Development and implementation of air pollution mitigation systems for animal husbandry in The Netherlands
Being one of the most densely populated nations in Europe, and housing an economically important livestock industry, the Netherlands face the challenge to strictly control environmental impacts of livestock production on residential and natural areas. The aim of this paper is to describe the main characteristics of the approaches followed in this policy with the focus on ammonia emission mitigation. It outlines technological developments and the implementation of mitigation technology in practice, and discusses benefits and drawbacks of the followed approach, and the possibility to make use of developed mitigation options in other regions with different productions settings. Since 1980 the ammonia emission from agriculture has been reduced by nearly 50%. This major achievement can be attributed to a number of general measures related to mandatory manure storage covering, low emission manure application techniques, and the implementation of low emission housing systems. Low emission housing systems have been developed for all main animal categories. Low emission is generally reached by restricting emitting surfaces, and quick removal and drying of manure. In general ammonia emissions were reduced by 50% and more, when compared to existing conventional systems. Higher reduction levels (70-90%) can be reached by air scrubbers. All measures were tested on practical farms using standardized measurement protocols. Low emission housing systems developed in one region cannot be simply transferred to other production regions. However, most of the mitigation principles that underlie these housing systems can be successfully applied in other settings as well, if modified and adapted to local conditions.
Air scrubbing techniques for ammonia and odor reduction at livestock operations : review of on-farm research in the Netherlands
Acid scrubbers and biotrickling filters have been developed for ammonia (NH3) removal at pig and poultry houses 
in The Netherlands over the last 20 years to prevent acidification and eutrophication of soils. Because of growing 
suburbanization, odor removal is increasingly considered important as well. In this review, we report the results of the on-farm 
research on full-scale operated scrubbers for treatment of exhaust air from animal houses with regard to NH3 and odor 
removal in The Netherlands. The NH3 removal of acid scrubbers ranged from 40% to 100% with an overall average of 96%. 
The NH3 removal of biotrickling filters ranged from -8% to +100% with an overall average of 70%. Minimum empty bed air 
residence times (EBRTs) were 0.4 to 1.1 s. For acid scrubbers, process control with pH measurement and automatic water 
discharge is sufficient to guarantee sufficient NH3 removal. For biotrickling filters, however, improvement of process control 
is necessary to guarantee sufficient NH3 removal. The odor removal of acid scrubbers ranged from 3% to 51% with an overall 
average of 27%. The odor removal of biotrickling filters ranged from -29% to +87% with an overall average of 51%. 
Minimum EBRTs were 0.5 to 2.3 s. Further research is necessary to explain this variation and to improve the odor removal 
efficiency of both acid scrubbers and biotrickling filters.
Mode of action of bredinin with guanylic acid on L5178Y mouse leukemia cells.
Moderate concentrations of bredinin (1.2 X 10(-5) M) strongly inhibited growth of L5178Y cells, with the effect being reversed by guanylic acid (GMP). However, at higher concentrations of breeding the inhibition was not reversed completely by GMP added in excess. Bredinin was cytocidal at concentrations above 2 X 10(-5) M, but 5 X 10(-5) M bredinin in the presence of excess GMP, bredinin was cytostatic. Bredinin inhibited nucleic acid synthesis of L5178Y cells, but bredinin itself was not incorporated into the nucleic acid. Inhibition of nucleic acid synthesis was clearly reversed by GMP. Similarly chromosomal aberrations in L5178Y cells caused by bredinin were reversed by GMP. In contrast, the effect of ahigh concentration of bredinin on cell multiplication was not reversed by GMP. The modal volume of L5178Y cells increased during incubation in the presence of bredinin and GMP for 24 hours, 5 X 10(-5) M bredinin with GMP causing a 70% increase in cell volume. This increase in cell volume was mainly due to an increase in the protein content of the cells. The cytostatic effect of bredinin with GMP was reversed completely by adenosine-3',5'-cyclic monophosphate (cyclic AMP). Other cyclic nucleotides and nucleotides were ineffective. The reversing effect of cyclic AMP on cell survival depended upon the concentration of GMP, and was not seen in the absence of GMP. It was concluded that cyclic AMP influences the secondary cytostatic effect of bredinin, and not the primary cytotoxic effect reversed by GMP.