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1.
J Environ Manage ; 260: 109923, 2020 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-32090794

RESUMEN

Eutrophication and associated algal blooms are principal environmental challenges confronting lakes in China, particularly in the Eastern Plains ecoregion. The empirical relationships between nutrient and chlorophyll a (Chla) level and Secchi depth (SD) are widely used as a theoretical basis for lake eutrophication management. However, these relationships are largely influenced by hydromorphological conditions and biogeochemical processes. Thus, there is a need to establish a type-specific understanding of these interactions. In the current study, lakes in the Chinese Eastern Plains ecoregion were subdivided into four lake types according to water retention time (LRT), water depth, and water area. Regression analyses indicated that the impacts of nutrient (total nitrogen, TN; total phosphorus, TP) concentrations on summer Chla were significantly reduced in lakes with high inorganic suspended solids (ISS) (P<0.05). Meanwhile, the decrease in SD in these lakes were found to relate mainly to non-algal turbidity. In lakes characterized by both short LRT and high ISS content, the Chla exhibited limited response to nutrients. In contrast, in lakes with low ISS content and long LRT, the observed slopes of both Chla=f(TP) and SD=f(Chla) were significantly steeper (P < 0.05). The factors limiting summer algal growth and the development of type-specific nutrient criteria (TN and TP) of all four investigated lake types in the Eastern Plains ecoregion are discussed in the context of specific nutrients. Based on these results, we establish type-specific eutrophication assessment equations of TN, TP, Chla, and SD in our study lakes. Our results may provide essential information for achieving the cost-effective eutrophication management of lakes both in the Eastern Plains ecoregion and elsewhere with similar climatic and hydromorphological conditions. Moreover, we believe that the subdivision of lakes to allow type-specific eutrophication management framework may prove valuable for other ecoregions where the interpretation of empirical nutrient-Chla and SD relationships suffer from similar serious limitations.


Asunto(s)
Clorofila A , Lagos , China , Clorofila , Monitoreo del Ambiente , Eutrofización , Nitrógeno , Nutrientes , Fósforo
2.
Ecotoxicology ; 29(2): 217-225, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-32030573

RESUMEN

The expansion of land use for agricultural interests and the excessive use of herbicides are among the causes of biodiversity losses in the Brazilian Cerrado biome. Therefore, we aimed to test the hypothesis that Dipteryx alata Vogel, a common species in this biome, is sensitive to nicosulfuron because of its high phytotoxicity. We evaluated physiological, biochemical and morphological responses in D. alata plants exposed to increasing doses of the herbicide. Young plants were transplanted to 10 L pots containing substrate composed of soil and sand (2:1) after fertilization. After an acclimation period, the following doses of nicosulfuron were applied: 0 (control), 6, 12, 24, 48, and 60 g a.e. ha-1. The experiment was conducted in a randomized block design factorial scheme with six doses of nicosulfuron, three evaluation times, and five replicates per treatment. The effects of the herbicide were assessed by measuring gas exchange, chlorophyll a fluorescence, photosynthetic pigments, membrane permeability, antioxidant enzymes and acetolactate synthase. Nicosulfuron altered the photosynthetic machinery and enzymatic metabolism of D. alata. Reductions in physiological traits, increased catalase and ascorbate peroxidase activities, enhanced malondialdehyde concentrations rate of electrolyte leakage and decreased acetolactate synthase activity in response to nicosulfuron all suggest that D. alata is sensitive to this herbicide.


Asunto(s)
Dipteryx/fisiología , Herbicidas/toxicidad , Piridinas/toxicidad , Compuestos de Sulfonilurea/toxicidad , Agricultura , Antioxidantes/metabolismo , Brasil , Catalasa/metabolismo , Clorofila A , Fotosíntesis
3.
Sci Total Environ ; 713: 136734, 2020 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-32019051

RESUMEN

Benthivorous fish disturbance and snail herbivory are two important factors that determine the community structure of submersed macrophytes. We conducted an outdoor mesocosm experiment to examine the separate and combined effects of these two factors on water quality and the growth of two mixed-cultivation submersed macrophytes, Vallisneria natans and Hydrilla verticillata, with different growth forms. The experiment involved two levels of fish (Misgurnus anguillicaudatus) disturbance crossed with two levels of snail (Radix swinhoei) intensity. The results revealed that fish activity rather than snail activity significantly increased the overlying water concentrations of total suspended solids (TSS), total nitrogen (TN), ammonia nitrogen (N-NH4), total phosphorus (TP) and phosphate phosphorus (P-PO4). However, no differences among treatments were observed for chlorophyll a (chl a) concentrations. Fish disturbance or snail herbivory alone did not affect the relative growth rate (RGR) of H. verticillata, but their combined effects significantly decreased the RGR of H. verticillata. Although snail herbivory alone did not affect the RGR of V. natans, fish disturbance alone and the combined effects of these factors drastically reduced its RGR. Both species exhibited increased free amino acid (FAA) contents and decreased ramet numbers, soluble carbohydrate (SC) contents and starch contents in the presence of the fish. Moreover, compared to H. verticillata, V. natans showed exceedingly low ramet numbers and starch contents in the presence of the fish. H. verticillata had a higher RGR and summed dominance ratio (SDR2) than V. natans in all treatments; H. verticillata also displayed a larger competitive advantage in the presence of fish disturbance. The present study suggests that (1) fish disturbance rather than snail activity increases water nutrient concentrations, (2) low snail density may be harmful to submersed macrophyte growth when the plants are under other abiotic stress conditions and (3) the competitive advantage of H. verticillata over V. natans is more preponderant in a turbid environment.


