Systematic approach to source-sink apportionment of copper in paddy fields: Experimental observation, dynamic modeling and prevention strategy.

The accumulation of heavy metals in paddy rice severely impacts the health of consumers and plants. In this study, a systematic approach to source-sink apportionment of copper in paddy fields was developed by considering all bioenvironmental interfaces. Experimental data from two experimental fields (namely Field A and Field B) in the first harvest period was collected. Then, mass-balance-based models with dynamic critical loads were established to evaluate the year of excess for copper. The results indicated that irrigation water contributed the highest portion (96.2-98.8%) of total copper inputs. Under the business-as-usual scenario, the soil copper concentration of Field A and Field B might exceed the Taiwanese national standard within 66 and 24 years, respectively. In addition, alternate wet-dry irrigation was found to be one of the total solutions to reducing copper accumulation in soils by 17-48%. It could also provide a significant reduction of water usage in paddy fields by ~25%, thereby increasing the resilience to extreme climate change events. Lastly, based on the field observations, three improvement strategies on sustaining soil quality towards better agricultural environment were proposed. The connection of copper accumulation in soils with dietary and ecological risks was also briefly illustrated.

Establishment of an Automatic Real-Time Monitoring System for Irrigation Water Quality Management.

In order to provide the real-time monitoring for identifying the sources of pollution and improving the irrigation water quality management, the integration of continuous automatic sampling techniques and cloud technologies is essential. In this study, we have established an automatic real-time monitoring system for improving the irrigation water quality management, especially for heavy metals such as Cd, Pb, Cu, Ni, Zn, and Cr. As a part of this work, we have first provided several examples on the basic water quality parameters (e.g., pH and electrical conductance) to demonstrate the capacity of data correction by the smart monitoring system, and then evaluated the trend and variance of water quality parameters for different types of monitoring stations. By doing so, the threshold (to initiate early warming) of different water quality parameters could be dynamically determined by the system, and the authorities could be immediately notified for follow-up actions. We have also provided and discussed the representative results from the real-time automatic monitoring system of heavy metals from different monitoring stations. Finally, we have illustrated the implications of the developed smart monitoring system for ensuring the safety of irrigation water in the near future, including integration with automatic sampling for establishing information exchange platform, estimating fluxes of heavy metals to paddy fields, and combining with green technologies for nonpoint source pollution control.

A multiple model approach for evaluating the performance of time-lapse capsules in trapping heavy metals from water bodies.

Adsorption by ion-exchange resins has been widely used as a cost-effective method for removing numerous hazardous materials, particularly heavy metals, from aqueous solutions. For effectively detecting the illegal discharge of industrial wastewater containing heavy metals, we developed "time-lapse capsules" to trap metallic ions from water bodies. Despite recent progress in the development of time-lapse capsules, a fundamental understanding was still needed to unravel the adsorption behavior of different heavy metals for further improvement of the design and scale-up of the capsule. In this study, three different approaches, viz., response surfaces (from the statistical point of view), time-dependent diffusion-controlled models (from the kinetic point of view), and adsorption isotherms (from the equilibrium point of view), were utilized to evaluate the effect of operating factors on the adsorption of heavy metals from watershed using time-lapse capsules. The obtained results indicated that the key parameters, such as adsorption rate constant, diffusivity, and maximum adsorption capacity, could provide insights into the basis of design criteria.