A retrospective study of pathologic findings in the Amazon and Orinoco river dolphin (Inia geoffrensis) in captivity.

River dolphins are especially susceptible to negative human impacts. For their conservation, attempts of relocation or procreation ex situ may become important in the future to avoid their extinction. Additional knowledge and medical experiences of river dolphin management in captivity may aid such conservation efforts. The medical records and necropsy and histopathology reports on 123 captive Amazon River dolphins (Inia geoffrensis) were re-viewed. Of these 123 animals, 105 were necropsied and 70 necropsies were supported with histopathology. Eighteen animals were not necropsied. Among wild-born animals, mortality was highest in the first 2 mo immediately postcapture and transport, accounting for 32 of 123 deaths. Pneumonia and skin lesions (cutaneous and subcutaneous ulcerations and abscesses) were the most common findings, found in 44 of 105 (42%) and 38 of 105 (36%) of gross diagnoses, respectively. At least 10 of 44 cases of pneumonia diagnosed grossly included a verminous component. Cachexia, from a variety of causes, was a major gross finding in 21 animals. Fifteen animals had histologic evidence of significant renal pathology, and this was the primary cause of death in 13 cases. Hepatic pathology was found in 18 cases, and bacterial sepsis was confirmed via histology in 16 cases. Based on these findings, it may be concluded that keys to successful maintenance of this species include 1) prophylactic anthelminthic and antibiotic therapy immediately post-capture; 2) maintenance of animals in larger enclosures than in past attempts, in compatible groups, and in facilities capable of separating aggressive animals; 3) maintenance in microbiologically hygienic water quality at all times; and 4) a proactive program of preventive medicine during the immediate postcapture, quarantine, and maintenance period of captivity.     

Nutrient Loading by Precipitation in the Maracaibo Lake Basin, Venezuela

Nutrient content and pH of rain samples collected at nine sites during 1988-1996 were studied to determine the amounts of N, P and S added by precipitation over Maracaibo Lake basin. The basin is a wide depression occupied by Lake Maracaibo and extensive alluvial plains and delimited by a mountainous zone of variable physiolgraphic characteristics with different cattle ranching and industrial activities. Rain pHs averaged ≈ 4 to 6, individual samples occasionally reached as low as pH 3 in the south basin. NH₄ ⁺ levels were significantly higher (up to 2.6 mg/l NH₄-N) than NO₃ ^? plus NO₂ ^?. Phosphorus levels were low, ranging from undetectable to 1.5 mg/l. The amounts of inorganic N/ha/yr added ranged from ≈ 5.4 Kg in the north to ≈ 8 Kg in the south basin; around the lakeshore, it was estimated that ≈ 9.8–16.8 Kg TN/ha (≈ 55 % as organic-N) are annually deposited. The annual amounts of SO₄-S/ha added range from ≈ 10 to 13 Kg. The contribution of precipitation to P in the ecosystem is very small; ≈ 0.02 – 0.8 Kg of PO₄-P/ha/yr was added in basin. The results of this study show that precipitation represents a significant factor for the total nitrogen and sulfur loading to Maracaibo Lake Basin.     

Reduced metribuzin pollution with phosphatidylcholine-clay formulations

BACKGROUND: Metribuzin is a widely used herbicide that has been identified as a groundwater contaminant. In this study, slow‐release formulations of metribuzin were designed by encapsulating the active ingredient in phosphatidylcholine (PC) vesicles and adsorbing the vesicles onto montmorillonite. RESULTS: The maximum active ingredient content in the slow‐release formulations was 246 g kg^?1. Infrared spectroscopy results revealed that the hydrophobic interactions between metribuzin and the alkyl chains on PC were necessary for encapsulation. In addition, water bridges connecting the herbicide and the PC headgroup enhanced the solubility of metribuzin in PC. Adsorption experiments in soils were performed to evaluate the relationship between sorption and leaching. Funnel experiments in a sandy soil revealed that the herbicide was not irreversibly retained in the formulation matrix. In soil column experiments, PC–clay formulations enhanced herbicide accumulation and biological activity in the top soil layer relative to a commercial formulation. PC–clay formulations also reduced the dissipation of metribuzin by a factor of 1.6–2.5. CONCLUSIONS: A reduction in the recommended dose of metribuzin can be achieved by employing PC–clay formulations, which reduces the environmental risk associated with herbicide applications. Moreover, PC and montmorillonite are non‐toxic and do not negatively affect the environment. Copyright © 2010 Society of Chemical Industry     

