Bioethanol production using high density Eucalyptus crops in Uruguay.

Experimental scale crops for Eucalyptus grandis, Eucalyptus benthamii, Eucalyptus dunnii and Eucalyptus tereticornis, at 2,220, 4,440 and 6,660 trees ha-1 were established in two soil units, at Paysandú and Tacuarembó, Uruguay. Wood samples were taken from twenty-two-months-old trees, and were used to produce bioethanol by pre-hydrolysis simultaneous saccharyfication and fermentation process (PSSF). Cellulose and lignin content was analyzed. Species and planting density affected biomass production at both sites; the highest value was obtained with E. dunnii at 6,660 trees ha-1 at Paysandú. Cellulose content of wood varied between species at both sites, but only between planting densities at Tacuarembó. The site effect showed that the highest amount of cellulose (14.7 Mg ha-1) was produced at Paysandú. E. benthamii and E. tereticornis wood showed higher lignin contents, conversely, the PSSF yields showed no differences, which led to a bioethanol average of 97 L Mg-1. Bioethanol productivity was associated to the biomass productivity. It was possible to obtain 2,650 L ha-1 of bioethanol using wood from E. benthamii, E. dunnii and E. grandis at 4,440 and 6,660 trees ha-1 at Paysandú, and with E. benthamii at 4,440 and 6,660 trees ha-1, and E. dunnii at 6,660 trees ha-1 at Tacuarembó.

Relevant factors in the eutrophication of the Uruguay River and the Río Negro.

In recent decades, there has been increasing eutrophication of rivers and lagoons in Uruguay and solutions leading to water purification are being sought. The growing pollution has been attributed to nitrogen and phosphorus compounds exported from the river basins with intensification of agricultural production and the absence of tertiary treatment for urban and industrial effluents. Although nitrogen and phosphorus are relevant to eutrophication, there are also other factors that can promote eutrophication and algal blooms. This paper reports a broad analysis of water quality variables recorded over 9 years (2009-2018) at 17 sampling stations on the Uruguay River and 16 sampling stations on the Río Negro, and explores their relationship with the changes of chlorophyll a (Chl-a) concentrations using a generalized linear model and a neural network simulation (NNS). The input variables were total phosphorus; total suspended solids; electrical conductivity of water (ECw); alkalinity; water temperature (T); water pH (pH) and sampling month. The NNS explained 79% of Chl-a variations and showed the most relevant variables to be T, ECw, and pH. Moreover, the NNS showed that replacement of current land uses by natural prairie would not significantly reduce Chl-a concentrations. The results showed that the main factors that drive Chl-a concentrations (i.e., algae) are not directly linked to agriculture land use.

Corrigendum: Dairy Calves in Uruguay Are Reservoirs of Zoonotic Subtypes of Cryptosporidium parvum and Pose a Potential Risk of Surface Water Contamination.

[This corrects the article DOI: 10.3389/fvets.2020.00562.].

Dairy Calves in Uruguay Are Reservoirs of Zoonotic Subtypes of Cryptosporidium parvum and Pose a Potential Risk of Surface Water Contamination.

Cryptosporidium parvum, a major cause of diarrhea in calves, is of concern given its zoonotic potential. Numerous outbreaks of human cryptosporidiosis caused by C. parvum genetic subtypes are reported yearly worldwide, with livestock or water being frequently identified sources of infection. Although cryptosporidiosis has been reported from human patients in Uruguay, particularly children, epidemiologic information is scant and the role of cattle as reservoirs of zoonotic subtypes of C. parvum has not been explored. In this study, we aimed to (a)-identify C. parvum subtypes infecting dairy calves in Uruguay (including potentially zoonotic subtypes), (b)-assess their association with calf diarrhea, (c)-evaluate their spatial clustering, and (d)-assess the distance of infected calves to surface watercourses draining the farmlands and determine whether these watercourses flow into public water treatment plants. Feces of 255 calves that had tested positive for Cryptosporidium spp. by antigen ELISA were selected. Samples had been collected from 29 dairy farms in seven Uruguayan departments where dairy farming is concentrated and represented 170 diarrheic and 85 non-diarrheic calves. Selected samples were processed by nested PCRs targeting the 18S rRNA and gp60 genes followed by sequencing to identify C. parvum subtypes. Of seven C. parvum subtypes detected in 166 calves, five (identified in 143 calves on 28/29 farms) had been identified in humans elsewhere and have zoonotic potential. Subtype IIaA15G2R1 was the most frequent (53.6%; 89/166), followed by IIaA20G1R1 (24.1%; 40/166), IIaA22G1R1 (11.4%; 19/166), IIaA23G1R1 (3.6%; 6/166), IIaA17G2R1 (3%; 5/166), IIaA21G1R1 (2.4%; 4/166), and IIaA16G1R1 (1.8%; 3/166). There were no significant differences in the proportions of diarrheic and non-diarrheic calves infected with any of the C. parvum subtypes. Two spatial clusters were detected, one of which overlapped with Uruguay's capital city and its main water treatment plant (Aguas Corrientes), harvesting surface water to supply ~1,700,000 people. Infected calves on all farms were within 20-900 m of a natural surface watercourse draining the farmland, 10 of which flowed into six water treatment plants located 9-108 km downstream. Four watercourses flowed downstream into Aguas Corrientes. Calves are reservoirs of zoonotic C. parvum subtypes in Uruguay and pose a public health risk.

