我国发展循环经济的政策与法律体系探讨

建立和完善循环经济政策应遵循三个原则：服务于我国循环经济概念与内涵原则。服务于循环经济实践的原则。用足用好现有政策和补充缺位政策相结合的原则。我国发展循环经济的政策与法律体系应包括四大类：基本政策、核心政策和基础性政策。技术政策可以融入这四类政策之中。基本政策是统领循环经济所有政策的根本。是资源环境与社会经济发展相融合的综合性政策。基础性政策是指为循环经济重点领域实践创造良好制度环境的政策。大致包括宏观经济政策、基本经济制度、基础性激励政策和考核政策等。核心政策是直接推动循环经济重点实践领域的政策。在核心政策中。需要切实落实和用足用好的现有对循环经济发展较有利的政策有：生态工业政策（包括产业结构调整政策、清洁生产政策）。资源综合利用和环保产业税费优惠政策。能源节约和再生能源政策。环境友好型产品标志（标识）政策；需要完善的薄弱政策有：生态工业园建设政策。废弃物回收、再利用、资源化和无害化产业政策。生态农业政策。资源开发利用政策；需要新建立的缺位政策主要涉及消费领域、环境友好型和资源能源节约型城镇基础设施和建筑领域。     

The effect of fetal gender on nuchal translucency at 10–14 weeks of gestation

Recent data have suggested that fetal nuchal translucency (NT) is affected by fetal gender. We investigated the size of this effect in 12 189 unselected pregnancies with known normal outcomes that had undergone NT measurements between 10 and 14 weeks of gestation. NT increased with gestation and was converted to multiples of the median (MoM) for the gestational day. The median NT MoM (95% CI) for female fetuses was 0.98 (0.97–0.99). This was significantly lower than that of the male fetuses (1.03; range1.02–1.04) (p<0.0005; Wilcoxon rank-sum test). The gender difference was not observed at 10 weeks but was observed from 11 weeks onwards. There is no obvious explanation for the above findings. Copyright © 2001 John Wiley & Sons, Ltd.     

秸秆覆盖条件下小麦生长季根系呼吸对土壤呼吸作用的贡献

在紫色土丘陵区连续6年进行秸秆覆盖试验的"旱三熟"农田系统中,于2012年12月—2013年4月小麦生长季内对土壤呼吸进行测定,并对小麦根系生物量、土壤温度、土壤水分和土壤有机碳含量等指标进行监测,以分析土壤呼吸动态变化的影响因素.结果表明,秸秆覆盖措施显著提高了土壤呼吸速率,秸秆覆盖(S)和秸秆覆盖+腐熟剂(SD)处理分别比对照(CK)增加了45.0%和29.4%.曲线估计表明,土壤呼吸作用与根系生物量呈显著线性关系,通过建立二者的线性回归方程,采用生物量外推法估算小麦根系呼吸作用占土壤呼吸作用的比例,在分蘖期(2012年12月)、拔节期(2013年1月)、抽穗期(2012年3月)和灌浆期(2013年4月),根系呼吸分别占土壤呼吸的28.2%、44.0%、56.9%、56.2%,平均贡献为46.3%,并呈先增加再降低的趋势,在抽穗期达到最大,与根系生物量的变化同步.按照不同处理建立根系生物量与土壤呼吸间的线性回归方程,经计算得出CK、S和SD 3个处理中,根系呼吸作用占土壤呼吸作用的比例分别为42.9%、43.8%和43.7%,秸秆覆盖对根系呼吸作用比例无显著影响.     

采暖锅炉氧腐蚀的原因与防腐对策

热水锅炉及其采暖系统在运行和停运期间都存在较严重的氧腐蚀,但由于主客观原因的限制,并没有引起人们的高度重视.氧腐蚀对锅炉及其采暖系统运行的安全性和经济性造成重大影响,严重时引起爆管,被迫停炉等危害.大力提倡节能减排的今天,延长锅炉的寿命,促进安全经济生产意义重大.本论文分析总结采暖锅炉目前的水质与防腐工作的现状,同时提出了对采暖锅炉今后锅炉及热力管网防腐的对策.     

华北平原典型城市(石家庄)地下水重金属污染源解析与健康风险评价

地下水重金属污染已引起全球的广泛关注,重金属来源解析及其健康风险评估将为地下水中重金属污染的精准防控提供数据和方法支撑.因此,选取华北平原典型城市——石家庄作为研究区,筛选20个样点,利用APCS-MLR模型和健康风险模型解析评估了石家庄市地下水中10种重金属的污染源及其健康风险.结果表明：①石家庄市地下水中典型重金属的浓度均值排序为：Fe>Zn>Mn>Cu>Al>Pb>Cr>As>Cd>Hg,其中ρ（Fe）和ρ（Pb）的均值分别为260.3 μg ·L^-1和10.01 μg ·L^-1;根据单因子和内梅罗指数,Pb、Fe和Cd是石家庄市地下水主要的污染重金属;②重金属浓度范围为47.30~2560 μg ·L^-1;就空间分布而言,重金属浓度在S3处最高（2560 μg ·L^-1）,而在S9处最低（47.30 μg ·L^-1）;③污染源解析结果表明：工农业活动、交通排放和地质背景是石家庄市地下水中重金属的3个主要来源,其中工农业活动对重金属的累积贡献率最大（47.83%）;④除工农业活动来源的重金属对成人造成潜在威胁（HI>1）外,其余来源的重金属对成人和儿童造成的非致癌风险均处于可接受水平（HI<1）,而致癌风险对成人和儿童均存在潜在威胁;工农业活动是非致癌风险（成人：52.46%,儿童：52.45%）和致癌风险（成人：65.22%,儿童：65.69%）的主要贡献者,其中Cd和As的致癌风险较高.因此,为了保障石家庄地下水环境安全,需严格控制污染来源,进一步加强地下水中重金属污染的风险管控.     

