A critical review on environmental implications, recycling strategies, and ecological remediation for mine tailings.

Mine tailings, generated from the extraction, processing, and utilization of mineral resources, have resulted in serious acid mine drainage (AMD) pollution. Recently, scholars are paying more attention to two alternative strategies for resource recovery and ecological reclamation of mine tailings that help to improve the current tailing management, and meanwhile reduce the negative environmental outcomes. This review suggests that the principles of geochemical evolution may provide new perspective for the future in-depth studies regarding the pollution control and risk management. Recent advances in three recycling approaches of tailing resources, termed metal recovery, agricultural fertilizer, and building materials, are further described. These recycling strategies are significantly conducive to decrease the mine tailing stocks for problematic disposal. In this regard, the future recycling approaches should be industrially applicable and technically feasible to achieve the sustainable mining operation. Finally, the current state of tailing phytoremediation technologies is also discussed, while identification and selection of the ideal plants, which is perceived to be the excellent candidates of tailing reclamation, should be the focus of future studies. Based on the findings and perspectives of this review, the present study can act as an important reference for the academic participants involved in this promising field.

Contamination characteristics and potential environmental implications of heavy metals in road dusts in typical industrial and agricultural cities, southeastern Hubei Province, Central China.

In November 2013, the total concentration of selected heavy metals in 43 urban dust samples, collected from two small-sized cities of industrial E'zhou and agricultural Huanggang, located in the southeastern Hubei province, central China, was detected quantitatively by flame atomic absorption spectrometric (FAAS) for ultimate purpose of pollution monitoring and risk evaluation. Results indicated that the mean concentrations exceeding their respective background values were observed for all the investigated metals, with the exception of Co (13.08mg kg-1) and Fe (38635.02mg kg-1) in Huanggang road dusts, whose average concentrations were close to the background levels. In comparison with the reference data reported from the selected cities worldwide, the urban road dusts were seriously polluted by heavy metals to diverse degrees. The contour distribution maps implied that obviously higher values zones were found between two different types of urban areas, located to both sides of the coastline of Yangtze River. Multivariate statistical analysis revealed that the enriched heavy metals had emanated from the combined effects of both natural sources and anthropogenic sources. Three pollution indices indicated that the riskiest element mainly comprising Cr, Ni, Cu, and Pb appeared to be the major contributors to the urban environmental pollution. Avoiding continuous damage requires, the riskiest metallic contaminants should be paid preferential attention to.

[Distribution, Sources and Risk Assessment of the PAHs in the Surface Sediments and Water from the Daye Lake].

8 surface sediments and 8 water samples were collected from the Daye Lake in August 2015.The 16 kinds of EPA control polycyclic aromatic hydrocarbons (PAHs) were analyzed by GC-MS.The results showed that the PAHs concentrations of surface sediments and water ranged from 35.94 ng·g-1 to 2032.73 ng·g-1 and from 27.94 ng·L-1 to 242.95 ng·L-1,with average contents of 940.61 ng·g-1 and 107.77ng·L-1,respectively.The distribution of PAHs in surface sediments indicated that the contents in the center samples were higher than those in the bank samples,but the water showed nearly the opposite tendency.The 4-5 rings high molecular weight PAHs were the main components in the surface sediments,and the 2,4 and 5 rings PAHs were given priority in water.Compared with the other domestic and oversea lakes,the PAHs pollution of the Daye Lake was at a moderate level.Source apportionment showed that the PAHs in surface sediments and water from the Daye Lake came from the combustion source,HWM-PAHs were the dominant part of the PAHs in the sediment,reflecting the sediment PAHs pollution under the effects of mining and smelting over a long period;All monomer PAHs and total PAHs content in sediment did not exceed the ERM and FEL limiting values,showing that there was no particularly serious ecological risk caused by PAHs in the surface sediments from the Daye Lake;the incremental lifetime cancer risks assessment showed that the uptake risk of PAHs in Daye Lake water through the ingestion and dermal absorption were both in the acceptable range recommended by the USEPA,but all sites had higher risk than the acceptable risk level recommended by the Sweden environmental protection agency and Royal society.The pollution of seven carcinogenic PAHs needs prevention and control.

[Pollution Characteristics and Risk Assessment of Heavy Metals in Water and Sediment from Daye Lake].

