Characterization of residues from dismantled imported wastes

Residues from the imported wastes dismantling process create a great burden on the ambient environment. To develop appropriate strategies for the disposal of such residues, their characteristics were studied through background value analysis and toxicity leaching tests. Our results showed that the heavy metals concentrations in residues were high, particularly those of Cu (7180 mg kg^?1), Zn (2783 mg kg^?1), and Pb (1954 mg kg^?1). Toxicity leaching tests revealed a high metal releasing risk of such residues if they are disposed of in a landfill. However, the residues of imported wastes were also found to have some intrinsic metal recycling value.     

Stabilization of heavy metals in MSWI fly ash using silica fume

The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR (²⁷Al and ²⁹Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals. At the addition of 20% silica fume, leaching concentrations for Cu, Pb and Zn of the hydrated paste cured for 7 days decreased from 0.32 mg/L to 0.05 mg/L, 40.99 mg/L to 4.40 mg/L, and 6.96 mg/L to 0.21 mg/L compared with the MSWI fly ash. After curing for 135 days, Cd and Pb in the leachates were not detected, while Cu and Zn concentrations decreased to 0.02 mg/L and 0.03 mg/L. The speciation of Pb and Cd by the modified version of the European Community Bureau of Reference (BCR) extractions showed that these metals converted into more stable state in hydrated pastes of MSWI fly ash in the presence of silica fume. Although exchangeable and weak-acid soluble fractions of Cu and Zn increased with hydration time, silica fume addition of 10% can satisfy the requirement of detoxification for heavy metals investigated in terms of the identification standard of hazardous waste of China.     

Inexact fuzzy-stochastic constraint-softened programming – A case study for waste management

In this study, an inexact fuzzy-stochastic constraint-softened programming method is developed for municipal solid waste (MSW) management under uncertainty. The developed method can deal with multiple uncertainties presented in terms of fuzzy sets, interval values and random variables. Moreover, a number of violation levels for the system constraints are allowed. This is realized through introduction of violation variables to soften system constraints, such that the model’s decision space can be expanded under demanding conditions. This can help generate a range of decision alternatives under various conditions, allowing in-depth analyses of tradeoffs among economic objective, satisfaction degree, and constraint-violation risk. The developed method is applied to a case study of planning a MSW management system. The uncertain and dynamic information can be incorporated within a multi-layer scenario tree; revised decisions are permitted in each time period based on the realized values of uncertain events. Solutions associated with different satisfaction degree levels have been generated, corresponding to different constraint-violation risks. They are useful for supporting decisions of waste flow allocation and system-capacity expansion within a multistage context.     

Study on phosphorus loadings in ten natural and agricultural watersheds in subtropical region of China

Water eutrophication in subtropical regions of southern China threatens watershed health and is of major concern. However, annual phosphorus (P) loading and its dominant causes are still unclear, especially at the watershed scale. In this study, we investigated dynamic P loadings and associated factors (e.g., land use, livestock production, and runoff depth) in ten watersheds that varied in area from 9 to 5,212 ha in a hilly area of Hunan Province, China. A flowmeter was installed at the outlet of each watershed, and total P (TP) and soluble P (SP) concentrations were monitored periodically from June 2010 to October 2012. The results showed that annual P loadings (APLs) in the ten watersheds ranged from 22.8 to 247.8 kg P/km² and that P loss primarily occurred from April to June of each year during the main rainfall season in the study area. In addition, the average eutrophication (>0.05 mg P/L) ratio for stream waters was 86.7 % during the study period, which was indicative of a potentially serious condition for the local water environments. Annual P loadings were linearly related to livestock density (LD; R?=?0.92, p?<?0.01), whereas the eutrophication ratio of stream water was significantly (p?<?0.05) correlated with LD (R?=?0.61), percentage cropland (R?=?0.71), and percentage forest cover (R?=??0.68). Thus, it is concluded that the control of livestock production has the greatest potential for reducing P loadings in watersheds in this subtropical area. This will be beneficial to the amelioration and protection of local environment.     

