A nonstationary time-series model is used to examine the changes occurring at sampling stations on the Chicago Sanitary and Ship Canal. Using data from upstream sampling sites, downstream levels of dissolved oxygen, total dissolved solids, nitrates and nitrites, and ammonia are accurately predicted. The method is simple, insensitive to extreme values, and responsive to changes in the system. 相似文献
The oxygenated species, massively produced in the energy production plants based on combustion processes, constitute one of the most numerous categories of hazardous air pollutants. Therefore, development of real time diagnostic tools are needed in order to study their formation during combustion processes and to reveal their presence both in the exhaust and in the atmosphere. In this work, oxygenated compounds were identified inside fuel-rich premixed ethylene/air flames by means of ultraviolet fluorescence spectroscopy with the support of qualitative chemical analysis of the sampled combustion gases.
Strong band progression, typical of aldehydic functionality, were recognized in fluorescence spectra (λexc=355 nm) measured in the early oxidation region of premixed flames varying the equivalence ratio from 3.0 up 21.6. Downstream of the oxidation region, spectroscopic signatures of pyrolytic species were found to prevail on those peculiar of oxygenated compound. The position and the extension of the two main flame zones were found to depend on the flame conditions (C/O ratio) due to the effect of the C/O ratio on the temperature history along the flame axis. This correlation was interpreted on the basis of the measured axial temperature profiles. 相似文献
Mixtures can be divided into simple (chemicals with comparable properties—health risk assessments on the chemicals) and complex,
which can be further subdivided into defined (a reasonably distinct composition, created at a specific time and place despite
dissimilar components—risk assessments on the common source) and coincidental (chemicals without similar properties or constant
composition in time or space—risk assessments on the receptor). Interactions recognized are: independent action, dose addition
(additivity), and potentiation (synergy and antagonism). Unpredicted outcomes need recognition. New approaches in higher education
and multidisciplinary investigations are essential. The community of the Society for Environmental Geochemistry and Health
should help clarify points such as when transformations in mixtures may become important enough to alter the classification
and the risk assessment. The multidisciplinary community is also well placed to support the integration of nonchemical influences
into mixture analysis and to contribute to the investigation of cumulative and multiple exposures. 相似文献
Zusammenfassung UNEP International Register of Potentially Toxic Chemicals (IRPTC) wurde von der ersten VN-Umweltkonferenz 1972 geschaffen.
Sein Einfu? und Zusammenwirken in den 80ziger Jahren mit anderen internationalen Programmen der WHO, FAO, OECD und EG in der
Chemikalienkontrolle wird beschrieben. Nach dem Erdgipfel von Rio 1992 werden im VN-Rahmen drei neue Gremien gebildet, die
das Fachprogramm des Kapitels 19 der Agenda 21 (umweltfreundliches Chemikalienmanagement) umsetzen sollen: die United nations
Commission of Sustainable Development, das Intergovernmental Forum on Chemical Safety und das Interorganization Programme
for the Sound Management of Chemicals. Der Erdgipfel brachte auch für IRPTC eine Neuorientierung. Seit 1996 hat UNEP Chemicals,
wie sich IRPTC nunmehr nennt, drei Aufgaben in sein Arbeitsprogramm aufgenommen, die beschrieben werden: das internationale
übereinkommen zum Prior Informed Consent, das internationale übereinkommen zur Kontrolle der Persistent Organic Pollutants,
und schlie?lich sein traditionelles Arbeitsgebiet des Informations-austausches über Stoffe wird weitergeführt.
Die Aussagen dieses Beitrages sind die Meinung des Autors. Sie müssen nicht mit der Auffassung des Umweitbundesamtes oder
von UNEP Chemicals übereinstimmen. 相似文献