Clomazone exposure-driven photosynthetic responses plasticity of Pontederia crassipes.

Clomazone is known to contaminate aquatic environments and have a negative impact on macrophytes. However, recent reports suggests that Pontederia crassipes Mart. can withstand clomazone exposure while maintaining growth rates. We hypothesized that this maintenance of growth is supported by photosynthetic plasticity of old leaves (developed before herbicide application), while new leaves (developed after application) exhibit phytotoxic symptoms. To investigate, two experiments were conducted with doses ranging from 0.1 mg L-1 to 0.5 mg L-1 plus untreated controls. Various parameters were measured in old and new leaves over 7, 12, and 15 d post-application, including visual symptoms, chlorophyll index, photosynthetic pigments, chlorophyll fluorescence, gas exchange, glycolate oxidase activity, carbohydrate content, leaf epidermis anatomy, and growth parameters. Clomazone exposure induced chlorosis, particularly in new leaves across all doses. These visual symptoms were accompanied by stomatal closure, restricting gas exchange and CO2 fixation, leading to reduced photosynthetic rates and carbohydrate synthesis. However, clomazone did not affect old leaves, which maintained photosynthetic activity, sustaining essential metabolic processes of the plant, including reproductive functions. By ensuring high reproductive rates and metabolic continuity, old leaves supported the species' persistence despite clomazone presence.

Floating treatment wetlands with Canna indica for the removal of Cr(III) and Cr(VI) from water: A comprehensive study.

The efficiency in Cr (III) and Cr (VI) removal by Floating Treatment Wetlands (FTWs) vegetated with Canna indica, metal accumulation in sediment and plants were determined. Plant tolerance and its morphological response to metal were studied. Treatments were 5 and 10 mg L-1 of Cr(III) (5Cr(III) and 10Cr(III), respectively), and 5 and 10 mg L-1 of Cr(VI) (5Cr(VI) and 10Cr(VI), respectively), with and without FTWs, and a biological control (BC: with FTW without Cr addition). After 35 days, Total-Cr removals in treatments with FTW were 99.6 %, 96.9 %, 96.9 % and 81.7 % in 5Cr(III), 10Cr(III), 5Cr(VI) and 10Cr(VI), respectively. In Cr (III) treatments, the sediment from the reactors without FTW accumulated significantly more metal than the sediments with FTW, while the opposite occurred in the Cr(VI) treatments. Chromium in sediment was accumulated mainly bound to organic matter in all treatments (38-64 %). Roots of C. indica were the main Cr accumulator organ in all treatments (76-88 %). In 10Cr(VI) treatment, Cr was translocated to aerial parts resulting in a decrease in plant biomass and Chlorophyll a concentration. C. indica modified its internal and external root morphology as a mechanism to tolerate Cr toxicity, without affecting removal efficiencies. FTWs vegetated with C. indica were efficient in the remediation of water bodies contaminated with Cr. In addition, these systems have an aesthetic value because they use an ornamental species.

Efecto del pulso de inundación sobre el ensamble de ostrácodos (Ostracoda: Podocopida) en microambientes en la Ciénaga Río Viejo, Colombia / Effect of the flood pulse on the ostracod assemblage (Ostracoda: Podocopida) in microenvironments in the Ciénaga Río Viejo, Colombia

Resumen Introducción: Las ciénagas hacen parte de la llanura de inundación de un río y son influenciadas por el pulso de inundación, fuerza que modula los cambios anuales en las variables bióticas y abióticas. Los ensambles biológicos tienen diferentes respuestas a este pulso y podrían presentar cambios en la composición y abundancia. Objetivo: Evaluar cómo se modifican las condiciones físico-químicas en los microambientes de vegetación flotante y el ensamble de ostrácodos a lo largo de un pulso de inundación en la Ciénaga Río Viejo, Santander, Colombia. Métodos: Se caracterizaron las variables físico-químicas de los microambientes de plantas acuáticas flotantes durante las cuatro fases hidrológicas del pulso de inundación: aguas bajas, altas, ascenso y descenso, en tres estaciones donde el pulso tuvo mayor efecto. Ostrácodos dulceacuícolas fueron recolectados de estos microambientes, identificados y contados. Resultados: Las condiciones ambientales dentro de los microhábitats fluctuaron siguiendo el pulso de inundación en el sistema. Se encontraron tres familias taxonómicas y seis especies de ostrácodos. No hubo diferencias en la composición y abundancia del ensamble de ostrácodos en el espacio y el tiempo, lo que sugiere que están protegidas contra los cambios ambientales causados por las fluctuaciones hidrológicas. La abundancia de especies cambió en respuesta a la variabilidad ambiental. Strandesia cf. sphaeroidea y Keysercypria sp. 2 están asociadas con aguas más someras y con mayor cobertura de vegetación acuática densa. Otras especies mostraron ser tolerantes a fluctuaciones hidrológicas y pueden estar relacionadas con la plasticidad ecológica, como Cytheridella ilosvayi, Diaphanocypris meridana y Stenocypris major, que han sido registradas en una variedad de ambientes acuáticos y con distribuciones a escala continental. Conclusiones: Los pulsos de inundación indujeron cambios ambientales en la Ciénaga de Río Viejo, pero los microhábitats con cobertura de vegetación flotante parecen estar protegidos contra el pulso hidrológico, permitiendo así que las comunidades de ostrácodos permanezcan casi sin alteraciones durante un pulso de inundación. Este conjunto de datos actualizado de agua dulce tropical contribuye a llenar los vacíos de conocimiento relacionados con la idoneidad del hábitat y la distribución de las comunidades de ostrácodos en Colombia.