Asunto(s)
Herbivoria , Calidad del Agua , Animales , Clorofila A , Hydrocharitaceae , Fósforo
4.
World J Microbiol Biotechnol ; 36(2): 20, 2020 Jan 18.
Artículo en Inglés | MEDLINE | ID: mdl-31955252

RESUMEN

Vinasse is a waste from the alcohol industry that can support microalgal growth because of its mineral and organic contents. Growing microalgae on waste can be a means of its remediation and decrease culture costs. The physiological knowledge of microalgae on waste can generate subsidies to increase biomass productivity. However, few studies have explored the photosynthetic metabolism of microalgae on complex matrices such as vinasse. In the present research, we investigated some physiological aspects related to photosynthesis and growth of several microalgae in centrifuged and diluted vinasse. The species investigated were Chlamydomonas sp., Chlorella sorokiniana, Chlorella vulgaris, Desmodesmus spinosus, Haematococcus pluvialis, Monoraphidium sp., Scenedesmus quadricauda and Tetraselmis gracilis. Daily cell density, in vivo chlorophyll a and final cellular biovolumes (96 h) were monitored to infer about population growth. Maximum and operational photosynthetic yields (ϕM and ϕ'M), photochemical (qP) and non-photochemical (NPQ) quenchings, light saturation curves and related parameters (α, rETRm and EK), as well as theoretical carbon fixation were evaluated using pulse amplitude modulated fluorometry (PAM). The results showed that chlorophyll a, photochemical (qP) and non-photochemical (NPQ) quenchings were not affected in vinasse, but photosynthetic yields, light curves parameters and autotrophic carbon fixation decreased. Connecting these results to the increase in productivities in vinasse lead us to the rationale that mixotrophic metabolism was supporting microalgae growth on the waste. This study offers important insights into the understanding of microalgal photosynthetic physiology on complex organic wastes, generating subsidies for optimization of biotechnological use of vinasse related to microalgae production.


Asunto(s)
Carbono/metabolismo , Residuos Industriales/análisis , Microalgas/crecimiento & desarrollo , Biodegradación Ambiental , Biomasa , Ciclo del Carbono , Clorofila A/metabolismo , Microalgas/metabolismo , Fotosíntesis
5.
Water Res ; 171: 115403, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-31901508

RESUMEN

Remote sensing reflectance (Rrs) values measured by satellite sensors involve large amounts of uncertainty leading to non-negligible noise in remote Chlorophyll-a (Chl-a) concentration estimation. This work distinguished between two main stages in the case of estimating distributions of Chl-a within the Gulf of St. Lawrence (Canada). At the model building stage, the retrieval algorithm used both in-situ Chl-a measurements and the corresponding Moderate Resolution Imaging Spectroradiometer (MODIS) L2-level data estimated Rrs at 412, 443, 469, 488, 531, 547, 555, 645, 667, 678 nm at a 1 km spatial resolution during 2004-2013. Through the training and validation of various models and Rrs combinations of the considered eight techniques (including support vector regression, artificial neural networks, gradient boosting machine, random forests, standard CI-OC3M, multiple linear regression, generalized addictive regression, principal component regression), the support vector regression (SVR) technique was shown to have the best performance in Chl-a concentration estimation using Rrs at 412, 443, 488, 531 and 678 nm. The accuracy indicators for both the training (850) and the validation (213) datasets were found to be very good to excellent (e.g., the R2 value varied between 0.7058 and 0.9068). At the space-time estimation stage, this work took a step forward by using the Bayesian maximum entropy (BME) theory to further process the SVR estimated Chl-a concentrations by incorporating the inherent spatiotemporal dependency of physical Chl-a distribution. A 56% improvement was achieved in the reduction of the mean uncertainty of the validation data decreased considerably (from 1.2222 to 0.5322 mg/m3). Then, this novel BME/SVR framework was employed to estimate the daily Chl-a concentrations in the Gulf of St. Lawrence during Jan 1-Dec 31 of 2017 (1 km spatial resolution). The results showed that the daily mean Chl-a concentration varied from 1.6630 to 3.3431 mg/m3, and that the daily mean Chl-a uncertainty reduction of the composite BME/SVR vs. the SVR estimation had a maximum reduction value of 1.0082 and an average reduction value of 0.6173 mg/m3. The monthly spatial Chl-a distribution covariances showed that the highest Chl-a concentration variability occurred during November and that the spatiotemporal Chl-a concentration pattern changed a lot during the period August to November. In conclusion, the proposed BME/SVR was shown to be a promising remote Chl-a retrieval approach that exhibited a significant ability in reducing the non-negligible uncertainty and improving the accuracy of remote sensing Chl-a concentration estimates.


