Alterations in flow regimes of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of flows incoming to the Delta (Paraná-Santa Fe section), flow characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental Flow Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the “Paraná Delta” Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903–1972) and two more altered periods (1973–1999 wet period and 2000–2014 dry period) were identified. Flow duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the flow regime were the lack of record of the extreme-low-flow component, the attenuation of monthly flow seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum flow dates. These alterations are consistent with the monthly and daily flow regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only slightly in the dry period. In the Delta Reserve rivers, concentrations of Escherichia coli, cadmium, lead, iron, manganese, and ammonium exceeded guideline levels under a severe drought and a dispersal of cyanobacteria appeared under a high-flow pulse in La Niña year. The ammonium concentration exceeded the level for human drink with the overbanking flood stage in El Niño year. These occasional detections pose a potential risk to the aquatic life and, especially, to the inhabitants of the Reserve. Flow duration curves, IHA, and EFC are useful tools to evaluate trends or changes of ecological and social relevance in flow regime characteristics.

Periphyton is ubiquitous in paddy field, but its importance in influencing the bioavailability of phosphorus (P) in paddy soil has been rarely recognized. A paddy field was simulated in a greenhouse to investigate how periphyton influences P bioavailability in paddy soil. Results showed that periphyton colonizing on paddy soil greatly reduced P content in paddy floodwater but increased P bioavailability of paddy soil. Specifically, all the contents of water-soluble P (WSP), readily desorbable P (RDP), algal-available P (AAP), and NaHCO₃-extractable P (Olsen-P) in paddy soil increased to an extent compared to the control (without periphyton) after fertilization. In particular, Olsen-P was the most increased P species, up to 216 mg kg⁻¹ after fertilization, accounting for nearly 60 % of total phosphorus (TP) in soil. The paddy periphyton captured P up to 1.4 mg g⁻¹ with Ca-P as the dominant P fraction and can be a potential crop fertilizer. These findings indicated that the presence of periphyton in paddy field benefited in improving P bioavailability for crops. This study provides valuable insights into the roles of periphyton in P bioavailability and migration in a paddy ecosystem and technical support for P regulation.

In this study, a new degradation path of sunscreen active ingredient, 2-ethylhexyl-4-methoxycinnamate (EHMC) and 4-methoxycinnamic acid (MCA) in the presence of sodium hypochlorite (NaOCl), was discussed. The reaction products were detected using gas chromatography–mass spectrometry (GC-MS). Since HOCl treatment leads to more polar products than EHMC, application of polar extracting agents, dichloromethane and ethyl acetate/n-hexane mixture, gave better results in terms of chlorinated breakdown products identification than n-hexane. Reaction of EHMC with HOCl lead to the formation of C=C bridge cleavage products such as 2-ethylhexyl chloroacetate, 1-chloro-4-methoxybenzene, 1,3-dichloro-2-methoxybenzene, and 3-chloro-4-methoxybenzaldehyde. High reactivity of C=C bond attached to benzene ring is also characteristic for MCA, since it can be converted in the presence of HOCl to 2,4-dichlorophenole, 2,6-dichloro-1,4-benzoquinone, 1,3-dichloro-2-methoxybenzene, 1,2,4-trichloro-3-methoxybenzene, 2,4,6-trichlorophenole, and 3,5-dichloro-2-hydroxyacetophenone. Surprisingly, in case of EHMC/HOCl/UV, much less breakdown products were formed compared to non-UV radiation treatment. In order to describe the nature of EHMC and MCA degradation, local reactivity analysis based on the density functional theory (DFT) was performed. Fukui function values showed that electrophilic attack of HOCl to the C=C bridge in EHMC and MCA is highly favorable (even more preferable than phenyl ring chlorination). This suggests that HOCl electrophilic addition is probably the initial step of EHMC degradation.