Abstract Introduction: Swamps are lowland shallow tropical lakes in rivers floodplains, characterized by annual flood pulses that modulate changes in biotic and abiotic variables. Biological assemblages have different responses to flood pulses, remaining either undisturbed or with significant changes in composition and abundance. Objective: To evaluate how physical and chemical conditions are modified in mixed macrophytes microenvironments and ostracod species assemblages throughout a flood pulse in Rio Viejo swamp, Santander, Colombia. Methods: We characterized physical and chemical variables of microenvironments of aquatic floating plants, during four different hydrologic periods of the flood pulse: low, high, rising, and descending waters, at three stations where the flood pulse have the most important effect. Freshwater ostracods were collected from such microenvironments, identified, and counted. Results: Environmental conditions within microhabitats fluctuated following the flood pulse in the system. Three taxonomic families and six species of ostracods were observed. No differences in the composition and abundance of the spatio-temporal ostracod assemblages were observed, suggesting that they are buffered against environmental changes driven by hydrological fluctuations. Species abundance changed in response to environmental variability. Species such as Keysercypria sp. and Keysercypria sp. 2 are associated to shallower waters and more likely to dense aquatic vegetation cover. Other species showed to be more tolerant to hydrological fluctuations and may be related to ecological plasticity, species such as Cytheridella ilosvayi, Diaphanocypris meridana and Stenocypris major that have been recorded in a variety of aquatic environments and with distributions at continental scale. Conclusions: Flood pulses induced environmental changes in Rio Viejo Swamp, but microhabitats in mixed macrophyte cover seems to be buffered against the hydrological pulse, thus allowing almost undisturbed ostracod assemblages throughout a flood pulse. This updated tropical freshwater dataset contributes towards filling the knowledge gaps related to habitat suitability and distribution of ostracods communities in Colombia.

Egeria densa remediates the aquatic environment and reduces 14C-deltamethrin bioaccumulation in Danio rerio.

Deltamethrin is an insecticide with high toxicity to non-target aquatic organisms. Environment-friendly alternatives to removing insecticides from water bodies, like phytoremediation, require species to uptake and/or dissipate pesticides from water. Our research investigated the ability of Egeria densa plants to absorb and dissipate 14C-deltamethrin from water, and bioaccumulation in Danio rerio. The variables were four densities of E. densa (0, 234, 337, and 468 g dry weight m-3), in tanks with seven adults of D. rerio, with three replicates. Dissipation was evaluated at 0, 24, 48, 72, and 96 h after application (HAA). After 96 HAA, the uptake of 14C-deltamethrin by plants and accumulation in fish were assessed. The E. densa increased 14C-deltamethrin dissipation and reduced bioaccumulation in zebrafish. The DT50 decreased 3-fold in treatments with 337 and 468 g m-3 of E. densa. The plants absorbed 32% of the 14C-deltamethrin applied, regardless of plant density. The bioaccumulation in fish was 8.21% without E. densa and only 1% in treatments with 468 g m-3 of plants. These results suggest phytoremediation using E. densa is a possible alternative to removing deltamethrin from water and reducing the accumulation in non-target organisms, reducing the environmental impact of insecticides in aquatic ecosystems.

Elemental mercury accumulation in Eichhornia crassipes (Mart.) Solms-Laubach.

The aquatic macrophyte Eichhornia crassipes has great potential for the control of Hg pollution in the environment. The aim of this study was to investigate the capability of E. crassipes to accumulate elemental mercury (Hg0). The plants were exposed for 30 days to 5, 10, 20, 40, and 80 mg of Hg0 in a 1-L Hoagland medium with the Hg0 settled at the bottom of the flask. The roots of the plants did not touch the mercury during the treatment. After exposure, the total Hg (T-Hg) concentrations in the roots, leaves, and stems were measured using a direct mercury (Hg) analyzer. The highest concentrations were found at 80 mg Hg0 treatment in the roots, leaves, and stems, in that order. The translocation factor indicated a poor capability of Hg to translocate from the roots to the shoots. The relative growth and the root-length inhibition measurements showed that the differences between Hg0 treatments were not significant. In addition, the treatments negatively affected the chlorophyll concentration. The carotenoid content was found to be significantly different at 20 and 40 mg of Hg0 in 1 L. Regarding the carbonyl index in root proteins, significant differences compared to control were found at the highest Hg treatment. Based on these results, it was shown that E. crassipes is able to take up elemental Hg from Hoagland medium. However, the Hg0 treatments did not show a strong stress-response activation mechanism in the evaluated plant tissues.

