The hygienic threshold limit values for ammonia （25 ppm） for animal welfare but also for occupational safety and health is often exceeded in floor housing systems for laying hens with long time storage of manure in ...The hygienic threshold limit values for ammonia （25 ppm） for animal welfare but also for occupational safety and health is often exceeded in floor housing systems for laying hens with long time storage of manure in bins below draining floors. The major reason for high ammonia concentrations is the large amounts of stored and exposed manure. The possibility to reduce ammonia release by reducing the amount of stored manure in bins in floor housing systems for laying hens has therefore been investigated. Investigations were carried out in a climate chamber equipped with a floor housing system with a manure removal system with two parallel motor driven conveyors placed below an elevated draining floor. The conditions when manure is stored in bins below draining floors were simulated by storing manure on the conveyors for several days at constant ventilation rates and temperatures. The investigations clearly showed that storage of manure in the bin caused a rapid increase in ammonia concentrations. After about 7 days storage of manure in the bin the ammonia concentration exceeded the hygienic threshold limit values. It can be concluded that long time storage of manure in storage bins below draining floors should not be recommended. It was possible to maintain the ammonia concentration below the hygienic threshold limit values when manure was removed frequently with conveyors. Floor housing systems for laying hens with elevated draining floors should therefore be equipped with manure removal systems that enable frequent removal of manure in the bins.展开更多
This study analyses evidence for reformed basin development and basin-mountain coupling associated with devel- opment of the Ordos Basin and the Laliang Mountains, China. Gaining an improved understanding of the timin...This study analyses evidence for reformed basin development and basin-mountain coupling associated with devel- opment of the Ordos Basin and the Laliang Mountains, China. Gaining an improved understanding of the timing and nature of uplift and evolution of the Ltiliang Mountains is important for the reconstruction of the eastern sedimentary boundary of the Ordos Basin （a major petroliferous basin） as well as for providing insight into the evolution and breakup of the North China Craton （NCC）. Based on systematic sampling for fission track analysis, it is suggested that the main phase of uplift of the Laliang Mountains occurred since later part of the Early Cretaceous. Three evolutionary stages of uplift and development are identified： slow initial uplift （120-65 Ma）, accelerated uplift （65-23 Ma）, and intensive uplift （23 Ma to present）, with the ma- jority of the uplift activity having occurred during the Cenozoic. The history of uplift is non-equilibrium and exhibits complex- ity in temporal and spatial aspects. The middle and northern parts of the Ltiliang Mountains were uplifted earlier than the southern part. The most intensive episode of uplift activity commenced in the Miocene and was associated with a genetic cou- pling relationship with the eastern neighboring Cenozoic Shanxi Grabens. The uplifting and evolutionary processes of the Ltiliang Mountains area since later part of the Early Cretaceous share a unified regional geodynamic setting, which was ac- companied by uplift of the Mesozoic Ordos Basin and development of the neighboring Cenozoic Shanxi Grabens. Collectively, this regional orogenic activity is related principally to the far-field effects of both the compression sourced from the south- western Tibet Plateau and westward subduction of the Pacific Plate in Cenozoic.展开更多
文摘The hygienic threshold limit values for ammonia （25 ppm） for animal welfare but also for occupational safety and health is often exceeded in floor housing systems for laying hens with long time storage of manure in bins below draining floors. The major reason for high ammonia concentrations is the large amounts of stored and exposed manure. The possibility to reduce ammonia release by reducing the amount of stored manure in bins in floor housing systems for laying hens has therefore been investigated. Investigations were carried out in a climate chamber equipped with a floor housing system with a manure removal system with two parallel motor driven conveyors placed below an elevated draining floor. The conditions when manure is stored in bins below draining floors were simulated by storing manure on the conveyors for several days at constant ventilation rates and temperatures. The investigations clearly showed that storage of manure in the bin caused a rapid increase in ammonia concentrations. After about 7 days storage of manure in the bin the ammonia concentration exceeded the hygienic threshold limit values. It can be concluded that long time storage of manure in storage bins below draining floors should not be recommended. It was possible to maintain the ammonia concentration below the hygienic threshold limit values when manure was removed frequently with conveyors. Floor housing systems for laying hens with elevated draining floors should therefore be equipped with manure removal systems that enable frequent removal of manure in the bins.
基金the National Natural Science Foundation of China(Grant Nos.41330315&41002071)MOST Special Funds from the State Key Laboratory of Continental Dynamics(Grant Nos.BJ091354&BJ081334)Special Fund from Ministry of Education for Doctoral Discipline in High School(Grant No.20116101110006)
文摘This study analyses evidence for reformed basin development and basin-mountain coupling associated with devel- opment of the Ordos Basin and the Laliang Mountains, China. Gaining an improved understanding of the timing and nature of uplift and evolution of the Ltiliang Mountains is important for the reconstruction of the eastern sedimentary boundary of the Ordos Basin （a major petroliferous basin） as well as for providing insight into the evolution and breakup of the North China Craton （NCC）. Based on systematic sampling for fission track analysis, it is suggested that the main phase of uplift of the Laliang Mountains occurred since later part of the Early Cretaceous. Three evolutionary stages of uplift and development are identified： slow initial uplift （120-65 Ma）, accelerated uplift （65-23 Ma）, and intensive uplift （23 Ma to present）, with the ma- jority of the uplift activity having occurred during the Cenozoic. The history of uplift is non-equilibrium and exhibits complex- ity in temporal and spatial aspects. The middle and northern parts of the Ltiliang Mountains were uplifted earlier than the southern part. The most intensive episode of uplift activity commenced in the Miocene and was associated with a genetic cou- pling relationship with the eastern neighboring Cenozoic Shanxi Grabens. The uplifting and evolutionary processes of the Ltiliang Mountains area since later part of the Early Cretaceous share a unified regional geodynamic setting, which was ac- companied by uplift of the Mesozoic Ordos Basin and development of the neighboring Cenozoic Shanxi Grabens. Collectively, this regional orogenic activity is related principally to the far-field effects of both the compression sourced from the south- western Tibet Plateau and westward subduction of the Pacific Plate in Cenozoic.