Asunto(s)
Clorofila A , Tecnología de Sensores Remotos , Teorema de Bayes , Canadá , Clorofila , Monitoreo del Ambiente , Incertidumbre
6.
Water Res ; 171: 115441, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-31927090

RESUMEN

This study is an analysis of relationships between microalgae (measured as chlorophyll a) and the fecal indicator bacteria enterococci. Microalgae blooms and enterococci exceedances have been occurring in Florida's recreational waterways for years. More recently, this has become a management concern as microalgae blooms have been attributed to potentially toxic cyanobacteria, and enterococci exceedances link to human infection/illness. Since both the microalgal blooms and bacterial exceedances occur in regions that receive managed freshwater releases from Lake Okeechobee, we hypothesized that both the blooms and exceedances are related to excess nutrients from the lake. Two experimental sites, on Lake Okeechobee and the St. Lucie River (downstream of the lake), plus a control site on the Loxahatchee River (which does not receive lake flow) were evaluated. The hypothesis was evaluated through three study components: 1) analysis of available long-term data from local environmental databases, 2) a year-long monthly sampling and analysis of chlorophyll a, enterococci, nutrients, and physical-chemical data, and 3) microcosm experiments with altered water/sediment conditions. Results support the hypothesis that excess nutrients play a role in both chlorophyll a and enterococci levels. For the St. Lucie River, analyses indicate that chlorophyll a correlated significantly with total Kjeldahl nitrogen (TKN) (R2 = 0.30, p = 0.008) and the strongest model for enterococci included nitrate-nitrite, TKN, total phosphorus, orthophosphorus, and turbidity in our long-term analysis (n = 39, R2 = 0.83, p ≤ 0.001). The microcosm results indicated that chlorophyll a and enterococci only persisted for 36 h in water from all sources, and that sediments from Lake Okeechobee may have allowed for sustained levels of chlorophyll a and enterococci levels. Overall similarities were observed in chlorophyll a and enterococci relationships with nutrient concentrations regardless of a Lake Okeechobee connection, as underscored by a study of flow out of the lake and downstream areas. This suggests that both nutrient-rich lake water and untreated surface water runoff contribute to microalgae blooms and enterococci exceedances in southeast Florida.


Asunto(s)
Lagos , Microalgas , Proliferación Celular , Clorofila , Clorofila A , Enterococcus , Monitoreo del Ambiente , Eutrofización , Florida , Nitrógeno , Fósforo
7.
Water Res ; 171: 115457, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-31931377

RESUMEN

Although estimates of total CO2 emissions from global estuaries are gradually decreasing, current numbers are based on limited data and the impacts of anthropogenic and seasonal disturbances have not been studied extensively. Our study estimates annual and seasonal CO2 fluxes in China's Yellow River Estuary (YRE) which incorporated spatiotemporal variations and the effects of water and sediment regulation (WSR). Aquatic metabolism was estimated using Odum's open water dissolved oxygen methods and used to represent the production and assimilation of CO2. Net ecosystem production (NEP) was used to represent the CO2 flux from biological activities and estimate the major CO2 emitters in the YRE. According to our measurements, the annual CO2 release was 6.14 ± 33.63 mol C m-2 yr-1 from 2009 to 2013 and the annual CO2 efflux from the 1521.3 km2 of estuarine surface area was 0.11 ± 0.61 Tg C yr-1 in the YRE. High CO2 emissions in autumn were balanced by high CO2 sequestration in summer, leading to a lower than expected annual net CO2 efflux. The system is an atmospheric CO2 source in spring and winter, near neutral in early summer, a large sink in late summer after WSR, and finally a large atmospheric CO2 source in autumn. Discharge events and seasonality jointly affect estuarine CO2 flux. High CO2 sequestration in summer is due mainly to a combination of high water temperature, chlorophyll a levels, dissolved inorganic carbon, and solar radiation and low turbidity, discharge, and chemical oxygen demand (COD) after WSR. WSR supports the high gross primary productivity rate which exceeds the increase in ecosystem respiration. Although the YRE, as a whole, is a source of atmospheric CO2, the amount of CO2 released is lower than the average estuarine value of mid-latitude regions. Our findings therefore suggest that global CO2 release from estuarine systems is overestimated if spatiotemporal variations and the effects of anthropogenic disturbance are excluded. The NEP method is effective for estimating the CO2 flux, especially in estuaries where CO2 variation is mainly due to biological processes.


