By using one static water system,the filtration rates of one kind of freshwater mussel Anodonta woodiana with different body weight(accounted by dry weight of soft tissue)were studied under semi-field conditions.Durin...By using one static water system,the filtration rates of one kind of freshwater mussel Anodonta woodiana with different body weight(accounted by dry weight of soft tissue)were studied under semi-field conditions.During the experiments,the water temperature and the suspended particulate matters concentration were kept relative invariable and there were four ambient ammonia concentration levels.The ambient water ammonia concentration was obtained by the excretion of the freshwater mussel and the accession of ...展开更多
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
基金Supported by National Natural Science Foundation of China(30700619)the Open Fund of Key Laboratory of Ecological Environment and Resources of Inland Fisheries,Chinese Academy of Fishery Sciences(YM2007-01)~~
文摘By using one static water system,the filtration rates of one kind of freshwater mussel Anodonta woodiana with different body weight(accounted by dry weight of soft tissue)were studied under semi-field conditions.During the experiments,the water temperature and the suspended particulate matters concentration were kept relative invariable and there were four ambient ammonia concentration levels.The ambient water ammonia concentration was obtained by the excretion of the freshwater mussel and the accession of ...
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.
