Empirical and simulated critical loads for nitrogen deposition in California mixed conifer forests

Empirical critical loads (CL) for N deposition were determined from changes in epiphytic lichen communities, elevated NO(3)(-) leaching in streamwater, and reduced fine root biomass in ponderosa pine (Pinus ponderosa Dougl. ex Laws.) at sites with varying N deposition. The CL for lichen community impacts of 3.1kg ha(-1) year(-1) is expected to protect all components of the forest ecosystem from the adverse effects of N deposition. Much of the western Sierra Nevada is above the lichen-based CL, showing significant changes in lichen indicator groups. The empirical N deposition threshold and that simulated by the DayCent model for enhanced NO(3)(-)leaching were 17kg N ha(-1) year(-1). DayCent estimated that elevated NO(3)(-) leaching in the San Bernardino Mountains began in the late 1950s. Critical values for litter C:N (34.1), ponderosa pine foliar N (1.1%), and N concentrations (1.0%) in the lichen Letharia vulpina ((L.) Hue) are indicative of CL exceedance.     

Effects of Conversion of Dry Tropical Forest to Agricultural Mosaic on Herpetofaunal Assemblages

Abstract: We explored the impact of forest conversion to agricultural mosaic on anuran, lizard, snake, and turtle assemblages of Neotropical dry forests. Over 2 years, we sampled 6 small watersheds on the west coast of Mexico, 3 conserved and 3 disturbed. The disturbed watersheds were characterized by a mosaic of pastures and cultivated fields (corn, beans, squash) intermingled with patches of different successional stages of dry forest. In each watershed, we conducted 11 diurnal and nocturnal time‐constrained searches in 10 randomly established plots. We considered vulnerability traits of species in relation to habitat modification. Eighteen anuran, 18 lizard, 23 snake, and 3 turtle species were recorded. Thirty‐six species (58%) occurred in both forest conditions, and 14 (22%) and 12 species (19%) occurred only in the conserved and disturbed sites, respectively. Assemblages responded differently to disturbance. Species richness, diversity, and abundance of lizards were higher in disturbed forests. Anuran diversity and species richness were lower in disturbed forest but abundance was similar in both forest conditions. Diversity, richness, and abundance of turtles were lower in disturbed forest. The structure and composition of snake assemblages did not differ between forest conditions. We considered species disturbance sensitive if their abundance was significantly less in disturbed areas. Four anuran (22%), 2 lizard (11%), and 3 turtle (100%) species were sensitive to disturbance. No snake species was sensitive. The decline in abundance of disturbance‐sensitive species was associated with the reduction of forest canopy cover, woody stem cover, roots, and litter‐layer ground cover. Anuran species with small body size and direct embryonic development were especially sensitive to forest disturbance. An important goal for the conservation of herpetofauna should be the determination of species traits associated with extinction or persistence in agricultural mosaics.     

Carbonate-induced enhancement of phenols degradation in CuS/peroxymonosulfate system: A clear correlation between this enhancement and electronic effects of phenols substituents

This study investigated the enhancement effects of dissolved carbonates on the peroxymonosulfate-based advanced oxidation process with CuS as a catalyst. It was found that the added CO₃²⁻ increased both the catalytic activity and the stability of the catalyst. Under optimized reaction conditions in the presence of CO₃²⁻, the degradation removal of 4-methylphenol (4-MP) within 2 min reached 100%, and this was maintained in consecutive multi-cycle experiments. The degradation rate constant of 4-MP was 2.159 min⁻¹, being 685% greater than that in the absence of CO₃²⁻ (0.315 min⁻¹). The comparison of dominated active species and 4-MP degradation pathways in both CO₃²⁻-free and CO₃²⁻-containing systems suggested that more CO₃•⁻/¹O₂ was produced in the case of CO₃²⁻deducing an electron transfer medium, which tending to react with electron-rich moieties. Meanwhile, Characterization by X-ray photoelectron spectroscopic and cyclic voltammetry measurement verified CO₃²⁻ enabled the effective reduction of Cu²⁺ to Cu⁺. By investigating the degradation of 11 phenolics with different substituents, the dependence of degradation kinetic rate constant of the phenolics on their chemical structures indicated that there was a good linear relationship between the Hammett constants σ_p of the aromatic phenolics and the logarithm of k in the CO₃²⁻-containing system. This work provides a new strategy for efficient removal of electron-rich moieties under the driving of carbonate being widely present in actual water bodies.     

