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21.
22.
Melbourne Water's Eastern Treatment Plant (ETP) produces a secondary-treated sewage effluent which is chlorinated and discharged into Bass Strait at Boags Rocks, Victoria, Australia. Disappearance of the sensitive brown seaweed Hormosira banksii from rock platforms immediately adjacent to the shore-line discharge was identified in the early 1990s. Subsequently, Melbourne Water and CSIRO undertook an environmental impact assessment and review of land and marine effluent disposal options, which included ambient water quality monitoring, biological monitoring, bioaccumulation studies and toxicity testing of existing effluent to assess the nature and magnitude of the environmental effects. This paper presents data from the toxicity monitoring programs since 2001. Chronic toxicity testing using macroalgal germination and cell division (H. banksii), microalgal growth rate (Nitzschia closterium) and scallop larval development (Chlamys asperrima), confirmed that ammonia was the major cause of effluent toxicity. Results from this toxicity monitoring program were used to develop action trigger values for toxicity for each species, which were then used in a refined monitoring program in 2005-2007. An upgrade of the ETP is in progress to improve nitrification/denitrification in order to reduce ammonia concentrations and the toxicity of the effluent. Toxicity testing with a simulated upgraded effluent confirmed that ammonia concentrations and toxicity were reduced. Estimated "safe" dilutions of effluent, calculated using species sensitivity distributions, decreased from 1:140-300 for existing ETP effluent to 1:20 for nitrified effluent, further confirming that treatment improvements should reduce the impact on marine biota in the vicinity of the discharge. 相似文献
23.
Effect of moisture content on ammonia emissions from broiler litter: A laboratory study 总被引:3,自引:0,他引:3
Zifei Liu Lingjuan Wang David Beasley Edgar Oviedo 《Journal of Atmospheric Chemistry》2007,58(1):41-53
A dynamic flow-through chamber system was designed to measure ammonia emissions from broiler litter and to investigate the
responses of ammonia emissions to litter moisture content under laboratory-controlled conditions. It was observed that ammonia
emissions from litter were very sensitive to litter moisture content. As water was added to the litter, the total ammoniac
nitrogen content (TAN) in the litter increased, and can potentially increase ammonia emissions. However, measurements of ammonia
concentrations in the chamber and total nitrogen losses from litter samples all suggested that water applied to the litter
also had an effect of suppressing ammonia emissions for a short time. After enough time (1 to 2 weeks) was allowed, higher
moisture content in litter eventually resulted in higher ammonia emissions. It was also noticed that, at very high litter
moisture content, even when more time was allowed, ammonia concentrations began to decrease as moisture content further increased. 相似文献
24.
Ines Hoog Subir K. Mitra Karoline Diehl Stephan Borrmann 《Journal of Atmospheric Chemistry》2007,57(1):73-84
In laboratory experiments the interactions of ammonia with ice crystals were studied within the temperature range between
0 and −20°C. In a first series of experiments dendritic ice crystals were grown from water vapor in presence of ammonia gas
in various concentrations between 4 and 400 ppbv. In a second series of experiments pure ice crystals were exposed to a humidified
ammonia–air mixture inside a horizontal flow tube. The influence of temperature, ammonia gas concentration (0.6, 1.5, and
10 ppmv), exposure time, and the presence of impurities such as sulfate on the ammonia uptake by the ice surface was investigated
by determining the ammonium content in the melt water of the ice crystals by ion chromatography. During the growth of ice
crystals significant amounts of ammonia (around 200 μg/l) were taken up even at small gas concentrations. In contrast, even
at high gas concentrations the uptake of ammonia by non-growing ice crystals was lower by approximately one order of magnitude.
The presence of sulfate on the ice surface affected an enhanced uptake of ammonia by a factor of 5–10. A model is presented
which describes the uptake of ammonia by ice considering the chemical processes occurring in the ice surface layer and simultaneous
diffusion of ammonia into bulk ice. Even the increased uptake of ammonia by growing ice is rather small compared to the uptake
by water droplets; thus, the major process for scavenging of ammonia from the atmosphere via the ice phase might not be the
direct uptake by ice crystals but the riming involving super-cooled droplets containing ammonia. 相似文献
25.
