湖南省大气湿沉降化学研究

以湖南省1999～2001年的酸雨监测数据为基础,运用统计学和线性回归分析方法研究了位于中国中南部的重酸雨区湖南省的大气降水的酸度和化学组成的分布特征以及季节变化规律。结果表明,大气降水以SO_4~(2-)为主,占总离子量的31％,大气降水阴阳离子基本平衡。降水年平均pH值为4.86,以春季酸度最大,降水离子总量以冬季最大。研究结果同时表明,降水酸度是主要酸性离子和主要碱性离子共同作用的结果,而且([H~+]+[NH_4~+])/([SO_4~(2-)]+[NO_3~-])比值的变化能较好的反映降水过程中强酸离子的中和现象。     

混合固定化酵母菌对苯并(α)芘污染土壤的修复

将3株酵母菌进行两两混合及3株混合后,采用物理法和化学法对其进行固定化包埋,用于多环芳烃苯并(α)芘污染土壤的修复.实验结果表明,酵母菌经过混合固定化包埋后,通过降解率及降解动力学分析可以得出,其降解效果明显好于游离菌,这是由于酵母菌经过包埋后,载体内部菌密度有效增加的结果.空白对照虽未接菌种,但污染物也有少量的下降,这是由于载体中含有一定量的活性炭,对污染物具有吸附作用,这种吸附作用随着时间的延长而趋于平缓.由实验结果还可以看出,物理法更适合对酵母菌进行混合固定化包埋,但并非混合酵母菌菌株越多,降解效果越好.菌株IM219-220-phy对苯并(α)芘的降解率最高达40.65%,半衰期为5.66 d.     

氨的超临界水氧化研究进展

在超临界水氧化过程中,氨作为含氮有机物氧化的中间产物,其氧化是有机物在超临界水中氧化降解速率的控制步骤.综述了氧化剂、温度、过氧量、停留时间和催化剂等因素对氨的超临界水氧化降解效果的影响,并总结了目前常用的两种反应动力学模型.与双氧水或氧相比,NO-3氧化荆具有更强的氧化能力;通过提高温度、过氧量和停留时间都可以促进氨的超临界水氧化降解.在氨的超临界水氧化中,当无催化剂作用时,氨的降解率很低;加入MnO2/CeO2等催化剂,可以显著提高氨的降解率.为加快超临界水氧化法处理含氮有机废水的应用进程,未来应侧重氨氧化机制的研究和催化剂的开发.     

HDTMA改性粉煤灰吸附酸性嫩黄染料废水

使用HDTMA（十六烷基三甲基溴化铵）对粉煤灰(FA)进行改性,并使用改性后粉煤灰（MFA）吸附处理酸性嫩黄染料废水。研究发现,由于改性剂HDTMA被涂敷在粉煤灰表面,使粉煤灰表面电性改变,大大增强了对酸性嫩黄的处理效果,酸性嫩黄去除率可由13.2％提高到95％以上。实验结果还表明,当染料浓度为50 mg/L时,100 mL染料中MFA的最佳投加量为700 mg;pH值对吸附效果没有显著影响;低温有利于吸附。HDTMA改性粉煤灰对酸性嫩黄染料的吸附规律可用Langmuir吸附等温式描述。     

Evaluation of three common alkaline agents for immobilization of multi-metals in a field-contaminated acidic soil

We investigated three common alkaline agents (NaOH, CaO, and Mg(OH)₂) for immobilization of four heavy metals (Pb, Zn, Cu, and Cd) in a field-contaminated soil and elucidated the underpinning principles. NaOH caused the highest pH spike in the soil, while CaO and Mg(OH)₂ served as a longer-lasting source of OH^-. Amending the soil with CaO or Mg(OH)₂ at ≥0.1 mol as OH^- (kg·soil)^?1 for 24 h was able to immobilize all four metals, while NaOH failed. NaOH leached up to 3 times more organic carbon than CaO and Mg(OH)₂, resulting in elevated leachability of the metals. Column elution tests showed that amendments by CaO and Mg(OH)₂ lowered the leachable Pb²⁺, Zn²⁺, Cu²⁺, and Cd²⁺ by 52–54%, 71–75%, 69–73%, and 68%, respectively, after 1440 pore volumes of elution. Sequential extraction revealed that the soil amendments converted the exchangeable fraction of the metals to the much less available forms. XRD and FTIR analyses indicated that formation of metal oxide precipitates and complexation with soil organic matter were responsible for the metals immobilization. Taken together the chemical cost, technical effectiveness, and environmental impact, CaO is the most suitable alkaline agent for remediation of soil contaminated with heavy metals.

