Two processes are currently being employed in North America for the desulfurization of coke oven gas, the Vacuum Carbonate System, and the Stretford System. A third, the Sulfi-ban Process, which was recently announced, now has several plants scheduled for construction. Overall operating requirements for each of these processes are considered in detail. Emphasis is placed on an identification of power and steam requirements, the types and amounts of solid and/or liquid waste streams produced together with methods for their treatment, and the net desulfurization efficiencies achieved by each process. Detailed estimates of capital and operating costs for desulfurization are considered, and equipment needs for environmental control requirements are discussed. 相似文献
The cardinalfish Siphamia versicolor (Perciformes: Apogonidae) forms a bioluminescent symbiosis with the marine luminous bacterium Photobacterium mandapamensis, harboring the bacteria in a ventral, disc-shaped light organ and using the bacterial light apparently for counterillumination
and attracting prey. Little definitive information has been available on the developmental and microbiological events surrounding
the initiation of symbiosis, a critical stage in the life history of the fish, in S.versicolor or any of the many other species of bacterially luminous fish. To identify the stage at which light organ formation begins,
to determine the origin of cells forming the light organ, and to characterize its bacterial colonization status during development,
early developmental stages of S.versicolor obtained and reared from wild-caught mouth-brooding males were examined with histological and microbiological methods. A
light organ primordium was not evident in embryos, post-embryos, or pre-release larvae, whereas the light organ began to form
within 1 day of release of full-term pre-flexion larvae from the mouths of male fish. Analysis of post-release larvae revealed
that the light organ arises from a proliferation and differentiation of intestinal epithelial cells, and that it quickly develops
structural complexity, including the formation of chambers and gaps contiguous with the intestinal epithelium. However, the
nascent light organ remained uncolonized by the symbiotic bacteria through several days of post-release development, even
in the presence of high numbers of the symbiotic bacteria. These results demonstrate that the inception of light organ formation
in S.versicolor occurs independently of its symbiotic bacteria and that receptivity to bacterial colonization apparently requires substantial
post-release development of the light organ. Larvae therefore most likely acquire their symbiotic bacteria from seawater,
during or shortly after the transition from the pre-flexion to the flexion developmental stage. 相似文献
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
From September to November 1991, UV-absorbing mycosporine-like amino acids (MAAs) were monitored in a natural population of
the sea urchin Sterechinusneumayeri from a coastal area of Anvers Island (Antarctic Peninsula). MAA concentrations were determined for specific tissues (gonad,
digestive tract and body wall) from adults collected at four depths (intertidal, 8, 15 and 24 m). Four MAAs were identified:
mycosporine-glycine, shinorine, porphyra-334 and paly-thine. Concentrations of MAAs among replicate individuals varied considerably.
Ovaries had high concentrations of MAAs (84 to 1389 μg g−1 dry wt), while testes had non-detectable levels. The relative abundance of specific MAAs in ovaries appeared to be related
to the spawning cycle. Digestive-tract samples had MAA concentrations as high as 3000 μg g−1 dry wt, but the mean MAA content in intertidal individuals decreased by 70% over 3 mo during spring. The body walls of sea
urchins had very low amounts of MAAs (≤ 0.08 μg g−1 dry wt). There were significant depth differences in the␣total MAA content of the ovary ( p <0.001), ( p <0.015), digestive tract ( p <0.001), and body wall with organisms from the intertidal and 8 m depth having the highest concentrations of MAAs. Biological
dosimetry indicated that UV-B (280 to 320 nm) wavelengths penetrated 3 to 7 m below the sea ice during the study period. The
total MAA content in ovaries decreased with depth on all sample dates; however, the MAA content of the digestive tract and
body wall did not exhibit a consistent pattern of change with depth. The MAA content of tissues did not change significantly
with the temporal gradient of light exposure that was established by both ozone depletion and increasing photoperiod, except
in the digestive tract sampled from intertidal specimens. Adult urchins are probably well-protected from UV exposure by the
water column and a calcareous test; however, the results of this study suggest that, even under ice cover, depth of habitation
is a determinant of MAA content in S. neumayeri. Large daily and seasonal fluctuations in the light regime, which are characteristic of Antarctic coastal environments, apparently
do not provide reliable cues to elicit a detectable, temporal, biochemical response.