Asunto(s)
Estuarios , Ríos , Dióxido de Carbono , China , Clorofila A , Ecosistema , Monitoreo del Ambiente , Procesos Heterotróficos , Estaciones del Año
8.
J Phys Chem Lett ; 11(3): 1059-1067, 2020 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-31952446

RESUMEN

The interplay between active molecules and the protein environment in light-harvesting complexes tunes the photophysics and the dynamical properties of pigment-protein complexes in a subtle way, which is not fully understood. Here we characterized the photophysics and the ultrafast dynamics of four variants of the water-soluble chlorophyll protein (WSCP) as an ideal model system to study the behavior of strongly interacting chlorophylls. We found that when coordinated by the WSCP protein, the presence of the formyl group in chlorophyll b replacing the methyl group in chlorophyll a strongly affects the exciton energy and the dynamics of the system, opening up the possibility of tuning the photophysics and the transport properties of multichromophores by engineering specific interactions with the surroundings.


Asunto(s)
Clorofila A/química , Clorofila/química , Complejos de Proteína Captadores de Luz/química , Modelos Moleculares , Temperatura Ambiental , Termodinámica , Agua/química
9.
J Environ Manage ; 260: 109898, 2020 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-31941639

RESUMEN

Eelgrass beds are highly productive and support diverse faunal assemblages; they also take in nutrients from the water and prevent excessive phytoplankton growth in eutrophic coastal waters through the reduction of available nutrients. Despite its importance, the global distribution of eelgrass has declined worldwide. In eutrophic areas with high chlorophyll a (Chl.a) concentrations, natural recovery of eelgrass beds after eutrophication is possible. To facilitate this, sufficient water clarity can be reached after a large enough decrease in phytoplankton concentration. In this study, we proposed a novel indicator for the maximum possible Secchi depth (MPSD), defined as the Secchi depth when the Chl.a concentration is equal to a reference Chl.a concentration. We applied the MPSD to evaluate water clarity improvements through the reduction of terrigenous anthropogenic nutrient loading. We found that phytoplankton did not control water clarity in the study area, which was instead controlled by background factors. Therefore, improvements in water clarity would not be expected after reducing terrigenous anthropogenic nutrient loading. The habitat of Zostera marina is determined by light availability, so we investigated a potential area with ≥20% surface irradiance and Z. marina existed in 27% of it (100 of 373 ha). The maximum further recovery of eelgrass by Secchi depth improvements to the MPSD was estimated at 36 ha. The impact of eelgrass recovery and expansion on phytoplankton growth from May to September was evaluated by a mathematical model under two scenarios: the current eelgrass distribution (100 ha) and potential maximum eelgrass distribution (373 ha). A Chl.a decrease of 1.0-3.0 µg l-1 from 4.0 to 7.0 µg l-1 was achieved in an area from May to July, and the improvement decreased with time. These evaluation methods and findings could help us gain a better understanding of the nutrient management in seagrass-vegetated semi-enclosed seas subjected to anthropogenic nutrient input.


Asunto(s)
Fitoplancton , Zosteraceae , Clorofila A , Nutrientes , Océanos y Mares
10.
Photochem Photobiol Sci ; 19(2): 180-192, 2020 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-31956889

RESUMEN

UV radiation affects the biochemical, physiological and morphological responses of plants. The effect is most pronounced at high altitude, such as alpine regions, and low latitude environments. The effect of UV radiation is impacted by different environmental conditions including temperature. We examined the response of the alpine plant Saxifraga hostii Tausch subsp. hostii growing at two altitudes (montane, 1100 m a.s.l. and alpine, 1500 m a.s.l.) in the Slovenian Alps. Selected ecophysiological, anatomical and pigment analyses along with measurements of the leaf optical properties were carried out during the growing season from July to September. Plants were grown under two different UV levels, near-ambient UV (UV) and reduced UV (UV-) radiation, and temperature conditions were monitored at both altitudes. Saxifraga hostii exhibited high photochemical efficiency of photosystem II and stomatal conductance under near-ambient UV radiation in August, which indicates that it is a well-acclimated plant. In September, photochemical efficiency was higher under reduced UV at the alpine altitude which together with a lower photosynthetic pigment content indicate delayed senescence for plants growing under reduced UV. Most leaf tissue thicknesses were not affected by UV radiation and altitude difference. There was a trend of increased stomatal density and reduced stomatal length on both leaf surfaces under near-ambient UV in August. However, there was no effect of UV attenuation or location at the alpine or montane site on the content of UV-B absorbing compounds, which implies the plant's tolerance of UV-B radiation. Saxifraga hostii leaves showed high absorption in the UV spectrum at higher altitudes, as shown by their optical properties. This study shows that Saxifraga hostii is well-acclimated to ambient UV radiation and to the environmental conditions at both altitudes. The effect of UV radiation is impacted by site conditions and this produces diverse plant responses, which contribute to the specific functional traits of Saxifraga hostii in the high-altitude environment.