This study evaluated the effect of Yucca schidigera extract on productive performance, egg quality, blood metabolites, immune function, and antioxidant parameters in laying hens. A total of 96 36-week-old hens were allocated into four groups, the control diet or the diet supplemented with 50, 100, or 150 mg/kg of yucca extract, from 36 to 52 weeks of age. Hens were divided into four equal groups replicated six times with four hens per replicate. As a result of this study, there were no linearly or quadratically differences in body weight change (BWC), feed consumption (FC), feed conversion ratio (FCR), and egg weight (EW) due to yucca treatments at different ages, except FCR and EW that were improved with yucca supplementation during 36–40 weeks of age. Supplemental dietary yucca up to 100 mg/kg diet led to significant improvement in egg number (EN) and egg mass (EM). Egg qualities were not linearly or quadratically affected by yucca treatments except shell thickness was quadratically (P < 0.001) increased with increasing yucca level up to 100 mg/kg diet. Dietary supplementation of yucca exhibited a positive impact on albumin and immunoglobulin G (IgG). Comparing to the control group, yucca addition to laying hen diets resulted in a significant linear (P < 0.001) and quadratic (P = 0. 010) decrease in blood ammonia-N and urea-N, respectively. The activity of superoxide dismutase (SOD) and reduced glutathione (GSH) level in serum were quadratically improved in yucca groups. The malondialdehyde (MDA) concentration was decreased with yucca addition in comparison with the control group. In conclusion, yucca supplemented up to 100 mg/kg diet can be used as effective feed additive to improve productive performance, blood profile, and antioxidant enzyme activities in laying hens.

We aimed to understand relationships of the weather as biometeorological and hospital admissions due to diseases of arteries and veins by subtypes, which have been scarcely studied, in a national setting in recent years. This is an ecological study. Ten percent of daily hospital admissions from the included hospitals (n = 1,618) across Germany that were available between 1 January 2009 and 31 December 2011 (n = 5,235,600) were extracted from Statistisches Bundesamt, Germany. We identified I70-I79 Diseases of arteries, arterioles and capillaries and I80-I89 Diseases of veins, lymphatic vessels and lymph nodes by International Classification of Diseases version 10 as the study outcomes. Daily weather data from 64 weather stations that covered 13 German states including air temperature, humidity, wind speed, cloud cover, radiation flux and vapour pressure were obtained and generated into physiologically equivalent temperature (PET). Two-way fractional-polynomial prediction was plotted with 95 % confidence intervals. For most of the subtypes from diseases of arteries and veins, hospital admissions slightly peaked in spring and dropped when PET was at 10 °C. There were no other large differences across 12 months. Admissions of peripheral vascular diseases, arterial embolism and thrombosis, phlebitis and thrombophlebitis, oesophageal varices and nonspecific lymphadenitis peaked when PET was between 0 and −10 °C, while others peaked when PET was between 0 and 10 °C. More medical resources could have been needed on days when PETs were at −10 to 10 °C than on other days. Adaptation to such weather change for health professionals and the general public would seem to be imperative.

Increased usage and discharge of sunscreens have led to ecological safety crisis, and people are developing the advanced oxidation processes (AOPs) to treat them. The present study aimed to determine the degradation efficiency and mechanism of the sunscreen agent p-aminobenzoic acid (PABA) using the UV/Fe²⁺/persulphate (PS) method. A series of irradiation experiments were conducted to optimise the system conditions and to study the impacts of the natural anion. Free radicals and degradation products were identified in order to clarify the degradation mechanism. Initial PS and Fe²⁺ concentrations showed significant impacts on PABA degradation. Natural anions, such as Cl⁻, NO₃ ⁻, H₂PO₄ ⁻ and HCO₃ ⁻, impeded PABA degradation because of ion (Fe²⁺) capture, radical scavenging or pH effects. Hydroxyl (HO·) and sulphate (SO₄ ·⁻) radicals were two main radicals observed in the UV/Fe²⁺/PS system; of these, SO₄ ·⁻ showed greater effects on PABA degradation. Over 99 % of the available PABA was completely degraded into carbon dioxide (CO₂) and water (H₂O) by the UV/Fe²⁺/PS system, and the remaining PABA participated in complex radical reactions. By-products were identified by total ion chromatography and mass spectrometry. Our research provides a treatment process for PABA with high degradation efficiency and environmental safety and introduces a new strategy for sunscreen degradation.

