Treibhausgasemissionen zukünftiger Erdgasbereitstellung für Deutschland

Ohne Zusammenfassung Original erschienen in UWSF – Z Umweltchem ?kotox 20(2):133–144 (2008) DOI: Herausgeber: Martin Pehnt und Eckard Helmers     

Phytotoxicities of fluoranthene and phenanthrene deposited on needle surfaces of the evergreen conifer, Japanese red pine (Pinus densiflora Sieb. et Zucc.)

Polycyclic aromatic hydrocarbons (PAHs) have been widely studied with respect to their carcinogenic and mutagenic effects on animals and human cells. Phenanthrene (PHE) and fluoranthene (FLU) effects on the needle photosynthetic traits of 2-year-old Japanese red pine (Pinus densiflora Sieb. et. Zucc.) seedlings were investigated. Three months after fumigation of foliage with solutions containing these PAHs (10 microM each), FLU had negative effects on net photosynthesis at near-saturating irradiance, stomatal conductance, initial chlorophyll fluorescence, and the contents of total chlorophyll, magnesium, and ribulose 1,5-bisphosphate carboxylase (rubisco) of current-year needles. PHE had similar negative effects to FLU but in lesser magnitude. The effects of the PAHs were mitigated by the addition of an OH-radical scavenger (mannitol) into the PAH solutions. PAHs deposited on the surface of pine needles may induce the generation of reactive oxygen species in the photosynthetic apparatus, a manner closely resembling the action of the herbicide paraquat.     

Phosphorus removal from municipal wastewater by hydrous ferric oxide reactive filtration and coupled chemically enhanced secondary treatment: part I--performance.

This work examines the performance of a hydrous ferric oxide (HFO) reactive filtration (RF) process with coupled chemically enhanced secondary treatment (RECYCLE) for phosphorus removal from municipal wastewater (HFO-RF-RECYCLE). A 3-month, 0.95-ML/d (0.25-mgd) demonstration of HFO-RF-RECYCLE was performed at a municipal wastewater treatment plant equipped with oxidation ditches and secondary clarifiers. Influent to the plant averaged 6.0 mg/L phosphorus, with a tertiary effluent average of 0.011 mg/L phosphorus. Iron doses to the plant were low, at 5 mg/L. Inline recycling of HFO solution rejects to the plant influent resulted in a maximum 90.3%, dose-dependent reduction of phosphorus in the secondary effluent at 4.5 ML/d (1.2 mgd). Other results included reduction of total suspended solids and turbidity. A mass balance analysis was performed. We conclude that HFO-RF-RECYCLE may allow very low levels of phosphorus discharge from municipal wastewater treatment plants with a ferric-iron-based tertiary filtration process and residual recycling.     

Aerobic and anaerobic transformations of sulfide in a sewer system--field study and model simulations.

The formation and fate of sulfide in a force main and a downstream-located gravity sewer were investigated in an extensive field study. Sulfide formation in the force main was significant. However, during 14 minutes of transport in the gravity sewer, the sulfide concentration decreased 30%, on average. An application of a conceptual sewer process model for simulating the formation and fate of sulfide was demonstrated. Overall, the model predicted that approximately 90% of the decrease of the sulfide concentration in the gravity sewer was the result of sulfide oxidation and that only a small fraction entered the sewer atmosphere, causing odor and corrosion. Even so, the model predicted concrete corrosion rates of up to 1.2 mm/y in the gravity sewer section.     

Harmful effects of atmospheric nitrous acid on the physiological status of Scots pine trees

An open top chamber experiment was carried out in the summer of 2003 to examine the effect of nitrous acid (HONO) gas on the physiological status of Scots pine saplings (Pinus sylvestris). Four-year-old pine trees were exposed to two different levels of HONO gas (at ca. 2.5 ppb and 5.0 ppb) and a control (filtered air) from early evening to early morning (18:00-6:00), in duplicate open top chambers. Significant decreases in the ratios of chlorophylls a to b, an increase in the carbon to nitrogen (C/N) ratio, and a reduction of maximum yield of PS II (F(v)/F(m)) in pine needles were also observed after the 2 months' fumigation. Cation contents of pine needles were also decreased by the fumigation with HONO gas. The results could be explained by the harmful effects of OH radicals, generated from photolysis of HONO gas, and/or aqueous phase HONO (NO(2)(-)/HONO), on the photosynthetic capacity of pine needles.     

