Pharmaceuticals, hazard and ecotoxicity in surface and wastewater in a tropical dairy production area in Latin America.

Pharmaceuticals comprise a complex group of emerging pollutants. Despite the significant number of pharmaceuticals used in veterinary medicine, the input of these compounds into the environment due to livestock activities has been scarcely described. This work assays for the first time in Central America the occurrence of pharmaceuticals in farm wastewater in an area devoted to dairy production, and in the surrounding surface waters. Among 69 monitored pharmaceuticals, a total of eight compounds were detected in wastewater samples collected from seven dairy farms after three sampling campaigns. Six pharmaceuticals were considered either of high (albendazole, lovastatin and caffeine) or intermediate estimated hazard (ciprofloxacin, acetaminophen and ketoprofen) based on the HQ approach, while 26% of the samples were considered of high estimated hazard according to the cumulative ∑HQ approach. Similarly, when ecotoxicological tests were applied, all the samples showed some level of toxicity towards Daphnia magna, and most samples towards Vibrio fischeri and Lactuca sativa. Fourteen pharmaceuticals were detected in surface water samples collected in the surroundings of the dairy production farms, including rural and urban areas. Seven out of these compounds showed high estimated risk (risperidone, diphenhydramine, trimethoprim, fluoxetine, ofloxacin, caffeine and ibuprofen), while three (gemfibrozil, ciprofloxacin and cephalexin) exhibited intermediate estimated risk. In a similar worrisome way, 27% of these samples were estimated to pose high environmental risk according to the pharmaceutical content. Despite being nontoxic for D. magna or V. fischeri, frequent inhibition (>20%) of GI in L. sativa was determined in 34% of surface water samples; such findings raise concern on the apparent inceptive environmental pollution and risk within the area. According to the pharmaceutical content patterns in both kinds of studied matrices, no clear evidence of significant contamination in surface water due to livestock activities could be retrieved, suggesting a main role of urban influence.

Biological treatment of pesticide-containing wastewater from coffee crops: selection and optimization of a biomixture and biobed design.

The biopurification systems (BPS) or biobeds are employed for the treatment of pesticide-containing wastewater of agricultural origin. The use of these devices for pesticide removal requires the proper optimization of the composition of biomixtures (BPS active matrix) according to the target pesticides applied on a specific crop and the available materials used in their elaboration. This work aims to design a biomixture for the simultaneous treatment of several pesticides applied in coffee crops, according to local practices in Costa Rica. Three biomixtures containing either coffee husk, coconut fiber or rice husk (as the lignocellulosic substrate) were applied for the removal of 12 pesticides. The profiles of pesticide elimination and the mineralization of radiolabeled chlorpyrifos (14C-chlorpyrifos) revealed that the best performance was achieved with the coconut fiber biomixture, even though similar detoxification patterns were determined in every biomixture (according to immobilization in Daphnia magna and germination tests in Lactuca sativa). The optimization of this biomixture's composition by means of a central composite design permitted the definition of two optimal compositions (compost:soil:coconut fiber, % v/v) that maximized pesticide removal: i. 29:7.3:63.7 and ii. 11:7.3:81.7. The validation of these optimized compositions also included the use of an alternative soil from another coffee farm and resulted in overall DT50 values of 7.8-9.0 d for the pesticide mixture. Considering the removal kinetics in the optimized biomixture, a 1 m3 BPS prototype was dimensioned to be eventually used in local coffee farms. This work provides relevant information for the design and implementation of BPS at on-farm conditions for the treatment of pesticide-containing wastewater of a major crop.

On-farm Occurrence of Pharmaceuticals and Their Environmental Hazard: Case Study of a Tropical Dairy farm.