Human activities in the Sabana de Bogotá, Colombia, release toxic metals such as lead (Pb) and chromium (Cr) into the environment polluting the air, water, and soil. Because birds are in contact with these pollutants and their sources, they may serve as bioindicator organisms. We evaluated the use of hummingbird feathers obtained from individuals captured in three sites of the Sabana de Bogotá as bioindicators of toxic metal pollution using spectrophotometric and spectroscopic methods based on single-feather samples. We also characterized the bacterial microbiota associated with hummingbird feathers by molecular identification using the 16S rRNA with a special focus on sporulated bacteria. Finally, we described the interactions which naturally occur among the feathers, their associated bacteria, and pollutants. We found differences in Pb and Cr concentrations between sampling sites, which ranged from 2.11 to 4.69 ppm and 0.38 to 3.00 ppm, respectively. This may reflect the impact of the activities held in those sites which release pollutants to the environment. Bacterial assemblages mainly consisted of sporulated bacilli in the Bacillaceae family (65.7 % of the identified morphotypes). We conclude that the feathers of wild tropical birds, including hummingbirds, can be used as lead and chromium bioindicators and that bacteria growing on feathers may in fact interact with these two toxic metals.

Cadmium (Cd) contamination is a worldwide environmental problem, and remediation of Cd pollution is of great significance for food production as well as human health. Here, the responses of sweet sorghum cv. ‘M-81E’ to cadmium stress were studied for its potential as an energy plant in restoring soils contaminated by cadmium. In hydroponic experiments, the biomass of ‘M-81E’ showed no obvious change under 10 μM cadmium treatment. Cadmium concentration was the highest in roots of seedlings as well as mature plants, but in agricultural practice, the valuable and harvested parts of sweet sorghum are shoots, so promoting the translocation of cadmium to shoots is of great importance in order to improve its phytoremediation capacity. Further histochemical assays with dithizone staining revealed that cadmium was mainly concentrated in the stele of roots and scattered in intercellular space of caulicles. Moreover, the correlation analysis showed that Cd had a negative relationship with iron (Fe), zinc (Zn), and manganese (Mn) in caulicles and leaves and a positive relationship with Fe in roots. These results implied that cadmium might compete with Fe, Zn, and Mn for the transport binding sites and further prevent their translocation to shoots. In addition, transmission electron microscopic observations showed that under 100 μM cadmium treatment, the structure of chloroplast was impaired and the cell wall of vascular bundle cells in leaves and xylem and phloem cells in roots turned thicker compared to control. In summary, morphophysiological characteristic analysis demonstrated sweet sorghum can absorb cadmium and the growth is not negatively affected by mild level cadmium stress; thus, it is a promising material for the phytoremediation of cadmium-contaminated soils considering its economic benefit. This study also points out potential strategies to improve the phytoremediation capacity of sweet sorghum through genetic modification of transporters and cell wall components.

Zebrafish (Danio rerio) embryos and larvae were selected to investigate the potential risk and aquatic toxicity of a widely used pharmaceutical, naproxen. The acute toxicity of naproxen to embryos and larvae was measured, respectively. The histopathology was investigated in the liver of zebrafish larvae after 8-day embryo-larvae exposure to naproxen. The values of 96-h LC₅₀ were 115.2 mg/L for embryos and 147.6 mg/L for larvae, indicating that zebrafish embryos were more sensitive than larvae to naproxen exposure. Large suites of symptoms were induced in zebrafish (D. rerio) early life stages by different dosages of naproxen, including hatching inhibition, lower heart rate, and morphological abnormalities. The most sensitive sub-lethal effect caused by naproxen was pericardial edema, the 72-h EC₅₀ values of which for embryos and larvae were 98.3 and 149.0 mg/L, respectively. In addition, naproxen-treated zebrafish larvae exhibited histopathological liver damage, including swollen hepatocytes, vacuolar degeneration, and nuclei pycnosis. The results indicated that naproxen is a potential threat to aquatic organisms.

In this study, nanoscale zerovalent iron (NZVI) immobilized on biomass carbon was used for the high efficient removal of BDE 209. NZVI supported on biomass carbon minimized the aggregation of NZVI particles resulting in the increased reaction performance. The proposed removal mechanism included the adsorption of BDE 209 on the surface or interior of the biomass carbon NZVI (BC-NZVI) particles and the subsequent debromination of BDE 209 by NZVI while biomass carbon served as an electron shuttle. BC-NZVI particles and the interaction between BC-NZVI particles and BDE 209 were characterized by TEM, XRD, and XPS. The removal reaction followed a pseudo-first-order rate expression under different reaction conditions, and the k ₒbₛ was higher than that of other NZVI-supported materials. The debromination of BDE 209 by BC-NZVI was a stepwise process from nona-BDE to DE. A proposed pathway suggested that supporting NZVI on biomass carbon has potential as a promising technique for in situ organic-contaminated groundwater remediation.