Dipotassium hydrogenorthophosphate

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Adequacy of study:

supporting study

Reliability:

other: conceptual model development. Reliability not applicable

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

review article or handbook

Title:

Unnamed

Year:

2007

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

1. Development of a conceptual model, exposure scenarios, effect evaluation and risk assessment protocol.
2. Implementation of the model and a set of examples based on generic European scenarios as well as a pan European probabilistic estimation
covering the diversity observed for the European conditions.

GLP compliance:

no

Remarks:

Not applicable

Test material

Test material information

Constituent 1

Reference substance name:

Pentasodium triphosphate

EC Number:

231-838-7

EC Name:

Pentasodium triphosphate

Cas Number:

7758-29-4

Molecular formula:

Na5P3O10 H5-xP3O10Nax (where x is approximately 5) 6H2O.Na5P3O10

IUPAC Name:

Pentasodium triphosphate

Results and discussion

Any other information on results incl. tables

The results presented in this report offer a new conceptual model for assessing the potential eutrophication risk associated to nutrient emissions and, in particular, to P. The exposure assessment is simple: a generic river basin model based on emission coefficients allowing the estimation of annual averaged TP concentrations based on upstream population density, P removal at the sewage treatment plant, and land uses. The model has been constructed on an excel datasheet, allowing a probabilistic implementation based on Monte Carlo analysis. A simplified exposure model has been developed and validated using Danube river basin data. The comparison of model predictions and measurements for this set of river sub-basins selected from the Danube catchment, indicated that the model offers acceptable predictions. It should be considered that the model is not a GIS based model, but a generic model offering an estimation for the annual average concentration. The spatial and temporal differences are not included in the model estimations; and obviously, the interpretation of these data must consider the characteristics of the proposed model. Due to differences in land use, population density and hydrology, different TP concentrations, and therefore different likelihoods for effects must be expected for different areas within the river basin. For example, for a single river basin, the TP concentration, would be different for stagnant waters located immediately upstream and immediately downstream of a large city; simply as the result in the point versus diffuse contributions. It should be noted that the point contribution of a one million inhabitants city is equivalent to the diffuse contribution of about half a million hectares of arable land. Therefore, good agricultural practices may produce better results for sensitive areas located upstream main cities while specific wastewater treatment may be better for downstream sensitive areas. Measures for mitigating P losses from agricultural land at the river basin scale level have been reviewed elsewhere (Djodjic et al., 2002; Ulen and Jakobsson, 2005). The high variability in the contribution of direct (STP) and indirect (diffuse) P sources to the overall load observed among river basins can also be identified within a catchment area; for example, Bowes et al. (2005) estimates that the proportion of P from direct STP emissions ranges from less than 10% to more than 90% for different areas of the River Avon basin. Similarly, the effect assessment has also been developed as a generic assessment for the most sensitive areas within the river basin. The protection of these sensitive areas is assumed to be essential for the overall protection of the river ecosystem. Following the principles of the European protocols developed for assessing the risk of industrial chemicals (ECB, 2003; SSC, 2003) the risk is established for the actual emission levels and the historical pollution is only considered regarding the monitoring programmes. In this model, the risk for the sensitive river areas (lakes, reservoirs, meadow zones, estuaries), is based on the TP concentration of the inflow water, historic loads resulting in a higher P level within the system (e.g. in the sediments) are not considered in this assessment. The assessment of estuaries was a discussion point during the Experts Workshop. The Experts considered that the selected classes cover the most sensitive ecosystem types. Estuaries are expected to be less sensitive, and consequently covered by the assessment. In addition, the exposure is estimated for the inflow concentration using worst case assumptions. As a consequence, no specific assessment for estuaries is required. The role of other nutrients and particularly nitrogen (N) is covered in the effect assessment as the approach is based on real field conditions. In fact, part of the variability observed for similar TP concentrations is the consequence of variations in concentrations of N and/or other nutrients. As the loads of different nutrients, particularly P and N, are expected to be associated, the role of this association should be considered.

The assessment can also be targeted for specific ecoregions where the overall risk is known or expected to be higher than the average. Then, the effect assessment should be based on specific data for the addressed eco-region & type-classes, while the simplified exposure model seems to be useful for the entire European continent provided that the river basin characteristics used in the input model may be appropriate for that area.