Phytoremediation of Industrial Sewage Sludge with Eichhornia crassipes, Salvinia molesta and Pistia stratiotes in Batch Fed Free Water Flow Constructed Wetlands.

Phytoremediation of industrial sewage sludge with Eichhornia crassipes, Salvinia molesta and Pistia stratiotes in pilot scale batch fed free water flow constructed wetlands was done in order to assess the suitability of remediated sludge as fertilizer. S. molesta showed the greatest decreases of Zn (36.0%), Fe (26.6%), Cu (32.6%), Cr (58.6%) and Ni, (26.9%) while P. startiotes and E. crassipes, respectively, showed the greatest Cd (27.1%) and Pb (42.4%) decreases. Metals, nutrients (total N and P) and fecal coliform in remediated sludge complied with regulatory standards and P. startiotes showed the greatest electrical conductivity (EC) (65.6%) decrease. The phytotoxicity assay on Lactuca sativa and Brassica oleraceae exhibited more than 50% of germination index from the sludge remediated with S. molesta. The results demonstrate that phytoremediation with hyper accumulators followed by phytotoxicity assay could be used to support decisions for the appropriate use of land disposed industrial sewage sludge.

Use of corticolous lichens for the assessment of ambient air quality along rural-urban ecosystems of tropics: a study in Sri Lanka.

Monitoring of air quality using lichens as bioindicators on the basis of lichen diversity and frequency is limited along rural-urban ecosystems in tropics. This study attempted to assess and correlate the use of corticolous lichens with atmospheric SO2 and NO2 in such an ecosystem in Sabaragamuwa Province in Sri Lanka. Nine sampling locations, each having three subsampling sites with 162 Mangifera indica and Cocos nucifera trees, were selected for the study. The coverage and frequency of lichens found on selected trees were recorded by 400-cm2 grids and identified using taxonomic keys. SO2 and NO2 levels at each site were determined by "Ogawa" passive air samplers. Data of lichen diversity were used to formulate the index of atmospheric purity (IAP). The environmental parameters related to lichen colonization were measured using standard methods. Data were analyzed using MINITAB 17. The mapping of spatial distribution of lichens and air pollutants were done using inverse distance weighting surface interpolation of geographical information system based on IAP values. A negative correlation was observed between IAP and SO2 and NO2 levels. The presence of the genus Pyxine in almost all urban sites indicated that it could be used as a reliable pollutant tolerant indicator in urban ecosystems. In addition, the index-based mapping techniques could be used successfully to see the effect of atmospheric pollution in urban ecosystems. These results conclude that corticolous lichens have the potential to be used as bioindicators of air quality monitoring along rural-urban ecosystems of tropics.

A comparison of the larvivorous habits of exotic Poecilia reticulata and native Aplocheilus parvus.

BACKGROUND: The exotic fish Poecilia reticulata is promoted in the tropics as a biological control agent for aquatic pathogenic carriers, such as mosquitoes. Such control measures are often adopted blindly, ignoring the potential of native species and the adverse effects of introduced species. The present study was conducted to assess the diet composition of two species of fish, the native Aplocheilus parvus and exotic P. reticulata, and to assess the availability of food items in their natural environment in four types of aquatic systems. Diet composition was estimated using 24 h gut contents analysis, in a clay quarry pit and a perennial reservoir for A. parvus, and in a man-made canal and a second-order natural stream for P. reticulata. Food items in these environments were quantified by analyzing water samples collected every 2 h. RESULTS: The diet of A. parvus in the clay quarry pit and reservoir consisted of adult or larval stages of Insecta, Maxillopoda and Malacostraca. In both habitats, A. parvus selectively fed on insect parts and insect larvae. The diet of P. reticulata consisted of filamentous algae, diatoms and detritus. The diet of A. parvus showed active selection of insectivore food items against their low availability. In contrast, the diet of P. reticulata showed consumption of food items in accordance with their availability in the environment. The highest mean number of food items in the gut for A. parvus was recorded around mid-day in the clay quarry pit, but no peak feeding time was identified in the perennial reservoir. For P. reticulata, peak feeding was recorded around mid-day in both the habitats. CONCLUSION: Irrespective of the type of environment and rate of occurrence, A. parvus preferred insect and insect larvae, whereas P. reticulata consumed the most readily available food items. The active selection of insects by A. parvus suggests they may have value as a biological control agent.

Species composition and population dynamics of malaria vectors in three previously ignored aquatic systems in Sri Lanka.

BACKGROUND: In 2015 alone there were an estimated 214 million new cases of malaria across the globe and 438,000 deaths were reported. Although indigenous malaria has not been reported in Sri Lanka since 2012, to date 247 imported cases of malaria have been identified. Knowledge of the locations, behaviour and vectorial capacity of potential malarial vectors is therefore needed to prevent future outbreaks. Attention is now being focused on some previously ignored habitats. METHODS: Active and abandoned granite and clay quarry pits, located in wet and intermediate zones, and agro wells located in the dry zone of Sri Lanka were mapped and sampled for 1 year, as potential mosquito breeding sites. Species composition and spatio-temporal variation in both malarial and other mosquito larvae were recorded. RESULTS: A total of 18 species of mosquito larvae were identified. Other than Anopheles culicifacies, the primary malaria vector, five species of potential malaria vectors (Anopheles vagus, Anopheles varuna, Anopheles nigerrimus, Anopheles peditaeniatus and Anopheles barbirostris) were found in all three aquatic systems. Additionally, Anopheles annularis was found in granite quarries and Anopheles subpictus and Anopheles pallidus in both types of quarry, but only during the initial sampling. Apart from potential malaria vectors, mosquito larvae such as Anopheles jamesii, Culex tritaeniorhynchus, Culex infula and Culex malayi were found in all three habitats at least once during the sampling period. Apart from potential malaria vectors and other mosquito larvae common to all three aquatic systems, Culex gelidus, Culex mimulus and Culex pseudo vishnui were detected in agro wells. Culex gelidus was also detected in granite quarry pits. Culex mimulus, Culex lutzia and Culex fuscocephala were detected in clay quarry pits. Accordingly, a total of 14, 13 and 15 mosquito species were identified in agro wells, granite and clay quarry pits, respectively. CONCLUSIONS: Although zero occurrence of indigenous malaria has been achieved in Sri Lanka, the current study emphasizes the potential for future epidemics. The presence of native flora and fauna in abandoned granite and clay quarry pits and the need to extract drinking water from agro wells demand bio-sensitive control methods in these three aquatic systems.

Organochlorine pesticide and heavy metal residues in some edible biota collected from Quanzhou Bay and Xinghua Bay, southeast China.

In order to assess the contamination of edible marine organisms in Quanzhou and Xinghua Bays, Fujian Province, China, concentrations of organochlorine pesticides (hexachlorocyclohexane isomers or HCHs and dichlorodiphenyltrichloroethane isomers/derivatives or DDTs) and heavy metals (Cu, Pb, Zn, As, Cr, Cd, Ni and Hg) in 13 species collected from different sites in the bays were analyzed by GC-ECD and ICP-MS. The concentration of the sum of DDTs exceeded that the sum of HCHs in the samples. Most of the organisms showed higher levels of DDTs than the first level criterion (10 ng/g) for marine biological quality in China (GB 18421-2001) but conformed to the first level criterion (20 ng/g) for HCHs. The estimated mean daily uptake of pesticides was below the level for minimal risk to the consumers. The levels of Cd, As and Pb in most organisms from both bays were markedly elevated and above the recommended legal limits for human consumption. Our results showed the need for routine monitoring of marine species contamination to ensure public and environmental health.