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41.
42.
Reductions in global bee populations are threatening the pollination benefits to both the planet and people. Whilst the contribution of bee pollination in promoting sustainable development goals through food security and biodiversity is widely acknowledged, a range of other benefits provided by bees has yet to be fully recognised. We explore the contributions of bees towards achieving the United Nation’s Sustainable Development Goals (SDGs). Our insights suggest that bees potentially contribute towards 15 of the 17 SDGs and a minimum of 30 SDG targets. We identify common themes in which bees play an essential role, and suggest that improved understanding of bee contributions to sustainable development is crucial for ensuring viable bee systems. 相似文献
43.
Jay A. Rosenheim 《Behavioral ecology and sociobiology》1989,25(5):335-348
Summary It has been suggested that parasite pressure favors the evolution of sociality within the Hymenoptera. I analyzed the impact of a chrysidid nest parasite, Argochrysis armilla, on its host, the solitary ground-nesting wasp, Ammophila dysmica, to assess the role of parasitism in favoring two steps towards sociality: aggregated nesting and delayed nest provisioning. The foraging strategy of Argochrysis armilla involves discovering host nests during excavation, learning the locations of discovered nest, and returning to oviposit in nests during nest provisioning; I therefore assessed the influence of host behavior on (1) parasite discovery of nests and (2) parasite oviposition in nests. Significantly fewer parasites discovered host nests that were excavated during the early morning and late afternoon, due to partial asynchrony of host and parasite activity. Nests excavated in areas of low nest density were also less likely to be discovered; use of low density nest sites increased during periods of high parasite activity. Due to a rapidly decelerating rate of parasite recruitment to nests under excavation, the duration of nest digging had only a limited influence on nest discovery by parasites. The probability of parasite oviposition in a host nest was determined by the number of parasites discovering the nest during excavation and by the time between nest excavation and provisioning; delaying nest provisioning reduced the risk of parasite oviposition. Delayed provisionings primarily appeared to be a result of the stochastic process of hunting and prey encounter. The number of provisions placed in a nest (one vs two) had no effect on the probability of nest parasitism. Spatial patterns of parasitism were directly density dependent in 1984 and density independent in 1986. In this system parasite pressure acts against the formation of nesting aggregations and in favor of delayed nest provisioning. The dependence of these results on species-specific aspects of the parasite's foraging strategy and the host's defensive strategy suggests, however, that different parasite species may generate qualitatively different selection pressures, potentially contributing to the diversity of nesting behavior in the Hymenoptera. 相似文献
44.
Male exposure mediated adverse reproductive outcomes in carbon disulphide exposed rayon workers 总被引:2,自引:0,他引:2
Patel KG Yadav PC Pandya CB Saiyed HN 《Journal of environmental biology / Academy of Environmental Biology, India》2004,25(4):413-418
The authors examined 100 carbon disulphide (CS2) exposed male workers who had been employed ten years prior to study were selected for the study. They were virtually obliged to participate in the study by the Medical Labor Inspector and all of them participated voluntary. The aim was to assess the effects of occupational exposure to carbon disulphide concentrations below the threshold limit value (31 mg/m3) on the reproductive functions with special emphasis on miscarriages. Specially, workers history records were build up on number of children, miscarriages and general weakness, mental fatigue etc. It was found that the incidences of number of miscarriages against number of living children correlated well with environmental concentration of CS2. Where the average CS2 levels were 1.695 ppm, the incidences of miscarriages was 5.71% (group 1). Where as in group 2 environmental concentrations were 12.28 ppm and the incidences of miscarriages were 18.91%. It was also found that in the spinning department the exposure exceeds many times the Threshold Limit Values (TL V). 相似文献
45.
Laboratory and modeling studies were conducted to assess the potential performance of a permeable reactive barrier constructed of a natural zeolite material at the West Valley Demonstration Project in western New York State. The results of laboratory column tests indicated that the barrier material would be effective at removing strontium from groundwater under natural gradient conditions. Two one-dimensional contaminant transport models were developed to interpret the data. A single-solute retardation factor model provided good agreement with the column test data, but time-consuming extraction and analysis of the zeolite material was required to parameterize the model. A preliminary six-solute model was also developed based on the assumption of competitive cation exchange as the primary removal mechanism. Both models yielded similar predictions of the long-term performance of the barrier, but the cation exchange model predicted higher effluent concentrations during the first 1000 pore volumes of operation. The cation exchange framework has several advantages, including the ability to calibrate the model using only data from column effluent samples, and the ability to account for site-specific differences in the groundwater cation composition. However, additional laboratory work is needed to develop a suitably robust model. 相似文献
46.
John T Novak Gregory Adams Yen-Chih Chen Zeynep Erdal Robert H Forbes Dietmar Glindemann J Ronald Hargreaves Lawrence Hentz Matthew J Higgins Sudhir N Murthy Jay Witherspoon 《Water environment research》2006,78(8):821-827
Eleven dewatered sludge cakes collected from anaerobic digesters at different treatment plants were evaluated for the amount, type, and pattern of odorous gas production. All but one of the sludge cakes were from mesophilic anaerobic digesters. One was from a thermophilic digester. The pattern and quantities of sulfur gases were found to be unique for each of the samples with regard to the products produced, magnitude, and subsequent decline. The main odor-causing chemicals were volatile sulfur compounds, which included hydrogen sulfide, methanethiol, and dimethyl sulfide. Volatile sulfur compound production peaked in 3 to 8 days and then declined. The decline was a result of conversion of organic sulfur compounds to sulfide. In one side-by-side test, a high-solids centrifuge cake generated more odorous compounds than the low-solids centrifuge cake. The data show that anaerobic digestion does not eliminate the odor potential of anaerobically digested dewatered cakes. 相似文献
47.
