positive relation between riverine TSM, POC, DOC and pesticides according to pesticide properties

Dynamique de transfert des pesticides en périodes de crue sur les bassins versants agricoles gascons

Ce travail de thèse porte sur l’étude des mécanismes et des bilans de transfert des pesticides vers les cours d’eau sur deux bassins versants agricoles emboités, de tailles différentes en Gascogne (Sud Ouest de la France) : la Save à Larra (1110 km2).et le Montoussé (3,28 km2) à Auradé. Dans cette région, les pratiques d’une agriculture intensive conduisent à des risques importants pour les ressources en eau, notamment pendant les périodes de crue. C’est pour cela que nous avons porté une attention particulière dans cette étude à ces événements au cours desquels une grande quantité de contaminants sont transportés par les cours d’eau. Quatorze molécules de pesticides (herbicides et fongicides) largement utilisées sur ces bassins versants ont été étudiées grâce à un échantillonnage intensif, notamment en périodes de crue, durant deux années hydrologiques (2007/2008 et 2008/2009). La majorité des molécules étudiées présentent des concentrations qui dépassent les limites autorisées par l’Union Européenne pour l’eau potable (0.1 μg.L-1 pour chaque molécule et 0.5 μg.L-1 pour l’ensemble des molécules), notamment en périodes de crue. L’analyse des hystérésis mises en évidence sur les relations entre les concentrations (pesticides, MES, COD, POC) et les débits du cours d’eau permet de mieux comprendre les mécanismes de transfert des pesticides et de leurs paramètres de contrôle. Ces hystérésis montrent pour un même débit des concentrations différentes en montée et en descente de crue ; elles peuvent être dextres (sens des aiguilles d’une montre) ou senestres (sens inverse) suivant l’origine des molécules et l’écoulement responsable de leur transfert des sols vers les eaux. C’est pourquoi nous avons procédé dans cette étude à une séparation des différentes composantes (ruissellement superficiel, écoulement hypodermique, écoulement de nappe) de l’écoulement fluvial pour mieux comprendre la dynamique de transferts des pesticides et de leurs paramètres de contrôle. On peut ainsi mettre en évidence des relations positives entre MES, COD, COP ou certaines molécules de pesticides et les débits des écoulements de surface (ruissellement superficiel ou écoulement hypodermique suivant les caractéristiques physico-chimiques des molécules). Les calculs de flux des différents pesticides exportés par les cours d’eau montrent que 60 à 90% (suivant les molécules) des transports annuels se font durant les épisodes de crue. Les flux spécifiques (masse exportée par unité de surface) calculés sont plus importants sur le bassin versant de la Save que sur celui du Montoussé et les relations flux spécifiques-débits mettent en évidence des concentrations plus élévées sur la Save où l’utilisation des pesticides est globalement plus importante que sur le Montoussé où les pratiques sont raisonnées. L’analyse des pesticides dans l’eau filtrée et non filtrée nous a permis d’estimer la distribution de chaque molécule entre les phases particulaires et dissoutes (Kd). De plus, les valeurs de flux calculés pour chaque crue nous ont permis d’estimer un Kd moyen pour chaque molécule. Ces valeurs de Kd présentent une très bonne relation avec les valeurs de Kow (coefficient de partage octanol-eau) extraites de la littérature. De même, les pourcentages calculés de chaque pesticide exporté sous forme particulaire sont aussi très bien corrélés au Kow de chaque molécule. ABSTRACT : The mechanisms of pesticides transport to stream flow were studied in two agricultural nested catchments of different size in Gascogne region (South West of France): the Save river basin at Larra (1110 km2) and the Montoussé experimental watershed at Auradé (3.28 km2). The intensive agricultural practices used in this region lead to an important risk for water resources by pesticides, especially during storm events. This is why we have paid special attention on storm events when a large quantity of contaminant was transported during hydrological periods. Fourteen molecules of pesticides (herbicides and fungicides) were investigated during the study period. Both of these groups are widely used for agricultural purposed in these catchments. The results achieved over the two years monitoring (2007-2009) enable us to emphasize the principal processes, implied in pesticide transfer on these agricultural catchments. The majority of compounds are detected during storm runoff events. And, the average concentrations of some pesticides are exceeded at the authorization limit of the European Union for pesticide concentrations in drinking water (0.1 µg.L-1 for individual pesticides and 0.5 µg.L-1 for total pesticides). To better understand the mechanisms of pesticide transport hysteresis, patterns on the concentration-discharge relationship (result of different concentration of pesticides in rising and falling limb of storm) were studied. However, clockwise or anticlockwise hysteresis patterns could be observed for some molecules of pesticide and their controlling factors such as dissolved organic carbon (DOC), particulate organic carbon (POC) and total suspended matters (TSM) according to their transfer dynamic in the catchment. We proceeded with hydrograph separation of the main stormflow components (surface runoff, subsurface flow and groundwater) so that the main pesticide routing could be traced for its soil-river transfers. We also came to the conclusion that there is a positive relationship between riverine TSM, DOC and pesticide, concentrations and the discharges of surface or subsurface runoffs according to pesticide properties. Pesticide flux calculation shows between 60 to 90% of the molecule transport takes place during storm periods. Specific flux calculation also demonstrated the higher flux value in Save catchment than in Aurade with higher pesticide concentration for a given specific discharge. The latter result may be due to the more consumption of pesticide in Save catchment. The analyses of pesticides both in filtered and unfiltered water enabled us to estimate the distribution of pesticides into particulate and dissolved phases. Moreover, the pesticide flux values allow calculating average partition coefficients kd between dissolved and particulate fractions which present good relationship with Kow values (octanol-water) extracted from literature. The percentage of each pesticide transported as particulate forms is also well correlated to Kow