Effects of payments for ecosystem services on wildlife habitat recovery

Conflicts between local people's livelihoods and conservation have led to many unsuccessful conservation efforts and have stimulated debates on policies that might simultaneously promote sustainable management of protected areas and improve the living conditions of local people. Many government‐sponsored payments‐for‐ecosystem‐services (PES) schemes have been implemented around the world. However, few empirical assessments of their effectiveness have been conducted, and even fewer assessments have directly measured their effects on ecosystem services. We conducted an empirical and spatially explicit assessment of the conservation effectiveness of one of the world's largest PES programs through the use of a long‐term empirical data set, a satellite‐based habitat model, and spatial autoregressive analyses on direct measures of change in an ecosystem service (i.e., the provision of wildlife species habitat). Giant panda (Ailuropoda melanoleuca) habitat improved in Wolong Nature Reserve of China after the implementation of the Natural Forest Conservation Program. The improvement was more pronounced in areas monitored by local residents than those monitored by the local government, but only when a higher payment was provided. Our results suggest that the effectiveness of a PES program depends on who receives the payment and on whether the payment provides sufficient incentives. As engagement of local residents has not been incorporated in many conservation strategies elsewhere in China or around the world, our results also suggest that using an incentive‐based strategy as a complement to command‐and‐control, community‐ and norm‐based strategies may help achieve greater conservation effectiveness and provide a potential solution for the park versus people conflict.     

广州市环境监测管理信息化建设中若干问题探讨

以广州市环境监测中心站推进信息化的实践为例，重点对环境监测管理信息化规划、开发和应用3个环节所涉及的信息化进程路线、应用系统开发的需求分析和推广应用等问题进行了一些探讨，提出切合自身的解决思路或办法。     

Revealing the impact of water conservancy projects and urbanization on hydrological cycle based on the distribution of hydrogen and oxygen isotopes in water

Environmental Science and Pollution Research - In recent years, the development and utilization of water resources have imposed great impacts on hydrological characteristics and ecological...     

Polycyclic aromatic hydrocarbon and n-alkane pollution characteristics and structural and functional perturbations to the microbial community: a case-study of historically petroleum-contaminated soil

Characterization of the typical petroleum pollutants, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, and indigenous microbial community structure and function in historically contaminated soil at petrol stations is critical. Five soil samples were collected from a petrol station in Beijing, China. The concentrations of 16 PAHs and 31 n-alkanes were measured by gas chromatography-mass spectrometry. The total concentrations of PAHs and n-alkanes ranged from 973 ± 55 to 2667 ± 183 μg/kg and 6.40 ± 0.38 to 8.65 ± 0.59 mg/kg (dry weight), respectively, which increased with depth. According to the observed molecular indices, PAHs and n-alkanes originated mostly from petroleum-related sources. The levels of ΣPAHs and the total toxic benzo[a]pyrene equivalent (ranging from 6.41 to 72.54 μg/kg) might exert adverse biological effects. Shotgun metagenomic sequencing was employed to investigate the indigenous microbial community structure and function. The results revealed that Proteobacteria and Actinobacteria were the most abundant phyla, and Nocardioides and Microbacterium were the important genera. Based on COG and KEGG annotations, the highly abundant functional classes were identified, and these functions were involved in allowing microorganisms to adapt to the pressure from contaminants. Five petroleum hydrocarbon degradation-related genes were annotated, revealing the distribution of degrading microorganisms. This work facilitates the understanding of the composition, source, and potential ecological impacts of residual PAHs and n-alkanes in historically contaminated soil.

     

Combined toxic impacts of thiamethoxam and four pesticides on the rare minnow (Gobiocypris rarus)

To examine pesticide mixture toxicity to aqueous organisms, we assessed the single and combined toxicities of thiamethoxam and other four pesticides (chlorpyrifos, beta-cypermethrin, tetraconazole, and azoxystrobin) to the rare minnow (Gobiocypris rarus). Data from 96-h semi-static toxicity assays of various developmental phases (embryonic, larval, juvenile, and adult phases) showed that beta-cypermethrin, chlorpyrifos, and azoxystrobin had the highest toxicities to G. rarus, and their LC₅₀ values ranged from 0.0031 to 0.86 mg a.i. L^?1, from 0.016 to 6.38 mg a.i. L^?1, and from 0.39 to 1.08 mg a.i. L^?1, respectively. Tetraconazole displayed a comparatively high toxicity, and its LC₅₀ values ranged from 3.48 to 16.73 mg a.i. L^?1. By contrast, thiamethoxam exhibited the lowest toxic effect with LC₅₀ values ranging from 37.85 to 351.9 mg a.i. L^?1. Rare minnow larvae were more sensitive than embryos to all the pesticides tested. Our data showed that a pesticide mixture of thiamethoxam–tetraconazole elicited synergetic toxicity to G. rarus. Moreover, pesticide mixtures containing beta-cypermethrin in combination with chlorpyrifos or tetraconazole also had synergetic toxicities to fish. The majority of pesticides are presumed to have additive toxicity, while our data emphasized that the concurrent existence of some chemicals in the aqueous circumstance could cause synergetic toxic effect, leading to severe loss to the aqueous environments in comparison with their single toxicities. Thence, the synergetic impacts of chemical mixtures should be considered when assessing the ecological risk of chemicals.