RESUMO
Positron Emission Tomography (PET) imaging after 90 Y liver radioembolization is used for both lesion identification and dosimetry. Bayesian penalized likelihood (BPL) reconstruction algorithms are an alternative to ordered subset expectation maximization (OSEM) with improved image quality and lesion detectability. The investigation of optimal parameters for 90 Y image reconstruction of Q.Clear, a commercial BPL algorithm developed by General Electric (GE), in PET/MR is a field of interest and the subject of this study. The NEMA phantom was filled at an 8:1 sphere-to-background ratio. Acquisitions were performed on a PET/MR scanner for clinically relevant activities between 0.7 and 3.3 MBq/ml. Reconstructions with Q.Clear were performed varying the ß penalty parameter between 20 and 6000, the acquisition time between 5 and 20 min and pixel size between 1.56 and 4.69 mm. OSEM reconstructions of 28 subsets with 2 and 4 iterations with and without Time-of-Flight (TOF) were compared to Q.Clear with ß = 4000. Recovery coefficients (RC), their coefficient of variation (COV), background variability (BV), contrast-to-noise ratio (CNR) and residual activity in the cold insert were evaluated. Increasing ß parameter lowered RC, COV and BV, while CNR was maximized at ß = 4000; further increase resulted in oversmoothing. For quantification purposes, ß = 1000-2000 could be more appropriate. Longer acquisition times resulted in larger CNR due to reduced image noise. Q.Clear reconstructions led to higher CNR than OSEM. A ß of 4000 was obtained for optimal image quality, although lower values could be considered for quantification purposes. An optimal acquisition time of 15 min was proposed considering its clinical use.
RESUMO
There is currently a growing interest in the so-called emerging pollutants, such as pesticides, pharmaceuticals, personal hygiene care products, drugs, etc., whose presence in natural ecosystems is not necessarily recent, but the development in latest years of new and more sensitive methods of analysis has allowed their detection. They can be present in the natural environment, food, and many products of everyday origin, which suggests that human exposure to them is massive and universal. Therefore, the study of this type of substances is becoming one of the priority lines of research of the main agencies dedicated to the protection of public and environmental health, such as the World Health Organization (WHO), United States Environmental Protection Agency (USEPA) or European Union (EU). In this sense, it is of vital importance to know the nature and quantity of this type of contaminants, to establish preventive mechanisms that minimize its presence in aquatic systems, with special requirements for human consumption. This study aimed to describe a protocol for a systematic review and meta-analysis to assess the status of pesticides in European waters. We will search for original studies in the PubMed/Medline, Scopus, Web of Science, EMBASE, ScienceDirect databases. Prevalence studies of emerging contaminants (pesticides) in water resources (watersheds, aquifers, rivers, marine and springs), wastewaters (influent and effluent), and drinking water should be included. Two reviewers will independently screen and assess the included studies, with any disagreements being resolved by a third reviewer. We will summarize the findings using a narrative approach and, if possible, conduct a quantitative synthesis (meta-analysis). We will conduct the protocol following the Preferred Reporting Items for Systematic Review and Meta-Analyses Protocols (PRISMA-P) guidelines. The review will summarize the current evidence on the presence of pesticides in European waters such as glyphosate, chlorpyrifos, pyrethroid pesticides, neonicotinoid pesticides, and/or fungicides, in samples of different water resources like wastewaters and drinking water. We expect that this systematic review will establish preventive mechanisms that minimize the presence of pesticides in water in the environment.