Improvement of the desorption of the herbicide norflurazon from soils via complexation with beta-cyclodextrin

The effect of beta-cyclodextrin (beta-CD) on the removal of the herbicide norflurazon (NFL) from soils has been investigated. The interaction of NFL with beta-CD in solution yielded the formation of a water-soluble inclusion complex at 1:1 stoichiometric ratio, which gave an increase in NFL solubility. Desorption studies of NFL previously adsorbed on six soils of different characteristics have been performed in the presence of 0.01 M beta-CD or 0.01 M Ca(NO(3))(2) as extractant solutions. Positive hysteresis was observed in all soils when 0.01 M Ca(NO(3))(2) solution was used, indicating that desorption of NFL from these soils was not completely reversible. On the contrary, the application of beta-CD solutions to soils where NFL had been previously adsorbed increased very much its desorption, and a negative hysteresis was obtained for all soils studied; that is, more NFL was desorbed with respect to NFL adsorption isotherm. A clear relationship was observed between the physicochemical characteristics of the soils and the beta-CD concentration necessary to remove the herbicide, the percentages of desorption observed for each soil being inversely related to the values obtained for the Freundlich sorption capacity parameter of the herbicide, K(f). In general, high desorption yields can be obtained with very low beta-CD concentrations, which is an important advantage from an economic point of view, although in those soils that present an extremely high NFL adsorption, higher amounts of beta-CD should be used. The results obtained indicate the high extracting power of beta-CD toward the herbicide previously adsorbed on the soils and the potential use of beta-CD for in situ remediation of pesticide-contaminated soils.     

Effect of organic amendments on the retention and mobility of imazaquin in soils

The influence of two organic amendments consisting of an urban waste compost (SUW) and a commercial amendment from olive mill wastes (OW) was assessed on the sorption properties and leaching of the ionizable herbicide imazaquin on four soils with different physicochemical characteristics. A loamy sand soil (CR), a loam soil (P44), a silt loam soil (AL), and a clay soil (TM), with low-medium organic matter contents, were chosen. Sorption-desorption experiments were performed on the original soils and on a mixture of these soils with the organic amendments at a rate of 6.25% (w/w). These mixtures were used just after preparation and after aging for 3 months. Imazaquin adsorption was higher on AL soil because of its high content of amorphous iron oxides, whereas it was related to the soils' organic matter (OM) contents on TM and CR soils and to acid pH on P44 soil. Addition of exogenous OM to soils caused a decrease in the adsorption of the herbicide with the only exception of CR soil, due to blocking of adsorptive surfaces and/or equilibrium pH rise. The extent of this decrease was dependent only on the nature of the added amendment on AL soil. The adsorbed amounts of imazaquin on aged organic fertilized soils were usually fairly close to that on original soils. Results of soil column experiments indicate that addition of exogenous organic matter cannot be considered as a regular practice for retarded movement of imazaquin.     

An Estimation of the Nitrogen and Phosphorus Loading by Wet Deposition over Lake Maracaibo,Venezuela

