Low concentration effects and different outcome in repeated reproduction tests with silver nanoparticles, silver nitrate and Folsomia candida (Collembola)

Background Toxicity of silver nanoparticles (AgNP) has been studied frequently due to a rise in application in various products. Various studies on AgNP toxicity with terrestrial and aquatic organisms confirmed their negative effects. In our previous experiments, strong variability was observed in the reproduction of Collembola (Folsomia candida) in different repeats. To investigate the effects of silver on the reproduction of Folsomia candida, they were exposed in laboratory-controlled conditions to AgNP and silver nitrate (AgNO3) at a concentration of 30 mg/kg dry soil for 28 days and compared to controlled individuals not exposed to silver. We repeated reproduction tests on the toxicity of silver to Folsomia candida four times throughout one year (April, July, October and January) in order to explore the temporal variability of their outcome. Results While adult survival was similar in all treatments and seasons, reproduction in the control increased from April to October. Significantly lower reproduction was found in January with only 385–424 juveniles per vessel, compared to 504–633 individuals in other months. Strong toxic effects of both silver treatments were observed in July, April and October. However, AgNP showed no toxic effects on the reproduction of F. candida in January. The relative toxicity of both substances varied between single experiments: AgNP were more toxic than AgNO3 in April and July, and less toxic in October and January. Conclusion These findings indicate that the reproduction of F. candida in the control had a significant effect on the results of the toxicology experiments. Moreover, we demonstrated the reproductive toxicity of AgNP in soil at a much lower concentration than reported thus far. Therefore, to guarantee reliability and reproducibility, we recommend to disregard any test results where the reproduction rate of F. candida in the control is significantly different from the average in the respective laboratory, even if the validity criteria of the test are met.

Seasonal effects on the outcome of reproduction tests with silver nanoparticles, silver nitrate and the Collembola Folsomia candida

Background Toxicity of silver nanoparticles (AgNP) is increasingly studied due to a rise in application in various products. Various studies on AgNP toxicity with terrestrial and aquatic organisms confirmed their negative effects. In our previous experiments, strong variability was observed in the reproduction of Collembola in different seasons. To investigate the effects of silver nanoparticles (AgNP) on the reproduction of Collembola in different seasons, Folsomia candida were exposed to AgNP and silver nitrate (AgNO 3 ) at a concentration of 30 mg/kg dry soil for 28 days. The reproduction tests were repeated during different seasons throughout one year in order to assess if animals’ sensitivity varied with the season. Results Significantly lower reproduction was found in the control in winter with only 101 (± 7) juveniles per adult, compared to 126-158 individuals in other seasons. Strong toxic effects (inhibition of reproduction by up to 50%) were observed during summer, spring and autumn in both treatments. However, AgNP showed no toxic effects on the reproduction of F. candida in winter. The relative toxicity of both substances varied with the seasons: AgNP were more toxic than AgNO 3 in spring and summer, and less toxic in autumn and winter. Conclusion These findings indicate that seasonal effects on the reproduction of Folsomia candida are significant. Moreover, we demonstrated the reproductive toxicity of AgNP in soil at a much lower concentration than reported thus far. These effects can mainly be attributed to soil conditions, which raises concern whether these commonly used test substrates are really protective.

Ecotoxicity test as an aid in the determination of copper guideline values in soils

ABSTRACT: The process of identifying a contaminated area involves a preliminary assessment consisting of chemical analysis and comparison with guideline values. In Brazil, these values are included in the CONAMA Resolution no. 420/2009, based on chemical analysis and phytotoxicity. The objective of this research was to evaluate the ecotoxicity of copper in two natural soils in the state of Rio de Janeiro, a Haplic Planosol (sandy) and a Red-Yellow Argisol (medium texture), to verify if the values established by the legislation offer protection to the soil fauna. Lethality and reproduction tests were performed with Eisenia andrei worms and Folsomia candida springtails. Results indicated copper values in Planosol as LC50 435 mg kg 1 and EC50 29 mg kg 1 for E. Andrei and LC10 137 mg kg 1 and EC50 117 mg kg 1 for F. candida. In Argisol, these results were LC50 690 mg kg 1 and EC50 61 mg kg 1 for E. andrei, and LC10 42 mg kg 1 and EC50 138 mg kg 1 for F. candida. Values reported are lower than the research value (200 mg kg-1) established by the CONAMA resolution 420/09, indicating that concentrations lower than the limit values may affect these organisms, depending on the type of soil. Worms were more sensitive than springtails to copper contamination, and sandy soil was more susceptible to ecotoxicity due to copper contamination, probably due to the greater bioavailability of the metal. Results of such ecotoxicity tests should be considered in the development of soil guideline values.

The ecological risk assessment of soil contamination with Ti and Fe at military sites in Ukraine: avoidance and reproduction tests with Folsomia candida

The aim of this research was to assess the effect of soil contamination with titanium (Ti) and iron (Fe) at military sites in Ukraine using the avoidance and reproduction tests with Folsomia candida (springtail). The soil used for the tests was sampled in 2017 from Dolyna, Ivano-Frankivsk region, Ukraine from two plots, namely a contaminated and a control site. The sample site is a former military site previously used for tank training. At the control site mainly the concentrations of Ti and Fe were exceeded. The control soil was free from contamination. The avoidance test and reproduction test were conducted with the use of springtail species F. candida. The following nine levels of contamination with heavy metals were established: 1%, 1.5%, 5%, 10%, 15%, 25%, 50%, 75% and 100%. The duration of the avoidance test was 7 days, and that of the reproduction test was 28 days. Overall, the results show that the avoidance and reproduction tests with collembolans have the potential to be used as screening tools in an ecological risk assessment of heavy metals. In the avoidance test, the concentrations from 1.5 to 100% significantly decreased the number of F. candida in the contamination site in comparison to the control site. At the same time, avoidance was not observed in the first concentration (1%). According to the reproduction test, the negative effect on the number of F. candida juveniles was observed beginning at the 10% dose. The half maximal effective concentration (EC50) for the avoidance test was 50.12%, while that for the reproduction test was 22.39%. The contamination with heavy metals at the military areas indicated the short- and long-term toxicity risk on the springtail F. candida.

An Improved Multipath Routing Scheme using Virtual Network Path Migration

Virtual Network Functions (VNFs) situation and tying within the sight of physical connection disappointments. A steering convention's duty lie s in deciding the manner in which switches speak with one another so as to advance any sort of bundles from a source to a goal utilizing the ideal way that would give the most proficiency. Continuous basic interactive media requires effective steering for information conveyance with ensured QoS fulfilling the stringent QoS prerequisites of sight and sound transmission for the most part means high vitality utilization. We propose a jump by-bounce dynamic disseminated directing plan for the execution of this system wide enhancement issue. The calculation created in this paper is gives multipath directing, uses every conceivable edge, ensures recuperation from single connection disappointment and accomplishes all these with at most one piece for every bundle as overhead while steering depends on goal address and approaching edge. The proposed calculation designs vitality mindful bunch comprising of one header hub and various part hubs. The Software Defined Networking (SDN) can possibly empower dynamic setup and control for the improved system the executives. This document introduces the plan of a virtualization organizer dependent on system strategy in SDN conditions. The proposed novel directing calculations for diminishing the vitality utilization of optical systems to rest cycle conventions in favor of utilize in the system hubs. Vitality Aware visual system conventions can affect the Quality-of-Services-(QoS), for example, bit-blunder-rate (BER) and postponement. Our reproduction tests demonstrate that way part, way relocation, and tweaked implanting calculations empower a substrate system to fulfill a lot bigger blend of virtual systems