خيارات البحث
النتائج 4271 - 4280 من 4,309
Simulating changes in cropping practices in conventional and glyphosate-resistant maize. II. Weed impacts on crop production and biodiversity النص الكامل
2017
Colbach, Nathalie | Darmency, Henri | Fernier, Alice | Granger, Sylvie | Le Corre, Valérie | Messéan, Antoine
Overreliance on the same herbicide mode of action leads to the spread of resistant weeds, which cancels the advantages of herbicide-tolerant (HT) crops. Here, the objective was to quantify, with simulations, the impact of glyphosate-resistant (GR) weeds on crop production and weed-related wild biodiversity in HT maize-based cropping systems differing in terms of management practices. We (1) simulated current conventional and probable HT cropping systems in two European regions, Aquitaine and Catalonia, with the weed dynamics model FLORSYS; (2) quantified how much the presence of GR weeds contributed to weed impacts on crop production and biodiversity; (3) determined the effect of cultural practices on the impact of GR weeds and (4) identified which species traits most influence weed-impact indicators. The simulation study showed that during the analysed 28 years, the advent of glyphosate resistance had little effect on plant biodiversity. Glyphosate-susceptible populations and species were replaced by GR ones. Including GR weeds only affected functional biodiversity (food offer for birds, bees and carabids) and weed harmfulness when weed effect was initially low; when weed effect was initially high, including GR weeds had little effect. The GR effect also depended on cultural practices, e.g. GR weeds were most detrimental for species equitability when maize was sown late. Species traits most harmful for crop production and most beneficial for biodiversity were identified, using RLQ analyses. None of the species presenting these traits belonged to a family for which glyphosate resistance was reported. An advice table was built; the effects of cultural practices on crop production and biodiversity were synthesized, explained, quantified and ranked, and the optimal choices for each management technique were identified.
اظهر المزيد [+] اقل [-]Marine Litter quantities on six Beaches of northern Svalbard in 2016 determined by citizen scientists النص الكامل
2017
Bergmann, Melanie | Gutow, Lars
Beaches on remote Arctic islands may be sinks for marine litter and reflect pollution levels of the surrounding waters particularly well. We provide the first quantitative data from surveys carried out by citizen scientists on six beaches of northern Svalbard. Litter quantities recorded by cruise tourists varied from 9-524 g m-2 and were similar to those from densely populated areas. Plastics accounted for >80% of the overall litter, most of which originated from fisheries. Our study highlights the potential of citizen scientists to provide scientifically valuable data on the pollution of sensitive remote ecosystems. The results stress once more that current legislative frameworks are insufficient to tackle the pollution of Arctic ecosystems.
اظهر المزيد [+] اقل [-]Organophosphorus flame retardants and plasticizers in water samples of the Rhine, Ems and Elbe Rivers in 2013 النص الكامل
2017
Wolschke, Hendrik | Sühring, Roxana | Xie, Zhiyong | Ebinghaus, Ralf
This study reports the occurrence and distribution of organophosphorus flame retardants and plasticizers (OPEs) in the Elbe and Rhine rivers. A special focus of this investigation concerns the potential impacts of a major flood event in 2013 on the OPE patterns and levels in the Elbe River. In this river, 6 of 13 OPEs were detected, with tris-ethyl-phosphate (TEP, 168 ± 44 ng/L), tris-1,3-dichloro-2-propyl-phosphate (TDCPP, 155 ± 14 ng/L) and tris-1-chloro-2-propyl phosphate (TCPP, 126 ± 14 ng/L) identified as the dominant compounds. Relative to previous studies, an increase in the concentrations and relative contributions of TDCPP to the total level of OPEs was observed, which was likely caused by its increased use as a replacement for the technical pentaBDE formulation. During the flood event, the concentrations of OPEs were similar to the normal situation, but the mass fluxes increased by a factor of approximately ten (~16 kg/d normal versus ~160 kg/d flood peak). No input hotspots were identified along the transects of the Elbe and Rhine rivers, and the mass flux of OPEs appeared to be driven by water discharge.
اظهر المزيد [+] اقل [-]Water pollution from agriculture: a global review. Executive summary
2017
Mateo-Sagasta, Javier | Zadeh, S.M. | Turral, Hugh | Burke, J.