Asunto(s)
Saxifragaceae/efectos de la radiación , Rayos Ultravioleta , Altitud , Carotenoides/metabolismo , Clorofila A/metabolismo , Complejo de Proteína del Fotosistema II/metabolismo , Hojas de la Planta/anatomía & histología , Hojas de la Planta/metabolismo , Hojas de la Planta/efectos de la radiación , Análisis de Componente Principal , Saxifragaceae/crecimiento & desarrollo , Saxifragaceae/metabolismo , Estaciones del Año , Eslovenia , Temperatura Ambiental
11.
Sci Total Environ ; 707: 135561, 2020 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-31972904

RESUMEN

Coastal eutrophication and its associated harmful algal blooms have emerged as one of the most severe environmental problems worldwide. Seaweed cultivation has been widely encouraged to control eutrophication and algal blooms. Among them, cultivated kelp (Saccharina japonica) dominates primarily by production and area. However, the responses of water quality and phytoplankton community to kelp farming remain unclear. Here, thirteen cruises were conducted in the kelp farms and control areas in the turbid, highly eutrophic Xiangshan Bay of the East China Sea from 2008 to 2015. Results indicated that kelp cultivation slightly increased dissolved oxygen and pH, but reduced dissolved inorganic nitrogen and phosphorus. We estimated that kelp harvesting would remove 297 t of nitrogen and 42 t of phosphorus from this bay annually. Because of decreased flow velocity, turbulence, and sediment resuspension, kelp farming greatly reduced suspended solids and increased transparency, resulting in increases in phytoplankton chlorophyll a and abundance. Additionally, kelp farming appreciably increased phytoplankton species number, Marglef richness, and Shannon-Wiener diversity indices by 51.6%, 40.1%, and 13.1%, respectively. Analysis of similarity and similarity percentages demonstrated that phytoplankton community composition differed significantly between the farm and control area, which was mostly attributed to long-chained diatoms and single-celled dinoflagellates. However, after the kelp harvesting, all measurements of water quality and phytoplankton biomass, diversity, and community composition exhibited no significant difference. Our study highlights that kelp cultivation alleviates eutrophication and acidification and enhances phytoplankton diversity, thus providing guidance for macroalgal aquaculture and remediation in eutrophic waters.


Asunto(s)
Acuicultura , Eutrofización , Kelp/crecimiento & desarrollo , Fitoplancton , Calidad del Agua , Bahías , China , Clorofila A , Nitrógeno , Fósforo
12.
J Photochem Photobiol B ; 203: 111768, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31931383

RESUMEN

In vitro callus cultures of Verbena officinalis L. were maintained on solid Murashige and Skoog medium, enriched with 1 mg dm-3 BA and 1 mg dm-3 IBA under LED lights (red, blue, red/blue 70%/30%), in darkness and under control fluorescent lamps. The measurements of 2 phenylpropanoid glycosides (verbascoside and isoverbascoside) and 23 phenolic acids were performed in methanolic extracts from the biomass collected after 2-, 3- and 4-week growth cycles using the HPLC-DAD method. The presence of verbascoside, isoverbascoside and additionaly 7 phenolic acids (protocatechuic, chlorogenic, vanillic, caffeic, ferulic, o-coumaric and m-coumaric acids) was confirmed in all extracts. Blue and red/blue lights stimulated the accumulation of verbascoside (max. of 6716 and 6023 mg 100 g-1 DW after a 4-week growth cycle) and isoverbascoside (max. 333 and 379 mg 100 g-1 DW also after 4 weeks). The maximum amounts of verbascoside and isoverbascoside were respectively 1.8- and 7.0-fold higher than under the control conditions. Phenolic acids were accumulated in different amounts, and the maximum total amounts ranged from 36 to 65 mg 100 g-1 DW. LED lights also stimulated their accumulation in comparison with darkness and control. The main phenolic acids included: m-coumaric acid (max. 39 mg 100 g-1 DW), ferulic acid (max. 12 mg 100 g-1 DW), and protocatechuic acid (max. 13 mg 100 g-1 DW). Additionally, the quantities of photosynthetic pigments (chlorophyll a, b and carotenoids) were estimated in acetonic extracts using spectrophotometry. Red/blue light stimulated the biosynthesis of pigments (max. total content 287 µg g-1 FW after 4-week growth cycles). This is the first study describing the effect of LED lights on the production of phenylpropanoid glycosides and phenolic acids in V. officinalis callus cultures. Very high amounts of verbascoside and isoverbascoside are interesting from a practical point of view.


