ESR15 Bilal Tariq

Project: Land cover mapping – plant toxin production and impact of policy

Principal supervisor: Dr. Carmel Ramwell

Project Findings: To predict the potential concentration of phytotoxins releasing from plants to the water sources, PEARL model was used. The PEARL model is recommended by FOCUS for the assessment of pesticides leaching to groundwater however PEARL also predicts concentrations at different depths in the soil that has the potential for lateral movement to surface water bodies. Limited numbers of phytotoxins were selected for model simulation in relation to different aspects of risk. These phytotoxins are supposed to be released from different types of plants such as ragwort, Rapeseed, Bracken, Potato, Buckwheat, Lupin and giant hogweed. Precipitation is the main driver for the toxin wash-off from the plant. Wash-off from the plant during precipitation events was considered as soil input. The soil input estimation was taken from other ESRs work and literature. There is no existing evidence that shows a direct relation between precipitation and wash-off but results from the current study show that high precipitation events generate more wash-off content as for some of the simulations the highest wash-off content was observed when the highest rainfall event occurred. Measured parameters from other ESRs were used, where possible otherwise estimated values were used as model input. The real soil data was used where possible otherwise sandy soil was used for other simulations which presents worst case scenario. Sandy soil is considered to have high hydraulic conductivity but clayey soil can also pose high leaching risk as it may show preferential flow through large fractures and macropores. In current study macropores flow is not considered as PEARL cannot simulate macropores flow. Simulation was run for 26 years, but first 6 years were considered as warm up period. For each individual toxin, leached mass and water percolated at different depths (3cm, 30cm, 1m) were calculated assuming a soil input (wash-off) to an area of 1ha. Phytotoxins with very high Koc and short half-lives such as a-solanine, fagopyrin and solasodine appear to be immobile within soil profile as their water concentration was zero even at 3cm thus they pose very little risk to water bodies particularly to groundwater. Phytotoxins with low Koc and long half-life such as PTA, seneciphylline and Linustatin were mobile and persistent within soil profile. The water concentration of these phytotoxins at 1m depth ranges between 0.009 and 7.328 ug/L thus they can pose potential risk to water bodies. The predicted soil and water concentrations were compared with measured concentrations for validation. Some of the results show good agreement. The more experimentally calculated data will provide a good validation for such risk assessments.

From the NaToxAq project Bilal achieved the following scientific profile:

Skills Learnt: