§ Mrs. Ann WintertonTo ask the Secretary of State for Environment, Food and Rural Affairs if she will make a statement on(a) the environmental harm caused by nitrate levels in the land phase of the hydrological cycle and (b) the source of the research upon which the theory is based. [29091]
§ Mr. MeacherNitrates in soil can leach into water. High nitrate levels in water contribute to eutrophication and reduce biodiversity. A risk assessment of such environmental harm is contained in a Regulatory Impact Assessment annexed to the Department's current consultation document "How should England implement the 1991 Nitrates Directive?" published on 20 December 2001.
A report by WRc to DETR in 1999 entitled "Diffuse pollution: sources of N and P" explains the scientific processes and extent of environmental harm and contains an extensive reference list. Copies of this report are available from the Foundation for Water Research.
§ Mrs. Ann WintertonTo ask the Secretary of State for Environment, Food and Rural Affairs what assessment she has made of research evidence showing that(a) the process of denitrification includes the addition of phosphate and (b) phosphate is the cause of eutrophication in saline water. [29085]
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§ Mr. MeacherThe research evidence suggests phosphate is not a significant influence on denitrification, though there are circumstances where phosphate limited plant growth can influence the capacity for denitrification to occur or where the anaerobic conditions required for denitrification also lead to the mobilisation of phosphorus from sediments.
The research evidence shows that for marine waters generally the growth of algae is limited by the amount of nitrogen available (rather than the amount of phosphorus), so eutrophication can result if there is an increase in nitrogen. The position in estuaries or transitional waters may be more complex, and in a few places the availability of phosphorus may be the limiting factor.