In order to classify the condition of surface water areas, the Ministry of the Environt needs to establish new environmental quality requirements and action programs for selected environmentally hazardous substances (EHS).
The report contains a review of eight potential sources of loss of the environmental hazardous substances (EHS) copper (Cu), zinc (Zn) and nickel (Ni) from agriculture and aquaculture. The report is thus limited to these three substances and the eight sources. The eight sources are:
To the extent possible, each of the sources is described in terms of the extent of the activity, the content of the three EHS, total input and potential reduction options. To the extent that economic data is available, the economic costs for the agricultural and aquaculture sectors of the different options are described.
The background for the analysis is the above mentioned need for new knowledge regarding the classification of surface water, but the analyses does not include an assessment of the effect that the different reduction options may have on the leaching of the EHS to the water environment; thus, available data is insufficient for conducting such an assessment. Accordingly, the analyses are primarily conducted with a view to establish and improve the knowledge base for assessing the economic consequences for agriculture and aquaculture associated with potential measures for reducing the loss of zinc, copper and nickel from the agricultural sector and aquaculture.
Comparison across sources show that manure is the largest source of EHS input to agricultural soils; all things being equal, the largest potential for reducing EHS input will therefore be in relation to manure. The options for reducing EHS via manure are centered on zinc and copper, and are primarily related to changes in the composition of fodder for cattle and pigs. For piglets, it is expected that reductions in EHS will entail significant production related consequences; this is, among others, a consequence of the already implemented ban on the use zinc for medical purposes. For slaughter pigs, cobber is typically added in excess of the norm, and based on this it is expected that there is potential for obtaining some level of reduction without production related consequences. Likewise, it is expected that the addition of zinc to fodder for slaughter pigs and sows can be reduced without significant consequences for production. For cattle, there is an over-supply of zinc and cobber, and accordingly there is expected to be potential for reducing the input without increasing costs for the agricultural sector.
Acidification of slurry has a negative impact on the loss of EHS from the soil to the water environment, as the acidification affects the mobility of EHS in the soil. Limitations on the use of acidification would accordingly contribute to reducing the loss of EHS to the water environment from slurry. All things being equal, such limitations would however entail a need for other technological solutions to address the problem of ammonia emissions, and these technologies are likely to increase costs for the agricultural sector. How large the additional costs will be will depends on which alternative technology that is chosen.
Sewage sludge is a residual product from the treatment of sewage water at water treatment facilities, and due to its content of plant nutrients, it can be used to fertilize agricultural soils, where it typically will replace synthetic fertilizer. Apart from essential plant nutrients, however, sewage sludge also contain copper, nickel and zinc. The only relevant option for reducing the input of EHS from sewage sludge is considered to be the imposition of limitations in the use of sewage sludge. Such limitations will be associated with costs for the agricultural sector, as it will entail an increase in expenses for buying synthetic fertilizers.
Bio ash is a residual product from energy production based on burning of wood, straw or wood pellets, and apart from plant nutrients (primarily P and K) it also contains varying amounts of EHS, which are transferred to the soil when bio ash is used as fertilizer. Based on the available data it is not possible to quantify the copper, zinc and nickel input to Danish agricultural soils through the application of bio ash. The input can be reduced by limiting the amount of bio ash used for fertilization, and for the agricultural sector, this will entail an economic cost in terms of increased expenses for buying synthetic fertilizer.
Synthetic fertilizer contain impurities including, among others, copper, nickel and zinc, and according the use of synthetic fertilizers entails an input of EHS to agricultural soils. For synthetic fertilizers, particularly the nickel content is problematic. The heavy metal content is linked to the phosphorous content of the fertilizers, and accordingly a relevant reduction option could be a tightening of the rules for applying phosphorous, especially on soils with a high phosphorous content, in order to ensure that the level of phosphorous application follows the specific phosphorous need of the plants. Regulation on the phosphorous application has been tightened in 2017-2018 with introduction of phosphorous ceilings, which limits the application of phosphorous on the farmland. Ambitions for a further reduction towards 2025 is in place (Jacobsen, 2022). The expected tightening of the regulations is expected to decrease the supply EHS to agricultural soils but the level is surrounded with uncertainty. The cost for the agricultural sector of such a tightening will depend on the more specific characteristics of the regulation, and accordingly they cannot be assessed here.
Liming products contain both copper, zinc and nickel, and when agricultural soils are limed are certain amount of EHS are also applied. The only real option for reducing the EHS input via liming is to limit the use of lime. The amount of lime applied to Danish agricultural soils is generally below the optimal level, and accordingly it is not considered likely that the amount of lime applied can be reduced without significant production related, and thereby also economic, consequences for the agricultural sector.
In relation to pesticides, it is concluded that the input of copper, nickel and zinc from the use of pesticides is insignificant, and that it accordingly is not relevant to target measures at reducing the input of EHS from pesticides.
Excipients containing copper are used in both marine and fresh water aquaculture. In marine aquaculture, products containing copper is used to impregnate net-cages and the use of these products can be reduced by transition to a new type of net-cages. As there a no effective alternatives to the currently used copper containing impregnation products, the transition will most likely require more frequent replacement of net-cages, and this will entail an increase in costs. However, the economic costs are expected to be fairly minor. In traditional freshwater aquaculture, copper containing products are used to disinfect the water. The use is however continuously reduced as a consequence of the ongoing transition from traditional aquaculture to aquaculture with recirculation. Accordingly, the potential economic effect is expected to be minor.
The overall conclusion of the analyses is that the current availability of data for assessing the input of EHS from the eight reviewed sources, and for assessing the costs of potential reduction options, generally is very limited, and for some of the sources practically non-existing.
Based on currently available data the immediate conclusion is, that it is likely to be possible to obtain reductions at fairly limited costs to aquaculture and the agricultural sector. However, it is not possible to assess how large reductions can be obtained before significant consequences in terms of production, and thereby also economy, will start to emerge. Accordingly, additional and more detailed analyses and modelling of factors affecting the economy, including the use of production factors, prices of these, production settings and market opportunities, are required if more in-depth assessments of reduction potentials, and the costs of realizing these potentials, are to be made. Such analyses represents a huge task and is beyond the scope of the current project.