Assuntos
Metanálise como Assunto , Praguicidas , Revisões Sistemáticas como Assunto , Poluentes Químicos da Água , Praguicidas/análise , Poluentes Químicos da Água/análise , Europa (Continente) , Humanos , Monitoramento Ambiental/métodos , Águas Residuárias/análise , Águas Residuárias/químicaRESUMO
The significant environmental issue of water pollution caused by emerging contaminants underscores the imperative for developing novel cleanup methods that are efficient, economically viable, and that are intended to operate at high capacity and under continuous flows at the industrial scale. This study shows the results of the operational design to build a prototype for the retention at lab scale of pollutant residues in water by using as adsorbent material, insoluble polymers prepared by ß-cyclodextrin and epichlorohydrin as a cross-linking agent. Laboratory in-batch tests were run to find out the adsorbent performances against furosemide and hydrochlorothiazide as pollutant models. The initial evaluation concerning the dosage of adsorbent, pH levels, agitation, and concentration of pharmaceutical pollutants enabled us to identify the optimal conditions for conducting the subsequent experiments. The adsorption kinetic and the mechanisms involved were evaluated revealing that the experimental data perfectly fit the pseudo second-order model, with the adsorption process being mainly governed by chemisorption. With KF constant values of 0.044 (L/g) and 0.029 (L/g) for furosemide and hydrochlorothiazide, respectively, and the determination coefficient (R2) being higher than 0.9 for both compounds, Freundlich yielded the most favorable outcomes, suggesting that the adsorption process occurs on heterogeneous surfaces involving both chemisorption and physisorption processes. The maximum monolayer adsorption capacity (qmax) obtained by the Langmuir isotherm revealed a saturation of the ß-CDs-EPI polymer surface 1.45 times higher for furosemide (qmax = 1.282 mg/g) than hydrochlorothiazide (qmax = 0.844 mg/g). Based on these results, the sizing design and building of a lab-scale model were carried out, which in turn will be used later to evaluate its performance working in continuous flow in a real scenario.
Assuntos
Ciclodextrinas , Poluentes Químicos da Água , Purificação da Água , Água , Furosemida , Poluentes Químicos da Água/química , Purificação da Água/métodos , Polímeros/química , Adsorção , Cinética , Hidroclorotiazida , Concentração de Íons de HidrogênioRESUMO
Solar heterogeneous photocatalysis was used to remove trihalomethanes (THMs) from drinking water. THMs, mainly trichloromethane (TCM), tribromomethane (TBM), bromodichloromethane (BDCM) and dibromochloromethane (DBCM) are one of the main class of disinfection by-products (DBPs). THMs were determined by HSGC-MS with detection limits (LODs) ranging from 0.5 µg L-1 to 0.9 µg L-1 for TCM and BDCM, respectively. Results show that a great proportion of THMs present in water are finally transferred to air as a result of their high volatility in the order TCM > BDCM > DBCM > TBM. The use of band-gap semiconductor materials (TiO2 and mainly ZnO) used as photocatalysts in combination with Na2S2O8 as electron acceptor and sulfate radical anion (SO4â¢-) generator enhanced the photooxidation of all THMs as compared to photolytic test. The time required for 50% of THMs to disappear (DT50) from water calculated for the most effective treatment (ZnO/Na2S2O8) were 12, 42, 57 and 61 min for TCM, TBM, BDCM, and DBCM, respectively. Therefore, solar heterogeneous photocatalysis can be considered as an interesting strategy for THMs removal, especially in sunny areas like Mediterranean basin.
Assuntos
Água Potável , Poluentes Químicos da Água , Óxido de Zinco , Clorofórmio , Desinfecção/métodos , Trialometanos , Abastecimento de ÁguaRESUMO
The Environmental Impact Assessment (EIA) is a legal and administrative tool aimed to identify, predict, and interpret the impact of a project or activity on the environment and human health. The EIA also evaluates the accuracy of the predictions and audits the effectiveness of the established preventive measures. Regarding the sanitation sector, efficiency of wastewater treatments and sanitation networks determine the pollutant level of the discharged liquid effluents and the subsequent impact on the environment and human health. This problematic makes necessary to assess how proper the regulatory follow-ups of sanitation projects is. This paper evaluates the performance of the Chilean EIA System concerning to sanitation projects. Taking into account that the more restrictive Environmental Impact Study (EIS) and more permissive Environmental Impact Declaration (EID) are the ways for projects' entry to the EIA System in Chile, 5336 sanitation projects submitted to EIA between 1994 and 2019 were complied. A representative sample of 76 projects (15 entered as EIS and 61 as EID) was analyzed by using a principal coordinate analysis (PCoA) through 14 selected performance indicators. Observed weaknesses have led to propose improvement opportunities of the EIA focused on the follow-ups after the environmental license is obtained, such as creation of a simplified sanctioning procedure, decentralization of decision-making, deadline establishment in each stage, and unified direct link for each project. These proposals seek to improve the effectiveness of monitoring and possible sanctions to early identify impacts of sanitation projects on the environment and human health. This paper introduces a robust methodology for evaluation criteria focused on the follow-ups analysis, which can be used in other countries that consider respectful sanitation projects have direct social and environmental benefits leading to long-term indirect cultural and economic values.
