The Greenhouse Emission Model (GEM) is a tool for assessment of exposure of plant protection products (PPPs) in surface water and groundwater resulting from the use for crops grown in greenhouses. It is used in the Dutch registration process for PPPs.
The assessments are based on exposure scenarios developed for typical high-tech greenhouses in the Netherlands. GEM includes scenarios for both soil-bound cultivation, i.e. crops grown directly in the soil within the greenhouse, and soilless cultivation, crops grown in substrate slabs (e.g. rockwool) or pots. Overall, GEM supports three assessment types:
- Surface water exposure assessment for PPPs used in soilless cultivation
- Surface water exposure assessment for PPPs used in soil-bound cultivation
- Groundwater (leaching) assessment for PPPs used in soil-bound cultivation
GEM requires the SPIN application for handling information on substances.
SAFE
For surface water assessments, the predicted PEC can be highly sensitive to the selected date of PPP application. To ensure a robust exposure assessment it is advisable to perform an ensemble of assessments with varying application dates. For this purpose the SAFE (Select Application date For Evaluation) tool has been developed, to assist the user with setting up and running such a series of assessments, based on a base assessment previously generated with GEM. To variants of the tool exist for soilless and soil-bound assessments for surface water assessment.
Version history
GEM 1.1.1 was released together with the scientific reports on the exposure scenarios for Dutch greenhouse horticulture in July 2015. A follow up version, GEM 2.2.2 was released in February 2016. In the latter version a number of refinements were added related to soilless cultivation. The refinements include additional discharge scenarios for the nitrate emission period 2018-2020 and also additional discharge scenarios that allow the filter rinsing water to be reused. In GEM 1.1.1 filter rinsing water is discharged to surface water. Also an application manager is added. This manager allows to set a certain time-period between pesticide application and discharge of recirculation water. Due to a bug in GEM 2.2.2, this version was replaced by the bug-fix release GEM 3.3.2, which is currently use in the Dutch pesticide registration procedure. A new GEM version has been developed and is expected to be released in the near future.