Flood event impact on pesticide transfer in a small agricultural catchment (Moutousse at Aurade, south west France)

In this paper, pesticide transfer dynamic is studied during two flood events in a small experimental catchment close to Toulouse (south west France). Thirteen pesticide molecules (herbicides, fungicides) have been analysed by multi-residue technique on filtered and unfiltered waters. The results show very high pesticide concentrations in the different fractions compared to low flow periods and to the data collected by the French institutional networks in charge of the pesticide river water pollution survey. Several molecules present concentration higher than 0.1 mgL-1 and even higher than 1 mgL-1 in the unfiltered waters. In the suspended matters the concentrations vary respectively between 0.1 and 30 mg g-1 according to the molecules and can represent 40 to 90% of the total concentration for low soluble molecules. All the molecule concentrations and fluxes increase during the flood flows and have positive relationships with the stream discharge, but hysteresis between rising and falling periods can be observed for some molecules. Pesticide concentrations in unfiltered waters and partitioning between dissolved and particulate fractions (Kd¼[diss]/[part]) are controlled by dissolved organic carbon and total suspended matter. A good negative relationship can be established between logKd and logKow for 6 molecules

Occurrence of metolachlor and trifluralin losses in the Save river agricultural catchment during floods

Rising pesticide levels in streams draining intensively managed agricultural land have a detrimental effect on aquatic ecosystems and render water unfit for human consumption. The Soil and Water Assessment Tool (SWAT) was applied to simulate daily pesticide transfer at the outlet from an agriculturally intensive catchment of 1110 km2 (Save river, south-western France). SWAT reliably simulated both dissolved and sorbed metolachlor and trifluralin loads and concentrations at the catchment outlet from 1998 to 2009. On average, 17 kg of metolachlor and 1 kg of trifluralin were exported at outlet each year, with annual rainfall variations considered. Surface runoff was identified as the preferred pathway for pesticide transfer, related to the good correlation between suspended sediment exportation and pesticide, in both soluble and sorbed phases. Pesticide exportation rates at catchment outlet were less than 0.1% of the applied amount. At outlet, SWAT hindcasted that (i) 61% of metolachlor and 52% of trifluralin were exported during high flows and (ii) metolachlor and trifluralin concentrations exceeded European drinking water standards of 0.1 µg L−1 for individual pesticides during 149 (3.6%) and 17 (0.4%) days of the 1998–2009 period respectively. SWAT was shown to be a promising tool for assessing large catchment river network pesticide contamination in the event of floods but further useful developments of pesticide transfers and partition coefficient processes would need to be investigated