Asunto(s)
Glucósidos/metabolismo , Hidroxibenzoatos/metabolismo , Luz , Fenoles/metabolismo , Verbena/metabolismo , Biomasa , Carotenoides/análisis , Clorofila/análisis , Clorofila A/análisis , Cromatografía Líquida de Alta Presión , Glucósidos/análisis , Hidroxibenzoatos/análisis , Fenoles/análisis , Fotosíntesis/efectos de la radiación , Análisis de Componente Principal , Análisis de Regresión , Espectrofotometría
13.
Sci Total Environ ; 713: 136515, 2020 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-31951840

RESUMEN

Understanding the ecological impacts of large-scale hydraulic projects is critical for maintaining ecosystem health while meeting human water needs. It is, however, currently hindered by a lack of direct evidence on ecological impacts associated with this type of project particularly on water quality and fish communities. Here, we characterized patterns and variations of fish communities and water quality in five impounded lakes of the Chinese South-to-North Water Diversion Project (SNWDP), with the aim of better understanding potential ecological impacts of inter-basin water transfers. We found that 1) the impacts of water transfer on water quality in the impounded lakes was generally characterized by hydrological parameters (e.g. total suspended solids, turbidity, transparency, chlorophyll a, dissolved oxygen, conductivity and total hardness) in an upstream-downstream direction; 2) increased hydrological connectivity may have favored biological invasion (e.g. Tridentiger bifasciatus) and promoted a potential biotic homogenization among the impounded lakes; and 3) there was a pattern of decreased fish abundance and biomass from the upstream to downstream lakes with fish communities strongly driven by changing water quality patterns across the impounded lakes. These findings improve our understanding of ecological impacts of large-scale hydraulic projects and provide a significant basis for water agencies with similar water transfer systems to optimize their water transfer management in order to minimize ecological impacts.


Asunto(s)
Lagos , Calidad del Agua , Animales , China , Clorofila A , Ecosistema , Agua
14.
Sci Total Environ ; 706: 135728, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31940730

RESUMEN

Pharmaceuticals and personal care products (PPCPs), such as the commonly prescribed antibiotic ciprofloxacin, are present and persistent in freshwaters, yet their effects on aquatic ecosystem functions at environmentally-relevant concentrations are rarely explored. Stream biofilms provide multiple functions in stream ecosystems, but their functional response to PPCP contaminants such as ciprofloxacin is unclear. To establish the effect of ciprofloxacin on aquatic biofilms, we colonized biofilms in situ on tiles (n = 80) at four sites along an urban stream in Gainesville, Florida, including two sites above and two sites below a wastewater treatment plant (WWTP). We then incubated the tiles and associated biofilms in the laboratory for 6 d exposing biofilms to either 0, 0.01, 0.1, or 1.0 µg/L (target concentrations) of ciprofloxacin. At the end of the 6 d laboratory exposure, we quantified gross primary production (GPP), respiration (R), and biomass (as chlorophyll a) of biofilms, and calculated response ratios for each response. All response metrics were significantly differed across sites (p < 0.01). Ciprofloxacin significantly decreased GPP (p < 0.05) regardless of treatment concentration, most notably at the site immediately below the WWTP, where there was no measurable GPP on any ciprofloxacin-treated biofilms. In contrast, respiration (R) was not significantly affected by ciprofloxacin, despite an apparent increase in R at the WWTP site. However, the WWTP site R was significantly different from the most upstream and downstream sites (p < 0.001) but was not significantly different from a nearby site upstream of the WWTP (p > 0.05). These results indicate that chronic exposure to ciprofloxacin through WWTP effluent can alter ecosystem functions performed by biofilms, which can have consequences for higher trophic levels and stream processes. By quantifying biofilm metabolic responses to ciprofloxacin exposure, this study supports the concept that pharmaceuticals and personal care products can induce sub-lethal effects on ecological processes at environmentally-relevant concentrations.