Assuntos
Meio Ambiente , Saneamento , Chile , Seguimentos , Humanos , LicenciamentoRESUMO
The effect of vermicompost added to a loam soil on the leaching behaviour of two herbicides (triclopyr and fluroxypyr) was examined. Mobility of the herbicides was assessed using disturbed soil columns under laboratory conditions. In both cases, the addition of vermicompost significantly increased the sorption of the compounds. For both, DT50 values were slightly higher in the amended soil, due to the increased adsorption. Rate constants (k) calculated according to pseudo-first order model were significantly lower in the case of triclopyr (very persistent), which led to a much lower degradation rate compared to fluroxypyr (persistent) in both unamended and amended soils. Values calculated for the experimental leaching index (ELI) in unamended and amended soils showed medium and high leachability for fluroxypyr (0.31 and 0.29) and triclopyr (0.72 and 0.70), respectively. Other index-based screening models (GUS, RLPI, LIX) also catalogue both herbicides as potential leachers. Results confirm that triclopyr and fluroxypyr may contaminate groundwater resources.
Assuntos
Acetatos/análise , Compostagem , Glicolatos/análise , Água Subterrânea/química , Modelos Teóricos , Piridinas/análise , Poluentes do Solo/análise , Solo/química , Acetatos/química , Adsorção , Glicolatos/química , Herbicidas/análise , Herbicidas/química , Piridinas/química , Poluentes do Solo/químicaRESUMO
The photocatalytic properties of silk fibroin (SF) incorporating TiO2 nanoparticles using an electrospinning technique were examined. Electrospun SF/TiO2 mats were successfully prepared and characterized by different techniques (XRD, FE-SEM, XPS, XDS, FTIR and BET). The photocatalytic efficiency of these materials were assessed by their ability to degrade four pesticides (boscalid, hexythiazox, pyraclostrobin and trifloxystrobin) in water exposed to solar irradiation. The effect of catalyst loading on the disappearance kinetics of the different pesticides was studied in order to determine the maximum degradation efficiency. The degradation rate significantly increases upon adding the TiO2. However, no significant differences (p < 0.05) were observed when the TiO2 loading was increased from 25 to 50 mg for most compounds. Thus, SF mats with 25 mg of TiO2 were selected. Therefore, a new and simple approach to produce materials with photocatalytic activity, safety and potential application in the purification of water contaminated by pesticides has been developed.
RESUMO
We have demonstrated the potential leaching of eight compounds, one insecticide (flonicamid) and seven fungicides (myclobutanil, penconazole, boscalid, difenoconazole, trifloxystrobin, pyraclostrobin and fenpyroximate) trough a typical Mediterranean soil (Calcaric regosol). The concentrations found in leaching water were in all cases above the limit set by the EU in groundwater (0.1 µg L-1). For this, the efficiency of different homogeneous (photo-Fenton and photo-Fenton-like) and heterogeneous (ZnO and TiO2) photocatalytic systems was tested in deionized water to choose the most appropriate treatment to remove pesticide residues from leaching water. The efficiency was in the order: ZnO + S2O82- (pH 7) > TiO2+ S2O82- (pH 7) > ZnO (pH 7) > TiO2 (pH 7) > Fe3+ (pH 3) > Fe3+ (pH 5) > Fe2+ (pH 3) > Fe2+ (pH 5). Thus, in the subsequent experiment we focus on the efficacy of solar heterogeneous photocatalysis (ZnO/Na2S2O8 and TiO2/ Na2S2O8) on their removal from leaching water. A fast removal was observed for all pesticides at the end of the photoperiod, noticeably higher in the case of ZnO system, with the exception of flonicamid, a recalcitrant pesticide where the degradation rate only reached about 20% after 240 min of solar exposure. Although the mineralisation of the initial dissolved organic carbon was not complete due to the presence of interfering substances in the leaching water, the conversion rate under ZnO/Na2S2O8 treatment was about 1.3 times higher than using TiO2/Na2S2O8.
