农用地土壤重金属生态安全阈值确定方法的研究进展

农用地土壤重金属生态安全阈值作为农用地土壤环境质量基准制定的重要依据,近年来随着多学科的共同发展,农用地土壤重金属生态安全阈值的确定方法变得越来越完善,但目前对其的研究综述却鲜见报道。因此,文章综述了农用地土壤重金属生态安全阈值的确定方法,详细阐述了点模型、概率模型以及经验模型中的代表方法在确定农用地土壤重金属生态安全阈值方面的概念、原理、发展及应用,并深入探讨了各方法的适用情况和优缺点,系统分析了各方法在确定农用地土壤重金属生态安全阈值时的不确定性及影响因素,最后在前人的研究基础上提出了今后的主要发展方向,以期为我国农用地土壤环境质量标准的完善与细化及农用地土壤其他污染物生态安全阈值的确定提供参考依据。     

基于离散元法的能源管传热过程模拟

采用自主研发的离散元软件MatDEM,依据能源管桩的现场热响应试验,提出了能源桩离散元数值模拟的建模方法,对能源管桩的热响应试验过程进行了模拟研究,得到了桩周土体的位移分布,桩芯和桩周土体的温度分布,通过与现场实测数据的对比,验证了利用离散元法研究能源桩换热性能的有效性,该方法在研究能源桩与土体的热-力学行为特征方面具有广阔的应用前景。     

双酚A对哺乳类实验动物雄性生殖系统发育的影响

内分泌干扰物双酚A(bisphenol A,BPA)对生殖系统尤其是雄性生殖系统的影响一直受到关注,然而目前相关研究中存在诸多不一致的结果.本文系统分析了低剂量BPA对哺乳类实验动物大鼠和小鼠雄性生殖系统发育影响的文献,重点关注睾丸和附睾的质量、睾丸组织学结构、附属腺和外生殖器参数、肛殖距、精子参数和性激素水平等指标的变化,并探讨了实验结果与实验设计某些因素的相关性.经分析发现,妊娠期BPA暴露对实验鼠雄性生殖系统的影响呈现比较一致的阳性结果,但是哺乳期暴露和妊娠至哺乳期的暴露存在很多矛盾的结果;而动物品系、给药方式等因素与实验结果之间没有明确的关系,即便相似甚至相同的实验设计下也出现了不同的结果.进一步分析发现,有些研究在实验质量控制方面存在一定的缺陷,这可能是造成矛盾结果的主要原因.综合来看,BPA在器官水平和组织病理学水平对雄性生殖系统发育的影响较弱,基于此类指标的效应判断容易受到实验设计因素和质量控制的影响,最终可能导致不一致的结果.由此建议,今后相关研究在加强质量控制的同时,应重点关注BPA对细胞和分子层面的损伤.     

白洋淀底栖藻类与多环芳烃生态风险相关性研究——基于综合生物反应指数法

湖泊富营养化与有机污染物的交互作用是当前国内外研究热点,为了建立富营养化湖泊中多环芳烃(PAHs)生态效应与底栖藻类群落之间的相关关系。本研究以白洋淀为研究区,选取8个国控样点作为采样点,依据人为干扰程度不同将8个采样点划分为3种生境:生境1(S1和S2)主要遭受上游府河废水排放影响;生境2(S3、S6和S8)主要遭受水产养殖和生活污水的影响;生境3(S4、S5和S7)遭受人为干扰较小。分别在2009年4月、8月和11月收集了底栖藻类样品,并测定了白洋淀中15种PAHs。运用RQ_((NC))和RQ_((MPC))等改进风险熵值(RQ)方法计算PAHs生态风险。研究结果表明:(1)底栖藻类群落指标AD、Chl a、Chl b/a、CHL、CYA、APA、GLU、LEU、PSC和AFDW的值在11月最高,其次是8月和4月;就空间分布而言,这些指标值在生境1中最高,其次是生境2和生境3;而Chl c/a和BAC值在8月最高,其次是11月和4月,从空间分布特征而言,这些指标值在生境3最高;(2)相关分析结果表明,Chl a、Chl b/a、CHL、CYA、APA、GLU、LEU、PSC和AFDW的指标与PAHs污染物浓度呈显著正相关,而Chl c/a和BAC指标与污染物PAHs浓度呈显著负相关;(3)就空间分异特征而言,生境1中的ΣPAHs浓度最高,就季节变化而言,PAHs的浓度从4月到8月逐渐增加,而从8月到11月逐渐下降。各类PAHs表现出与ΣPAHs相同的时空变化特征;(4)IBR与RQ_(ΣPAHs(NCs))呈正相关关系(r=0.827,P0.01);除RQAcy(NCs)外,其他种类PAHs生态风险均与IBR呈相正相关关系(r=0.699~0.899),其中RQ_(BaP(NCs))与IBR显著正相关(r=0.899,P0.01)。此外,除沉积物TP外,IBR与TSI、水中TN、水中TP和沉积物TN也呈显著正相关(r=0.722~0.862)。因此,在富营养化湖泊中应考虑运用底栖藻类IBR生态监测PAHs污染水平。     

