Spatio-temporal Identification of Regions with Anomalous Values of 222 Rn in Groundwater of Madurai District, Tamilnadu, India

Measurement of dissolved radon (222 Rn) activity concentration in groundwater samples from private and public hand pumps, and in bore wells located at Madurai district of Tamilnadu, India, are presented. The study attempts to identify the background value of 222 Rn in groundwater of hard rock terrain and the main aquifer contributing 222 Rn, and to determine if any correlation exists with observed field parameters. Measured parameters included pH, TDS, Temperature and 222 Rn in 42 samples for two seasons (South West Monsoon [SWM] and North East Monsoon [NEM]). The results show that the 222 Rn activity concentration of the samples ranged from 0.049 to 59.952 Bq/L in South west monsoon and 0.12 to 211.60 Bq/L in North east monsoon. The higher activity was noted in NEM and the highest 222 Rn concentrations were observed in granitic terrains in both seasons. The average values of the parameters studied shows that there is a general decrease of TDS and Temperature, but an increase in 222 Rn and pH during NEM. The spatial representation of the activity shows that maximum values are in the north eastern part of the study area. Further, correlations between the measured parameters show that temperature has a negative correlation to the samples of charnockite formation during both seasons; pH and TDS also show negative relationships to 222 Rn during SWM

Risk assessment in ballast water management

The risk assessment (RA) developed according to the BWM Convention is the most recently agreed global RA for bioinvasions. It was developed to enable a selective ballast water management (BWM) approach according to the BWM Convention and the G7 Guidelines. It describes three different BWM RA methods, “environmental matching”, “species’ biogeographical” and “species-specific” RA. The environmental matching RA between the areas of ballast water origin and discharge considers non-biological parameters as surrogates for the species survival potential in the new environment. The species’ biogeographical RA identifies species with overlapping distribution in the donor and recipient ports and biogeographic regions which is taken as direct indications of the similarity of the environmental conditions and hence species survival in the new environment. The species-specific RA is focused on life history information and physiological tolerances to identify a species’ physiological limits estimating its potential to survive or complete its life cycle in the new environment and considers target species. There are two fundamentally different RA approaches under the BWM Convention, the selective and the blanket approach. A blanket approach means that all ships intending to discharge ballast water in a port are required to conduct BWM. The selective approach means that appropriate BWM measures are required depending on different risk levels posed by the intended ballast water discharge. In one instance ships may be exempted from BWM requirements provided that the risk level of a ballast water discharge is acceptable. In another instance, if the risk is identified as (very) high, ships may be required to take additional measures based on the G13 Guidelines. The risk level is a RA result and input data reliability is of key importance. The chapter provides detailed step-by-step RA models for exemptions and for selective BWM measures, ready to be used by administrations