Παρασκευή 30 Ιουνίου 2017
Effects of biotic and abiotic factors on the temporal dynamic of bat-fruit interactions
Source:Acta Oecologica, Volume 83
Author(s): Rafael de Souza Laurindo, Renato Gregorin, Davi Castro Tavares
Mutualistic interactions between animals and plants vary over time and space based on the abundance of fruits or animals and seasonality. Little is known about this temporal dynamic and the influence of biotic and abiotic factors on the structure of interaction networks. We evaluated changes in the structure of network interactions between bats and fruits in relation to variations in rainfall. Our results suggest that fruit abundance is the main variable responsible for temporal changes in network attributes, such as network size, connectance, and number of interactions. In the same way, temperature positively affected the abundance of fruits and bats. An increase in temperature and alterations in rainfall patterns, due to human induced climate change, can cause changes in phenological patterns and fruit production, with negative consequences to biodiversity maintenance, ecological interactions, and ecosystem functioning.
from Environmental Medicine via xlomafota13 on Inoreader http://ift.tt/2sbhFYC
via IFTTT
Evaluating the performance and intellectual structure of construction and demolition waste research during 2000–2016
Abstract
Construction and demolition (C&D) waste diminishes scarce land resources and endangers human health and the surrounding environment. Quantitative and visualized analysis was conducted to evaluate worldwide scientific research output on C&D waste from 2000 to 2016. The related information of 857 publications was collected from SCI-Expanded database and statistically analyzed. The number of documents about C&D waste presented a general growth during the last 17 years. Construction and Building Materials publication ranked first in the most productive journals. China and Spain acted as dominated roles comparing to other countries, and Hong Kong Polytechnic University was the institution with the largest amount of C&D waste research. Recycled aggregates, sustainable C&D waste management, and the rewarding program and commerce system were the hottest topics during 2000–2016 and in the near future according to the intellectual structure analysis.
from Environmental Medicine via xlomafota13 on Inoreader http://ift.tt/2t1atkA
via IFTTT
Occurrence, distribution, and risk assessment of antibiotics in the Songhua River in China
Abstract
The occurrence, distribution, and risk assessment of antibiotics in freshwater systems are receiving global attention, because of their impact on the environment and human health. However, few studies have focused on this topic in Northeast China and its Songhua River, the third-largest river in China. This study investigated the occurrence and distribution of 12 antibiotics, including three cephalosporins (cefazolin, cefmetazole, cefotaxime), three macrolides (azithromycin, clarithromycin, roxithromycin), three fluoroquinolones (ofloxacin, norfloxacin, flumequine), and three sulfonamides (sulfadiazine, sulfapyridine, sulfamethoxazole) in the mainstream and tributaries of the Songhua River. A total of 152 surface water samples were collected in January, May, July, and October 2016. These samples were analyzed using solid-phase extraction (SPE) and ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The results indicated the wide use of all 12 antibiotics in the mainstream of the Songhua River. Sulfamethoxazole and cefazolin were the dominant antibiotics, with maximum concentrations of 73.1 and 65.4 ng L−1, respectively. Other antibiotics were present at mean concentrations below 15 ng L−1, except cefmetazole, present at a mean concentration of 35.6 ng L−1. The spatial distribution of antibiotics showed that unbalanced regional development may lead to the distribution pattern of the antibiotics in the tributaries and the mainstream. Thus study also assessed the seasonal variation of antibiotics in urban surface water; cephalosporin, sulfonamide, fluoroquinolone, and macrolide concentrations were significantly higher during the icebound season than during non-icebound season. This may be due to the low temperature and water flow of the river in winter. Risk assessment showed that azithromycin, clarithromycin, roxithromycin, flumequine, and sulfamethoxazole posed a low or median risk to the aquatic organisms in the mainstream. The potential risks created by antibiotics to the aquatic environment should not be neglected in the Songhua River. The potential risks created by antibiotics to the aquatic environment should not be neglected in the Songhua River.
from Environmental Medicine via xlomafota13 on Inoreader http://ift.tt/2swbiym
via IFTTT
Phytoremediation of cadmium-polluted soil by Chlorophytum laxum combined with chitosan-immobilized cadmium-resistant bacteria
Abstract
This study examined the performance of the chitosan-immobilized cadmium-resistant bacteria Arthrobacter sp. and Micrococcus sp. on cadmium phytoremediation by Chlorophytum laxum in cadmium-polluted soil. These immobilized cadmium-resistant bacteria can survive in cadmium-contaminated soil and significantly increased soil cadmium solubility, but the ability of chitosan-immobilized cells to increase cadmium solubility was lower than that of free cells. A pot experiment demonstrated that chitosan-immobilized Micrococcus sp. promoted the growth of C. laxum planted in cadmium-contaminated soil. A significant increase in the cadmium concentration in the roots and aboveground parts of C. laxum was found in plants inoculated with free and chitosan-immobilized cells of these bacteria. The performance of Arthrobacter sp. free cells to augment cadmium accumulation in C. laxum was a little bit better than that of chitosan-immobilized Arthrobacter sp., except at 9 weeks after planting. The phytoextraction coefficient, bioaccumulation factor, and translocation factor of C. laxum inoculated with free and chitosan-immobilized cells of cadmium-resistant bacteria were higher than those of the uninoculated control and increased with time. Our findings suggest that chitosan-immobilized cells can be exploited to enhance the efficiency of cadmium phytoremediation by C. laxum.
from Environmental Medicine via xlomafota13 on Inoreader http://ift.tt/2t0Kp94
via IFTTT
Effects of low doses of glyphosate on DNA damage, cell proliferation and oxidative stress in the HepG2 cell line
Abstract
We studied the toxic effects of glyphosate in vitro on HepG2 cells exposed for 4 and 24 h to low glyphosate concentrations likely to be encountered in occupational and residential exposures [the acceptable daily intake (ADI; 0.5 μg/mL), residential exposure level (REL; 2.91 μg/mL) and occupational exposure level (OEL; 3.5 μg/mL)]. The assessments were performed using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell proliferation, alkaline comet assay and cytokinesis-block micronucleus (CBMN) cytome assay. The results obtained indicated effects on cell proliferation, both at 4 and 24 h. The levels of primary DNA damage after 4-h exposure were lower in treated vs. control samples, but were not significantly changed after 24 h. Using the CBMN assay, we found a significantly higher number of MN and nuclear buds at ADI and REL after 4 h and a lower number of MN after 24 h. The obtained results revealed significant oxidative damage. Four-hour exposure resulted in significant decrease at ADI [lipid peroxidation and glutathione peroxidase (GSH-Px)] and OEL [lipid peroxidation and level of total antioxidant capacity (TAC)], and 24-h exposure in significant decrease at OEL (TAC and GSH-Px). No significant effects were observed for the level of reactive oxygen species (ROS) and glutathione (GSH) for both treatment, and for 24 h for lipid peroxidation. Taken together, the elevated levels of cytogenetic damage found by the CBMN assay and the mechanisms of primary DNA damage should be further clarified, considering that the comet assay results indicate possible cross-linking or DNA adduct formation.
from Environmental Medicine via xlomafota13 on Inoreader http://ift.tt/2sw5EfG
via IFTTT