Asunto(s)
Biopelículas/efectos de los fármacos , Ciprofloxacino/toxicidad , Microalgas/efectos de los fármacos , Contaminantes Químicos del Agua/toxicidad , Biomasa , Clorofila A , Ecosistema , Florida
15.
Environ Monit Assess ; 192(2): 88, 2020 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-31900672

RESUMEN

The formation of an oil-suspended particulate material aggregate (OSA) is one of the weathering processes that occur after the spill of oil in marine environments, responsible for the dispersion of hydrocarbons. Oil and particle aggregates are formed from the interaction between small oil droplets and suspended particulate matter (SPM). In general, SPM are fine particles which may be inorganic minerals or organic particles in the water column. OSAs provide vertical dispersion of oil along the water column depending on the acquired density (buoyancy), and may remain near the surface, water column, or bottom of water bodies. The present study examines the formation of these aggregates through the laboratory simulation of an oil spill in the waters of the São Paulo river estuary. The main objective was to investigate the dispersion of polycyclic aromatic hydrocarbons (PAHs), verifying which estuary characteristics most influenced the formation of OSAs and in addition to determine the regions of probable ecotoxicological impact due to the negative buoyancy of the formed aggregate. The results show that there was greater dispersion to the water column, mainly of lighter PAHs, ranging from 85,804.05 ng g-1 (P11C) to 566,989.84 ng g-1 (P17C). The percentage of dispersed PAH concentration per experimental unit ranged from 9.90% in unit P2 to 75.27% in unit P18. The formation of OSAs was influenced mainly by salinity and chlorophyll a. As the most vulnerable regions, the impacts are one mouth (P2 and P4), one central region (P7, P8, and P10), and one source (P18).


Asunto(s)
Monitoreo del Ambiente , Hidrocarburos Policíclicos Aromáticos/análisis , Contaminantes Químicos del Agua/análisis , Clorofila A , Ecotoxicología , Estuarios , Sedimentos Geológicos , Material Particulado/análisis , Contaminación por Petróleo/análisis , Ríos , Salinidad
16.
Environ Monit Assess ; 192(2): 94, 2020 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-31907685

RESUMEN

A multimetric water quality standards (WQS) attainment indicator (MMI) was created to assess the habitat quality of the Chesapeake Bay and its tidal tributaries. The indicator uses metrics of dissolved oxygen concentrations, water clarity assessments, underwater bay grass acreages, and season-specific chlorophyll a distributions. This suite of metrics is recognized as symptomatic of eutrophication and responsive to nutrient and sediment management actions. Habitat criteria for these metrics were established by the US Environmental Protection Agency (USEPA) to protect the survival, growth, and reproduction of tidal bay living resources. The criteria were adopted into state WQS used to define outcome targets of the regulatory 2010 Chesapeake Bay Total Maximum Daily Load (TMDL). Direct accounting of monitoring results compared with state standards would be the most direct measure of water quality status related to achieving habitat health goal conditions under the TMDL. However, the Chesapeake Bay Program long-term water quality monitoring program that supports Clean Water Act 303d water quality impairment assessments does not provide sufficient measurement resolution across all temporal scales represented in these TMDL-related WQS. Recognizing data and analysis gaps, we developed the indicator to provide estimates of WQS attainment for the Chesapeake Bay. The structure of the indicator uses metrics that have been measured consistently with the historical Chesapeake Bay tidal water quality data collections since 1985. The ability to compute scores on contemporary and historical data will provide for bay-wide and spatially explicit long-term trend evaluations of habitat quality.


Asunto(s)
Bahías/química , Monitoreo del Ambiente/métodos , Calidad del Agua/normas , Clorofila A/análisis , Ecosistema , Eutrofización/fisiología , Oxígeno/análisis , Estados Unidos , United States Environmental Protection Agency
17.
Chem Biodivers ; 17(2): e1900399, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31909554

RESUMEN

Water stress is one of the main abiotic factors that reduces plant growth, mainly due to high evaporative demand and low water availability. In order to evaluate the effects of drought stress on certain morphological and physiological characteristics of two canola cultivars, we conducted a factorial experiment based on a completely randomized design. The findings show that drought stress exacerbations result in the plant's response to stress due to increased canola resistance caused by changes in plant pigments, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase and malondialdehyde, glucose, galactose, rhamnose and xylose. These in turn ultimately influence the morphological characteristics of canola. Drought stress reduces the concentration of carotenoids, chlorophyll a, chlorophyll b, total chlorophylls; however, glucose, galactose, rhamnose, xylose, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase, malondialdehyde (in leaves and roots) and the chlorophyll a and b ratios were increased. Reduction of plant height, stem height, root length, fresh and dry weight of canola treated with 300 g/l PEG compared to non-treatment were 0.264, 0.236, 0.394, 0.183 and 0.395, respectively. From the two canola cultivars, the morphological characteristics of the NIMA increased compared to the Ks7 cultivar. Interaction effects of cultivar and drought stress showed that NIMA cultivar without treatment had the highest number of morphological characteristics such as carotenoid concentration, chlorophyll a, chlorophyll b, total chlorophylls a and b, whereas the cultivar with 300 g/l PEG (drought stress) had the highest amount of proline, malondialdehyde, soluble sugars and enzymes in leaves and roots. Increasing activity of oxidative enzymes and soluble sugars in canola under drought stress could be a sign of their relative tolerance to drought stress.