定性与定量评估4种重金属及2种农药混合物对费氏弧菌的毒性相互作用

重金属与农药共同暴露产生的联合毒性作用可以对实际环境产生潜在的风险。为了研究重金属与农药混合物在不同浓度比毒性相互作用(协同、拮抗与加和)及其定量评估相互作用大小,根据单个物质无观测浓度(NOEC)、5%效应浓度(EC5)、10%效应浓度(EC10)和50%效应浓度(EC50),设计3组混合物体系(即农药-农药、重金属-重金属和农药-重金属)分别按NOEC、EC5、EC10和EC50浓度比的12条混合物射线,测试单个化合物及混合物对以费氏弧菌的发光抑制急性毒性,利用浓度加和(CA)、独立作用(IA)、模型偏差比(MDR)及其观测值置信区间定性和定量评估12条混合物射线的毒性相互作用。结果表明,农药-农药二元混合物体系和农药-重金属六元混合物体系均产生明显的协同作用,其中农药-农药混合物体系中,混合物射线EE-NOEC在50%效应下协同作用大小达到30.6(MDRCA和MDRIA数值);混合物射线EE5、EE10的协同作用大小接近于混合物射线EE-NOEC,混合物射线EE50的效应大于15%时CA和IA计算的MDR值均在置信区间上限的上方,即混合物发生协同作用;农药-重金属混合物体系的4条混合物射线EE-NOEC、EE5、EE10和EE50在所有测试浓度水平的MDR值均在置信区间上限的上方,呈现出明显的协同作用;在50%效应下,混合物射线EE-NOEC、EE5、EE10和EE50的MDRCA和MDRIA值分别为4.05和4.91、6.12和7.98、3.70和4.60、2.62和2.59。重金属-重金属四元混合物体系除了EC50浓度比混合物表现出拮抗作用,其余混合物在所有测试浓度范围的MDR值均在置信区间范围内,均为加和作用。因此,混合物的毒性相互作用大小随着组分浓度比变化而发生变化。     

Investigation of phosphate adsorption from an aqueous solution using spent fluid catalytic cracking catalyst containing lanthanum

A spent fluid catalytic cracking (FCC) catalyst containing lanthanum (La) was used as a novel adsorbent for phosphorus (P) in simulated wastewater. The experiments were conducted in a batch system to optimize the operation variables, including pH, calcination temperature, shaking time, solid-liquid ratio, and reaction temperature under three initial P-concentrations (C₀ = 0.5, 1.0, and 5.0 mg/L). Orthogonal analysis was used to determine that the initial P-concentration was the most important parameter for P removal. The P-removal rate exceeded 99% and the spent FCC catalyst was more suitable for use in low P-concentration wastewater (C₀ <5.0 mg/L). Isotherms, thermodynamics and dynamics of adsorption are used to analyze the mechanism of phosphorus removal. The results show that the adsorption is an endothermic reaction with high affinity and poor reversibility, which indicates a low risk of second releasing of phosphate. Moreover, chemical and physical adsorption coexist in this adsorption process with LaPO₄ and KH₂PO₄ formed on the spent FCC catalyst as the adsorption product. These results demonstrate that the spent FCC catalyst containing La is a potential adsorbent for P-removal from wastewater, which allows recycling of the spent FCC catalyst to improve the quality of water body.

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Can floor-area-ratio incentive promote low impact development in a highly urbanized area?—A case study in Changzhou City,China

As an environmental friendly measure for surface runoff reduction, low impact development (LID) has been applied successfully in urban areas. However, due to high price of land and additional expense for LID construction in highly urbanized areas, the developers of real estate would not like to proceed LID exploitation. Floor area ratio (FAR) refers to “the ratio of a building’s total floor area to the size of the piece of land upon which it is built.” Increasing FAR indicates that the developers can construct higher buildings and earn more money. By means of awarding FAR, the developers may be willing to practice LID construction. In this study, a new residential district is selected as a case study to analyze the tradeoff between the runoff reduction goal achieving by LID practices and the incentive of awarding FAR to promote LID construction. The System for Urban Stormwater Treatment and Analysis IntegratioN (SUSTAIN) model is applied to simulate the runoff reduction under various LID designs and then derive the Pareto-optimal solutions to achieve urban runoff reduction goals based on cost efficiency. The results indicates that the maximum surface runoff reduction is 20.5%. Under the extremity scenarios, the government has options to award FAR of 0.028, 0.038 and 0.047 and the net benefits developers gain are 0 CNY, one million CNYand two million CNY, respectively. The results provide a LID construction guideline related to awarding FAR, which supports incentive policy making for promoting LID practices in the highly urbanized areas.

