In the Philippines, phytoremediation studies on heavy metals are mainly concentrated in mining areas amidst several reports of heavy metal contamination even in non-mining sites in various parts of the country. Such was the case Balili River which was reportedly contaminated with mercury (Hg) and lead (Pb). Aquatic macrophytes growing in the river could offer the solution to this problem via phytoremediation. Thus, this study was conceptualised to determine the uptake of Hg and Pb in selected dominant macrophytes of the river namely Amaranthus spinosus, Eleusine indica and Pennisetum purpureum. Soil, water and plant samples gathered from the study sites were submitted to Department of Science and Technology-Cordillera Administrative Region (DOST-CAR) laboratory for Hg and Pb determination. Soil and wastewater of Balili River were found contaminated with Pb but not with Hg. The soil recorded higher Hg concentration than water while Pb concentrations did not differ between the two media. The aquatic macrophytes in the study registered consistently higher Hg and Pb in their shoots > roots but differed in their capacities and distribution in the shoot organs. Hg and Pb accumulation was significantly (p = 0.00) higher in stem of P. purpureum while in E. indica, leaf had the highest accumulation, though not statistically significant (p = 0.09). For A. spinosus, Hg was highest in its leaf while Pb in stem, though not statistically significant (p = 0.06). Among the three macrophytes, P. purpureum showed the highest potential for Hg uptake and translocation and for Pb uptake. On the other hand, the highest Pb internal transfer was recorded in E. indica. These results contradict initial findings that Pb is mostly accumulated in plant roots with minimal shoot translocation. Also, these results show that local macrophytes in Balili River, even if obnoxious weeds, are ecologically important and could be used for phytoremediation of local rivers that are recipient of small-scale mine tailings.
The study presents the morphology, anatomy and mathematical modelling in Benguet lily (Lilium philippinense Baker), a threatened species from the Cordillera Central Range and was often misidentified with the weedy L. formosanum. The plant is an annual herb with linear, spiral leaves; pure white, perfect, funnel-shaped, showy flowers; septicidal elongated capsule; and, brown, light, winged seeds. New findings in the study include the description of the capsule and seeds, biometric measurements of the different plant organs, the significant correlation and regression model of plant height and stem diameter for certain floral measurement, and its diagnostic characteristics vis-à-vis L. formosanum. Interesting findings on the taxon's anatomy show a cross between a typical monocot and a typical dicot anatomy. It has a bifacial leaf structure (a common dicot character) but its spongy layer is not as widely spaced like in dicot leaf. The stem has a distinct cortex and pith (a dicot character) but has a scattered vascular bundles (a monocot character). Lastly, some roots have a narrow pith at the centre of the stele (a monocot character) while some roots have metaxylem elements at the centermost structure (a dicot character). Further studies need to be conducted to determine the ecological significance of these features.