Coal fly ash effluent affects the distributions of Brachionus calyciflorus sibling species

Research on freshwater water quality criteria, sediment quality criteria and ecological risk assessment of triclosan in China

Triclosan (TCS) is a broad-spectrum antimicrobial agent commonly used in pharmaceuticals and personal care products (PPCPs). The widespread use of TCS makes it frequently detected in various environmental mediums. In view of the high detection frequency of TCS in the aquatic environment and sediments, and its toxic effects on aquatic species, it is critical and necessary to derive Chinese TCS water quality criteria (WQC) and sediment quality criteria (SQC) for protecting Chinese aquatic organisms, and perform the ecological risk assessment. In fact, former research had derived the WQC of TCS mainly based on acute and chronic toxicity data. As an endocrine disrupting chemical (EDC), TCS poses adverse effects on the growth, development and reproduction of aquatic organisms at much lower concentration. Considering nonlethal endpoints are sensitive endpoints for EDCs, TCS long-term water quality criteria (LWQC) was derived based on reproduction and growth related endpoints. In this work, the acute toxicity data of 19 aquatic organisms and the chronic toxicity data of 15 aquatic organisms were obtained through collection and screening. The best fitting model of species sensitivity distribution (SSD) models including Normal, Log-Normal, Logistic and Log-Logistic of toxicity data was selected to derive WQC. The short-term and long-term WQC of TCS for Chinese aquatic organisms were 6.22 μg/L and 0.25 μg/L, respectively. Furthermore, through the phase-equilibrium partitioning method, SQC was derived based on WQC. SQC-low (SQC-L) and SQC-high (SQCH) were 0.13 mg/kg and 3.26 mg/kg, respectively. Moreover, the exposure concentration (EPC) data of TCS in Chinese rivers and sediments were collected. And through the hazard quotient (HQ) method and the joint probability curve (JPC) method we found that there were certain TCS ecological risks in Chinese rivers and sediments. Our work will provide a valuable reference for protecting aquatic organisms and minimizing TCS ecological risk in China.

Mineralogy Characteristic Study and Exploration on the Valuable Metals Enrichment of Coal Fly Ash

The separation and enrichment can be targeted to enrich in fly ash and reduce the cost of leaching and recovering of fly ash. Regarding their different properties, the single-component separation was used to obtain uncompleted burned carbon, glass microbeads, minerals, and other characteristic components from the ash. Also, the mineral composition of each component was analyzed by electron microscopy. The metal minerals were mainly concentrated in the mineral components. Besides, the electron probe microanalysis shows that the Pt content in the minerals of fly ash was significantly correlated with the metal contents of Ni and Cu. After the obtainment of the characteristics of fly ash metal enrichment, the heavy minerals with Cu, Ni, Pt, Pd, and other target metal elements were enriched by gravity separation and flotation. The enrichment coefficients of Cu, Ni, Pt, and Pd were 1.45, 1.33, 1.90, and 1.60, respectively, and the recovery rates were 77%, 81%, 97%, and 88%, respectively. Since the yield of heavy minerals obtained by separation was 62.24%, it indicated the physical separation method could significantly reduce the cost of leaching and recovering of fly ash metal resources.

Complete mitochondrial genome of the freshwater monogonont rotifer Brachionus calyciflorus (Rotifera, Brachionidae)

The two complete mitochondrial genomes were sequenced from the Netherlands strain of the freshwater monogonont rotifer Brachionus calyciflorus. The mitochondrial genome sequences were 27,698 bp and 9,906 bp in size, respectively. The gene order and contents of the two B. calyciflorus strains were mostly identical to one another, except for the additional identification and translocation of several tRNAs in mitochondrial DNA I and II. Of 13 protein-coding genes (PCGs), three genes (ND1, ND5, and ND3) had incomplete stop codons. Furthermore, the start codon of ND2, CO2, and CO3 and ND4 genes was ATT, GTG, and ATA, respectively, while the start codon of other PCGs was ATG. The base composition of 13 PCGs of B. calyciflorus (the Netherlands strain) mitogenome showed 31.1% for A, 37.6% for T, 16.5% for C, and 14.8% for G, respectively.

Morphological differentiation of Brachionus calyciflorus caused by predation and coal ash pollution

Different rotifer stains exhibited remarkably morphological differences which could not be eliminated under laboratory conditions. In the present study, we hypothesized that predation pressure and pollution might be two forces driving morphological differentiation of rotifer. To test this hypothesis, rotifers (Brachionus calyciflorus) belonging to two sibling species were collected from three special lakes (with coal ash pollution, high predation pressure or neither) and cultured for more than three months to investigate their potential differentiation in morphology. Twelve morphological parameters were measured and compared among three lakes at four food density (Scenedesmus obliquus). The results showed that most of the tested morphological parameters changed in response to food level and differed among three habitats. Rotifers from the habitat with high predation pressure evolved stable long posterior lateral spine and relatively small body size. Rotifers collected from the polluted habitat was of smaller body size, compared with those from ordinary habitat. Bigger eggs were laid by rotifers from polluted area or lake with high predation pressure, enabling newborns more resistant to pollution or predation, and thus ensuring the survival rate of newborns. Finally, we concluded that both predation and pollution could affect the morphological differentiation and evolution of rotifers.

Full life-cycle toxicity assessment on triclosan using rotifer Brachionus calyciflorus

Triclosan (TCS) is an antimicrobial and is an aquatic contaminant. Little is known on aquatic toxicity of TCS. Rotifers are common members of freshwater zooplankton. In this study, Brachionus calyciflorus was chosen as a test organism to assess the acute and complete life cycle toxicity of TCS in this study. The acute toxicity results showed that the 24-h median lethal concentration (LC50) of TCS was 345±0.11μg/L (95% confidence limits of 212-564µg/L). Reproductive bioassays demonstrated that TCS could inhibit the population growth rate at the concentration higher than 1.0μg/L. Resting egg production encompasses the full life-cycle of rotifer, and thus its hatching rate were explored to assess the toxicity of TCS towards rotifer population at TCS concentrations ranging from 0.1 to 200µg/L at two different growth periods. When resting eggs were exposed to TCS during the formation period, 0.1 and 1.0µg/L of TCS increased the hatching rate from 0.402 to 0.502, and 0.475, respectively. Exposure to 100 and 200µg/L of TCS reduced the hatching rate to 0.309 and 0.275, respectively. When the resting eggs were formed in the control medium and hatched in medium with TCS, their hatching rates were not significantly influenced by TCS, except that 200µg/L of TCS decreased the hatching rate from 0.402 to 0.34 significantly. The effects of TCS exposure on the hatching rate during the formation period were greater than those during the resting egg hatching period.