Agricultural pesticides and veterinary substances in Uruguayan beeswax.

Over the last decade, Uruguay has expanded and intensified its rainfed crop production. This process has affected beekeeping in several ways: for example, by reducing the space available. This has increased the density of apiaries, the risk of varroosis and acaricide use. Additionally, the dominance of no-tillage crops has increased the frequencies of application and of loads of pesticides in regions where such crops share the land with beekeeping and honey production. Therefore, the exposure of bees to xenobiotics (agricultural pesticides and veterinary products) has increased in line with pollution of hives and their products. To document pollution from hive exposure to pesticides, we surveyed the presence of 30 xenobiotics normally used in Uruguay, in recycled beeswax (RB) and in honey cappings (HC) from the main Uruguayan beekeeping regions. There was contamination of all the analyzed samples (RB and HC) with the herbicide atrazine at a range of 1-2 ng g-1. At least three or four additional xenobiotics were detected: insecticides (chlorpyrifos-ethyl and thiacloprid); fungicides (azoxystrobin and tebuconazole); and veterinary products (coumaphos, ethion, and tau-fluvalinate). The frequency of detection of chlorpyrifos-ethyl and coumaphos in RB samples was higher than in those of HC. Moreover, the concentrations of azoxystrobin, coumaphos, and tebuconazole in RB samples were higher than in HC samples. Therefore, we suggest the use of HC to produce recycled printed beeswax films for use in hives to minimize pollution transfer.

Neonicotinoids transference from the field to the hive by honey bees: Towards a pesticide residues biomonitor.

The beehive as a quantitative monitor of pesticide residues applied over a soybean crop was studied through a semi field experiment of controlled exposure of honey bees to pesticides in macro tunnels. The distribution within exposed beehives of pesticides commonly used in soybean plantation, was assessed. Residue levels of insecticides in soybean leaves, honey bees, wax, honey and pollen were analyzed. The transference from pesticides present in the environment into the beehive was evidenced. The obtained results allow relating pesticide concentrations present in the environment with traces found in foraging bees. Therefore, pesticide transference ratios could be calculated for each detected compound (acetamiprid, imidacloprid and thiamethoxam) which showed a linear inverse trend with their 1-octanol/water partition coefficient (Kow). The least transferred pesticide to the hive (acetamiprid) has the highest vapor pressure (Vp). This study gives new insights on the usefulness of monitoring the environment through beehives aiming to evaluate if agroecosystems remain sustainable. It also contributes to generate valuable information for model building aiming to predict environmental quality through beehive's analysis.

Screening of endocrine disruption activity in sediments from the Uruguay River.

Sediment constitutes an important sink of endocrine disruptor compounds; however, the potential of sediments to act as a source of endocrine disruptors should be more extensively investigated. The main objective of this study was to determine whether exposure of immature common carp to Uruguay River sediments undergo physiological and endocrine alterations. The lower Uruguay River watershed supports intensive agricultural and forest production, receives municipal sewage discharge and industrial effluent, and a new large pulp mill was constructed in 2006. A 30-day semi-static assay was performed using sediments from four sites along the Uruguay River and compared with an unexposed group in dechlorinated water as a negative control. We focused on two upstream and two downstream sites of a new elemental chlorine free pulp mill. The results showed that plasma vitellogenin levels increased in fish along the river and significant differences were found between the exposed and unexposed groups. Condition factor and gonadosomatic index were not different; however, a significant difference in hepatosomatic index was observed in fish exposed to sediment from an industrial site. A significant reduction in primary spermatocyte accumulation was observed in the exposed group compared with that in the control group, and some individuals exposed to sediments from industrial sites presented with testis-ova. Our results suggest that Uruguay River sediments act as an important source of estrogenic compounds that could be responsible for the alterations observed. Future studies are needed to identify the causal agents and determine exposure routes.