Animal husbandry wastewaters represent an important source of pharmaceuticals into the environment. This work aimed to evaluate the occurrence of pharmaceuticals and their hazard in wastewater from a model dairy farm from Costa Rica. Among the seven pharmaceuticals detected (acetaminophen, caffeine, carbamazepine, ibuprofen, ketoprofen, risperidone, sulfamethazine), caffeine, ibuprofen and acetaminophen showed the highest concentrations, while caffeine, carbamazepine and risperidone were the most frequently detected compounds. High (HQ ≥ 1) or medium (0.1 ≤ HQ < 1) hazard were estimated for three (caffeine, ibuprofen, risperidone) and two (acetaminophen, ketoprofen) pharmaceuticals, respectively; similarly, high overall hazard (∑HQ) and significant ecotoxicity were determined in samples from all sampling points. According to our results, the release of these aqueous matrices is a matter of environmental concern, as the treated wastewater is used for farm irrigation or directly released into nearby water streams. This work contributes to the knowledge on the scarcely described occurrence and risk of pharmaceuticals in Latin American regions.

Occurrence and risk assessment of pharmaceuticals in hospital wastewater in Costa Rica.

This work aims to determine the occurrence, hazard and prioritization of pharmaceuticals from hospital wastewater in Costa Rica through the monitoring of 70 compounds and assessing their environmental risk through a hazard quotient approach (HQ). Moreover, the quantification of selected antibiotic resistance genes (ARGs) was conducted for the first time in this matrix in this geographical location. Thirty-four pharmaceuticals were detected, being caffeine, 1,7-dimethylxanthine, acetaminophen, ibuprofen, naproxen, ciprofloxacin and ketoprofen the most frequent (>50% of the samples). Eighteen pharmaceuticals exhibited high hazard (HQ ≥ 1), while five more showed medium hazard (1 > HQ ≥ 0.1). Prioritization, which also included frequency parameters, revealed caffeine, lovastatin, diphenhydramine, acetaminophen, ibuprofen, ciprofloxacin, and sildenafil as the compounds of major concern. Similarly, cumulative hazard per sample (ΣHQ) estimated high hazard towards aquatic organisms in every sample. All selected ARGs, except mcr-1 (polymyxin resistance), were detected. Among genes conferring resistance to beta-lactams, blaCTX-M and blaKPC were the most abundant, related to resistance to cephalosporins and carbapenems. Ecotoxicological evaluation showed mostly low toxicity towards Daphnia magna and Vibrio fischeri, contrary to the marked effect observed towards Lactuca sativa. These findings provide relevant and novel information on the risk posed by hospital wastewater and their pharmaceutical content in the Latin American environmental context.

Use of organic fertilizers in solar photo-Fenton process as potential technology to remove pineapple processing wastewater in Costa Rica.

Background: This work studied the use of the organic fertilizers DTPA-Fe and EDDS-Fe as iron chelates for solar driven photo-Fenton process at natural pH. This process was proposed to investigate its performance on removing a mixture of agrochemicals (propiconazole, imidacloprid and diuron) from pineapple processing wastewater to obtain a suitable effluent to be reused in the agricultural sector. Methods: Experiments were carried out in a solar simulator with a stirred cylindric photoreactor, with a volume of 150 mL and controlled temperature (20°C). The first set of experiments was carried out with ultrapure water to determine optimal iron and H 2O 2 concentrations. The second was performed with simulated wastewater of pineapple processing. Results: The optimized operational conditions for both iron complexes were 10 mg L -1 of Fe (III) and 25 mg L -1 of H 2O 2, since more than 80% of micropollutants (MP) (at an initial concentration of 1 mg L -1 of each compound) were removed in only 20 min with both DTPA-Fe and EDDS-Fe. The effect of organic matter and inorganic salts on radicals scavenging and chelates stability was also investigated in the experiments performed with synthetic pineapple processing wastewater. The results disclosed differences depending on the iron complex. Nitrites were the principal component influencing the tests carried out with EDDS-Fe. While carbonates at low concentration only significantly affected the experiments performed with DTPA-Fe, they were the major influence on the MPs removal efficiency decrease. In contrast, the presence of Ca 2+ and Mg 2+ only influence on this last one. Finally, the results of phytotoxicity disclosed the suitability of treated effluent to be reused in the agricultural sector.  Conclusions: This work demonstrated that solar powered photo-Fenton catalysed by iron fertilizer EDDS is a suitable technology for depolluting water streams coming from pineapple processing plants at circumneutral pH, and its subsequent reuse for crop irrigation.