A mixture of ten metals (As, Cd, Cr, Cu, Fe, Pb, Hg, Ni, Se and Zn) at the Great Lakes Water Quality Objective levels was found to reduce the primary productivity of four cultured freshwater algae (, , and ) as well as natural phytoplankton from Lake Ontario water. The metal mixture also caused a reduction in the reproduction and transport of an amino acid analogue (α-aminoisobutyric acid) by . The depuration and exchange of the amino acid analogue were not affected by the metal mixture. The nitrogenase activity of was, however, reduced in the presence of the metal mixture. 相似文献
48.
Jay S. Gregg Steven J. Smith 《Mitigation and Adaptation Strategies for Global Change》2010,15(3):241-262
As co-products, agricultural and forestry residues represent a potential low cost, low carbon, source for bioenergy. A method
is developed for estimating the maximum sustainable amount of energy potentially available from agricultural and forestry
residues by converting crop production statistics into associated residue, while allocating some of this resource to remain
on the field to mitigate erosion and maintain soil nutrients. Currently, we estimate that the world produces residue biomass
that could be sustainably harvested and converted into nearly 50 EJ yr−1 of energy. The top three countries where this resource is estimated to be most abundant are currently net energy importers:
China, the United States (US), and India. The global potential from residue biomass is estimated to increase to approximately
50–100 EJ yr−1 by mid- to late- century, depending on physical assumptions such as of future crop yields and the amount of residue sustainably
harvestable. The future market for biomass residues was simulated using the Object-Oriented Energy, Climate, and Technology
Systems Mini Climate Assessment Model (ObjECTS MiniCAM). Utilization of residue biomass as an energy source is projected for the next century under different climate
policy scenarios. Total global use of residue biomass is estimated to be 20–100 EJ yr−1 by mid- to late- century, depending on the presence of a climate policy and the economics of harvesting, aggregating, and
transporting residue. Much of this potential is in developing regions of the world, including China, Latin America, Southeast
Asia, and India. 相似文献
49.
J. I. Nirmal Kumar Kanti Patel Rita N. Kumar RohitKumar Bhoi 《Mitigation and Adaptation Strategies for Global Change》2010,15(8):811-824
Reducing carbon emissions from deforestation and degradation in developing countries is of the central importance in efforts to combat climate change. A study was conducted to measure carbon stocks in various land-use systems including forms and reliably estimates the impact of land use on carbon (C) stocks in the forest of Rajasthan, western India (23°3′–30°12′N longitude and 69°30′–78°17′E). 22.8% of India is forested and 0.04% is the deforestation rate of India. In Indian forest sector of western India of Aravally mountain range covered large area of deciduous forest and it’s very helpful in carbon sequestration at global level. The carbon stocks of forest, plantation (reforestation) and agricultural land in aboveground, soil organic and fine root within forest were estimated through field data collection. Results revealed that the amount of total carbon stock of forests (533.64?±?37.54 Mg·ha?1, simplified expression of Mg (carbon) ·ha?1) was significantly greater (P?<?0.05) than the plantation (324.37?±?15.0 Mg·ha?1) and the agricultural land (120.50?±?2.17 Mg·ha?1). Soil organic carbon in the forests (172.84?±?3.78 Mg·ha?1) was also significantly greater (P?<?0.05) than the plantation (153.20?±?7.48 Mg·ha?1) and the agricultural land (108.71?±?1.68 Mg·ha?1). The differences in carbon stocks across land-use types are the primary consequence of variations in the vegetation biomass and the soil organic matter. Fine root carbon was a small fraction of carbon stocks in all land-use types. Most of the soil organic carbon and fine root carbon content was found in the upper 30-cm layer and decreased with soil depth. The aboveground carbon (ABGC): soil organic carbon (SOC): fine root carbon ratios (FRC), was 8:4:1, 4:5:1, and 3:37:1 for the forest, plantation and agricultural land, respectively. These results indicate that a relatively large proportion of the C loss is due to forest conversion to agricultural land. 相似文献
50.
Qiusheng Wu Charles R. Lane Lei Wang Melanie K. Vanderhoof Jay R. Christensen Hongxing Liu 《Journal of the American Water Resources Association》2019,55(2):354-368
In terrain analysis and hydrological modeling, surface depressions (or sinks) in a digital elevation model (DEM) are commonly treated as artifacts and thus filled and removed to create a depressionless DEM. Various algorithms have been developed to identify and fill depressions in DEMs during the past decades. However, few studies have attempted to delineate and quantify the nested hierarchy of actual depressions, which can provide crucial information for characterizing surface hydrologic connectivity and simulating the fill‐merge‐spill hydrological process. In this paper, we present an innovative and efficient algorithm for delineating and quantifying nested depressions in DEMs using the level‐set method based on graph theory. The proposed level‐set method emulates water level decreasing from the spill point along the depression boundary to the lowest point at the bottom of a depression. By tracing the dynamic topological changes (i.e., depression splitting/merging) within a compound depression, the level‐set method can construct topological graphs and derive geometric properties of the nested depressions. The experimental results of two fine‐resolution Light Detection and Ranging‐derived DEMs show that the raster‐based level‐set algorithm is much more efficient (~150 times faster) than the vector‐based contour tree method. The proposed level‐set algorithm has great potential for being applied to large‐scale ecohydrological analysis and watershed modeling. 相似文献