Heavy metal sorption by aquatic plants in Taiwan

Constructed Wetlands as a Landscape Management Practice for Nutrient Removal from Agricultural Runoff—A Local Practice Case on the East Coast of Taiwan

Runoff with excessive nutrients from rice paddy fields that releases into the Pacific Ocean has been a possible cause of water body pollution and harm to marine life. Constructed wetlands had developed for decades but were rarely implemented in treating agricultural pollution in Taiwan. Moreover, the environmental policies haven’t provided enough instructions, support, or compensation for the establishment of this practice. The rice paddy field that was chosen in this study is located in Xinshe, Taiwan. It is close to the Pacific Ocean where coral reefs are nearby and fishery resource is abundant. In this study, the northern half of the whole organic field was chosen, and the contributing area is approximately 1 × 105 m2. Four plots of constructed wetlands (approximately 17.5 m wide, 16.7 m long, and 0.2 m deep each, covering 1164.74 m2 of the total area) and employing surface flow were established as CW treatment. Water spinach (Ipomoea aquatica) was used for treating the nutrient runoff from organic rice paddy fields. Water samples of input and output of constructed wetlands were collected during 51 days of the experimental period (from the first day of rice transplantation to 10-days before harvest). Ammonia, nitrate, nitrite, phosphate, and total phosphorus concentrations were analyzed to calculate the nutrient load. The runoff of rice paddy fields without constructed wetlands was also sampled as a reference (RPF treatment). In average, about 54.3% ammonia and 42.7% nitrate was removed from the runoff that went through the CW treatment, while 4.2% ammonia and 51.3% nitrate increase were found at the output of the RPF treatment. Meanwhile, 35.6% of total phosphorus and 29.5% of phosphate were removed from the runoff of constructed wetlands. Only 16.4% total phosphorus and 6.4% phosphate were removed from the RPF treatment. Results indicate that constructed wetlands are promising treatment for agricultural runoff and the result can be used as a reference for the future environmental policies enactment in Taiwan.

Quinolone and Organophosphorus Insecticide Residues in Bivalves and Their Associated Risks in Taiwan

Bivalves, such as freshwater clams (Corbicula fluminea) and hard clams (Meretrix lusoria), are the most extensive and widely grown shellfish in land-based ponds in Taiwan. However, few studies have examined the contamination of bivalves by quinolone and organophosphorus insecticides. Thus, we adapted an established procedure to analyze 8 quinolones and 12 organophosphorus insecticides using liquid and gas chromatography–tandem mass spectrometry. Surveys in Taiwan have not noted high residual levels of these chemicals in bivalve tissues. A total of 58 samples of freshwater or hard clams were obtained from Taiwanese aquafarms. We identified 0.03 mg/kg of enrofloxacin in one freshwater clam, 0.024 mg/kg of flumequine in one freshwater clam, 0.02 mg/kg of flumequine in one hard clam, 0.05 mg/kg of chlorpyrifos in one freshwater clam, 0.03 mg/kg of chlorpyrifos in one hard clam, and 0.02 mg/kg of trichlorfon in one hard clam. The results indicated that 5.17% of the samples had quinolone insecticide residues and 5.17% had organophosphorus residues. However, the estimated daily intake (EDI)/acceptable daily intake quotient (ADI) indicated no significant risk and no immediate health risk from the consumption of bivalves. These results provide a reference for the food-safety screening of veterinary drugs and pesticides in aquatic animals. Aquatic products should be frequently screened for residues of prohibited chemicals to safeguard human health.

A comparative study on characterization of textile wastewaters (untreated and treated) toxicity by chemical and biological tests

Toxicity of textile wastewaters (untreated and treated) and their ingredient chemicals was quantified in terms of their chemical characteristics, fish (Gambusia affinis) mortality and end point growth responses of duckweed (Lemna aequinoctialis) in short-term bioassays. Other parameters of fish bioassay were erythrocyte morphology and its counts. Despite of a definite correlation between data of biological tests (LC/EC(50) values) with that of chemical tests, biological tests were found to be relatively more sensitive to both wastewaters and ingredient chemicals. Amongst all the examined parameters of test organisms, fish RBCs (morphology and counts) sensitivity to pollutants in the wastewaters was usually maximum and therefore, their study should be included in the routine fish bioassay. Other advantage of biological test such as on Lemna is even detection of eutrophic potential of wastewaters, as noted at their higher dilutions. The ingredient chemicals (major) contributing maximum toxicity to textile dye wastewater were, acids (HCl and H(2)SO(4)), alkali (Na(2)O SiO(2)), salt (NaNO(2)) and heavy metal (Cu), whereas dyes (4) were relatively less toxic.