Correlation of low-volatile organic chlorine (LVOCl) and PCDD/Fs in various municipal waste incinerators (MWIs)

Medium- and low-volatile organic chlorine (M/LVOCl) and PCDD/Fs in flue gas from various municipal waste incinerators (MWIs) were monitored. The sample for M/LVOCl was collected in an adsorption tube which was thermally desorbed and the amount of chlorine was measured by atomic emission spectrometry (AES) detection using radiofrequency helium plasma. The helium plasma excited chlorine having an optical emission line of 837.6 nm was monitored. The MVOCl and LVOCl were organic chlorine groups whose boiling points (bp) ranged from 70-120 degrees C and 170-270 degrees C, respectively. The compounds having bp 120-170 degrees C were distributed in two tubes. LVOCl correlated well with PCDD/Fs (ng/Nm3, r=0.81) in a wide range of 0.01-100 ng/Nm3 of PCDD/Fs, while the correlation of LVOCl vs. TEQ was less related (r=0.69). These results agreed with the fact that LVOCl monitored the amount of organic chlorine without molecular structure information, which is critical to toxicity. Since the bp of LVOCl was not identical with that of PCDD/Fs, the regression was effected by the conditions of the gas treatment devices. Because most data of 2001 were collected just after the installation of PCDD/Fs in MWIs, the regression of 2001 was slightly different from that of 2002-2003. Eliminating these initial unsteady data, the regression of LVOCl vs. PCDD/Fs became better, giving r= 0.86. Besides having PCDD/Fs as surrogates, M/LVOCl is valuable as a versatile element-selective organic chlorine monitor to improve thermal process control.     

The rationales behind the unit-segment theory and its analysis methodology for modeling vehicular movement networks

The theory of space accessibility analysis, space syntax, has been considered for capturing trip-makers’ route-choice decisions with an understanding that, while selecting routes, trip-makers tend to follow forward-facing fields traditionally represented by axial lines. But the idea of treating axial lines as a set of roadway segments representing an urban texture has remained under scrutiny when distinct procedures have been tested without much success. Nor has the axial-line theory seemed to gain much popularity within the orthodox transportation planning community. Studies show that a long axial line is found gaining configurational centrality, in general, for being well connected to its incident lines. Fragmenting a long axial line results in weakening it (in centrality terms), but also in generating a locally oriented model. Recent investigations, dealing with this problem, have resulted in the emergence of the unit-segment theory, which has turned out to be more sensitive to the local structures located within a large urban texture than the axial counterpart for the purpose of modeling vehicular movement networks without using origin–destination trip-counts. Essentially, the question now is: Is the unit-segment analysis also capable of generating syntax configurations that are equally sensitive to large and complex urban textures? What should be the methodology of such an analysis? This paper throws deeper insights into these questions by producing theoretical and empirical research findings and seeks to develop a common ground for both transportation planning and space syntax communities to work together for gaining a better understanding of how urban configurations relate to urban vehicular movement networks.     

Static and Dynamic Behavior of Fibrous Polymeric Composite Materials at Different Environmental Conditions

The study of static and dynamic behavior of environmentally conditioned fibre reinforced polymeric (FRP) composites is necessary and crucial to examine the durability, reliability and sustainability of these noble materials. FRP composites are being used all around the globe and substituting the conventional materials, starting from mini toys to large aerospace components. Present review has introduced to accumulate and understand the disseminate literature in concentrating the significance of understanding the static and dynamic behavior of FRPs with changing environmental conditionings (hygrothermal, low and high temperature, salt solution, freeze thaw, UV light) and with the interaction of different nano-fillers. Their stability and integrity in diverse service environments may be reformed by their reactions against different nature of loadings i.e. static or dynamic and the components such as fibre, matrix and fibre/matrix interfaces in those environments. The static and dynamic states of loading may come with a possible weaker region to encounter the durability and integrity of the composites. To understand the exact failure modes that correlates the position of environmentally conditioned interfaces and dynamic state of loadings, thus confusing the estimation of its overall performance and mechanical behavior. Interface reliability and durability is vital since in-service environments the degradation in the interfacial region leads to complete composite failure. Therefore, the study of combined effects of various in-service environmental conditions and the role of static and dynamic behavior on the interface will be a crucial part related to the multiaxial dynamic states of failures occurring in FRP’s.