One hundred and four surface samples and 40 profiles samples in agricultural soils collected from Huizhou in south-east China were monitored for total contents of 8 heavy metals, and analyzed by ...multivariate statistical techniques and enrichment factor (EF), in order to investigate their origins. The results indicate that the concentrations of Cu, Zn, Ni, Cr, Pb, Cd, As and Hg in soils are 16.74, 57.21, 14.89, 27.61, 44.66, 0.10, 10.19 and 0.22mg/kg, respectively. Compared to the soil background contents in Guangdong Province, the mean concentrations of Hg, Cd, Zn, Pb and As in soil of Huizhou are higher, especially Hg and Cd, which are 2.82 and 1.79 times the background values, respectively. Cr, Ni, Cu, partially, Zn and Pb mainly originate from a natural source. Cd, As, partially, Zn mainly come from agricultural practices. However, Hg, partially, Pb originate mainly from industry and traffic sources.
► The concentrations of Hg and Cd are high in agricultural soil of Huizhou. ► Cr, Ni, Cu, partially, Zn and Pb mainly originate from a natural source. ► Cd, As, partially, Zn mainly come from agricultural practices. ► Hg, partially, Pb originate mainly from industry and traffic sources.
Antibiotic contamination attracts growing concerns because of their deleterious effects on the ecosystem and human health. In this study, 43 antibiotics in wastewater from a variety of sources and ...water of the Yangtze River in Chongqing City in western China were measured. Thirty compounds were detected, and their concentrations were highest in leachates from the municipal solid waste treatment facilities (landfills and incineration plants) with total concentrations of 3584–57,106 ng/L. The total concentrations in influents of municipal and industrial wastewater treatment plants (WWTPs) were comparable (401–7994 ng/L versus 640–8945 ng/L). The concentrations in raw sewage from swine farms (with a total of 10,219–39,195 ng/L) and poultry farms (1419–36,027 ng/L) were noticeably higher than those from other farms (54.0–5516 ng/L). Fluoroquinolones were the dominant antibiotics contributing over 50% in all the sources, and sulfonamides and imidazole fungicides contributed 3.2–34%, whereas tetracyclines and macrolides had minor contributions. The overall antibiotic removal rates were highest in solid waste treatment facilities (88% on average), comparable between municipal and industrial WWTPs (61%), and lowest in animal farms (39%). The mass loads to the investigated municipal WWTPs via influent wastewater ranged from 7.80 to 1531 kg/year (53.2–2482 μg/day per capital). The influent mass loads to the industrial WWTPs and farms were 3.7–50 kg/year and 0.9–5437 g/year, respectively. We estimated that the mass inventories of antibiotics from these sources to the environment via effluent discharges were approximately 2044 kg for municipal WWTPs, 61 kg for industrial WWTPs, and 34 kg for animal farms in the whole city. Antibiotic concentrations in the Yangtze River water were substantially low (< 492 ng/L, with a mean of 57.8 ng/L) suggesting dissipation during the movement.
The emission, mass balance, and distribution characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) as well as those of heavy metals (Hg, Cd, Pb, Cr, and Cu) were ...investigated during the cocombustion of 5%, 10%, 15%, and 20% sewage sludge (SS) in a pulverized coal power plant. The PCDD/F emissions increased from 7.00 to 32.72 pg I-TEQ/Nm3 as the amount of SS in the mixed fuel (MF) increased. High sulfur content and relatively low chlorine levels in MF resulted in lower PCDD/F emissions. SS exhibited a remarkable difference in congener profiles compared with flue gas, bottom ash, and fly ash. The negative dioxin mass balance indicated that the cofiring of SS with coal in power plants was not a source but a sink of dioxins. The concentrations and emission factors of heavy metals in flue gas and bottom ash, as well as fly ash, all exhibited a tendency to increase with increasing input values of heavy metals in MF. The distribution characteristics of the investigated heavy metals were primarily dependent on the evaporative properties of these metals. The availability of chlorine could alter the heavy metal distribution behavior. The emitted pollutants in the power plant were below the legal limits.
Since the 2010 s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled ...e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-pdioxins and furans（PCDD/Fs） after stricter environmental regulations. PM_（2.5） and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32 pg TEQ/（kg·day）, which far exceeded the tolerable daily intake（TDI） limit（1–4 pg TEQ/（kg·day）. Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.