为探究冬季室温不同铁碳内电解基质下4种水生植物及其组合对人工湿地污水的净化效果,通过构建小试试验装置来探究冬季室温铁碳内电解质下菖蒲、鸢尾、金鱼藻、狐尾藻4种水生植物及菖蒲+鸢尾、金鱼藻+狐尾藻、菖蒲+鸢尾+金鱼藻+狐尾藻3种组合在不同试验时间内对污水中COD、NH_3+-N、TN、TP 4种污染物的净化效果。结果表明:冬季室温不同铁碳内电解基质下,4种植物及其组合对COD、TN、TP去除效果均较好,无显著性差异。NH3+-N净化效果较好的是菖蒲组和金鱼藻+狐尾藻组合。研究发现,铁碳内电解基质在COD、TN、TP的去除过程中发挥了主要作用。在TN去除方面,铁碳内电解质与植物的组合效果比单纯内电解质对污水的净化效果好。4种植物及其组合在NH_3+-N去除方面均发挥了重要作用,且不同处理间存在显著差异。 相似文献
26.
Kawakita Hideyo Watanabe Jun-Ichi FUSE Tetsuharu Furusho Reiko Abe Shinsuke 《Earth, Moon, and Planets》2002,90(1-4):371-379
The ortho-to-para ratio (OPR) of a cometary molecule is one of primordial character in comets. The OPR which is characterized
by a spin temperature, is thought to reflect the formation conditions of the molecule. In this paper we show the high-dispersion
spectrum of cometary NH2 in Comet C/2001 A2 (LINEAR), from which the OPR of NH2 is determined based on the fluorescence excitation model. Since the NH2 is a photodissociation product of cometary ammonia, we applied the permutation group theory to the whole reaction system
(i.e. the photodissociation reaction of ammonia to NH2 and H) in order to derive the OPR of ammonia from that of NH2.
The derived OPR of ammonia is 1.12 ± 0.03 in Comet C/2001 A2 (LINEAR). This value corresponds to a spin temperature of 30+3
-2 K. If this reflects the temperature where the comet formed in the protosolar nebula, our result indicates that thiscomet
was formed in the region of the giant planets between Jupiter and Neptune. 相似文献
27.
28.
Punit Kumar Mudgal Anil Kumar Sharma C. D. Mishra S. P. Bansal K. S. Gupta 《Journal of Atmospheric Chemistry》2008,61(1):31-55
This is the first study, which shows both NH3 and NH4+ to inhibit the autoxidation of aqueous SO2 in the pH range 7.0–8.5. The rate of the autoxidation, R
aut
, in both buffered and unbuffered media at a fixed pH is in conformity with the rate law:
where R
0
is rate in the absence of the inhibitors, B is a pH dependent empirical constant and [Inh]T is the analytical concentration of NH3 or NH4+. Both ammonia and ammonium ions appear to inhibit the autoxidation either by scavenging SO4− radicals or by forming less-reactive /unreactive Co(II)-NH3 complexes or both. The atmospheric relevance of the inhibition by ammonia and ammonium ions is discussed. 相似文献
29.
Continuous weekly monitoring on the concentration of gases and aerosols in urban ambient air by a four-stage filter-pack method
was carried out for 7 years in order to study not only the acid-base balance of acid-related (HNO3, NO3
−, and non-sea-salt-(nss-)SO4
2−) and alkali-related (NH3, NH4
+, and nss-Ca2+) chemical species but also its influence on the acidification of precipitation. The concentrations of the total nitrate (=
NO3− + HNO3) and nss-SO42− showed a similar seasonal variation: high in the summer and low in the winter. The total nitrate and nss-SO42− accounted for 0.43 and 0.57 of the acid-related species, respectively, on an equivalent basis. The total ammonium (= NH3 + NH4+) accounted for more than 0.9 of the alkali-related species, except for a springtime nss-Ca2+ episodic peak. The alkali-related species were generally overabundant compared with the acid-related species in the HNO3-NO3−-nss-SO42−-NH3-NH4+-nss-Ca2+ system. The alkali-rich distribution was especially pronounced in the winter, but the acid-related species was comparable
to the alkali-related species in the summer, which was attributed to the larger H+ deposition by precipitation in the summer. This study can provide a methodology to associate survey results obtained by a
filter-pack method with those of precipitation. 相似文献
30.