Toward Sustainable Environmental Quality: Priority Research Questions for Asia.

Environmental and human health challenges are pronounced in Asia, an exceptionally diverse and complex region where influences of global megatrends are extensive and numerous stresses to environmental quality exist. Identifying priorities necessary to engage grand challenges can be facilitated through horizon scanning exercises, and to this end we identified and examined 23 priority research questions needed to advance toward more sustainable environmental quality in Asia, as part of the Global Horizon Scanning Project. Advances in environmental toxicology, environmental chemistry, biological monitoring, and risk-assessment methodologies are necessary to address the adverse impacts of environmental stressors on ecosystem services and biodiversity, with Asia being home to numerous biodiversity hotspots.

Partitioning and Bioaccumulation of Legacy and Emerging Hydrophobic Organic Chemicals in Mangrove Ecosystems.

Knowledge regarding partitioning behavior and bioaccumulation potential of environmental contaminants is important for ecological and human health risk assessment. While a range of models are available to describe bioaccumulation potential of hydrophobic organic chemicals (HOCs) in temperate aquatic food webs, their applicability to tropical systems still needs to be validated. The present study involved field investigations to assess the occurrence, partitioning, and bioaccumulation behavior of several legacy and emerging HOCs in mangrove ecosystems in Singapore.

Multi-tool assessment of trace metals in mangroves combining sediment and clam sampling, DGT passive samplers and caged mussels.

The rapid loss of mangroves globally has triggered a call for a better understanding of this habitat, including its dynamics and the threats it is exposed to. The present paper reports the study of trace metals at nine mangrove sites in Singapore in 2012/2013, using the simultaneous application of various tools, namely sediment analyses, the technique of diffusive gradients in thin-films (DGT) and caged/native bivalves (for both chemical and biomarker analyses). DGT devices were successfully deployed over 28days in tropical mangrove waters, and the concentration measured with DGT showed significant correlation with the accumulation for Cu, Zn and Cd in caged mussels, and Cu for native clams, supporting the relevance of DGT to predict metal bioaccumulation.

Use of a suite of biomarkers to assess the effects of carbamazepine, bisphenol A, atrazine, and their mixtures on green mussels, Perna viridis.

The present study investigated the toxicity of several emerging contaminants: the pharmaceutical drug carbamazepine (CBZ), the plasticizer bisphenol A (BPA), and the herbicide atrazine (ATZ) in a marine bivalve. Green mussels (Perna viridis) were exposed to different concentrations of CBZ, BPA, and ATZ, either individually or as mixtures over a 7-d period, and a suite of molecular and cellular biomarkers were analyzed: biomarkers of immunotoxicity (total hemocyte count, phagocytosis, extracellular lysozyme), genotoxicity (Comet assay), neurotoxicity (inhibition of acetylcholinesterase [AChE]), endocrine disruption (vitellin-like proteins), and detoxification enzymes (cytochrome P4501A [CYP1A], 7-ethoxyresorufin O-deethylase [EROD], and glutathione-S-transferase [GST]). Results of the single-chemical exposure tests highlighted the relatively low toxicity of CBZ because most biomarker responses observed were recorded at concentrations well above environmental levels.

Pharmaceutically active compounds and endocrine disrupting chemicals in water, sediments and mollusks in mangrove ecosystems from Singapore.

This study investigated the occurrence of bisphenol A (BPA), atrazine and selected pharmaceutically active compounds (PhACs) in mangrove habitats in Singapore in 2012-2013, using multiple tools (sediment sampling, POCIS and filter feeder molluscs). Using POCIS, the same suite of contaminants (atrazine, BPA and eleven PhACs) was detected in mangrove waters in 28-days deployments in both 2012 and 2013. POCIS concentrations ranged from pg/L to μg/L.

Direct injection of tissue extracts in liquid chromatography/tandem mass spectrometry for the determination of pharmaceuticals and other contaminants of emerging concern in mollusks.

In the present study, a straightforward approach was validated for the analysis of pharmaceutically active compounds and endocrine-disrupting chemicals in the mollusk tissues, with a focus on two species commonly consumed in Southeast Asia (green mussels: Perna viridis; lokan clams: Polymesoda expansa). This approach relied on a simple solvent extraction (shaker table) followed by direct injection in liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). This "cleanup-free" approach was made possible by the use of isotopically labeled surrogates (to correct for matrix effects) and a post-column switch on the LC-MS/MS system (to remove potential interfering material).

Alumina nanoparticles enhance growth of Lemna minor.

The industrial use of nanoparticles is rapidly increasing, and this has given rise to concerns about potential biological impacts of engineered particles released into the environment. So far, relatively little is known about uptake, accumulation and responses to engineered nanoparticles by plants. In this study, the effects of alumina nanoparticles on growth, morphology and photosynthesis of Lemna minor were quantified.

In vivo exposure to microcystins induces DNA damage in the haemocytes of the zebra mussel, Dreissena polymorpha, as measured with the comet assay.

The Comet assay was used to investigate the potential of the biotoxin microcystin (MC) to induce DNA damage in the freshwater zebra mussel, Dreissena polymorpha. Mussels maintained in the laboratory were fed daily, over a 21-day period, with one of four strains of the cyanobacterium, Microcystis aeruginosa. Three of the strains produced different profiles of MC toxin, while the fourth strain did not produce MCs.

Pseudodiarrhoea in zebra mussels Dreissena polymorpha (Pallas) exposed to microcystins.

Microcystins are produced by bloom-forming cyanobacteria and pose significant health and ecological problems. In this study we show that zebra mussels respond differently to different strains of Microcystis aeruginosa, and that a highly toxic strain causes zebra mussels to produce large quantities of mucous pseudofaeces, 'pseudodiarrhoea', that are periodically expelled hydraulically through the pedal gape by shell valve adductions rather than by the normal ciliary tracts. Analysis of the pseudofaecal ejecta showed that the proportion of Microcystis aeruginosa relative to Asterionella formosa was high in the pseudofaeces and even higher in the 'pseudodiarrhoea' when a mixed diet was given to the mussels.

Genetic and physiological responses of flounder (Platichthys flesus) populations to chemical contamination in estuaries.

We sampled and analyzed European flounder (Platichthys flesus) from two highly contaminated estuaries (Seine and Loire, France) and one moderately contaminated estuary (reference site: Ster, France). Significant and convergent modifications of the allelic frequencies for the loci phosphoglucomutase (PGM), glucose phosphate isomerase 2 (GPI-2), mannose phosphate isomerase (MPI), and aspartate aminotransferase (AAT-2) were evident for fish in the contaminated sites versus fish from the reference site. Back-calculation from otoliths showed that the average growth rate of fish between the first and the second winter was greater at the reference site (approximately 150 mm/year) than at the contaminated sites (approximately 100 mm/year).