The concentration of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the ambient air of a municipal solid waste incinerator (MSWI) during its running and non-running periods was ...monitored in this study to investigate the contribution of the MSWI to PCDD/F pollution in the vicinal environment. Results show that the PCDD/F levels for the normal MSWI running period and after shut-down ranged 0.156–1.44pgI-TEQ/m3 (0.514pgI-TEQ/m3) and 0.158–0.648pgI-TEQ/m3 (0.345pgI-TEQ/m3), respectively. Significant differences were found between the results of the two surveys in 2011 and 2012. High PCDD/F levels were observed in two of the seven study sites in 2011, and these levels directly declined in 2012. A dramatic increase in PCDD/F concentrations was observed in two sites in 2012. Comparison of congener and homologue fingerprint characteristics in the two surveys, together with principal component analysis, revealed that the PCDD/F levels in all of the samples collected in 2012 and in three of the samples collected in 2011 are mainly influenced by heavy traffic. MSWI is the primary PCDD/F emission sources of the PCDD/Fs detected in the remaining samples collected in 2011.
The potential for Hg release during municipal solid waste incineration (MSWI) is attracting increased attention due to high volume of municipal waste being treated by incineration in China. Emission ...amounts have been estimated using emission factors developed for other countries. To fine tune our emission estimate total mercury (THg) and mercury speciation were measured using isokinetic sampling in eight plants, of which six used grate furnace combustor (GFC) and two circulation fluidized bed combustors (CFBCs). Results showed that average THg concentration (19.5±13.6μg/Nm3) in flue gas at the facilities that used CFBC was significantly lower than that at those using GFC (51.4±28.3μg/Nm3, p=0.002). Gaseous oxidized mercury (GOM), gaseous elemental mercury (GEM, Hg0), and particulate mercury (Hgp) represented 95.5±3.8%, 4.1±3.9% and 0.4±0.3% in GFC, and 63.8±8.6%, 33.6±10.5% and 2.6±1.9% in CFBC, respectively. The measured average THg emission factor for the 8 MSWI plants was 208±130mg/t in the Pearl River Delta (PRD) region, with 217±158mg/t and 188±17.7mg/t were from GFC and CFBC, respectively. Using the average emission factor the estimated total mercury emissions from MSWI were 4.67±2.91t in China, and 770±65.5kg in the PRD region in 2010. Of these, 4240±210kg, 408±231kg and 14.8±14.1kg, and 688±37kg, 78.9±40.6kg and 3.2±3.0kg were GOM, Hg0, and Hgp, respectively. Mercury emissions will continue to increase as the amounts of MSW being incinerated increases.
► Mercury in the flue gas was measured for 8 municipal waste incinerators in China. ► Mercury concentration in flue gas differed as a function of incineration method. ► Gaseous oxidized mercury was the dominant form released. ► Air pollution control devices are important for reducing mercury emissions. ► Total emissions will increase as the amount of waste incinerated in China increases.
The emission characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDD/Fs） and heavy metals were evaluated during co-combustion of sewage sludge with coal from a circulating ...fluidized bed incinerator. The stack gas, slag and fly ash samples were sampled and analyzed. The gas-cleaning system consisted of electrostatic precipitators and a semi-dry scrubber. Results showed that the stack gas and fly ash exhibited mean dioxin levels of 9.4 pg I-TEQ/Nm3 and 11.65 pg I-TEQ/g, respectively, and showed great similarities in congener profiles. By contrast, the slag presented a mean dioxin level of 0.15 pg I-TEQ/g and a remarkable difference in congener profiles compared with those of the stack gas and fly ash. Co-combusting sewage sludge with coal was able to reduce PCDD/Fs emissions significantly in comparison with sewage sludge mono-combustion. The leaching levels of Hg, Pb, Cd, Ni, Cr, Cu, and As in the fly ash and slag were much lower than the limits of the environmental protection standard in China. These suggest that the co-combustion of sewage sludge and coal is an advisable treatment method from an environmental perspective.