An integrative water quality evaluation in two surface water bodies from a tropical agricultural region in Cartago, Costa Rica.

A monitoring study was carried out in two micro-catchments in the Reventazón basin, in Northern Cartago, Costa Rica; pesticide occurrence and water quality were analyzed. Twelve pesticides were detected, five insecticides (chlorpyrifos, carbofuran, cypermethrin, imidacloprid, and oxamyl), four fungicides (carbendazim, imazalil, metalaxyl, and thiabendazole), and three herbicides (diuron, linuron, and terbutryn); eight of them presented risk quotients RQ >1, which implies a high risk for the environment. The water quality evaluation included fourteen physicochemical and microbiological parameters, out of which thermotolerant coliforms, nitrate, and total phosphorus exceeded a selected threshold value in every sample. Five metals were also included in the evaluation, Pb was the most frequent, followed by few detections of Cd, Cu, and Cr. Four water quality indexes (WQIs) were applied, two of them, the CCME WQI, based on physicochemical parameters, and the BMWP-CR WQI, based on benthic macroinvertebrate recount adapted to Costa Rican species, categorized all the sampling points as "bad" and "very bad" quality. This work of monitoring is important in the Latin American region, where there is a lack of information for regulation improvement and management decisions. These results showed poor management of the micro-catchments in this agricultural rural area.

Environmental monitoring and risk assessment in a tropical Costa Rican catchment under the influence of melon and watermelon crop pesticides.

A monitoring network was established in streams within a catchment near the Costa Rican Pacific coast (2008-2011) to estimate the impact of pesticides in surface water (84 samples) and sediments (84 samples) in areas under the influence of melon and watermelon production. A total of 66 (water) and 47 (sediment) pesticides were analyzed, and an environmental risk assessment (ERA) was performed for four taxa (algae, Daphnia magna, fish and Chironomus riparius). One fungicide and seven insecticides were detected in water and/or sediment; the fungicide azoxystrobin (water) and the insecticide cypermethrin (sediments) were the most frequently detected pesticides. The insecticides endosulfan (5.76 µg/L) and cypermethrin (301 µg/kg) presented the highest concentrations in water and sediment, respectively. The ERA revealed acute risk in half of the sampling points of the melon-influenced area and in every sampling point from the watermelon-influenced area. Safety levels were exceeded within and around the crop fields, suggesting that agrochemical contamination was distributed along the catchment, with potential influence of nearby crops. Acute risk was caused by the insecticides chlorpyrifos, cypermethrin and endosulfan to D. magna, fish and C. riparius; the latter was the organism with the overall highest/continuous risk. High chronic risk was determined in all but one sampling point, and revealed a higher number of pesticides of concern. Cypermethrin was the only pesticide to pose chronic risk for all benchmark organisms. The results provide new information on the risk that tropical crops pose to aquatic ecosystems, and highlight the importance of including the analysis of sediment concentrations and chronic exposure in ERA.

Canine brucellosis in Costa Rica reveals widespread Brucella canis infection and the recent introduction of foreign strains.