Spatial traffic noise pollution assessment – A case study

Objectives: Spatial assessment of traffic noise pollution intensity will provide urban planners with approximate estimation of citizens exposure to impermissible sound levels. They could identify critical noise pollution areas wherein noise barriers should be embedded. The present study aims at using the Geographic Information System (GIS) to assess spatial changes in traffic noise pollution in Tehran, the capital of Iran, and the largest city in the Middle East. Material and Methods: For this purpose, while measuring equivalent sound levels at different time periods of a day and different days of a week in District 14 of Tehran, wherein there are highways and busy streets, the geographic coordination of the measurement points was recorded at the stations. The obtained results indicated that the equivalent sound level did not show a statistically significant difference between weekdays, and morning, afternoon and evening hours as well as time intervals of 10 min, 15 min and 30 min. Then, 91 stations were selected in the target area and equivalent sound level was measured for each station on 3 occasions of the morning (7:00–9:00 a.m.), afternoon (12.00–3:00 p.m.) and evening (5:00–8:00 p.m.) on Saturdays to Wednesdays. Results: As the results suggest, the maximum equivalent sound level (Leq) was reported from Basij Highway, which is a very important connecting thoroughfare in the district, and was equal to 84.2 dB(A), while the minimum equivalent sound level (Leq), measured in the Fajr Hospital, was equal to 59.9 dB(A). Conclusions: The average equivalent sound level was higher than the national standard limit at all stations. The use of sound walls in Highways Basij and Mahallati as well as widening the Streets 17th Shahrivar, Pirouzi and Khavaran, benchmarked on a map, were recommended as the most effective mitigation measures. Additionally, the research findings confirm the outstanding applicability of the Geographic Information System in handling noise pollution data towards depicting noise pollution intensity caused by traffic

Dynamique de transfert des pesticides en périodes de crue sur le bassin versant de la Save (Sud-Ouest de la France)

L’objectif de cette étude est de déterminer le rôle des périodes de crue dans l’exportation des pesticides sur un bassin versant agricole de taille moyenne grâce à un suivi à pas de temps réduit des variations de débits et de concentrations des pesticides dans les fractions dissoute et particulaire. Les résultats montrent que les molécules présentent des teneurs supérieures à celles observées par les réseaux institutionnels. Ces teneurs sont en général corrélées positivement aux débits. Certaines molécules montrent des concentrations supérieures à 0,1 μg.L-1, voire même à 1 μg.L-1 pour aclonifen, isopruturon, linuron, métolachlore. Les relations débit-concentration mettent en évidence des hystérésis (teneurs différentes entre la montée et la descente de crue) dextres ou senestres suivant les molécules, dues à des contributions variables des différents écoulements (ruissellements de surface et hypodermique, écoulement de nappe) à l’exportation totale des pesticides par la rivière. Les teneurs en pesticides sont également corrélées aux MES ou au COD suivant les caractéristiques des molécules

Evaluation of Heavy Metal Contamination Potential in Surface Soil of Oil Pipelines in the North of Persian Gulf

The purpose of this study was to determine the concentration of heavy metals (Pb, Ni, Cr and V) in soil and evaluate the potential environmental risk of heavy metals in the surface soils of Assaluyeh-Bandar Abbas gas condensates pipeline base. For this purpose, 10 stations were randomly selected in a longitudinal transect and soil sampling was performed. Acid digestion of samples was performed and after their filteration, the concentration of each heavy metal was measured using atomic absorption spectroscopy thriugh calibration solutions. According to the results obtained, the mean concentrations of pb, Ni, Cr and V heavy metals in the study area were be 7.4±1.4, 42.5±2.4, 53.6±5.9 and 19.7± 2.5 mg/kg, respectively. As the findings of this work were all in the permissible level provided in national environmental standards, it was proved that the construction of the pipeline did not result in heavy metal contamination in the environment. However, human activities may have increased the concentration of metals. In this study, significant correlations were observed between Pb and V (P<0.01) and Cr and V (P<0.05) and also between Ni and Cr (P<0.05). The results of calculating geoaccumulation (Igeo), modified concentration degree (mCd) and potential ecological risk indices showed that the soils of studied areas were as unpolluted soil, very low pollution and low potential ecological risk categories, respectively