Effects of dams on As and Hg concentrations in three southeastern Brazil fluvial systems: Ocean inputs, sources and seasonal dynamics among environmental compartments.

Damming rivers for hydropower generation interferes in the flow of water bodies and, consequently, in trace element biogeochemistry and transport. This study focused on the effects of dams on the seasonal dynamics of arsenic (As) and mercury (Hg) in three fluvial systems (Itabapoana River, Flechas Channel and Paraíba do Sul River) and on the input of these elements to the ocean. The elements were evaluated in suspended particulate matter (SPM), surface sediments, and the roots of the aquatic macrophyte Eichhornia crassipes. Our results showed that the proximity of the dams in the Flechas Channel and Rio Itabapoana in relation to their mouth (distances of 4 km and 58 km, respectively) changed As and Hg seasonal dynamics in the environmental compartments analyzed, with the Flechas Channel being the most impacted area. In contrast, the lower part of the Paraíba do Sul River that has more distant dams to its mouth (distance of 184 km) did not show such marked changes, suggesting that most of the inputs are coming from the long river reach. The isotopic and elemental composition of organic matter indicated the soils of native forests as the main source of trace elements to the water bodies. Flow rate was the main driver controlling As and Hg ocean inputs, with higher inputs observed in the Paraíba do Sul River (9.69 and 0.59 t∙year-1, respectively) compared to the other assessed fluvial systems. Also, this study demonstrated that, if a dam is closer to the mouth of a river, less contaminants will be input.

Low biological phosphorus removal from effluents treated by slow sand filters.

The legislation for environment protection requires strict controls of the wastewater releasing in water bodies. The wastewater treatment plants (WWTP) have been used for organic matter degradation; however, the residual total phosphorus (TP) removal has not been efficient. TP and nitrogen present in wastewater are associated to eutrophication of water bodies and algae growth. Therefore, this study discusses the efficiency of phosphorus removal by a slow filter (SF), complementary to a WWTP and the microbial community involved. The results showed that the use of SF, with or without macrophytes, is not suitable to remove TP. Spatial variation in microbial communities distributed in three distinct zones was identified in the SF. Proteobacteria, Bacteroidetes, Chloroflexi and Firmicutes covered the hydrolytic and fermentative bacteria. The acetogenesis, nitrification, and denitrification, as well as the removal of phosphorus from the effluent, were performed by representatives affiliated to different groups. Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria among these, Dokdonella sp., Frateuria sp., Comamonas sp., Diaphorobacter sp., Nitrosospira sp., Ferruginibacter sp., Flavobacterium sp., and the uncultured OD1 were the most abundant bacteria in the SF. The low efficiency for TP removing from SF effluents can be explained by the low abundance of phosphorus accumulating organisms (PAOs), with the association of the low concentration of biodegradable organic matter in the inlet effluent. Therefore, the alternative to using SF as a complement to WWTPs, as recommended by some Brazilian environmental agencies, did not prove to be viable and new approaches must be evaluated. KEY POINTS: • The phosphorus removal was performed by a slow filter system in a WWTP but obtained a low efficiency. • Microbial spatial variation was distributed into distinct zones from slow filter. • Low abundance of PAOs was observed due to the low availability of organic matter.

Isolated and combined effects of glyphosate and its by-product aminomethylphosphonic acid on the physiology and water remediation capacity of Salvinia molesta.

We evaluate the isolated and combined effects of glyphosate and its by-product aminomethylphosphonic acid (AMPA) and the potential of the aquatic macrophyte Salvinia molesta to remove these chemicals from contaminated water. Plants were exposed to environmentally relevant concentrations of glyphosate (0, 20, 40, 60, 80 and 100 µg l-1) or AMPA (0, 10, 20, 30, 40 and 50 µg l-1) for seven days. Then, based on the effective concentrations of glyphosate found to reduce photosynthetic rates by 10% (EC10) and 50% (EC50), the plants were exposed to combinations of 0, 16 and 63.5 µg glyphosate l-1 and 0, 5, 15, 25 µg AMPA l-1. The EC(10) and EC(50) were lower for AMPA (6.1 µg l-1 and 28.4 µg l-1 respectively) than for glyphosate (16 and 63.5 µg glyphosate l-1 respectively). When occurring together, the deleterious effects of those chemicals to plants increased. S. molesta plants removed up to 74.15% of glyphosate and 71.34% of AMPA from culture water. Due to its high removal efficiency, S. molesta can be used in phytoremediation programs. It will be important to evaluate the combined effects of glyphosate and AMPA in any toxicological studies of the herbicide.

Surfactant and temperature as forcing functions on the growth of Egeria densa and Chara sp.: a modeling approach.

The wide use of detergents combined with rising water temperature is currently issuing of environmental concern. To evaluate the effect of sodium dodecyl sulfate (SDS) and temperature on macrophyte and talophyte growth, bioassays were conducted with distinct SDS concentrations (0.5 and 8.0 mg L-1) and temperatures (25 and 27 °C). The length of the Egeria densa and Chara sp. and the number and lengths of shoots were measured. Kinetic models were used to verify the temperature and SDS concentrations, as driving factors in the growth. The 2 °C increase in thermal condition interfered positively in both elongation and shoot development in the E. densa growth. For Chara sp., this tendency was not observed for the relative contribution of the shoots, but the number was higher at 25 °C. The higher concentrations of SDS (8.0 mg L-1) reduced the shoots' number and the relative contribution for Chara sp. and E. densa; meanwhile, the decrease in the growth coefficient was observed only for E. densa at 25 °C. In the Chara sp. development, the SDS addition interfered negatively in the growth coefficient. The predicted response of growth models will bring comprehensive knowledge of macrophytes and talophyte metabolism, and the interaction between plant species and forcing functions in modeling approaches will assist in finding the key processes driving plant growth under specific stressors.

Electrostatic spraying of imazamox to control the floating aquatic plant Salvinia molesta and its effects on environmental indicators of water quality.

This study aimed to assess, in a microcosm condition, the efficacy of electrostatic spraying of herbicide imazamox in the control of Salvinia molesta and the effects of decomposition of plant material on water quality. The herbicide rates used were 600, 700, 800, and 900 g ai ha-1 and spray volume of 50 L ha-1 in electrostatic application. Control effectiveness was assessed at 7, 15, 30, 45, and 60 days after application (DAA), expressed in percentage (0-100%) of visible injury symptoms in the plants, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), chlorophyll a and pheophytin a contents at 0, 7, 15, 30, 45, and 60 DAA, and fresh and dry biomass at 60 DAA. Imazamox was effective in controlling 63% of S. molesta with 900 g ai ha-1 in 45 DAA and 30% with 800 g ai ha-1 in 30 DAA, and reduced 82.3% and 17.5% of fresh weight and 62.6% and 9.3% of dry weight of plant at 60 DAA, respectively. The imazamox spray reduced chlorophyll a with all doses applied and increased BOD5 in 45 DAA with 900 g ai ha-1 and COD in all assessment periods, but for temperature, dissolved oxygen, electrical conductivity, and pH, there was no significant effect after spraying. The herbicide imazamox reduced S. molesta plants with 900 g ai ha-1, without causing significant effects on environmental indicators of water quality. Electrostatic spraying of herbicide can be used in management strategies of aquatic plants to reduce plant density in water bodies and maintain the colonization of plants at a level not harmful to the aquatic biota.

Evaluation of Enydra anagallis remediation at a contaminated watercourse in south Brazil.

The aim of this study was to investigate the phytoremediation potential promoted by Enydra anagallis at anthropogenic polluted area - Santa Bárbara Stream, south Brazil. The watercourse was selected considering it is the main source of water to Pelotas city and the presence of high levels of nutrients and toxic metals. The phytoremediation indexes as bioconcentration factor (BCF), translocation factor (TF), and plant effective number (PEN) were estimated. The results highlighted the possibility of application of E. anagallis in phytoextraction of Ca, K, Mg and P, showing the ability of maintaining high levels of elements in aerial parts of the plant. It was also detected the rhizofiltration mechanism (BCF > 1.0 and TF < 1.0), with possible application for the removal of aluminum, arsenic, chromium, copper, iron, manganese, sodium, nickel, lead, sulfur, vanadium and zinc. Regarding the Plant Effective Number (PEN), it can be highlighted the values found for Al (55 plants), P (38 plants) and S (56 plants), being the number of plants needed for removal of 1 g. Thus, E. anagallis showed natural potential for removing contaminants from the aquatic environment and along with further studies, it could be a good recovery alternative for other contaminated watercourses.