硅胶腕带被动采集多环芳烃的可行性分析

多环芳烃（polycyclic aromatic hydrocarbons,PAHs）对人体危害巨大,目前关于人体暴露于大气环境PAHs研究主要以主动采样方式开展。硅胶腕带作为一种新的大气被动采样装置,具有体积小、价格低、耐磨耐热、无毒无味等优点,适合人体环境暴露监测。国际上研究刚起步,尚未建立完善的腕带被动采样与主动采样技术之间的定量关系。本研究于2019年秋冬季和2021年冬季在西安市城区,同时开展硅胶腕带被动采样与大气主动采样对低分子量（MW＜203 g·mol^?1）PAHs的对比实验,力求建立两者的联系。2019年和2021年西安冬季大气中低分子量PAHs浓度分别为(52.81±14.76) ng·m^?3和(134.59±39.48) ng·m^?3,与前人研究相当。相对应的腕带浓度为(183.07±40.43) ng·d^?1和(524.99±150.32) ng·d^?1。Pearson相关分析发现：萘、苊烯、1-甲基萘、2-甲基萘、荧蒽以及总PAHs的主、被动采样之间显著相关（P＜0.05）,相关系数均大于0.4,证明硅胶腕带被动采样方法适用于低分子量PAHs的人体暴露监测。     

Evaluation on exposures to particulate matter at a junior secondary school: a comprehensive study on health risks and effective inflammatory responses in Northwestern China

Air pollutant measurement and respiratory inflammatory tests were conducted at a junior secondary school in Xi’an, Northwestern China. Hazardous substances including particulate matters (PMs), black carbon (BC) and particle-bounded polycyclic aromatic hydrocarbons (PAHs) were quantified both indoors and outdoors of the school. Source characterization with organic tracers and particle-size distribution demonstrated that the school’s air was mostly polluted by combustion emissions from the surrounding environment. The evaluation of health assessment related to air quality was conducted by two methods, including potential risk estimation of air pollutants and direct respiratory inflammatory test. The incremental lifetime cancer risks associated with PAHs were estimated and were 1.62 × 10⁻⁶ and 2.34 × 10⁻⁶, respectively, for indoor and outdoor fine PMs. Both the values exceeded the threshold value of 1 × 10⁻⁶, demonstrating that the carcinogenic PAHs are a health threat to the students. Respiratory inflammatory responses of 50 students who studied in the sample classroom were examined with a fractional exhaled nitric oxide (FeNO) test, with the aid of health questionnaires. The average FeNO concentration was 17.4 ± 8.5 ppb, which was slightly lower than the recommended level of 20 ppb established by the American Thoracic Society for children. However, a wide distribution and 6% of the values were > 35 ppb, suggesting that the potentials were still high for eosinophilic inflammation and responsiveness to corticosteroids. A preliminary interpretation of the relationship between air toxins and respiratory inflammatory response demonstrated the high exposure cancer risks and inflammatory responses of the students to PMs in the city.

     

Comparing urban solid waste recycling from the viewpoint of urban metabolism based on physical input-output model: A case of Suzhou in China

Investigating impacts of urban solid waste recycling on urban metabolism contributes to sustainable urban solid waste management and urban sustainability. Using a physical input-output model and scenario analysis, urban metabolism of Suzhou in 2015 is predicted and impacts of four categories of solid waste recycling on urban metabolism are illustrated: scrap tire recycling, food waste recycling, fly ash recycling and sludge recycling. Sludge recycling has positive effects on reducing all material flows. Thus, sludge recycling for biogas is regarded as an accepted method. Moreover, technical levels of scrap tire recycling and food waste recycling should be improved to produce positive effects on reducing more material flows. Fly ash recycling for cement production has negative effects on reducing all material flows except solid wastes. Thus, other fly ash utilization methods should be exploited. In addition, the utilization and treatment of secondary wastes from food waste recycling and sludge recycling should be concerned.     

Kappaphycus alvarezii waste biomass: A potential biosorbent for chromium ions removal

The Cr(III) sorption experiments onto Kappaphycus alvarezii waste biomass were conducted at different pH values (2–6) under the conditions of initial metal concentration of 10–50 mg/L and the chemical compositions of Cr-Cu and Cr-Cd. The Cr(III) sorption capacities were slightly dependent on pH, and the maximum sorption capacity was 0.86 mg/g at pH 3. The sorption capacities increased with increase in the initial metal concentration, whereas it was suppressed by the presence of Cu(II) and Cd(III) in the solution. The Cr(III) sorption equilibrium was evaluated using Langmuir, Freundlich and BET isotherms. The sorption mechanisms were characterised using scanning electron microscopy and Fourier transform infrared spectroscopy. The main mechanisms were ion exchange coupled with a complexation mechanism. Kappaphycus alvarezii waste biomass represents a potential for Cr(III) ion removal from aqueous solution.