Received: 19 February 1997 / Accepted: 26 March 1997 相似文献
Across the western United States, environmental water transaction programs (EWTPs) restore environmental flows by acquiring water rights and incentivizing changes in water management. These programs have evolved over several decades, expanding from relatively simple two‐party transactions to multiobjective deals that simultaneously benefit the environment and multiple water‐using sectors. Such programs now represent an important water management tool and provide an impetus for collaboration among stakeholders; yet, most evaluations of their effectiveness focus exclusively on environmental outcomes, without adequate attention to impacts on other water users or local economies. To understand how these programs affect stakeholders, a systematic, multiobjective evaluation framework is needed. To meet this need, we developed a suite of environmental and socioeconomic indicators that can guide the design and track the implementation of water transaction portfolios, and we applied them to existing EWTPs in Oregon and Nevada. Application of the indicators quantifies impacts and helps practitioners design water transaction portfolios that avoid unintended consequences and generate mutually beneficial outcomes among environmental, agricultural, and municipal interests. 相似文献
Photocatalytic membranes reactors have become one of the most efficient technologies to treat polluted waters. However, a major drawback is the unilateral irradiation of the membrane, where only one side of the membrane is exploited. To overcome this issue, we developed a reactor where the membrane can be irradiated on both sides. Polyacrylonitrile membranes containing different amounts of TiO2 nanoparticles up to 60% were first prepared by electrospinning. These membranes were used in a 3D-printed crossflow photocatalytic membrane reactor for the degradation of methylene blue under different combinations of lights. The use of both sides of the photocatalytic membrane significantly enhanced the photocatalytic activity for the decolorization of methylene blue in water. The prepared membranes showed the best decolorization rate for a loading of 60% of TiO2 and the use of dual ultraviolet lights, where the methylene blue solution was completely discolored after 90 min. This is the first report of a such system configuration, and this new irradiation concept is promising for photocatalytic membrane reactions and water cleaning.
Three new modes of luminescence are described for Gazza minuta (Bloch) (Perciformes: Leiognathidae) as observed in specimens collected in the Philippines in April and May, 1982: discrete projected luminescence (DPL), ventral body flash, and buccal luminescence. DPL sharply contrasts with previously reported modes of diffuse luminescence in leiognathids (counterillumination and opercular flash) in being a pair of bright collimated beams of light emanating from the fish in an anteroventral direction. The brightness, coherence, directionality, and control of DPL suggest striking similarities to luminescence in anomalopid (flashlight) and monocentrid (pinecone) fishes and perhaps in certain apogonids (cardinalfishes). The structural correlate for DPL is a small clear patch of skin lying at the posterior margin of each opercular cavity. Luminescence from the internally located light organ traverses transparent bone and translucent muscle before passing through the clear skin of the patch area. Behavioral and anatomical observations of ventral body flash and buccal luminescence are also presented. These new modes of luminescence indicate a much greater than expected diversity of luminescent behaviors in leiognathids, perhaps greater than that of any other organism yet studied. The internal location of the light organ is recognised as providing the potential for this diversity. 相似文献
There is a strong political divide on climate change in the US general public, with Liberals and Democrats expressing greater belief in and concern about climate change than Conservatives and Republicans. Recent studies find a similar though less pronounced divide in other countries. Its leadership in international climate policy making warrants extending this line of research to the European Union (EU). The extent of a left–right ideological divide on climate change views is examined via Eurobarometer survey data on the publics of 25 EU countries before the 2008 global financial crisis, the 2009 ‘climategate’ controversy and COP-15 in Copenhagen, and an increase in organized climate change denial campaigns. Citizens on the left consistently reported stronger belief in climate change and support for action to mitigate it than did citizens on the right in 14 Western European countries. There was no such ideological divide in 11 former Communist countries, likely due to the low political salience of climate change and the differing meaning of left–right identification in these countries. 相似文献
ABSTRACT. This paper describes the meteorological patterns that produced the combination of heavy rains in August 1971 that resulted in record floods in New Jersey. Daily and hourly precipitation data and selected recurrence frequencies of rainfall amounts are tabulated. History of previous heavy rainfalls in New Jersey indicates that occurrences of very heavy rains are frequently associated with tropical disturbances. Flood damages, fatalities, warnings issued and areas of record river stages are summarized. 相似文献