REMOVAL OF AMMONIACAL NITROGEN FROM MUNICIPAL LANDFILL LEACHATE WITH FLOATING Typha domingensis (TYPHACEAE) / Eliminación del nitrógeno amoniacal del lixiviado de vertedero municipal con Typha domingensis (TYPHACEAE) en flotación

ABSTRACT A promising method for the treatment of effluents is the use of floating macrophytes. Ammoniacal nitrogen is a typical compound present in urban landfill leachates and its removal is important due its toxicity to several organisms. Therefore, the study evaluated Typha domingensis survival and nitrification potential artificially floating in domestic solid waste leachate. Plants were exposed for 35 days to leachate (100, 75 and 50 %) and to rainwater with N:P:K (control). Dissolved oxygen (DO) of the treatments was periodically measured, and ammoniacal nitrogen, nitrite and nitrate were analyzed before and after exposure. At the end of the experiment, plant survival rate was calculated. After two weeks, DO increased twice in the control, three times in 50 % leachate, four times in 75 % leachate, and eight times in 100 % leachate. At the end of the experiment, ammoniacal nitrogen was no longer detected, there was a significant reduction of nitrite, and a significant increase of nitrate in the treatments containing leachate. Plant survival was higher in those individuals exposed to 100 % leachate and decreased at lower leachate concentrations: 98 %, 94 %, 92 %, and 86 %. The study demonstrated that the ammoniacal nitrogen concentration of the leachate was not toxic to T. domingensis, and that it was efficient in the removal of this compound from the effluent, indicating that the species may be used artificially floating for the removal of this contaminant from domestic solid waste landfill leachate when in low concentrations.

RESUMEN Un método prometedor para el tratamiento de efluentes es el uso de macrófitas flotantes. El nitrógeno amoniacal es un componente típico de lixiviados de vertederos urbanos y su remoción es importante debido a su toxicidad para diversos organismos. Por eso, el estudio evaluó la supervivencia y el potencial de nitrificación de Typha domingensis flotando artificialmente en lixiviados de residuos sólidos domésticos. Las plantas fueron expuestas por 35 días a lixiviado (100, 75 y 50 %) y al agua de lluvia con N:P:K (control). El oxígeno disuelto (OD) fue medido periódicamente; el nitrógeno amoniacal, el nitrito y el nitrato fueron analizados antes y después de la exposición; al final del experimento, la tasa de supervivencia de las plantas fue calculada. Después de dos semanas, el OD aumentó dos veces en el control, tres veces en el lixiviado 50 %, cuatro veces en el lixiviado 75 % y ocho veces en el lixiviado 100 %. Al final del experimento, el nitrógeno amoniacal no fue más detectado, hubo una reducción significativa de nitrito y un aumento significativo de el nitrato en los tratamientos que contenían lixiviado. La supervivencia de las plantas fue mayor en aquellos individuos expuestos al lixiviado 100 % y se redujo en las menores concentraciones: 98 %, 94 %, 92 % y 86 %. El estudio demostró que la concentración de nitrógeno ammoniacal del lixiviado no fue tóxica para T. domingensis y que ésta fue eficiente en la remoción del compuesto del efluente, indicando que la especie puede ser utilizada flotando artificialmente para la remoción del contaminante de lixiviados de residuos sólidos domésticos en bajas concentraciones.

Is arsenite more toxic than arsenate in plants?

In order to evaluate the differential absorption and toxicity of arsenate (AsV) and arsenite (AsIII), Lemna valdiviana plants were grown in a nutrient solution and subjected to 0.0 (control); 0.5; 1.0; 1.5; 2.0; 3.0; 4.0; 5.0 and 7.5 mg L-1 of AsIII or AsV for three days. Exposure to both chemical forms resulted in As bioaccumulation, although AsIII-grown plants showed higher As content in tissues. In AsV-grown plants, the relative growth rate (RGR) decreased to 50%, at a concentration of 4.0 mg L-1, while for treatments with AsIII, the same decrease was observed at 1.0 mg L-1. The tolerance index decreased with increasing concentrations, with lower values for AsIII. Plants treated with AsIII showed increased superoxide anion levels, whilst higher levels of hydrogen peroxide were present in AsV-treated plants. Moreover, malondialdehyde (MDA) levels were higher for plants subjected to AsIII when compared to AsV at lower concentrations. Concentrations of 1 mg L-1 of AsIII and 4 mg L-1 of AsV showed equivalent MDA levels. Superoxide dismutase and catalase activities were increased at low concentrations and were inhibited at higher concentrations of AsIII and AsV, whereas peroxidase activity was positively modulated by increased AsIII or AsV concentrations. In conclusion, L. valdiviana plants took up and accumulated arsenic as AsIII or AsV, demonstrating the potential for phytoremediation of this metalloid. Furthermore, AsIII-exposed plants showed enhanced toxicity when compared to AsV, at the same applied concentration, although toxicity was more related to internal As concentrations, regardless of the chemical form applied.

Imidacloprid modifies the mitotic kinetics and causes both aneugenic and clastogenic effects in the macrophyte Bidens laevis L.