Brucellosis is a prevalent disease in Costa Rica (CR), with an increasing number of human infections. Close to half of homes in CR have one or more dogs, corresponding to ∼1.4 million canines, most of them in the Central Valley within or near the cities of San José, Heredia, and Alajuela. From 302 dog sera collected from this region, 19 were positive for Brucella canis antigens, and five had antibodies against smooth lipopolysaccharide, suggesting infections by both B. canis and other Brucella species. B. canis strains were isolated in the Central Valley from 26 kennel dogs and three pet dogs, all displaying clinical signs of canine brucellosis. We detected three recent introductions of different B. canis strains in kennels: two traced from Mexico and one from Panama. Multiple locus-variable number tandem repeats (MLVA-16) and whole-genome sequencing (WGSA) analyses showed that B. canis CR strains comprise three main lineages. The tree topologies obtained by WGSA and MLVA-16 just partially agreed, indicating that the latter analysis is not suitable for phylogenetic studies. The fatty acid methyl ester analysis resolved five different B. canis groups, showing less resolution power than the MLVA-16 and WGSA. Lactobacillic acid was absent in linages I and II but present in linage III, supporting the recent introductions of B. canis strains from Mexico. B. canis displaying putative functional cyclopropane synthase for the synthesis of lactobacillic acid are phylogenetically intertwined with B. canis with non-functional protein, indicating that mutations have occurred independently in the various lineages.

Amendments with pyrolyzed agrowastes change bromacil and diuron's sorption and persistence in a tropical soil without modifying their environmental risk.

Knowledge of pesticides fate in tropical soils and how it could be affected by pyrolyzed biomass as amendment is limited. Combining conventional and radiotracer methods, as well as risk assessment tools, the effects of several charred agrowastes on the sorption, persistence, and ecological risk of the herbicides bromacil (BMC) and diuron (DRN) were evaluated in a tropical agricultural soil under laboratory conditions. Pineapple stubble (PS), palm oil fiber (PF), and coffee hull (CH) were charred at 300 (torrefied) and 600 °C (biochar) and applied to the soil at 10 and 20 t ha-1 rates. The sorption coefficients (Koc) in unamended soil for BMC and DRN were 18.4 and 212.1 L kg-1, respectively. The addition of torrefied PS and PF caused a 3 to 4-fold increment in BMC sorption and a 3 to 6-fold change in DRN's sorption. The only biochar that affected the sorption was PS that increased DRN's sorption 3.5 times. The application of coffee hull materials had no significant effect. In terms of degradation (half-life, DT50), for unamended soil BMC's degradation (300 days) was limited compared to DRN (73 days). Alternatively, biodegradation (mineralization half-life time, MT50) was 1278 d for BMC and 538 for DRN. While only PF and CH torrefied increased BMC's persistence, all the torrefied affected DRN's persistence. However, despite the observed effects, the predicted ecological risk was not mitigated. Our results highlight the need for scientific evidence on the use of pyrolyzed organic amendments to assess potential benefits and prevent unintended impacts in tropical agroecosystems.

Pharmaceuticals in farms and surrounding surface water bodies: Hazard and ecotoxicity in a swine production area in Costa Rica.

The presence of pharmaceuticals in the environment is known to have multiple origins; livestock activities comprise one scarcely studied source, both globally and specially in Latin-America. This work aims to study the occurrence of pharmaceuticals in wastewater from swine farms and their surrounding surface waters, in a highland livestock production area of Costa Rica. The monitoring of 70 pharmaceutical active compounds resulted in the detection of 10 molecules in farm wastewater (influents and effluents of the on-farm treatment system), including compounds of animal and human use. A 57% of effluents showed high hazard (ΣHQ > 1), mainly due to the compounds risperidone, ketoprofen, ibuprofen and naproxen. Additionally, ecotoxicological tests with Daphnia magna and Microtox classified at least 21% of the effluents as very toxic (10 < TU ≤ 100); likewise, 86% of effluents exhibited germination index (GI) inhibition values over 90% for Lactuca sativa. Seven molecules were detected in surface water, six of them of human use (1,7-dimethylxanthine, caffeine, cephalexin, carbamazepine, gemfibrozil, ibuprofen) and one (acetaminophen) of dual (human and veterinary) use; nonetheless, most of the detections were found in sampling points closer to human settlements than animal farms. Considering the set of molecules and their distribution, the livestock influence on surface water seems minimal in comparison with the urban influence. Only 16% of surface water samples showed high risk, mainly due to ibuprofen, gemfibrozil and caffeine; similarly, 45% samples presented GI inhibition >20% (no toxicity was determined towards Daphnia magna or Microtox). These findings in surface water suggest an incipient environmental risk in the area.

