The effect of the dumping of waste-acid from the titanium-dioxide production on the chlorophyl-a concentration of North Sea water: A time series analysis

Since 1963 the waste-acid of the German titanium dioxide industry is discharged off the Dutch coast. From March 1980 on the dumping takes place in an area situated 40–80 km from the coast. Although about 2 500 000 kg waste-acid is discharged every day, until now no effects could be found on the plankton.This paper describes the study on the effects of the dumping on the chlorophyl-a concentration of the seawater at a site north of the dumping area, with the help of time series analysis. It is shown that considerable changes in the chlorophyl concentration occur during the dumping period and that these changes coincide with certain events within the dumping history. However, it is most remarkable that the starting of the dumping itself does not show an effect on the chlorophyl concentrations. Explanations are suggested, but could not be investigated yet.This study shows also that collecting data without a proper statistical design make it impossible to draw unambiguous conclusions based on those data.     

Breeding Birds as a Farm Product

Abstract: Since the 1950s, meadowbird populations have been under increasing threat from radical changes in farming practices. We studied the possibilities for conserving meadowbirds on modern, intensive dairy farms in the Netherlands. Here, the conventional strategy for the conservation of meadowbirds is to restrict farming intensity and compensate farmers for their production losses. To increase the breeding success of meadowbirds, however, dairy farmers can fine-tune farming practices to yearly and local circumstances. Because this fine-tuning is difficult to enforce by legislation, we propose that farmers be paid for clutches bred on their land. Thus, farmers are paid for what they produce, but not restricted in their farming practices. The results of the first small-scale experiments, in which breeding success was compared between farms where farmers were paid for meadowbird clutches and farms where farmers were not paid, are encouraging. Breeding success of meadowbirds was significantly higher where farmers were paid than where they were not ( breeding success of Lapwing [   Vanellus vanellus ]: 64.7% on paid farms, 48.2% on unpaid farms; Black-tailed Godwit [   Limosa limosa ]: 63.1% paid, 39.3% unpaid). The effects on meadowbird populations could not yet be detected. The per-clutch payment system is less expensive than compensation for income losses: paying for clutches costs 40 Euro per clutch, whereas compensating for income losses costs 100–400 Euro per clutch (1 Euro is approximately equal to 1 U.S. dollar). Farmers are enthusiastic, and the system encourages cooperation between farmers and nature conservationists.     

Development of biodiversity in field margins recently taken out of production and adjacent ditch banks in arable areas

Taking field margins out of intensive cultivation is a common form of agri-environmental scheme and on-farm nature management. Typically, no nutrients or pesticides are applied in these margins, which may be sown either with a crop or with grasses and native flowering plants. In some cases the margins are mown, while in others they are left alone. Newly established grass margins are less species-rich than field boundaries or road verges with a long history, justifying the expectation that field margins, if properly managed and given time and appropriate seed sources, could develop into relatively species-rich vegetation. We studied the biodiversity of both margins taken out of production and adjacent ditch banks in the years following initial establishment of the margins. To this end we combined the data of three different projects in order to increase the sensitivity of the statistical analyses. The results showed that the plant species richness of the field margins increased in the years following establishment over a period of four years. In addition, shifts in species composition indicated a decrease in soil nitrate concentrations. The species richness of both butterflies and dragonflies may increase. The most striking result was the marked increase in the plant species richness of the adjacent ditch banks in the five years following creation of the margins. Here, too, changes in species composition indicated a decrease in soil nitrate. In the years following establishment of the field margins there was no increase in the cover of agriculturally harmful weeds in these margins. However, the number of harmful nematodes increased. Our results show the short term effect of establishing field margins. Long term effects are still in need for further research.     

Spatial and temporal analysis of pesticides concentrations in surface water: pesticides atlas

Dutch water boards have a well-established program for monitoring pesticide contamination of surface waters. These monitoring data have been processed into a graphic format accessible online and designed to provide insight into pesticide presence in Dutch surface waters and trends over time: the Pesticides Atlas (http://www.pesticidesatlas.nl). With this tool one can easily get maps of where a pesticide is being measured and where it might possibly constitute an environmental problem over the years. Presently, results of the periods 1997/1998 until 2005/2006 are available at the level of individual active ingredients. At a national level, the percentage of pesticides concentrations that exceed the maximum tolerable risk has declined 30% to 38% over the years 2003/2004 compared with 1997/1998. This means that surface water quality in the Netherlands has improved with respect to pesticides, however there are still many locations at which the measured concentrations exceed the environmental quality standards. The results on linking land use to pesticides concentrations were shown to assist in optimization of monitoring programs. By developing the present Internet tool, many new opportunities for environmental risk assessment and risk management were identified, e.g. optimization of monitoring strategies and communication to policymakers.