Imidacloprid (IMI) is a neonicotinoid insecticide widely used in agricultural activities all around the world. This compound is transported from croplands to surrounding freshwater ecosystems, producing adverse effects on non-target organisms. Because of the relevance of aquatic macrophytes in the above-mentioned environments and the lack of studies of potential effects of IMI on them, this work aimed to assess the mitotic process and potential genotoxicity in the aquatic macrophyte Bidens laevis L. Although the analysis of the Mitotic Index (MI) showed that IMI was not cytotoxic, the Cell Proliferation Kinetics (CPK) frequencies evidenced modifications in the kinetics of the mitotic process. Indeed, the anaphases ratio decreased at 10 and 100 µg/L IMI, while at 1000 µg/L an increase of prophases ratio and a decrease of metaphases ratio were observed. Regarding genotoxicity, IMI produced an increase of the abnormal metaphases frequency from 10 µg/L to 1000 µg/L as well as an increase in clastogenic anaphases-telophases frequency at 100 and 1000 µg/L. In addition, aneugenic anaphases-telophases and C-mitosis frequencies also increased at 1000 µg/L, confirming the effects on the mitotic spindle. Considering the genotoxic effects on B. laevis through two different mechanisms (aneugenic and clastogenic) and the wide spread use of IMI in agriculture, these mechanisms of toxicity on macrophytes should be considered among other recognized effects of this insecticide on aquatic biota.

Assessment of a coastal lagoon metal distribution through natural and anthropogenic processes (SE, Brazil).

The present study intends to assess the metal pollution of a eutrophic coastal lagoon, analyzing the long-term and actual metal content in surface sediments, suspended particles, aquatic macrophyte and fish species, and the loads emitted from natural processes and anthropogenic sources, including the relative emission of domestic untreated sewage. Distribution indicated contamination of suspended particles with Cd and the predominance of Pb in the bioavailable form in surface sediments which may explain Cd and Pb contamination in fish. Domestic untreated sewage was an important source of Cu and due to the lagoon's management, this source may be increasing the metal content in the lagoon's surface sediments. Soil loss, atmospheric deposition and solid waste disposal also contributed to metal inputs to the lagoon. Extensive contamination has been prevented by the lagoon's management such as sandbar opening. Metal retention within the watershed soils reduce the effective metal transference and lagoon pollution.

Enhanced rhizoremediation of crude oil-contaminated mangrove swamp soil using two wetland plants (Phragmites australis and Eichhornia crassipes).

Comparative studies of enhanced rhizoremediation with biostimulation and bioaugmentation techniques in remediation of oil-contaminated mangrove environment were investigated. Contaminated soils at 7190 mg/kg of oil were subjected to the following treatments: soil (S), soil + oil (SO), soil + oil + fertilizer (NPK) (SOF), soil + oil + fertilizer + microorganisms (SOFM), soil + oil + fertilizer + microorganisms + solarization (SOFMS) (triplicates): two sets planted with P. australis, E. crassipes, and one unplanted. These were studied comparatively for 120 days for culturable (aerobic, mesophilic) heterotrophic and hydrocarbon-utilizing microbial populations, and soil residual TPH. Results showed culturable heterotrophic and hydrocarbon-utilizing microbial populations and TPH loss in planted soils were consistently higher than those in unplanted receiving corresponding treatments (P Ë‚ 0.05). There were 44.4, 71.8, 74.7, and 67.5, and 50.5, 71.8, 82.3, and 71.8% reduction in residual TPH in soil planted with P. australis and E. crassipes respectively for treatments PSO, PSOF, PSOFM, and PSOFMS as against 20.0, 62.6, 67.5, and 67.5% losses in SO, SOF, SOFM, and SOFMS. Treatments PSOFM and SFOM recorded the highest TPH loss with daily residual TPH loss in the order as follows: E. crassipes (49.20 mg/kg/day) ˃ P. australis (44.64 mg/kg/day) ˃ unplanted soil (40.32 mg/kg/day). Enhanced rhizoremediation was more effective than biostimulation and bioaugmentation techniques.

Continuous dye adsorption and desorption on an invasive macrophyte (Salvinia minima).

The continuous adsorption-desorption of methylene blue (MB) on an invasive macrophyte, Salvinia minima, was investigated in fixed-bed columns. The effects of bed depth (h) (9.30, 18.70, and 28 cm), inlet dye concentration (C0) (51 ± 1.20, 154 ± 2.00, and 250 ± 1.50 mg L-1), and flow rate (Q) (7 and 14 mL min-1) on dye removal and breakthrough curves were assessed. Thomas, modified dose-response (MDR) and bed depth service time (BDST) models were fitted to the experimental data. Desorption and regeneration studies were also performed. The breakthrough time was affected by h, C0, and Q. The dynamic bed capacity at the breakthrough point (qb) increased with increasing h but decreased with increasing C0 and Q. Dynamic bed capacities (qe) from 318 to 322 mg g-1 were achieved at h = 28 cm, C0 = 154 ± 2.0, or 250 ± 1.50 mg L-1, independently of the Q value. High MB removals were also observed (75-78%). FTIR analysis revealed that hydroxyl and carboxyl groups could be involved in dye adsorption. MDR and BDST models were both successfully used to predict the breakthrough curves of MB adsorption onto S. minima. A high regeneration efficiency (> 87%) was obtained after three adsorption-desorption cycles. These results confirm that the use of S. minima biomass could be a very efficient and eco-friendly alternative for MB adsorption in continuous mode.