Asunto(s)
Brassica napus/crecimiento & desarrollo , Sequías , Estrés Fisiológico , Brassica napus/metabolismo , Carotenoides/metabolismo , Catalasa/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Glucosa/metabolismo , Hojas de la Planta/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/metabolismo , Ramnosa/metabolismo , Superóxido Dismutasa/metabolismo
18.
Chemosphere ; 242: 125231, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31704521

RESUMEN

A large number of metals is present in aquatic ecosystems, often occurring simultaneously, however, the isolated toxicity of them are better well known than their mixtures. Based on that, for the first time we aimed to test the effects of zinc (Zn) and aluminum (Al) mixtures to the microalgae Raphidocelis subcapitata. Regarding isolated toxicity, the 96 h IC50 of Zn and Al based on specific growth rates occurred, respectively, at 0.40 and 27.40 µM, thus Zn was ≈70-fold more toxic than Al. Both Zn and Al altered the cell size and complexity of R. subcapitata at the highest concentrations, although only during Zn exposure was the chlorophyll a fluorescence significantly diminished. Microalgae exposed to Al produced more ROS than during Zn exposure. Moreover, algae produced less ROS at the highest Zn concentration than in the lower concentrations. According to species sensitivity curves (SSD), R. subcapitata was the most sensitive organism to Zn and one of the most sensitive to Al. With respect to mixture toxicity tests, there were significant deviations for both CA (concentration addition) and IA (independent action) models, although data best fitted the CA model and DL (dose level-dependence) deviation, in which metals showed synergic effects at low concentrations and antagonist effects at higher concentrations.


Asunto(s)
Aluminio/toxicidad , Ecotoxicología/métodos , Microalgas/efectos de los fármacos , Zinc/toxicidad , Clorofila A/metabolismo , Sinergismo Farmacológico , Metales/toxicidad , Especies Reactivas de Oxígeno/metabolismo , Pruebas de Toxicidad/métodos , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad
19.
Chemosphere ; 242: 125228, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31677507

RESUMEN

The uptake and accumulation of three imidazolium ionic liquids with different alkyl chain lengths ([C2min]Br, [C4min]Br, [C8min]Br) in rice seedlings were investigated. All three different ILs were primarily accumulated in roots, while only a little amount of ILs were translocated and accumulated in stems and leaves. Accumulation and transportation of ILs in rice depend on the concentration and the alkyl chain length of ILs. ILs contents in the roots, stems and leaves decreased as ILs alkyl chain length increased. Growth inhibition results showed that the toxic effects of ILs on rice growth depends on the alkyl chain length: [C8min]Br >[C4min]Br >[C2min]Br. As markers of defense and phytotoxicity, the plant antioxidant enzymes and biochemical stress responses were also assessed. All different ILs significantly increased malondialdehyde (MDA), catalase (CAT), peroxidase (POD) and dismutase (SOD) activities in rice tissue. Compared to the control group, the contents of chlorophyll a reduced by 59.56%, 62.28% and 69.74% after addition of [C2min]Br, [C4min]Br, and [C8min]Br, respectively. This study provides important information for a better understanding on the uptake and accumulation of imidazolium ILs by agricultural plants.


Asunto(s)
Imidazoles/farmacocinética , Líquidos Iónicos/farmacocinética , Oryza/efectos de los fármacos , Plantones/efectos de los fármacos , Antioxidantes/análisis , Clorofila A/metabolismo , Enzimas/efectos de los fármacos , Enzimas/metabolismo , Imidazoles/química , Líquidos Iónicos/química , Líquidos Iónicos/toxicidad , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Relación Estructura-Actividad
20.
Bull Environ Contam Toxicol ; 104(1): 114-120, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31724078

RESUMEN

The study was to identify the potential tolerance of Crotalaria juncea to diclosulam uptake and translocation and its effects on the physiological metabolism of plants. Two experiments were carried out; I-Evaluation of uptake and translocation of 14C-diclosulam (35 g a.i. ha-1) in C. juncea, at seven and 14 days after emergence. II-Evaluation of chlorophyll a transient fluorescence of dark-adapted C. juncea leaves when applied diclosulam in pre-emergence. Plants of C. juncea presented an anatomical/metabolic barrier to diclosulam translocation in the stem, which may confer tolerance to this herbicidal, besides reduced translocation due to low accumulation in the cotyledons. In addition, plants can maintain photosynthetic metabolism active when growing in soil with diclosulam by not changing the dynamics of energy dissipation. Thus, when cultivated in soil with residual of diclosulam, C. juncea can tolerate the herbicide to maintain plant growth.


Asunto(s)
Crotalaria/fisiología , Herbicidas/metabolismo , Sulfonamidas/metabolismo , Triazoles/metabolismo , Transporte Biológico , Clorofila A , Hojas de la Planta/metabolismo , Suelo
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