Pesticide occurrence and water quality assessment from an agriculturally influenced Latin-American tropical region.

A monitoring study was carried out in three agriculturally influenced microcatchments in Costa Rica during 2012-2014, for pesticides and water quality parameters. A total of 42 pesticides were analyzed, detecting the following in water samples: two herbicides (oxyfluorfen, diuron), four insecticides (carbofuran, chlorpyrifos, oxamyl, ethion), and two fungicides (thiabendazole, carbendazim); while in sediment samples only the insecticides, chlorpyrifos and cypermethrin were found. Water quality was also assessed by the Canadian Council of Ministers of the Environment Water Quality Index and the National Sanitation Water Quality Index, the first one classified most of the sampling point as marginal and poor quality while the second one classified most of them as good quality, the most affected parameters were nitrate, phosphorous, suspended solids and organic matter content. The results suggest that the water quality in the microcatchments seems to be affected by the nearby agricultural and urban activities in the region.

Validation of a methodology by LC-MS/MS for the determination of triazine, triazole and organophosphate pesticide residues in biopurification systems.

Biopurification systems are useful in the management of pesticide residues and provide an option to dispose wastewaters of agricultural origin derived from pesticide application practices. The analysis of pesticide residues in the biopurification system biomixture is necessary to determine whether the removal of the target compounds occurs with reliable results. In this study, the pesticide extraction methodology was optimized and validated in a biomixture composed of coconut fiber, compost and soil, to determine a total of 43 molecules, distributed among triazines (10), triazoles (13) and organophosphates (20) using liquid chromatography coupled to a triple quadrupole mass spectrometer. For the validation, the parameters of linearity, matrix effect, limit of determination (LOD), specificity, selectivity, precision, trueness and robustness in the proposed biomixture were evaluated. The analyses of those parameters revealed satisfactory results of the method for most of the compounds, with the exception of diclorvos and ciromazine, for which the development of an alternative method is recommended. Once the extraction methodology was validated, the removal of eight molecules was assayed in a biopurification system used for the simultaneous treatment of a mixture of pesticide commercial formulations. Although most of the compounds were at least partially removed, none of them was eliminated at levels below the LOD. The removal pattern of ametryn, atrazine, chlorpyrifos, malathion and terbutryn was comparable to those obtained in other efficient biomixtures, and the highly recalcitrant triadimenol was eliminated; nonetheless, tebuconazole and diazinon were not significantly removed.

Occurrence of pharmaceuticals, hazard assessment and ecotoxicological evaluation of wastewater treatment plants in Costa Rica.

The continuous release of pharmaceuticals from WWTP effluents to freshwater is a matter of concern, due to their potential effects on non-target organisms. The occurrence of pharmaceuticals in WWTPs and their associated hazard have been scarcely studied in Latin American countries. This study aimed at monitoring for the first time the occurrence of 70 pharmaceutical active compounds (PhACs) in WWTPs across Costa Rica; the application of the hazard quotient (HQ) approach coupled to ecotoxicological determinations permitted to identify the hazard posed by specific pharmaceuticals and toxicity of the effluents, respectively. Thirty-three PhACs were found, with 1,7-dimethylxanthine, caffeine, acetaminophen, ibuprofen, naproxen, ketoprofen and gemfibrozil being the most frequently detected (influents/effluents). HQ for specific pharmaceuticals revealed 24 compounds with high/medium hazard in influents, while the amount only decreased to 21 in effluents. The top HQ values were obtained for risperidone, lovastatin, diphenhydramine and fluoxetine (influent/effluent samples), plus caffeine (influent) and trimethoprim (effluent). Likewise, the estimation of overall hazard in WWTP samples (sum of individual HQ, ∑HQ) demonstrated that every influent and 96% of the effluents presented high hazard towards aquatic organisms. Ecotoxicological analysis (Daphnia magna, Lactuca sativa and Microtox test) revealed that 16.7% of the effluents presented toxicity towards all benchmark organisms; the phytotoxicity was particularly frequent, as inhibition values ≥20% in the germination index for L. sativa were obtained for all the effluents. The ∑HQ approach estimated the highest hazard in urban wastewater, while the ecotoxicological results showed the highest toxicity in hospital and landfill wastewater. Likewise, ecotoxicological results and ∑HQ values showed a rather poor correlation; instead, better correlations were obtained between ecotoxicological parameters and HQ values for some individual pharmaceuticals such as cephalexin and diphenhydramine. Findings from this study provide novel information on the occurrence of pharmaceuticals and the performance of WWTPs in the tropical region of Central America.