Assuntos
Resíduos de Praguicidas , Poluentes Químicos da Água , Purificação da Água , Catálise , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/química , Luz Solar , Titânio/química , ÁguaRESUMO
The removal of 17 pesticides (pymetrozine, flonicamid, imidacloprid, acetamiprid, cymoxanil, thiachloprid, spinosad, chlorantraniliprole, triadimenol, tebuconazole, fluopyram, difenoconazole, cyflufenamid, hexythiazox, spiromesifen, folpet and acrinathrin) found in agro-wastewater from washing of containers and phytosanitary treatments equipment, has been carried out using sodium persulfate (Na2S2O8) at pilot plant scale under natural sunlight. Persulfate is a strong oxidant, inexpensive and environmentally appropriate. However, this oxidant is slow in kinetics under ordinary conditions. Na2S2O8 can be activated by ultraviolet light, generating SO4- radicals, which are also a very strong oxidizing species (E0â¯=â¯2.6â¯V). Previously, preliminary experiments were carried out at laboratory scale using a photoreactor to optimize the Na2S2O8 (300â¯mgâ¯L-1) concentration on the rate constants of the found pesticides. The residual levels of the studied pesticides in agro-wastewater (900â¯L) were in the range 0.02-1.17â¯mgâ¯L-1 for acrinathrin and fluopyram, respectively. After treatment, nearly complete degradation (>97%) of the parent molecules was achieved although 13% of initial DOC was measured. No significant differences (pâ¯<â¯0.05) were found when comparing grown broccoli using reclaimed and unreclaimed water.
Assuntos
Resíduos de Praguicidas/análise , Compostos de Sódio/química , Sulfatos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Agricultura , Resíduos de Praguicidas/química , Luz Solar , Águas Residuárias/química , Poluentes Químicos da Água/químicaRESUMO
This study aims to demonstrate a technically feasible alternative to remove pesticide residues from agro-waste water produced in farms from remnants in containers and treatment tanks, rinse in tanks after treatments, and cleaning of machines and equipment. For this, the photocatalyzed degradation of 12 pesticides commonly used on vegetables, vines, citrus and fruit crops was investigated in aqueous suspensions of TiO2 in tandem with Na2S2O8 at pilot plant scale under natural sunlight in Murcia (SE of Spain) during summer and winter seasons. Previously, preliminary experiments were carried out at laboratory scale using a photoreactor to optimize the photocatalyst (200â¯mgâ¯L-1) and oxidant (250â¯mgâ¯L-1) concentrations on the rate constants of the studied pesticides. The photodegradation of all pesticides can be modelled assuming a pseudo-first-order kinetics. The time needed for disappearance of 90% (DT90) of the studied pesticides, was lower than 4â¯h in summer in all cases with the exception of cyproconazole (4.9â¯h), while, cyproconazole (8.9â¯h), metalaxil (6.1â¯h) and propyzamide (7.9â¯h) showed DT90 higher than 6â¯h in winter. The reaction rate was enhanced 3-fold in summer season, which is directly correlated to the higher accumulated fluence per time received during this season (about a factor of 2.9 higher than in winter). In both cases, the higher and lower degradation rates were obtained for cyprodinil and cyproconazole, respectively. The total fluence to get a 90% reduction (H90) ranged from 4.6 to 5.2â¯Jâ¯cm-2 (cyprodinil) to 71.5-76â¯Jâ¯cm-2 (cyproconazole).