Industrial Acidic Wastewater Treatment by Sulfate Reducing Microorganisms

The effluents of polymerization plants are acidic due to the use of sulfuric acid as flocculation agent and their wastewater contains high amounts of sulfate ions. In wastewater industry, several physical, chemical and biological treatment methods are used. The main purpose of this study is to examine the feasibility of anaerobic biological treatment of sulfate in industrial effluents by using sulfate-reducing bacteria. The research method is quantitative, and experiments and data collection from 2017-2020. The main variables of this research are temperature, effluent pH and the population of microorganisms. Experiments at two temperature levels of 25 and 60 oC and two different pHs, 7.5 and 8.5, were performed and four series of experiments were done. The results showed that by increasing the temperature of the solution from 25° to 60 °C at a concentration of 50 mg/L sulfate ion and a pH of 7.5, microorganisms showed 17.6% better performance. Also, the performance of microorganisms in anaerobic biological treatment at concentration of 50 mg/L of sulfate ion was 45.3% minimum and 49.9% at maximum. Comparison of experimental results at two different pHs of 7.5 and 8.5, indicates that at the same temperatures of 25 and 65°C, with increasing pH, the performance of microorganisms has improved by 16.4%. The efficiency of wastewater treatment increases 19.6% by changing pH from 7.5 to 8.5. Results showed that the correlation between temperature and sulfate ion concentration follows the 1st degree equation. Also, the weak pH environment provides suitable conditions for the removal of ions in the effluents, and the correlation between increasing the pH of the solution and decreasing the concentration of sulfate ions is a 2nd degree equation. Study showed that temperature and pH are the two effective factors in the process of biological treatment of effluents

Innovative Sequencing Batch Electrocoagulation Reactors (SBERs) for Brine Treatment in Brackish Water Desalination System

This study aims to provide a green process implementation method for treating brine in the desalination system of brackish water with two stages of reverse osmosis. In this study, real samples taken from the first and second stages of the brackish water reverse osmosis (BWRO) plant were utilized to assess the performance of innovative sequencing batch electrocoagulation reactors (SBERs) with complementary processes (addition of chemicals and antiscalants, settling, microfiltration, UV, and ultrafiltration). According to the measurements, the TDS of the brackish water taken from the aquifer ranged from 3,229 to 3,664 mg/L, whereas that of the first-stage RO brine was between 5,500 and 7,700 mg/L, that of the second-stage RO brine was between 9,500 and 10,600 mg/L, and that of tap water was between 278 and 408 mg/L. The results of the study showed that the average removal of TDS, hardness, and ions in direct current (DC) was higher than in alternating current (AC) and that for Al-Al electrodes is more than that for Al-Fe electrodes. For the samples that were taken from the brine to the second stage RO with a TDS level of 9423 mg/L (with an increase in pH to 9 and with a temperature of 11 °C), the amount of TDS removal was 14%, and the amounts of hardness and scaling ions like calcium, magnesium, and sulfate (the amount of sulfate in quantities above 1400 mg/L) were removed equal to 35.5, 29, 35, and 30%, respectively. The TDS can be successfully reduced by electrocoagulation and scale-forming precursor ions can be eliminated by combining electrocoagulation and chemical precipitation.The results of the research showed that the third alternative was more advantageous than the others for the development phase of the desalination system under study after multiple options were analyzed technically, environmentally, and economically. The results of the research showed that the third alternative was more advantageous than the others for the development phase of the desalination system under study after multiple options were analyzed technically, environmentally, and economically.This option will direct brackish water to two RO (one stage)/SBERs processes. The RO desalination plant's brine and the SBER effluent are then combined to provide industrial water or irrigation water for plants that can tolerate salt. This method has been proposed as the best option for desalination system development because it reduces the total volume of rejected brine and increases the water supply (drinking, industrial, or agricultural)

Recent Advancements in Aptamer-bioconjugates: Sharpening Stones for Breast and Prostate Cancers Targeting

Breast and prostate cancers are common types of cancers with various strategies, such as chemotherapy and radiotherapy, for their therapy. Since these methods have undesired side effects and poor target affinity, neoteric strategies—known as aptamer-based smart drug delivery systems (SDDSs)—have been developed in recent years to overcome the obstacles of current treatment, and investigated for a clinical trial. The high affinity and versatility of aptamers for binding to the corresponding targets make them highly noticeable agents in the drug delivery domains. In addition to their exceptional benefits, aptamers are able to overcome tumor resistance because of their high selectivity and low toxicity. Furthermore, aptamers can conjugate with various drugs, nanoparticles and antibodies and effectively deliver them to the specific breast and prostate cells. This review highlights the current researches in aptamer-conjugate developments for targeting breast and prostate cancers, with the special focus on the nanoparticle-aptamer bioconjugates, systematic evolution of ligands by exponential enrichment (SELEX) system and SDDS, especially cutting-edge articles from 2008 to present. Finally, the future prospects and challenges are described