Ecotoxicological test based on inhibition of fungal laccase activity: Application to agrochemicals and the monitoring of pesticide degradation processes.

Ecotoxicological evaluations require the use of assays with several bioindicators from different trophic levels. Only a few ecotoxicological tests using fungi have been developed, reason why, detection of adverse effects from compounds that exert fungicide action may be overlooked. This work developed a toxicity test based on the inhibition of laccase enzymatic activity in the fungus Trametes versicolor. The test was applied to several fungicides and succeeded to determine inhibition values (half maximum effective concentration, EC50) for most of them (flusilazole, imazalil, pyrimethanil, tetraconazole), though a clear dose-response was not evident for others (thiabendazole, metalaxyl). The application on atrazine (herbicide), imidacloprid (insecticide) and oxytetracycline (antibiotic), proved the proposed test is suitable towards other agrochemicals. The test was also used to estimate the detoxification resulting from two different approaches employed in the removal of agrochemicals. (a) First, in the liquid-phase elimination by fungal biomass simultaneously removing atrazine, imazalil, tebuconazole and triadimenol, the test showed a significant decrease in toxicity by biodegradation (adsorption contribution to detoxification was negligible). (b) Second, a solid-phase biomixture (used for pesticide degradation from agricultural wastewater) partially removed atrazine, imazalil, metalaxyl and pyrimethanil after 33 d; nonetheless, this system could not reduce the toxicity of the matrix, and higher laccase inhibition was detected after the treatment. The design test increases the battery of available bioassays to determine the toxicity of agrochemicals, and provides an interesting tool to monitor biodegradation processes.

Impaired pesticide removal and detoxification by biomixtures during the simulated pesticide application cycle of a tropical agricultural system.

Biopurification systems (BPS) or biobeds have been developed to attenuate point-source contamination due to inappropriate pesticide handling or disposal of agricultural wastewaters. The biomixture used for this strategy should be able to remove different active ingredients but its efficiency can vary due to the constant load of pesticides from crop application programs. For that reason, the performance of biomixtures in conditions that mimic the real pesticide treatment before their implementation in field settings should be assayed. This study aimed to evaluate the removal and detoxifying capacity of a previously formulated biomixture (coconut fiber, 50% v/v; compost, 25%; and soil pre-exposed to pesticides, 25%) during a simulated cycle of pesticide application (93 days) for potato production. The scheme included a first application of linuron followed by a weekly alternated treatment of the mixtures chlorpyrifos/metalaxyl and malathion/dimethomorph, and antibiotics at day 72. The biomixture showed efficient removal of linuron (half-life <15 days), and a fluctuating transformation rate for the other compounds. A constant and sustained removal was observed for malathion and methalaxyl. In contrast, lower efficiency and accumulation was described for chlorpyrifos and dimethomorph. Following antibiotic treatment, changes on pesticide removal were observed only in the case of chlorpyrifos, whose removal was slightly enhanced. Furthermore, acute toxicity assays showed limited detoxification of the matrix, especially when compounds began to accumulate. Summarizing, our experiments showed that the proposed biomixture does not support a proper removal of the pesticides during the simulated application cycle of potato production. Further optimization of a biopurification system is required to guarantee the successful elimination of pesticide combinations when applied in field conditions.