Assuntos
Praguicidas/química , Luz Solar , Titânio/química , Águas Residuárias/química , Poluentes Químicos da Água/análiseRESUMO
Investigations of anthropogenic contaminants in fresh- and wastewater have shown a wide variety of undesirable organic compounds such as Endocrine Disruptors (EDs). As a result, wastewater treatments using innovative technologies to remove those organic compounds are required. In this paper, the photodegradation of six EDs in wastewater at pilot plant scale is reported. The EDs were bisphenol A, bisphenol B, diamyl phthalate, butyl benzylphthalate, methylparaben and ethylparaben. Commercial TiO2 nanopowders (P25, Alfa Aesar and Kronos vlp 7000) were used as photocatalysts. The operating variables (type and loading catalyst, effect of electron acceptor and pH) were previously optimized under laboratory conditions. The results show that the use of TiO2 alongside an electron acceptor like Na2S2O8 strongly enhances the degradation rate of the studied compounds compared with photolytic tests, especially P25. The oxidation rates of the EDs at pilot plant scale were calculated following the disappearance of the target compound as a function of fluence (H). The ED degradation followed a pseudo-first order kinetics in all cases. In our experimental conditions, the half-fluence (H50) varied from 79 to 173â¯Jâ¯cm-2 (photolytic test), 10-117â¯Jâ¯cm-2 (TiO2 vlp 7000) and 3-58â¯Jâ¯cm-2 (TiO2 P25), for bisphenol B and butyl benzylphthalate, respectively. It is concluded that solar photocatalysis using the tandem TiO2/Na2S2O8 can be considered as an environmental-friendly tool for water detoxification and a sustainable technology for environmental remediation, especially in the Mediterranean Basin, where many places receive more than 3000â¯h of sunshine per year. Although the cost depends on the nature of the pollutant, the treatment cost was estimate to be about 150 m-3 for photocatalytic treatment with TiO2 P25.
Assuntos
Disruptores Endócrinos/efeitos da radiação , Recuperação e Remediação Ambiental/métodos , Fotólise , Luz Solar , Titânio/química , Águas Residuárias/química , Catálise , Disruptores Endócrinos/química , Recuperação e Remediação Ambiental/economia , Parabenos , Fenóis , Ácidos Ftálicos , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiaçãoRESUMO
Endocrine disruptors (EDs) are xenobiotics that interfere with the synthesis, secretion, transport, binding, action, and elimination of the natural hormones. In this paper, the photodegradation of six EDs in municipal wastewater treatment plant effluents at pilot plant scale is reported. The EDs were bisphenol A, bisphenol B, diamyl phthalate, butyl benzylphthalate, methyl p-hydroxybenzoate, and ethyl 4-hydroxybenzoate. ZnO as photocatalyst in tandem with Na2S2O8 as electron acceptor under natural sunlight were used. The process was previously optimized under laboratory conditions through a photoreactor under artificial UVA irradiation studying the role of some key operating parameters (catalyst loading, effect of electron acceptor, and pH). Results carried out at pilot plant scale show that addition of ZnO in tandem with Na2S2O8 strongly enhances degradation rates compared with photolytic test. At the end of the irradiation time (240 min), the remaining amounts of EDs ranged from 24% (butyl benzylphthalate) to 0% (< LOQ bisphenol B). The degradation rates were in the order: bisphenols > parabens > phthalates. After the photoperiod, 83% of the initial dissolved organic carbon was removed and toxicity decreased to acceptable values (11% inhibition to Vibrio fisheri). The photodegradation process was found to follow pseudo-first-order kinetic model with DT50 ranging from 5 min (bisphenol B) to 102 min (butyl benzylphthalate). Thereby, photocatalytic oxidation using ZnO is an area of environmental interest for the treatment of polluted water, particularly relevant for Mediterranean countries, where solar irradiation is highly available.
Assuntos
Disruptores Endócrinos/análise , Processos Fotoquímicos , Luz Solar , Águas Residuárias/química , Poluentes Químicos da Água/análise , Compostos Benzidrílicos , Catálise , Disruptores Endócrinos/química , Oxirredução , Parabenos , Fenóis , Fotólise , Ácidos Ftálicos , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Óxido de ZincoRESUMO
The mobility of two relatively new antranilic diamide insecticides, cyanantraniliprole (CY) and cholantraniliprole (CH) in soil was examined, by means of disturbed columns loaded with a typical semiarid Mediterranean soil (Calcaric fluvisol) under laboratory conditions. Both insecticides appeared in leachates, with 52% of CY and 41% of CH of the initial mass added (1 µg g-1) present. For CY, 21% and 19% were recovered from the upper and bottom layers of the soil, respectively, while for CH, 33% and 22% were recovered from the upper and bottom layers respectively. Based on the calculated half-lives (29 and 27 days for CY and CH, respectively) and their log K OC (about 2.5 for both), the calculated Groundwater Ubiquity Score (GUS) index was higher than 5 for both, indicating they have the potential to leach. Two transformation products, C13H9Cl2N2O (IN-ECD73) and C19H12BrClN6O (IN-J9Z38) corresponding to the degradation of CH and CY, respectively were also identified and detected in leachates and soil.
