The nematode Caenorhabditis elegans receives increasing attention in sediment ecotoxicology and new toxicity tests with sensitive test parameters are under development. In this study, the motility of C. elegans could be measured for the first time online in sediment, using the Multispecies Freshwater Biomonitor. Whereas single nematodes could not be recorded, groups of 10 nematodes gave typical locomotive signals in different media (water, agar, sediment) with comparable precision and accuracy. The results of this study encourage to develop a new rapid online whole-sediment toxicity test with behaviour as sensitive test parameter. 相似文献
The nematode Caenorhabditis elegans was exposed over a whole fife-cycle (72 h) to several concentrations of 4-nonylphenol (NP; nominal concentrations: 0-350 microg/l). Growth and reproduction of C. elegans were enhanced at NP concentrations of 66 and 40 microg/l, respectively, with effects showing dose-response relationships. These stimulatory effects might be of ecological relevance in benthic habitats, where organisms can be exposed to high concentrations of NP. 相似文献
We analyzed a large dataset to quantify adult annual survival probability and remigration intervals for the Tortuguero, Costa
Rica green turtle population. Annual survival probability was estimated at 0.85 (95% CI 0.75–0.92) using a recovery model
and at 0.85 (95% CI 0.83–0.87) using an open robust design model. The two most common modes of remigration are 2 and 3 years.
Annual survival probability is lower and remigration intervals are shorter than for other green turtle populations. Explanations
for short remigration intervals include reproductive compensation due to historic population declines, availability of better
quality food items, favorable environmental conditions, and short distance to the main foraging grounds. Variation in survival
and remigration intervals have profound consequences for management and life history evolution. The short remigration intervals
of Tortuguero green turtles partly offset mortality caused by turtle fishing in Nicaragua and mean that low juvenile survival
represents a more urgent threat to the population than low adult survival. Low adult survival probability could result in
selective pressure for earlier age at maturity. 相似文献
The effects of solar and artificial ultraviolet radiation on the motility and graviorientation of three strains of the dinoflagellate Prorocentrum were studied. P. micans isolated from the Baltic Sea shows a pronounced negative gravitaxis which switches to a positive one even after short exposure times to either solar or artificial UV irradiation. In constrast P. minimum strains isolated from the Kattegat and the Atlantic coast off Portugal showed only a weak upward orientation. In all three strains the linear swimming velocity decreases after short exposure times and, in addition, the percentage of motile cells in the populations drastically decreases. Removing the ultraviolet component of solar radiation with a cut-off filter prolongs the tolerated exposure times. 相似文献
Forests are one of the most cost-effective ways to sequester carbon today. Here, I estimate the world’s land share under forests required to prevent dangerous climate change. For this, I combine newest longitudinal data of FLUXNET on forests’ net ecosystem exchange of carbon (NEE) from 78 forest sites (N?=?607) with countries’ mean temperature and forest area. This straightforward approach indicates that the world’s forests sequester 8.3 GtCO2year?1. For the 2 °C climate target, the current forest land share has to be doubled to 60.0% to sequester an additional 7.8 GtCO2year?1, which demands less red meat consumption. This afforestation/reforestation (AR) challenge is achievable, as the estimated global biophysical potential of AR is 8.0 GtCO2year?1 safeguarding food supply for 10 billion people. Climate-responsible countries have the highest AR potential. For effective climate policies, knowledge on the major drivers of forest area is crucial. Enhancing information here, I analyze forest land share data of 98 countries from 1990 to 2015 applying causal inference (N?=?2494). The results highlight that population growth, industrialization, and increasing temperature reduce forest land share, while more protected forest and economic growth generally increase it. In all, this study confirms the potential of AR for climate change mitigation with a straightforward approach based on the direct measurement of NEE. This might provide a more valid picture given the shortcomings of indirect carbon stock-based inventories. The analysis identifies future regional hotspots for the AR potential and informs the need for fast and forceful action to prevent dangerous climate change.
Methyl tert-butyl ether (MTBE) and benzene are added to gasoline to improve the combustion process and are found in the urban environment as a consequence of vehicular traffic. Herein we evaluate urinary MTBE (MTBE-U) and benzene (BEN-U) as biomarkers of exposure to urban traffic. Milan urban policemen (130 total) were investigated in May, July, October, and December for a total of 171 work shifts. Personal exposure to airborne benzene and carbon monoxide (CO), and atmospheric data, were measured during the work shift, while personal characteristics were collected by a questionnaire. A time/activity diary was completed by each subject during the work shift. Spot urine samples were obtained for the determination of MTBE-U and BEN-U. Median personal exposure to CO and airborne benzene were 3.3 mg/m(3) and 9.6 μg/m(3), respectively; median urinary levels in end-of-shift (ES) samples were 147 ng/L (MTBE-U) and 207 ng/L (BEN-U). The time spent on traffic duty at crossing was about 40% of work time. Multiple linear regression models, taking into account within-subject correlations, were applied to investigate the role of urban pollution, atmospheric conditions, job variables and personal characteristics on the level of biomarkers. MTBE-U was influenced by the month of sampling and positively correlated to the time spent in traffic guarding, CO exposure and atmospheric pressure, while negatively correlated to wind speed (R(2) for total model 0.63, P<0.001). BEN-U was influenced by the month and smoking habit, and positively correlated to urinary creatinine; moreover, an interaction between CO and smoking was found (R(2)=0.62, P<0.001). These results suggest that MTBE-U is a reliable marker for assessing urban traffic exposure, while BEN-U is determined mainly by personal characteristics. 相似文献
It is necessary to develop a medical waste management system featuring nonburning treatment and safety functions for small
medical institutions. In this article, the development of a waste management system without oxygen injection was achieved
by means of hybrid heating using microwave energy and an electric heater. The shape of the microwave reactor was a rectangular
parallelepiped with a volume of about 0.1 m3. In the experimental setup, microwave energy (2.45 GHz, about 800 W) was injected from the top of the reactor, while the
heater (about 1 kW) was located at the bottom. Heat insulators were set into all the walls of the reactor. The gases generated
in the system were vented through water and activated carbon. Five paper-based diapers with absorbed water were used as the
waste sample. For the evaluation of performance, the reduction rate was defined as the ratio (in percent) of the weight before
and after treatment. The reduction rate as a function of treatment time and the effect of the position of the waste in the
reactor on the reduction rate and the uniformity of treatment were examined for about 3 kg of waste. It was found that the
reduction rate reached as low as 4.2% at 3 h and then 3% after 8 h. The treated profile strongly depended on the position
of the waste in the reactor. In particular, it was clarified that a metal cylindrical enclosure and a needle electrode played
an important role in attaining uniform treatment of the waste. 相似文献