Simultaneous removal of neonicotinoid insecticides by a microbial degrading consortium: Detoxification at reactor scale.

Neonicotinoid insecticides show high persistence in the environment, and standard biological approaches such as biopurification systems have shown mostly inefficient removal of such compounds. In this work, soil pre-exposed to imidacloprid was used to obtain presumptive imidacloprid-degrading consortia. Cometabolic enrichment yielded a microbial consortium composed of eight bacterial and one yeast strains, capable of degrading not only this compound, but also thiamethoxam and acetamiprid, as demonstrated in cross-degradation assays. The biological removal process was scaled-up to batch stirred tank bioreactors (STBR); this configuration was able to simultaneously remove mixtures of imidacloprid + thiamethoxam or imidacloprid + thiamethoxam + acetamiprid, reaching elimination of 95.8% and 94.4% of total neonicotinoids, respectively. Removal rates in the bioreactors followed the pattern imidacloprid > acetamiprid > thiamethoxam, including >99% elimination of imidacloprid in 6 d and 17 d (binary and ternary mixtures, respectively). A comprehensive evaluation of the detoxification in the STBR was performed using different biomarkers: seed germination (Lactuca sativa), bioluminescence inhibition (Vibrio fischeri), and acute oral tests in honeybees. Overall, ecotoxicological tests revealed partial detoxification of the matrix, with clearer detoxification patterns in the binary mixture. This biological approach represents a promising option for the removal of neonicotinoids from agricultural wastewater; however, optimization of the process should be performed before application in farms.

Removal of triazines, triazoles and organophophates in biomixtures and application of a biopurification system for the treatment of laboratory wastewaters.

Biopurification systems (BPS) have been barely explored for removing complex mixtures of pesticides. In this study, the potential of a biomixture to remove simultaneously a mixture of herbicides (triazines), fungicides (triazoles) and insecticides (organophosphates) is presented. Also, a BPS using the same biomixture was used for treating a pesticide testing laboratory wastewater containing a mixture of 38 compounds. Ecotoxicological assays were conducted on the BPS elutriates to investigate the mixture detoxification. A mixture (concentrations of 4-8 mg kg-1) run in small-scale biomixture systems (SSB) for 128 d showed 59.3% removal of triazines, 68.5% of organophosphates and no elimination of triazoles. The treatment of the laboratory wastewater (individual concentrations range: 0.0036-0.25 mg kg-1) in the pilot-scale BPS for 281 d resulted in the elimination pattern of organophosphates (90.0%) > triazoles (73.4%) > carbamates (71.3%) > triazines (54.3%). Complete detoxification towards Daphnia magna and partial detoxification in Lactuca sativa seeds germination occurred in the BPS. Although the pesticide mixture complexity is higher in the BPS, the lower concentrations found in this matrix, could explain removal differences between SSB and BPS and the apparent inhibition in the elimination of carbamates and some triazines observed in the latter. These findings suggest that disposal of pesticide-containing laboratory-wastewater should be done in separate containers, according to chemical groups before their treatment in separate BPS, in order to reduce treatment periods. Monitoring the treatment process in the BPS with a battery of ecotoxicological tests is strongly recommended.

Removal of Two Neonicotinoid Insecticides and Mineralization of 14C-Imidacloprid in Biomixtures.

Environmental contamination with neonicotinoid insecticides represents an issue of wide concern due to their negative effects on pollinators. The goal of this work was to evaluate the potential use of biomixtures employed in biopurification systems (BPS) to remove two neonicotinoid pesticides, imidacloprid and thiamethoxam, from wastewater of agricultural origin. The removal was assayed by quantification of the parent compounds and the detection of putative transformation products of imidacloprid by means of LC-MS/MS, and mineralization of radiolabeled imidacloprid. Two biomixtures (B1, B2) were prepared using coconut fiber, compost and two soils pre-exposed to imidacloprid (volumetric composition 50:25:25). After spiking of neonicotinoids and 228 days of treatment, the removal ranged from 22.3%-30.3% and 38.6%-43.7% for imidacloprid and thiamethoxam, respectively. Transformation products imidacloprid-urea, desnitro-imidacloprid and desnitro-olefin-imidacloprid were detected in both biomixtures. The mineralization of 14C-imidacloprid revealed DT50 (mineralization half-lives) values of 3466 and 7702 days in the biomixtures B1 and B2, respectively, markedly lower than those in the soil used in their preparation (8667 and 9902 days, respectively). As demonstrated by these findings, the high persistence of these compounds in the BPS suggests that additional biological (or physicochemical) approaches should be explored in order to decrease the impact of neonicotinoid-containing wastewater of agricultural origin.