Nutrient and organic matter removal from low strength sewage treated with constructed wetlands.

The role of Eichhornia crassipes for removing pollutants from low strength sewage was evaluated in three pilot-scale constructed wetlands (CW): CW 1, planted with E. crassipes in a filter media; CW 2, unplanted, composed by filter media; and CW 3, composed by E. crassipes floating on the sewage. The operation was divided into three stages by varying the nominal hydraulic retention time into: (I) 24 h; (II) 48 h; (III) 72 h. Temporal sampling profiles were carried out with collection of the influent and effluent samples to determine temperature, pH, chemical oxygen demand (COD), TKN and TP. Contents of TP and TN were analyzed in the plant tissue of the macrophyte. The best removal efficiency rates for phosphorus (38%) and TKN (47%) were obtained in CW 3 for 72 h. The highest COD removal was observed in the CW 2 (80%) for 48 h. The macrophyte E. crassipes contributed to the absorption process with uptake rate percentages of 8.3% (CW 1) and 9.0% (CW 3) for TN and 0.78% (CW 1) and 1.56% (CW 3) for TP on the dry matter of the plant. The chosen species planted in the systems contributed to the achievement of higher nutrient removal.

Microhabitat preferences of the freshwater prawn Macrobrachium jelskii (Decapoda: Palaemonidae)

We analyzed the microhabitat preferences of Macrobrachium jelskii (Miers, 1877) males and females inhabiting an urban water reservoir in Cruz das Almas, Bahia, Brazil. Prawns were collected monthly, from March 2015 to February 2016, in three microhabitats, using a sieve. Each microhabitat was dominated by one macrophyte species: Eleocharis sp. (M1), Cabomba sp. (M2), and Nymphaea sp. (M3). The prawns were measured (carapace length), and categorized as juvenile males, adult males, juvenile females, non-ovigerous adult females and ovigerous adult females. An analysis of variance (ANOVA) was used to compare the number and size of individuals. The sex ratio and frequency of ovigerous females in the three microhabitats were also calculated. The sex ratio was biased towards females in M1 and did not deviate from 1:1 in M2 and M3. When prawns were separated into five categories we observed that non-ovigerous adult females were more abundant in M1, while adult males were the most abundant demographic category in M2 and M3. Juveniles of both sexes and ovigerous females showed no microhabitat preference, although M1 and M2 appeared to be more suitable for the latter. Adult females were the largest individuals in all microhabitats. Food availability, lower depth and lower predation pressure in M1 are the main factors that make M1 more suitable for M. jelskii, particularly non-ovigerous adult females and larger adult males. Intraspecific competition for shelter in M1 might also occur and adult females win this competition due to their larger body size. Therefore, adult males are found in higher abundance in M2 and M3 and the juvenile of both sexes spread evenly across all microhabitats. Our results help to understand the ecological role and the niche used by M. jelskii. Future studies on the habitat choice and predation under laboratory conditions should help to understand the behavior of this species.

Nós analisamos as preferências de micro-habitat de machos e fêmeas de Macrobrachium jelskii (Miers, 1877) em um açude urbano em Cruz das Almas, Bahia, Brasil. As amostras foram coletadas mensalmente, de março de 2015 a fevereiro de 2016, com o auxílio de uma peneira em três diferentes micro-habitats. Cada micro-habitat teve predomínio de uma espécie de macrófita: Eleocharis sp. (M1), Cabomba sp. (M2) e Nymphaea sp. (M3). Os camarões foram categorizados como machos (jovens e adultos) e fêmeas jovens, adultas não ovígeras e ovígeras e tiveram seu comprimento de carapaça medido. A ANOVA foi usada para comparar as diferenças entre o número e o tamanho dos indivíduos entre os micro-habitats. A razão sexual e a frequência de fêmeas ovígeras em cada micro-habitat também foram calculadas. A razão sexual foi desviada para as fêmeas em M1, mas em M2 e M3 não houve diferença do padrão 1: 1. Quando os camarões foram separados nas cinco categorias, observamos que as fêmeas adultas não ovígeras foram mais abundantes em M1, enquanto os machos adultos foram a categoria demográfica mais abundante em M2 e M3. Indivíduos jovens não mostraram preferência por nenhum dos micro-habitats. M1 e M2 se mostraram adequados para fêmeas ovígeras, devido à maior frequência destas nestes dois micro-habitats se comparado à M3. As fêmeas adultas foram os maiores indivíduos em todos os micro-habitats. A disponibilidade de alimento, a menor profundidade e a menor pressão de predação em M1 são os principais fatores que tornam este micro-habitat mais adequado para M. jelskii, particularmente para fêmeas adultas não ovígeras e machos adultos e fêmeas jovens de maiores tamanhos. Além disso, consideramos também a competição intraespecífica por abrigo em M1, a qual as fêmeas adultas vencem devido ao seu maior tamanho corporal. Como consequência, os machos adultos são encontrados em maior abundância em M2 e M3 e os juvenis de ambos os sexos se espalham uniformemente em todos os micro-habitats. Nossos resultados ajudam a entender o papel ecológico e a utilização de nicho por M. jelskii. Futuros estudos sobre a escolha do habitat e relação presa-predador em condições de laboratório poderão ajudar a entender melhor o comportamento dessa espécie.