Assuntos
Água Subterrânea/química , Inseticidas/análise , Poluentes do Solo/análise , Solo/química , Poluentes Químicos da Água/análise , ortoaminobenzoatos/análise , Clima Desértico , Monitoramento Ambiental , Medição de Risco , EspanhaRESUMO
This paper reports the use of solar heating techniques, solarization (S) and biosolarization (BS) as a strategy for the environmental restoration of soils containing neonicotinoid, acetamiprid (AC), imidacloprid (IM) and thiamethoxam (TH), and diamide, chlorantraniliprole (CL) and flubendiamide (FB) insecticide residues. For this, a semiarid Mediterranean soil (Haplic calcisol) was covered with low-density polyethylene (LDPE) during the hot season, to raise the maximal soil temperatures. Compost from sheep manure (CSM), meat-processing waste (MPW) and sugar beet vinasse (SBV) were used as organic wastes. The results showed that both S and BS increase insecticide disappearance rates compared with the non-disinfected soil, the increase in soil temperature and added organic matter playing a key role. The dissipation rates of TH and AC in soil were satisfactorily described by first-order (monophasic) kinetics, while IM, CL and FB showed a deviation from exponential behaviour. For them, the best results were obtained applying biphasic kinetics with a rapid initial degradation followed by a slower decline of their residues. The findings suggest that S and BS (especially using MPW) can be considered as a valuable tool for enhancing the detoxification of soils polluted with these insecticides.
RESUMO
The leaching potential of three insecticides (spirodiclofen, spiromesifen, and spirotetramat) was assessed using disturbed soil columns. Small quantities of spirodiclofen and spiromesifen were detected in leachate fraction, while spirotetramat residues were not found in the leachates. In addition, the transformation products (enol derivatives) are relatively more mobile than the parent compounds and may leach into groundwater. Moreover, the use of disinfection soil techniques (solarization and biosolarization) to enhance their degradation rates in soil was investigated. The results show that both practices achieved a reduction in the number of juvenile nematodes, enhancing in a parallel way degradation rates of the insecticides and their enol derivatives as compared with the non-disinfected soil. This behavior can be mainly attributed to the increase in soil temperature and changes in microbial activity. All insecticides showed similar behavior under solarization and biosolarization conditions. As a consequence, both agronomic techniques could be considered as suitable strategies for detoxification of soils polluted with the studied pesticides.
Assuntos
Inseticidas , Solo/química , Animais , Nematoides , Praguicidas/química , Poluentes do Solo , Compostos de EspiroRESUMO
The photodegradation of flubendiamide (benzenedicarboxamide insecticide), a relatively new insecticide was investigated in aqueous suspensions binary (ZnO of and TiO2 ) and ternary (Zn2 TiO4 and ZnTiO3 ) oxides under artificial light (300-460 nm) irradiation. Photocatalytic experiments showed that the addition of semiconductors, especially ZnO and TiO2 , in tandem with an electron acceptor (Na2 S2 O8 ) enhances the degradation rate of this compound in comparison with those carried out with catalyst alone and photolytic tests. The photocatalytical degradation of flubendiamide using ZnO/Na2 S2 O8 and TiO2 /Na2 S2 O8 followed first-order kinetics. In addition, desiodo-flubendiamide was identified during the degradation of flubendiamide. Finally, application of these reaction systems in different waters (tap, leaching and watercourse) showed the validity of the treatments, which allowed the removal of flubendiamide residues in these drinking and environmental water samples.
Assuntos
Benzamidas/química , Óxidos/química , Fotólise , Sulfonas/química , Poluentes da Água/química , Purificação da Água/métodos , Benzamidas/metabolismo , Catálise , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/metabolismo , Semicondutores , Sulfonas/metabolismo , Titânio/química , Poluentes da Água/metabolismo , Óxido de Zinco/químicaRESUMO
In this study, the leaching of 14 substituted phenylurea herbicides (PUHs) through disturbed soil columns packed with three different soils was investigated in order to determine their potential for groundwater pollution. Simultaneously, a series of experiments were conducted to demonstrate the effect of four different organic wastes (composted sheep manure (CSM), composted pine bark (CPB), spent coffee grounds (SCG) and coir (CR)) on their mobility. All herbicides, except difenoxuron, showed medium/high leachability through the unamended soils. In general, addition of agro-industrial and composted organic wastes at a rate of 10% (w/w) increased the adsorption of PUHs and decreased their mobility in the soil, reducing their leaching. In all cases, the groundwater ubiquity score (GUS) index was calculated for each herbicide on the basis of its persistence (as t ½) and mobility (as K OC). The results obtained point to the interest in the use of agro-industrial and composted organic wastes in reducing the risk of groundwater pollution by pesticide drainage.