This study aimed to quantify the co-pyrolytic synergistic effects of textile dyeing sludge (TDS) and waste biochar (WBC) for an optimal utilization of secondary resources and to mitigate ...environmental pollution and waste volume. TDS and WBC had a strong synergistic effect between 800 and 900 °C in the CO2-assisted atmosphere. With the increased TDS fraction, NH3 emission fell significantly regardless of the atmosphere type. The CO2 atmosphere changed S in TDS char and released SO2 in the range of 800–1000 °C. With the temperature rise, an unstable N structure turned into a more stable heterocyclic N structure in the CO2 and N2 atmospheres. Regardless of the atmosphere type and temperature, the C-containing functional groups in co-pyrolytic biochar existed mainly as C-C/C-H. In the CO2 atmosphere, inorganic S, aliphatic S, and thiophene S in the co-pyrolytic biochar disappeared and became more stable sulfones. The co-pyrolysis inhibited the formation of S-containing compounds. The retention ability of the co-pyrolytic biochar peaked for most of the heavy metals in the N2 atmosphere but was better for Pb and Zn in the CO2 than N2 atmosphere. Simultaneous optimization showed the co-pyrolysis of 10% TDS and 90% WBC at above 950 °C in the N2-CO2 or CO2 atmosphere as the optimal operational settings combined.
Display omitted
•Co-pyrolysis inhibited NH3 and SO2 emissions in N2 atmosphere.•Release intensity of CO in CO2 was higher from WBC than blend atmosphere.•CO2 atmosphere delayed the decomposition of protein-N.•Co-pyrolysis enriched the production of phenol compounds.•CO2 atmosphere showed the better retention ability for Pb and Zn.
Display omitted
•Textile dyeing sludge (TDS) and bamboo torrefied at 250 °C (T250) performed the best.•The performance of T250 in 20%O2/80%CO2 was 3.6 times that of TDS in air.•Torrefaction and ...oxy-fuel co-combustion reduced SO2 emissions by 55.09%.•The increased K in the co-combustion preferentially reacted with S.•20%O2/80%CO2 enhanced the S retention and the capture of SO2 by K/Ca.
Emission-to-ash desulfurization and full waste circularity can be enhanced by the proper selection of multiple wastes and operational conditions. In this context, a new combination of textile dyeing sludge (TDS), bamboo residues (BR), torrefaction, and oxy-fuel (O2/CO2) atmosphere was proposed in this study. Their blend (0.5TDS) torrefied at 250 °C (T250) improved its co-combustion performance by 17.30% based on the comprehensive combustion index (CCI). The CCI value of T250 in the oxy-fuel atmosphere of 20% O2/80% CO2 was about 3.6 times that of the mono-combustion of TDS in the air atmosphere. The co-combustion interaction reduced SO2 emission since the increased alkali metals and alkaline earth metals (especially K) preferentially reacted with S to form sulfate at ≤ 700 °C. Compared to the air mono-combustion of TDS, T250 in 20% O2/80% CO2 reduced SO2 emission (mg/MJ) by 55.09%. With the temperature rise from 700 to 900 °C, K-sulfate was completely transformed into aluminosilicate and released the captured SO2 in which case Ca became the main S-fixing agent. The shift from air to 20% O2/80% CO2 retained sulfate in the bottom ash. Our findings provide new and practical insights into sustainable, efficient, and clean co-combustion and energy utilization.
Chronic exposure to low levels of heavy metals threatens human health. However, few studies evaluated the health effects and spatial distributions of chronic exposure to heavy metals in metropolitan ...residents throughout mainland China using unified sampling methods and evaluation indicators at the national level. Here, the concentrations and spatial distributions of heavy metals (As, Cd, Cr, Sb, Pb, and Hg) in the hair of 1202 metropolitan residents from mainland China were analyzed, and differences in age and sex were evaluated. Most target metals exhibited higher concentrations in the hair of residents from South Central China. Generally, male hair had higher As and Se concentrations, whereas female hair had higher Cd and Pb levels (p < 0.05). A significant pairwise correlation existed between most metals in hair, especially Cd–Pb (r = 0.638, p < 0.05). The Se/heavy metal molar ratio is used as an indicator to assess the detoxification ability. The results demonstrated that protecting metropolitan residents in South Central China from heavy metals in their daily life is crucial, particularly for Hg, Pb, and Cr with Se/(Hg, Pb, or Cr) molar ratios < 1. This is the first study to comprehensively consider the antagonistic effects of Se and heavy metals using the molar ratio of Se/heavy metals to evaluate health implications and propose health management policies for metropolitan residents in China.