In order to make an estimation of thewet deposition levels of the major nitrogen compoundsin Lake Maracaibo system, the precipitation wascollected by events at five sites located on shorearound the Lake from 1991 to 1994. Also the phosphorusconcentrations were determined in rain samples. RainpHs averaged about 5 to 6. NH₄ ⁺ levels weresignificantly higher (up to 1.44 mg L^-1NH₄-N) than NO₃ ^-plus NO₂ ^-ions which resulted in the highest pHs values in thestrait Maracaibo. The strait is the nearest zone toAmmonia Plant located upwind at the TablazoPetrochemical Complex. At the strait, theinorganic-nitrogen ((NH₄ + NO₃ +NO₂)-N) concentrations were greater than organicnitrogen levels, but at the other sites were lower.Phosphorus levels were low, ranging from undetectableto 1.5 mg L^-1; organic-P was estimated to accountfor about 40% of total-P. Total mean nitrogen wetdepositions were 6.93 kg ha^-1 yr^-1 (≈59% asNH₄-N) at the strait and 9.85–16.84 kg ha^-1yr^-1 (≈55% as organic-N) around the lakeshore.Inorganic and organic nitrogen account for about equalportions of the total nitrogen loading. These amountsrepresents ≈24% of the annual total-N inputsby the tributary rivers to the lake and aresubstantially higher than those reported in the shoreof Lake Valencia (north-central part of Venezuela) andother tropical areas. The contribution ofprecipitation to P in lake is very small; ≈0.6 kg ha^-1 of total-P are added annually. The N and Pinputs were greater than the sewage contributions. Themean molar ratio N/P is ≈22 at the straitsite whilst at lake sites the N/P ratio isconsistently >22 (about 35～1 to 100～1). The results of this preliminary study show that the atmosphere represents a significant factor for the total nitrogen loading to Lake Maracaibo system.     

Preparation and characterization of inclusion complex of norflurazon and beta-cyclodextrin to improve herbicide formulations

The formulation of inclusion complexes of the herbicide norflurazon as guest and beta-cyclodextrin (beta-CD) as host has been studied as a first step in the use of cyclodextrins to obtain improved formulations of this herbicide. The interaction of norflurazon with beta-CD produced the formation of an inclusion complex in solution and in solid state. The inclusion of norflurazon in beta-CD in solution was studied by phase solubility, and an apparent stability constant of 360 M(-)(1), a 1:1 stoichiometric ratio for the complex, and up to 5-fold increase in norflurazon solubility were determined. Three processing methods (kneading, spray drying and vacuum evaporation) were used to prepare norflurazon-beta-CD solid inclusion complexes. X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy techniques were used to study the solid complexes. From the different solid systems, an increase of norflurazon aqueous dissolution rate was obtained in comparison to the uncomplexed herbicide. This finding is a first step to obtain controlled release and/or protective formulations of norflurazon, which allow a more rational application of norflurazon, diminishing the use of organic solvents and increasing its efficacy.     

FTIR study of glyphosate-copper complexes

Complexes of the herbicide glyphosate (GPS) and the heavy metal Cu were studied by infrared spectroscopy under controlled pH, in order to know the mechanisms involved in the formation of these complexes. In CuGPS(-), the IR spectrum shows participation of the carboxylate and phosphonic moieties of the GPS molecule. The formation of the complex produces a lower symmetry in the phosphonate group because of loss of the resonance situation of PO(3)(2)(-) groups, with a subsequent split of their absorption bands. Carboxylate groups are participating by forming unidentate complexes. No conclusion is reached about the involvement of the amino group, but previous EPR findings indicate coordination of GPS to Cu via nitrogen. Consequently, glyphosate in this complex functions with a tridentate character by forming two chelate rings. A study of the CuGPSH species was not possible due to overlapping of its absorption bands with those of free GPS species.     

Mineral contents of the muscle tissue and the digestive gland of Octopus vulgaris during short‐term starvation

We used spectrometry to study variation in the contents of minor (B, Cu, Fe, Mn and Zn) and major essential elements (Ca, K, Mg, Na and P) in the muscle tissue and digestive glands of Octopus vulgaris after 1, 2, 4 or 8 days of starvation and in fed controls. The contents of the major essential elements remained constant during 8 days of starvation. Na was the principal element found in both tissues, followed by K, P and Mg. The contents of the minor essential elements were higher in the digestive gland than in the muscle tissue, with increased contents of Fe, Mn and Zn (p < .05) during starvation, confirming the high capacity of this organ to accumulate trace minerals. In muscle tissues, B, Fe and Mn contents were lower and Cu and Zn contents higher, in starved animals than in fed animals (p < .05). Significant negative correlations between the digestive gland index and the contents of Cu, Fe and Zn suggested that the loss of weight of the digestive gland during starvation is responsible for this increase in mineral concentration. This and further information on variation in mineral content will help to optimize performance of diets formulated for the octopus.