Assuntos
Herbicidas/química , Esterco , Compostos de Fenilureia/química , Pinus , Casca de Planta/química , Poluentes do Solo/química , Adsorção , Animais , Coffea , Poluição Ambiental , Água Subterrânea , Lignina/análogos & derivados , Sementes , Ovinos , Solo , Resíduos SólidosRESUMO
In this study, we examined the effect of four different organic wastes--composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)--on the sorption, persistence and mobility of eight symmetrical and two asymmetrical-triazine herbicides: atrazine, propazine, simazine, terbuthylazine (chlorotriazines), prometon (methoxytriazine), prometryn, simetryn, terbutryn (methylthiotriazines), metamitron and metribuzin (triazinones). The downward movement of herbicides was monitored using disturbed soil columns packed with a clay loam soil (Hipercalcic calcisol) under laboratory conditions. For unamended and amended soils, the groundwater ubiquity score (GUS) was calculated for each herbicide on the basis of its persistence (as t½) and mobility (as KOC). All herbicides showed medium/high leachability through the unamended soils. The addition of agro-industrial and composted organic wastes at a rate of 10% (w:w) strongly decreased the mobility of herbicides. Sorption coefficients normalized to the total soil organic carbon (KOC) increased in the amended soils. These results suggest that used organic wastes could be used to enhance the retention and reduce the mobility of the studied herbicides in soil.
Assuntos
Herbicidas/química , Resíduos Industriais , Resíduos de Praguicidas/química , Eliminação de Resíduos/métodos , Triazinas/química , Agricultura , Herbicidas/análise , Resíduos de Praguicidas/análise , Solo/química , Triazinas/análiseRESUMO
In this study, we examined the effect of four different organic wastes (OW)-composted sheep manure (CSM), spent coffee grounds (SCG), composted pine bark (CPB) and coir (CR)-on the potential groundwater pollution of propanil and isoxaben (herbicides), cadusafos (insecticide) and pencycuron (fungicide) under laboratory conditions. For this purpose, leaching studies were conducted using disturbed soil columns filled with a clay loam soil (Hipercalcic calcisol). The addition of organic matter (OM) drastically reduced the movement of the studied pesticides. The results obtained point to the interest in the use of agro-industrial and composted OW in reducing the groundwater pollution by pesticide drainage.
Assuntos
Fungicidas Industriais/química , Água Subterrânea/análise , Herbicidas/química , Inseticidas/química , Poluentes Químicos da Água/química , Poluição Química da Água/prevenção & controle , Silicatos de Alumínio/química , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Argila , Meia-Vida , Solo/química , Espectrometria de Massas em TandemRESUMO
Sulfonylurea herbicides (SUHs) are a family of environmentally compatible herbicides but their high water solubility, moderate to high mobility through the soil profile, and slow degradation rate make them potential contaminants of groundwater as demonstrated in this paper. The photodegradation of a mixture of 30 SUHs in aqueous suspensions of semiconductor materials (ZnO and TiO2 in tandem with Na2S2O8 as electron acceptor) under artificial light (300-460 nm) irradiation was investigated. As expected, the influence of both semiconductors on the degradation of SUHs was very significant in all cases. Photocatalytic experiments show that the addition of photocatalyst, especially for the ZnO/Na2S2O8 system, greatly improves the removal of SUHs compared with photolytic tests, significantly increasing the reaction rates. The first-order equation (monophasic model) satisfactorily explained the disappearance process although it overlooked small residues remaining late in the process. These residues are important from an environmental point of view and the Hoerl function (biphasic model), was a better predicter of the results obtained. In our conditions, the average time required for 90% degradation was about 3 and 30 min for ZnO/Na2S2O8 and TiO2/Na2S2O8 systems, respectively.