Microhabitat preferences of the freshwater prawn Macrobrachium jelskii (Decapoda: Palaemonidae)

ABSTRACT We analyzed the microhabitat preferences of Macrobrachium jelskii (Miers, 1877) males and females inhabiting an urban water reservoir in Cruz das Almas, Bahia, Brazil. Prawns were collected monthly, from March 2015 to February 2016, in three microhabitats, using a sieve. Each microhabitat was dominated by one macrophyte species: Eleocharis sp. (M1), Cabomba sp. (M2), and Nymphaea sp. (M3). The prawns were measured (carapace length), and categorized as juvenile males, adult males, juvenile females, non-ovigerous adult females and ovigerous adult females. An analysis of variance (ANOVA) was used to compare the number and size of individuals. The sex ratio and frequency of ovigerous females in the three microhabitats were also calculated. The sex ratio was biased towards females in M1 and did not deviate from 1:1 in M2 and M3. When prawns were separated into five categories we observed that non-ovigerous adult females were more abundant in M1, while adult males were the most abundant demographic category in M2 and M3. Juveniles of both sexes and ovigerous females showed no microhabitat preference, although M1 and M2 appeared to be more suitable for the latter. Adult females were the largest individuals in all microhabitats. Food availability, lower depth and lower predation pressure in M1 are the main factors that make M1 more suitable for M. jelskii, particularly non-ovigerous adult females and larger adult males. Intraspecific competition for shelter in M1 might also occur and adult females win this competition due to their larger body size. Therefore, adult males are found in higher abundance in M2 and M3 and the juvenile of both sexes spread evenly across all microhabitats. Our results help to understand the ecological role and the niche used by M. jelskii. Future studies on the habitat choice and predation under laboratory conditions should help to understand the behavior of this species.

RESUMO Nós analisamos as preferências de micro-habitat de machos e fêmeas de Macrobrachium jelskii (Miers, 1877) em um açude urbano em Cruz das Almas, Bahia, Brasil. As amostras foram coletadas mensalmente, de março de 2015 a fevereiro de 2016, com o auxílio de uma peneira em três diferentes micro-habitats. Cada micro-habitat teve predomínio de uma espécie de macrófita: Eleocharis sp. (M1), Cabomba sp. (M2) e Nymphaea sp. (M3). Os camarões foram categorizados como machos (jovens e adultos) e fêmeas jovens, adultas não ovígeras e ovígeras e tiveram seu comprimento de carapaça medido. A ANOVA foi usada para comparar as diferenças entre o número e o tamanho dos indivíduos entre os micro-habitats. A razão sexual e a frequência de fêmeas ovígeras em cada micro-habitat também foram calculadas. A razão sexual foi desviada para as fêmeas em M1, mas em M2 e M3 não houve diferença do padrão 1: 1. Quando os camarões foram separados nas cinco categorias, observamos que as fêmeas adultas não ovígeras foram mais abundantes em M1, enquanto os machos adultos foram a categoria demográfica mais abundante em M2 e M3. Indivíduos jovens não mostraram preferência por nenhum dos micro-habitats. M1 e M2 se mostraram adequados para fêmeas ovígeras, devido à maior frequência destas nestes dois micro-habitats se comparado à M3. As fêmeas adultas foram os maiores indivíduos em todos os micro-habitats. A disponibilidade de alimento, a menor profundidade e a menor pressão de predação em M1 são os principais fatores que tornam este micro-habitat mais adequado para M. jelskii, particularmente para fêmeas adultas não ovígeras e machos adultos e fêmeas jovens de maiores tamanhos. Além disso, consideramos também a competição intraespecífica por abrigo em M1, a qual as fêmeas adultas vencem devido ao seu maior tamanho corporal. Como consequência, os machos adultos são encontrados em maior abundância em M2 e M3 e os juvenis de ambos os sexos se espalham uniformemente em todos os micro-habitats. Nossos resultados ajudam a entender o papel ecológico e a utilização de nicho por M. jelskii. Futuros estudos sobre a escolha do habitat e relação presa-predador em condições de laboratório poderão ajudar a entender melhor o comportamento dessa espécie.