The surface water and surface sediments were collected from Daye Lake in April 2014. The concentrations of heavy metals were determined by atomic absorption spectroscopy. The pollution potential health risk and ecological risk of heavy metals in water and sediment were assessed by the health risk assessment model and the potential ecological risk index method. The results showed that the concentrations of the heavy metals (Ni, Cd, Cu and Pb) was 49.27 µg·L-1, 2.19 µg·L-1, 12.18 µg·L-1, 12.13 µg·L-1(water) and 78.46 mg·kg-1, 77.13 mg·kg-1, 650.13 mg·kg-1 and 134.22 mg·kg-1 (sediment). Enrichment coefficient indicated that the enrichment of Cd, Cu and Pb was more serious, especially the accumulation of Cd was the most obvious. Compared to typical lakes in China, the contents of heavy metals in water and sediment were relatively high. The spatial pollutant distribution of the heavy metals in water and sediment all presented that the concentrations of the heavy metals were relatively higher in east and west of Daye Lake, relatively more uniform in the middle, and their origins were mainly from human activities. The results of environmental risk indicated that the carcinogens and chemical non-carcinogens health risk values of heavy metals by drinking water pathway were 9.77E-08~1.63E-05a-1. Therefore, the pollution of Ni and Cd should be the primary control target for environmental health risk management. The descending order of pollution degree of four metals in sediment was Cd> Cu> Pb> Ni, and Cd was the main contributor of the potential ecological risk elements.

[Characteristics and Sources of Elements of a PM10 Measurements from a Typical Industrial City in Eastern Hubei Province].

In order to investigate the characteristics and sources of elements in atmospheric aerosols (PM10) measurements, samples were collected between April 2012 and February 2013 in Huangshi, a typical industrial city in the east of Hubei province, China. These samples were analyzed for seventeen elements using wavelength dispersive X-ray fluorescence spectrometry. In addition, the pollution characteristics of fourteen elements were analyzed by an enrichment factor (EF) method, and the sources of these elements were studied by a principal component analysis (PCA) and positive matrix factorization (PMF) method. The result from the EF indicated that the concentration of the seventeen elements in the PM10 measurements varied from 0.01-9.83 µg·m-3. The elemental concentration of S was the highest and Ni and V was the lowest during the monitoring period in Huangshi. Daily levels of Pb and Cd exceeded the annual reference values set by the National Ambient Air Quality Standard (GB3095-2012) by 36.4% and 89.1%, respectively. An analysis of EF showed that Ti, V, Mn, and Ni elements were mildly enriched, indicating they were affected by both natural and anthropogenic sources. Ca, Cr, and Ba elements were moderately enriched and Cu, Zn, Pb, Sn, Sb, and Fe were highly enriched or hyper accumulated, suggesting they are mainly sourced from human activities. There were four sources significantly contributing to the elements in the PM10measurement, which were determined using PCA and PMF analysis. These were soil and fugitive dust, coal combustion, industry exhausts, and motor vehicle emissions. The results of the two models supported each other and had good consistency.

[Concentration and Size Distribution of Bioaerosols in Indoor Environment of University Dormitory During the Plum Rain Period].

Bioaerosols of university dormitory can spread through air and cause a potential health risk for student staying in indoor environment. To quantify the characteristics of bioaerosols in indoor environment of university dormitory, concentration and size distribution of culturable bioaerosols were detected during the plum rain period, the correlations of culturable bioaerosol with concentration of particulate matter, the ambient temperature and relative humidity were analyzed using Spearman's correlation coefficient and finally the changes of size distribution of culturable bioaerosol caused by activities of students were detected. The results showed that the mean concentrations of culturable airborne bacteria and fungi were (2133 +/- 1617) CFUm' and (3111 +/- 2202) CFU x m(-3). The concentrations of culturable airborne bacteria and fungi exhibited negative correlation with PM1, PM2.5, and PM10, respectively. The respirable fractions of bacteria exhibited positive correlation with PM2.5, and the respirable fractions of fungi exhibited significant positive correlation with PM10. Ambient temperature had positive correlation with culturable airborne bacteria and fungi, and relative humidity had negative correlation with culturable airborne bacteria and fungi. In the afternoon, concentrations of culturable airborne fungi in indoor environment of university dormitory significantly increased, and the size distribution of culturable hioaerosols was different in the morning and afternoon.