河北省近岸海域氮磷变化及其影响因素分析

根据2011—2018年河北省近岸海域海水、入海河流、降水中氮和磷的监测数据,分析了海水中氮和磷的变化趋势及其影响因素。结果表明:2011—2018年,河北省近岸海域海水中无机氮(DIN)和无机磷(DIP)的平均浓度均低于第二类海水水质标准,海域富营养化状况以贫营养和轻度富营养为主,超标(第二类海水水质标准限值)点位和中度、重富营养区域主要集中在沧州市近岸海域。河北省近岸海域海水中DIN的平均浓度在2011—2014年、2015—2017年呈现阶段性上升趋势,2018年大幅下降; DIP的平均浓度在2011—2013年无明显波动,2014年陡增后开始逐年下降; N/P在2011—2014年无明显变化,2015—2018年呈逐年上升趋势。自2016年起,入海河流中氨氮和总磷的平均浓度、降水中氨氮的平均浓度均呈逐年下降趋势。近岸海域海水、入海河流、降水中的氮和磷表现出一定的相关性和协同性,陆源污染输入总量降低是海水中氮磷浓度降低的主要原因。应警惕污染物控制力度的不同所导致的海水中生源要素结构的改变,及其引发的潜在海洋生态风险。     

Nanoanalytics: history,concepts, and specificities

Environmental Science and Pollution Research - This article deals with analytical chemistry devoted to nano-objects. A short review presents nano-objects, their singularity in relation to their...     

Potential health risks of toxic heavy metals and nitrate via commonly consumed bivalve and vegetable species in Ho Chi Minh City,Vietnam

Environmental Science and Pollution Research - This study aimed to evaluate the health risks of cadmium (Cd), lead (Pb), inorganic arsenic (As), and nitrate exposure through the consumption of...     

曝气冲刷对膜生物反应器膜污染的控制机理研究进展

膜污染是膜生物反应器(MBR)进一步推广应用的瓶颈问题。曝气冲刷是一种操作简单、无二次污染的MBR膜污染控制技术,但在缓解膜污染的同时也显著增加了系统的运行能耗。优化曝气能耗需深入理解膜污染控制的流体力学机理和生物化学机理。重点综述了曝气冲刷通过剪切力去除膜表面污垢的作用机理,以及曝气冲刷影响污泥混合液的作用机理。在综述的基础上展望了未来研究的发展方向。     

Iron (Fe2+)-induced toxicity produces morphological and physiological changes in roots in Panax ginseng grown in hydroponics

ABSTRACT

Rusty roots markedly influence on ginseng cultivation, and this phenomenon often attributed to iron (Fe) induced toxicity. To examine the physiological mechanisms underlying Fe-initiated toxicity as evidenced by rusty roots in Panax ginseng, morphological and physiological changes in roots were investigated in hydroponics using Fe²⁺ concentrations of 50 (control), 100, 200, 400 or 600 µM. Compared with control, reddish-brown deposition at the root surface increasingly appeared as Fe²⁺ concentration increased (≥200 µM). The pH also rose as Fe levels were elevated. Higher external Fe²⁺ concentrations produced changes in root organelles and cell structures. Structural alterations in mitochondria due to excess Fe storage, protoplast shrinkage and cell vacuolation as well as formation of central vacuole with deposits in roots were observed. In addition, apparent cell wall thickening, cell wall folding and shrinkage, damage of cell membranes and a large amount of cell debris occurred at higher external Fe²⁺ concentrations (≥400 µM). The Fe²⁺ mediated damage resulting in morphological and physiological changes in ginseng roots was concentration and pH dependent.     

Antagonistic effect of natural habitat conversion on community adjustment to climate warming in nonbreeding waterbirds

Although the impacts of climate and land-use changes on biodiversity have been widely documented, their joint effects remain poorly understood. We evaluated how nonbreeding waterbird communities adjust to climate warming along a gradient of land-use change. Using midwinter waterbird counts (132 species) at 164 major nonbreeding sites in 22 Mediterranean countries, we assessed the changes in species composition from 1991 to 2010, relative to thermal niche position and breadth, in response to regional and local winter temperature anomalies and conversion of natural habitats. We observed a low-level, nonsignificant community adjustment to the temperature increase where natural habitat conversion occurred. At the sites affected by natural habitat conversion, the relative increase of warm-dwelling species in response to climate warming was 6 times lower and the relative species decline was 3 times higher than in the sites without natural habitat conversion. We found no evidence of community adjustment to climate warming when natural habitat conversion was >5% over 15 years. This strong negative effect suggests an antagonistic interaction between climate warming and habitat change. These results underline the importance of habitat conservation in community adjustment to climate warming.     

Discussion

Environmental and Ecological Statistics -     

铁铝盐基离子对土壤中水溶性氟环境效应的影响

氧化物或粘土矿物可吸附氟离子,但磷酸根离子与氟离子存在竞争吸附效应,造成氟的环境存在量、存在形态及生物效应更加复杂,影响了环境中氟污染的治理.试验选用典型贵州黄壤和石灰土,通过向模拟高氟污染土壤中添加铁铝盐基离子和磷酸盐,采用两因素最优设计,研究外源物质对土壤中水溶性氟的影响.结果表明,FeCl3·6H2O或AlCl3·6H2O都能降低土壤中水溶性氟,而KH2PO4使土壤中水溶性氟增加,对黄壤和石灰土中水溶性氟影响效果大小依次为FeCl3·6H2O(AlCl3·6H2O)、KH2PO4.同时表明,采用铁铝盐基离子改变黄壤性质,达到降氟效果仍有很大潜力,而石灰土环境在高添加铁铝盐基离子水平下继续添加FeCl3·6H2O或AlCl3·6H2O降低土壤中水溶性氟的作用较弱.从土壤pH看,黄壤水溶性氟受试验因子影响复杂,土壤pH低水溶性氟不一定低,pH在4～6时,氟元素的形态及有效性尤其复杂,而石灰土中水溶性氟基本随pH降低而降低.     

BOD微生物传感检测仪中高效微生物膜的研究

为了制备高效微生物膜,从污水中筛选菌种（QT2061）,经BIOLOG鉴定为枯草芽孢杆菌。并以聚乙烯醇为包埋剂制作BOD生物传感器微生物膜,通过对国家标准样品及几种典型水样的检测,结果表明,该微生物传感器的响应时间为8 min,可连续稳定测试10 d以上;对国家标准溶液的测试结果准确度较高,相对误差≤5%;对实验中几种水样均有响应,测试结果与5日法的测试结果有良好的相关性（相对偏差≤5%）。     

大型活动拥挤踩踏事故BP神经网络安全评估方法应用分析

根据大型活动拥挤踩踏事故是一个极其复杂的多因素、多变量、多层次的人-机-环境系统,利用数学建模的思路,引入人工神经网络评估方法;以沈阳世博会开幕式为例,通过前馈型BP网络训练和测试,将开幕式举办过程中的人员拥挤踩踏事故风险系统划分为人的因素、物的因素、环境因素、管理因素4个子系统和拥挤踩踏事故综合评估总系统,分别对其进行拟合分析,在各个系统的拟合残差满足条件的情况下,得出量化的评估预测值及BP神经网络的使用范围。研究实例表明,BP神经网络评估结果直观易懂,可操作性强,是值得推广运用的一种评估方法。