     

Biodegradation of waste refrigerator polyurethane by mealworms

● Waste refrigerator polyurethane (WRPU) was ingested and biodegraded by mealworms. ● The carbon in WRPU-based frass was lower than that in WRPU. ● Urethane groups in WRPU were broken down after ingestion by mealworms. ● Thermal stability of WRPU-based frass were deteriorated compared to that of WRPU. ● Gut microbiomes of mealworms fed using WRPU were distinct from that fed using bran. Refrigerator insulation replacement results in discarding a large amount of waste refrigerator polyurethane (WRPU). Insect larvae like mealworms have been used to biodegrade pristine plastics. However, knowledge about mealworms degrading WRPU is scarce. This study presents an in-depth investigation of the degradation of WRPU by mealworms using the micro-morphology, composition, and functional groups of WRPU and the egested frass characteristics. It was found that the WRPU debris in frass was scoured, implying that WRPU was ingested and degraded by mealworms. The carbon content of WRPU-based frass was lower than that of WRPU, indicating that mealworms utilized WRPU as a carbon source. The urethane groups in WRPU were broken, and benzene rings’ C=C and C–H bonds in the isocyanate disappeared after being ingested by mealworms. Thermal gravimetric-differential thermal gravimetry analysis showed that the weight loss temperature of WRPU-based frass was 300 °C lower than that of WRPU, indicating that the thermal stability of WRPU deteriorated after being ingested. The carbon balance analysis confirmed that carbon in the ingested WRPU released as CO₂ increased from 18.84 % to 29.80 %, suggesting that WRPU was partially mineralized. The carbon in the mealworm biomass ingesting WRPU decreased. The possible reason is that WRPU does not supply sufficient nutrients for mealworm growth, and the impurities and odor present in WRPU affect the appetite of the mealworms. The microbial community analysis indicated that WRPU exerts a considerable effect on the gut microorganism of mealworms. These findings confirm that mealworms degrade WRPU.     

Real-time location algorithms of drinking water pollution sources based on domain knowledge

Environmental Science and Pollution Research - The real-time location of pollution sources is the process of inverting pollution sources based on the dynamic optimization model constructed by the...     

Stream Nitrogen Sources Apportionment and Pollution Control Scheme Development in an Agricultural Watershed in Eastern China

A modeling system that couples a land-use-based export coefficient model, a stream nutrient transport equation, and Bayesian statistics was developed for stream nitrogen source apportionment. It divides a watershed into several sub-catchments, and then considers the major land-use categories as stream nitrogen sources in each sub-catchment. The runoff depth and stream water depth are considered as the major factors influencing delivery of nitrogen from land to downstream stream node within each sub-catchment. The nitrogen sources and delivery processes are lumped into several constant parameters that were calibrated using Bayesian statistics from commonly available stream monitoring and land-use datasets. This modeling system was successfully applied to total nitrogen (TN) pollution control scheme development for the ChangLe River watershed containing six sub-catchments and four land-use categories. The temporal (across months and years) and spatial (across sub-catchments and land-use categories) variability of nonpoint source (NPS) TN export to stream channels and delivery to the watershed outlet were assessed. After adjustment for in-stream TN retention, the time periods and watershed areas with disproportionately high-TN contributions to the stream were identified. Aimed at a target stream TN level of 2 mg L^?1, a quantitative TN pollution control scheme was further developed to determine which sub-catchments, which land-use categories in a sub-catchment, which time periods, and how large of NPS TN export reduction were required. This modeling system provides a powerful tool for stream nitrogen source apportionment and pollution control scheme development at the watershed scale and has only limited data requirements.     

Rockburst hazard determination by using computed tomography technology in deep workface

The rockburst in mines results from the dynamic load coupled with static one in coal seams around workface zones, so it is essential to learn the stress distribution of the coal and surrounding rock for determination of rockburst risk areas. The relationship between the elastic wave velocity and stress applied on coal sample was investigated systematically by laboratory testing, theoretically analysis, as well as on-site observation, and a positive correlation between them under uniaxial compression was put forward. Furthermore, it is drawn that the anomaly of elastic wave velocity reflects the stress changes: the positive anomaly ascertains the stress concentration while the negative anomaly estimates the mining destress and weaken degree, and corresponding assessment criterions and parameters were established respectively. The hazard areas and degree of an island longwall face 16302C were forecasted before coal winning based on the elastic wave anomaly distribution rules using active tremor velocity inversion, monitoring results of mining shocks during exploitation indicate that the consistency between locations of big tremors and where forecasted by computed tomography (CT) exceed 80%. The successful application of this technology achieved remarkable economic and social benefits for disaster control in rockburst mines.     

Application of an integrated biomarker response index to assess ground water contamination in the vicinity of a rare earth mine tailings site

We utilized a multi-biomarker approach (Integrated Biomarker Response version 2, IBRv2) to investigate the scope and dispersion of groundwater contamination surrounding a rare earth mine tailings impoundment. Parameters of SD rat included in our IBRv2 analyses were glutathione levels, superoxide dismutase, catalase, and glutathione peroxidase activities, total anti-oxidative capacity, chromosome aberration, and micronucleus formation. The concentration of 20 pollutants including Cl^?, SO₄ ^2?, Na⁺, K⁺, Mg²⁺, Ca²⁺, TH, COD_Mn, As, Se, TDS, Be, Mn, Co, Ni, Cu, Zn, Mo, Cd, and Pb in the groundwater were also analyzed. The results of this study indicated that groundwater polluted by tailings impoundment leakage exhibited significant ecotoxicological effects. The selected biomarkers responded sensitively to groundwater pollution. Analyses showed a significant relationship between IBRv2 values and the Nemerow composite index. IBRv2 could serve as a sensitive ecotoxicological diagnosis method for assessing groundwater contamination in the vicinity of rare earth mine tailings. According to the trend of IBRv2 value and Nemerow composite index, the maximum diffusion distance of groundwater pollutants from rare earth mine tailings was approximately 5.7 km.