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Heavy metals are an important class of chemical contaminants and food is a major vehicle for entry into the ecosystem. Crucian carp (Carassius auratus Gibelio) is an aquatic organism affected by metals and constitutes a major source of contaminated food in the subsidence area. Therefore, cadmium, copper, lead, and zinc were determined in the water of subsidence pools and different tissues of Carassius auratus Gibelio. In addition, the metal concentrations in water and fish from this study were compared with national and international quality guidelines and literature values. The concentrations of metals in water were in the range of 4.05 to 15.49 µg L -1 for zinc, 3.03 to 5.43 µg L -1 for lead, 0.33 to 1.48 µg L -1 for cadmium, and 7.25 to 26.93 µg L -1 for copper, which are within the permissible levels for culturing fish. Metal concentrations in tissues (viscera, gills, and muscle) varied significantly depending on the site. In Carassius auratus Gibelio, the accumulation of metals was in the sequence viscera > gills > muscle. Metal Downloaded by [Universite Laval] at 17:39 27 December 2014 2 concentrations in muscle (Zn, 8.63 to 10.5 mg kg -1 ; Pb, 0.12 to 0.36 mg kg -1 ; Cd, 0.005 to 0.01 mg kg -1 ; Cu, 1.14 to 1.77 mg kg -1 ) of Carassius auratus Gibelio were far below the permissible limits proposed by Food and Agriculture Organization/World Health Organization and Chinese legislation, suggesting that the fish were safe for human consumption. Correlations between metal concentrations in tissues of Carassius auratus Gibelio and in water are reported.

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Earthworm mucus is rich in nutrients that can initiate the mineralization and humification of organic matter and is of great importance for contaminated soil remediation and sludge reutilization. In this study, six voltage and current combinations were utilized to promote earthworm mucus production (5 V and 6 V at 10, 20 and 30 mA, respectively), to explore the compositional changes of the mucus produced under different electrical stimuli, and to propose the best electrical stimulation group and mucus fraction applicable to soil heavy metal pollution remediation and sludge reutilization. The results showed that the mucus produced by the six electrical stimuli was mainly composed of proteins, amino acids, carbohydrates, fatty acids, and polysaccharides, with small amounts of alcohol, phenol, and ester organic substances. Under different electrical stimuli, each component changed significantly (P < 0.05). pH and conductivity were higher at 6 V 20 mA, total nitrogen and phosphorus contents reached their maximum at 5 V 30 mA, and total potassium at 6 V 10 mA. Protein, amino acids, and carbohydrates were most abundant in the mucus produced at 5 V 10 mA, while trace metal elements reached their lowest values at 5 V 10 mA. Finally, based on principal component analysis and combined with previous studies, it was concluded that the mucus produced at 5 V 10 mA was weakly alkaline, high in amino acids and nutrients and low in trace metal elements, and most suitable for sludge and straw composting experiments, soil remediation and amendment experiments.

The subsidence pond is an important water resource for coal mining areas in China. In order to take full advantage of the subsidence pond, a floating photovoltaic cover or a pillaring photovoltaic cover were installed on the surface water of the subsidence pond in the Huainan coal field. Different photovoltaic systems (floating/pilling cover) equipped in the subsidence pond may affect the water quality; thus, assessing the metals in the subsidence pond with the solar photovoltaic system is of great importance for environment control. In this research, surface water samples were collected from three different subsidence ponds, with or without the solar photovoltaic system. The concentrations of Pb, Cr, Ni, Cu, As, Mn, and Zn in the water of the subsidence pond were determined using ICP-MS and AFS. Then, the health risk posed by the heavy metal in different subsidence pond waters via the ingestion pathway was evaluated and analyzed using the assessment model recommended by USEPA. The results indicated that the mean concentrations of Pb, Cr, Ni, Cu, As, Mn, and Zn in the water of different subsidence ponds were less than the environmental quality standards for surface water (China, Grade II). Cr showed a higher non-carcinogenic risk than the other metals, and the photovoltaic cover actually decreased the total non-carcinogenic risk in the photovoltaic subsidence pond compared with the natural subsidence pond. Non-carcinogenic risks of single and total heavy metals in the subsidence ponds with or without solar photovoltaic systems were below 1; thus, these risks in different subsidence ponds were considered to be at an acceptable level. However, the potential single carcinogenic risks of Cr, Ni, and As; and the multielement carcinogenic risks of Pb, Cr, Ni, and As exceeded the limits of 1 × 10−6 and 1 × 10−4, respectively, suggesting that these metals showed single and total potential health risks in the subsidence pond, with or without the solar photovoltaic system. Further, the subsidence pond with the photovoltaic cover showed higher total carcinogenic risks in comparison with the natural subsidence pond. Therefore, a subsidence pond with a solar photovoltaic system should be monitored periodically to ensure the water safety.

Copper mine tailings pose many threats to the surrounding environment and human health, and thus, their remediation is fundamental. Coal spoil is the waste by-product of coal mining and characterized by low levels of metals, high content of organic matter, and many essential microelements. This study was designed to evaluate the role of coal spoil on heavy uptake and physiological responses of Lolium perenne L. grown in copper mine tailings amended with coal spoil at rates of 0, 0.5, 1, 5, 10, and 20%. The results showed that applying coal spoil to copper mine tailings decreased the diethylenetriaminepentaacetic acid (DTPA)-extractable Cd, Cu, Pb, and Zn contents in tailings and reduced those metal contents in both roots and shoots of the plant. However, application of coal spoil increased the DTPA-extractable Cr concentration in tailings and also increased Cr uptake and accumulation by Lolium perenne L. The statistical analysis of physiological parameters indicated that chlorophyll and carotenoid increased at the lower amendments of coal spoil followed by a decrease compared to their respective controls. Protein content was enhanced at all the coal spoil amendments. When treated with coal spoil, the activities of superoxide dismutases (SOD), peroxidase (POD), and catalase (CAT) responded differently. CAT activity was inhibited, but POD activity was increased with increasing amendment ratio of coal spoil. SOD activity increased up to 1% coal spoil followed by a decrease. Overall, the addition of coal spoil decreased the oxidative stress in Lolium perenne L., reflected by the reduction in malondialdehyde (MDA) contents in the plant. It is concluded that coal spoil has the potential to stabilize most metals studied in copper mine tailings and ameliorate the harmful effects in Lolium perenne L. through changing the physiological attributes of the plant grown in copper mine tailings.

Exploitation and utilization of coal can result in a series of ecological environment problems. Coal waste was the solid waste released in the process of coal mining. When coal waste was dumped to form pile, it not only occupies lots of arable land, but also endangers the ecological system in coal mine district. In this study, coal waste pile of Panyi coal mine were surveyed for naturally occurring plant species and limiting factors for plant residence. The plant species, Summed dominance ratio, Species diversity index and Evenness index were calculated for the plant communities grown at the bottom of pile. Heavy metal concentrations and chemical properties in coal waste compared with uncontaminated soil were also determined. Results showed that two stable plant communities (Synodon dactylon + Setaria viridis community and Humulus scandens community) could adapt to the harsh conditions at the bottom of coal waste pile. Synodon dactylon and Humulus scandens were the dominant plants that may prove useful in future revegetation programs of coal waste pile. Elevated levels of Cd and electrical conductivity and lower levels of total P and total K might be the limiting factors affecting the residence and growth of pioneering plants.