Acute contact toxicity test of insecticides (Cipermetrina 25, Lorsban 48E, Thionex 35) on honeybees in the southwestern zone of Uruguay.

Glyphosate-resistant soybean cultivation is expanding rapidly in Uruguay, with its land area having increased by 95 times during the past 10 years. Because of the region's Neotropical conditions, insecticide use is required to ensure adequate soybean productivity. However, in areas shared by soybean crops and beekeepers - such as the southwestern zone of Uruguay (SWZU) - the use of insecticides can increase the risks of honeybee death and honey contamination. Uruguayan commercial and legal guidelines set out practices and field doses designed to prevent acute intoxication with insecticides. However, honeybees in the SWZU are predominantly a polyhybrid subspecies different from that used to set international reference values, and hence they may have a different acute toxicity response, thus rendering such precautions ineffective. The aim of this work was to assess the acute toxicity response of polyhybrid honeybees in the SWZU to cypermethrin (commercial formulation: Cipermetrina 25 Agrin®), chlorpyrifos (commercial formulation: Lorsban 48E®), and endosulfan (commercial formulation: Thionex 35®). Acute toxicity bioassays were conducted to determine the median lethal dose (LD(50)) of each insecticide for the honeybees. The results indicate that, compared with EU reference values, SWZU honeybees have a higher toxicological sensitivity to chlorpyrifos and endosulfan, and a lower toxicological sensitivity to cypermethrin, based on the commercial formulations tested. However, when these results were adjusted according to their field dose equivalents, only chlorpyrifos emerged as a potential problem for beekeeping, as the maximum recommended field dose of Lorsban 48E® for soybean crops in Uruguay is 23 times the corresponding LD(50) for honeybees in the SWZU.

Detection of pesticides in active and depopulated beehives in Uruguay.

The influence of insecticides commonly used for agricultural purposes on beehive depopulation in Uruguay was investigated. Honeycombs, bees, honey and propolis from depopulated hives were analyzed for pesticide residues, whereas from active beehives only honey and propolis were evaluated. A total of 37 samples were analyzed, representing 14,800 beehives. In depopulated beehives only imidacloprid and fipronil were detected and in active beehives endosulfan, coumaphos, cypermethrin, ethion and chlorpyrifos were found. Coumaphos was present in the highest concentrations, around 1,000 µg/kg, in all the propolis samples from active beehives. Regarding depopulated beehives, the mean levels of imidacloprid found in honeycomb (377 µg/kg, Standard Deviation: 118) and propolis (60 µg/kg, Standard Deviation: 57) are higher than those described to produce bee disorientation and fipronil levels detected in bees (150 and 170 µg/kg) are toxic per se. The other insecticides found can affect the global fitness of the bees causing weakness and a decrease in their overall productivity. These preliminary results suggest that bees exposed to pesticides or its residues can lead them in different ways to the beehive.

Preliminary field study of hepatic porphyrin profiles of Astyanax fasciatus (Teleostei, Characiformes) to define anthropogenic pollution.

The implementation of eco-toxicological assessment in South America is presently limited due to significant scientific information gaps concerning native species and their potential use as biomarkers. Recently, a common southern hemisphere fish species, Astyanax fasciatus, has been pointed out as a potential bio-indicator to anthropogenic pollution. This is a small, abundant, Neotropical characid, which is widely distributed from Central America south, to the Rio de la Plata Basin of western Uruguay. Our study found a statistically significant increase of coproporphyrin, uroporphyrin and protoporphyrin concentrations in hepatic tissues of A. fasciatus collected from a stream segment with high anthropogenic disturbance (due mainly to agricultural derivatives and motor vehicle transportation activities). Although the area studied showed differences in up and downstream limno-chemical parameters, these differences were not related to the increase of hepatic porphyrin concentrations. Based on the results of our study, we conclude that A. fasciatus is a good bio-indicator of exposure to environmental contaminants, and we propose that this abundant fish species be considered as a sentinel organism for monitoring potential disturbances to freshwater ecosystems.