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10kV线路杆.上补偿与配变低压侧补偿的对比分析

配电网中最常用的无功补偿方式主要有杆.上无功补偿以及配电变压器低压侧集中补偿。为对这两种方式进行量化对比分析,在对线路杆.上补偿和配电变压器低压侧补偿的理论分析基础上,建立评价指标体系,通过对10 kV典型线路建模并进行仿真潮流计算和无功优化,量化对比分析不同负荷水平下杆.上无功补偿和配电变压器低压侧补偿的效果.结果表明:配电变压器低压侧补偿更有利于无功功率的就地补偿,并且能够减少网络损耗,提高系统运行的经济性。     

HEPA空气净化器对学校室内颗粒物的净化效果研究

为了解HEPA（high efficiency particle air filter,高效空气过滤器）空气净化器在小学教室和寝室的净化效果,于2019年3—4月在北京市一所全寄宿小学开展了一项HEPA空气净化器的交叉干预研究.记录干预组、非干预组室内和室外PM_2.5、PM₁₀、PM₁的浓度,计算空气净化器的净化率;采用多元线性回归模型探索净化效果的影响因素.结果表明:①空气净化器对PM_2.5、PM₁₀、PM₁的净化率分别为41.3%〔Q_l~Q_u（下四分位数~上四分位数,下同）:0~53.1%〕、40.7%（10.5%~46.2%）和34.9%（9.6%~40.3%）,其中对PM_2.5的净化率最高;寝室的净化率高于教室的净化率.②当室外PM_2.5浓度为[115,150）μg/m3时对PM_2.5的净化率最高,为52.83%（50.26%~56.13%）,PM₁₀和PM₁亦有类似结果.③多元线性回归分析表明,室外PM_2.5浓度 < 35 μg/m3时,开门通风和室内人员活动分别使室内PM_2.5浓度下降3.73 μg/m3〔95%置信区间（95% CI）:（0.60 μg/m3,6.86 μg/m3）〕和升高3.4 μg/m3（0.22 μg/m3,6.58 μg/m3）;室外PM_2.5浓度为[35,150）μg/m3时,空气净化器使室内PM_2.5浓度下降33.36 μg/m3（16.47 μg/m3,50.25 μg/m3）;室外PM_2.5浓度≥150 μg/m3时,空气净化器和开门通风分别使室内PM_2.5浓度下降48.87 μg/m3（25.62 μg/m3,72.12 μg/m3）和升高37.65 μg/m3（5.60 μg/m3,69.69 μg/m3）.研究显示:空气净化器可同时降低室内PM_2.5、PM₁₀、PM₁的浓度;当室外PM_2.5浓度 < 35 μg/m3时,不需开启空气净化器;当室外PM_2.5浓度为[35,150）μg/m3时,空气净化器有较好的净化效果,偶尔开窗通风不影响空气净化器的净化效果;当室外PM_2.5浓度≥150 μg/m3时,开启空气净化器时应关闭门窗,以免影响其净化效果.      

Investigation of the effects of humic acid and H<Subscript>2</Subscript>O<Subscript>2</Subscript> on the photocatalytic degradation of atrazine assisted by microwave

A solution of atrazine in a TiO₂ suspension, an endocrine disruptor in natural water, was tentatively treated by microwave-assisted photocatalytic technique. The effects of mannitol, oxygen, humic acid, and hydrogen dioxide on the photodegradation rate were explored. The results could be deduced as follows: the photocatalytic degradation of atrazine fits the pseudo-first-order kinetic well with k = 0.0328 s^?1, and ·OH was identified as the dominant reactant. Photodegradation of atrazine was hindered in the presence of humic acid, and the retardation effect increased as the concentration of humic acid increased. H₂O₂ displayed a significant negative influence on atrazine photocatalysis efficiency. Based on intermediates identified with gas chromatography-mass spectrometry (GC-MS) and Liquid chromatography-mass spectrometry (LC-MS/MS) techniques, the main degradation routes of atrazine are proposed.