Ranil Kavindra Asela Kularatne

This article provides an assessment of the efficiency and efficacy of Sri Lanka's legislation Marine Pollution Prevention Act No. 35 of 2008 (administered by the Marine Environmental Protection Authority/MEPA), for protecting Sri Lankan waters from pollution. Although there are provisions to control pollution - from ships, harbors/ports, any facility used by ships and offshore petroleum exploration projects - and to deal with offences, imposing both criminal and civil liabilities for offenders, there are some serious loopholes. This includes failure to address land-based pollution sources, unclear provisions for ballast water disposal and no consideration for pollution from other offshore projects, etc. The Act requires significant amendments considering the international conventions pertaining to marine pollution control, both ratified and unratified by Sri Lanka. The success of amending the Act must also be monitored by MEPA with other government agencies implementing the international instruments dealing with marine environmental monitoring ratified by Sri Lanka.

This article discusses bioaccumulation and temporal variation of heavy metals in three edible lagoon fish species with references to gender. Cd and As were undetected in the three fish species (i.e., below the method detection limits of 1 μg Cd/kg wet weight and 2 μg As/kg wet weight) irrespective of the periods, and Cd was undetected in the water too (i.e., below the detection limit of 0.0003 mg/L). Except for Zn (which was mainly available as Zn²⁺ in the water), Pb was present largely as low labile metal-chloride complexes and As as HAsO₄²⁻ as per Visual MINTEQ, version 3.1. Bio-transfer factors of Sn (which was also undetected in the water; below the detection limit of 0.05 mg/L), Hg, Pb, and Zn were Arius maculatus (a carnivore) exhibited higher Zn, Hg, and Sn accumulations during the drier periods (June–September) compared with Mugil cephalus (a detritivore/herbivore) and Etroplus suratensis (an omnivore). Pb was detected only in A. maculatus (July–August) possibly due to biomagnification. Zn was present in higher levels in all species (irrespective of sex) compared with the other metals, but levels were below admissible limits. However, the relationship between temporal variation of Zn and gender in all species was insignificant. In M. cephalus, the temporal variation of Sn and Hg between the sexes was also insignificant. Female A. maculatus and E. suratensis showed higher Hg concentrations, while males showed higher Sn concentrations. Temporal variation patterns of Pb were unclear.

This article discusses key mechanisms involved in removing 1 mg/L Mn from synthetic wastewaters in constructed wetlands comprising water hyacinth (Eichhornia crassipes (Mart.) Solms) grown under different nutrient levels of 1‐fold (28 mg/L and 7.7 mg/L of total nitrogen and total phosphorus, respectively), 2‐fold, 1/4‐fold, and 1/8‐fold. A mass balance was carried out to evaluate the key removal mechanisms. Phytoremediation mainly due to phytoextraction substantially contributed to manganese removal. However, chemical precipitation was absent, suggesting that manganese has a higher solubility in the given average pH (6.2 to 7.1) conditions in constructed wetlands. Bacterial mediated immobilization mechanisms also did not contribute to manganese removal. Sediments constituted a minor sink to manganese, implying that manganese has a poor adsorption potential. Constructed wetlands comprising water hyacinth are effective at removing manganese from wastewaters despite the fact that the plants are grown under higher or lower nutrient conditions.