Pesticide monitoring and ecotoxicological risk assessment in surface water bodies and sediments of a tropical agro-ecosystem.

A pesticide monitoring study including 80 and 60 active ingredients (in surface waters and sediments, respectively) was carried out in a river basin in Costa Rica during 2007-2012. A special emphasis was given on the exceptional ecological conditions of the tropical agro-ecosystem and the pesticide application strategies in order to establish a reliable monitoring network. A total of 135 water samples and 129 sediment samples were collected and analyzed. Long-term aquatic ecotoxicological risk assessment based on risk quotient in three trophic levels was conducted. Short-term risk assessment was used to calculate the toxic unit and prioritization of sampling sites was conducted by the sum of toxic units in both aquatic and sediment compartments. Dimethoate (61.2 µg/L), propanil (30.6 µg/L), diuron (22.8 µg/L) and terbutryn (4.8 µg/L) were detected at the highest concentrations in water samples. Carbendazim and endosulfan were the most frequently detected pesticides in water and sediment samples, respectively. Triazophos (491 µg/kg), cypermethrin (71.5 µg/kg), permethrin (47.8 µg/kg), terbutryn (38.7 µg/kg), chlorpyrifos (18.2 µg/kg) and diuron (11.75 µg/kg) were detected at the highest concentrations in sediment samples. The pesticides carbendazim, diuron, endosulfan, epoxyconazole, propanil, triazophos and terbutryn showed non-acceptable risk even when a conservative scenario was considered. Sum TUsite higher than 1 was found for one and two sampling sites in water and sediment compartments, respectively, suggesting high acute toxicity for the ecosystem. MAIN FINDING OF THE WORK: Exceptional ecological conditions of the tropical agro-ecosystem affect the fate of pesticides in water and sediment environment differently than the temperate one.

Removal of herbicides in a biopurification system is not negatively affected by oxytetracycline or fungally pretreated oxytetracycline.

The disposal of agricultural antibiotic-containing wastewater in biopurification systems (BPS) employed in the treatment of pesticides, may negatively affect the removal capacity of these devices. This work aimed to employ a fungal pretreatment of oxytetracycline (OTC)-rich wastewater, before its disposal in a BPS used for the treatment of two pesticides. The fungal treatment at reactor scale (stirred tank reactor, 3L) with biomass of Trametes versicolor efficiently removed 100 mg L-1 OTC in only 60 h. However, ecotoxicity tests on seed germination with Lactuca sativa revealed that antibiotic elimination did not correlate with a decrease in toxicity. After the pretreatment, treated OTC was discarded in biomixtures used for the elimination of the herbicides ametryn and terbutryn. The co-application of treated or untreated OTC did not inhibit the removal of the herbicides; moreover, in both cases their removal seemed to be slightly enhanced in the presence of OTC or its residues, with respect to antibiotic-free biomixtures. Estimated half-lives ranged from 28.4 to 34.8 d for ametryn, and 34.0-51.0 d for terbutryn. In addition, the biomixture was also able to remove OTC in the presence of the herbicides, with an estimated half-life of 38 d. Remarkably, the toxicity of the wastewater containing OTC or treated OTC was mostly eliminated after its disposal in the biomixture. Overall results suggest that, given the high efficiency of the biomixture, the fungal pretreatment of OTC-containing wastewater is not mandatory before its disposal in the BPS.