Micro-fibre content of South Africa's sandy beach sediments from 2016 to 2017 النص الكامل
2017
de Villiers, Stephanie
In 2016 and 2017 the Department of Environmental Affairs conducted sampling at more than 150 sandy beach sites along the South African coastline, to quantify the extent of micro-plastic pollution at an average spatial sampling scale of about 15 km. Most of the sites along the west coast were sampled 3 times, to investigate seasonal variability. The east and south coasts were sampled twice, during low and higher river runoff conditions, respectively. At all sites, plastic micro-fibres were found to be the dominant micro-plastic constituents present, and the quantitative data for that is presented in this dataset. One of the problematic issues related to comparison of global micro-plastic pollutant levels, presently, is the lack of agreed to measurement methodologies and reporting units. This dataset represents results for samples taken along the high-level water mark, as a composite sample of about 1 L consisting of aliquots taken from at least 3 different sampling spots, sampled to a depth of 5 cm. The micro-fibre count is reported as the number of fibres per liter (or #F/dm3). In order to convert this to other units for comparison with other studies, sediment dry bulk density measurements are included. Data is also provided for the dominant sediment grain size (fine sand is 63 to 250 µm, and medium-coarse sand 250 µm to 1 mm) , and the temperature and salinity of surf-zone water at the time of sampling.
اظهر المزيد [+] اقل [-]Policy augmented scaling model for a fully validated CSAP-the happy seeder technology to curb air pollution and build resilience.
2017
CGIAR Research Program on Climate Change, Agriculture and Food Security
Innovation made in interest of sustainable development is transformed as scalable practice through business model underpinned by national policy. It has led to continuously improved value to services and product adapted to dynamic climate challenges. Residue burning has sensitized the public-private institutes to collaborate and pool national resources for scaling
اظهر المزيد [+] اقل [-]Smog in our brains: Gender differences in the impact of exposure to air pollution on cognitive performance in China
2017
Chen, Xi | Zhang, Xiaobo | Zhang, Xin
While there is a large body of literature on the negative health effects of air pollution, there is much less written about its effects on cognitive performance for the whole population. This paper studies the effects of contemporaneous and cumulative exposure to air pollution on cognitive performance based on a nationally representative survey in China. By merging a longitudinal sample at the individual level with local air-quality data according to the exact dates and counties of interviews, we find that contemporaneous and cumulative exposure to air pollution impedes both verbal and math scores of survey subjects. Interestingly, the negative effect is stronger for men than for women. Specifically, the gender difference is more salient among the old and less educated in both verbal and math tests.
اظهر المزيد [+] اقل [-]Smog in our brains: Gender differences in the impact of exposure to air pollution on cognitive performance in China النص الكامل
2017
Chen, Xi | Zhang, Xiaobo | Zhang, Xin
While there is a large body of literature on the negative health effects of air pollution, there is much less written about its effects on cognitive performance for the whole population. This paper studies the effects of contemporaneous and cumulative exposure to air pollution on cognitive performance based on a nationally representative survey in China. By merging a longitudinal sample at the individual level with local air-quality data according to the exact dates and counties of interviews, we find that contemporaneous and cumulative exposure to air pollution impedes both verbal and math scores of survey subjects. Interestingly, the negative effect is stronger for men than for women. Specifically, the gender difference is more salient among the old and less educated in both verbal and math tests.
اظهر المزيد [+] اقل [-]Upscaling the pollutant emission from mixed recycled aggregates under compaction for civil applications النص الكامل
2017
Pérez Galvín, Adela | Ayuso Muñoz, Jesús | Barbudo Muñoz, M. Auxiliadora | Cabrera, Manuel | López Uceda, Antonio | Rosales, Julia
In general terms, plant managers of sites producing construction wastes assess materials according to concise, legally recommended leaching tests that do not consider the compaction stage of the materials when they are applied on-site. Thus, the tests do not account for the real on-site physical conditions of the recycled aggregates used in civil works (e.g., roads or embankments). This leads to errors in estimating the pollutant potential of these materials. For that reason, in the present research, an experimental procedure is designed as a leaching test for construction materials under compaction. The aim of this laboratory test (designed specifically for the granular materials used in civil engineering infrastructures) is to evaluate the release of pollutant elements when the recycled aggregate is tested at its commercial grain-size distribution and when the material is compacted under on-site conditions. Two recycled aggregates with different gypsum contents (0.95 and 2.57%) were used in this study. In addition to the designed leaching laboratory test, the conventional compliance leaching test and the Dutch percolation test were performed. The results of the new leaching method were compared with the conventional leaching test results. After analysis, the chromium and sulphate levels obtained from the newly designed test were lower than those obtained from the conventional leaching test, and these were considered more seriously pollutant elements. This result confirms that when the leaching behaviour is evaluated for construction aggregates without density alteration, crushing the aggregate and using only the finest fraction, as is done in the conventional test (which is an unrealistic situation for aggregates that are applied under on-site conditions), the leaching behaviour is not accurately assessed.
اظهر المزيد [+] اقل [-]