过氧化氢对铜绿微囊藻的损伤效应研究

采用室内培养的方法研究了不同浓度H2O2对铜绿微囊藻(Microcystic aeruginosa)藻细胞的损伤效应.结果表明,H2O2浓度越大,对藻细胞的毒害作用越大.24 h之后,铜绿微囊藻藻细胞数、叶绿素a、类胡萝卜素和蛋白质含量及总抗氧化能力(T-AOC)都快速下降,而MDA含量显著增加,同时培养基中的H2O2含量也迅速降低;随着处理时间的增加,毒性效应逐渐增强;72 h之后,藻细胞各指标值都降得很低,MDA含量也增加到最大,培养基中H2O2也逐渐被消耗和分解,藻细胞的损伤效应也达到最大.其中,H2O2浓度为50 mg·L-1时,能够有效的去除藻细胞,并且对藻细胞的生理指标及抗氧化能力都有很强的损伤效应.     

《大气污染防治法(修订草案)》的若干修改建议

《大气污染防治法》(修订草案)有很多突破,但是针对性、策略性、特色性和可实施性均存在欠缺,需要进一步把生态文明、绿色化、区域协同发展的要求纳入立法目的,体现在体制制度和机制的设计中;理顺立法体例,保证规定的逻辑性;坚持空间管控和多规合一,坚持空气质量目标管理的思路,采取实际大气环境容量和实时排放流量控制相结合的工作模式;明确行动计划与现行环境保护规划、各专项环保规划的关系;理顺监管体制,创新区域联合防治的制度和机制,弥补侵权法律责任和法律救济规定的不足,保持信息公开申请和环境民事公益诉讼提起条件的前后贯通性。只有这样,才能既体现立法修改的必要性和针对性,又体现立法规定的时代性和特色性,展现法律措施的严格性和法律责任的严厉性。     

人工湿地常用生物陶粒基质LDHs覆膜改性及其除磷效果研究

分别利用3种二价金属化合物和3种三价金属化合物,采用水热共沉淀法在碱性条件下对人工湿地中常用的生物陶粒基质进行层状双金属氢氧化物(LDHs)覆膜改性,并将9种不同类型的LDHs覆膜改性生物陶粒基质和普通生物陶粒基质分别填充于10个垂直流人工湿地模拟实验柱中,进行除磷净化实验.结果表明,9种不同类型的改性生物陶粒基质均能有效提高磷素的净化效果;Zn系LDHs改性生物陶粒对总磷、溶解性总磷、磷酸盐均有很好的处理效果,其中Zn Fe-LDHs、Zn Co-LDHs和Zn Al-LDHs对总磷的平均去除率均在92%以上,对溶解性总磷和磷酸盐的平均去除率均超过95%;其对磷素的净化机理主要集中于物理化学作用,同时还应与其对微生物生长的促进作用有关.     

纳米Ag粒子在我国主要类型土壤中的迁移转化过程与环境效应

随着纳米技术的快速发展,纳米材料进入环境并不断累积,因此开展纳米材料的环境安全性研究具有重要意义.纳米银(Ag NP)是目前应用最广泛的人工纳米材料之一.本课题组拟以Ag NP为研究对象,系统研究其在我国主要类型土壤中的迁移、转化过程及其生态环境效应;基于同步辐射技术、同位素技术和量子化学计算等方法,揭示Ag NP与土壤中主要矿物或有机质之间的相互作用规律;探明Ag NP对土壤中微生物、动物和植物的致毒过程及其作用机制;发展Ag NP在土壤中迁移的数学模型,预测其在土壤中的迁移、滞留通量进而评价其淋溶风险,为Ag NP的安全利用提供重要理论基础和技术支撑.     

纳米氧化锌对大型溞肠道组织毒性效应及机理研究

研究了不同浓度纳米氧化锌（ZnONP）及其在水中释放的对应浓度的Zn²⁺溶液对大型溞（Daphnia magna）肠道组织显微和亚显微结构的影响,探讨了ZnONP对大型溞的肠道组织毒性效应特征和作用机理.结果表明,0.3 mg·L^-1-Zn²⁺组（Zn²⁺浓度0.170 mg·L^-1）和0.3 mg·L^-1 ZnONP溶液皆对大型溞的肠道造成损伤,主要导致大型溞中肠与直肠之间的连接处发生扭曲,其中ZnONP对肠道组织结构弯曲影响最为明显,0.3 mg·L^-1 ZnONP组引起大型溞个体最大肠道弯曲率高达42%.大型溞肠道组织HE染色结果显示,ZnONP暴露会造成大型溞肠道上皮组织断裂、胞间连接空泡化、纹状缘模糊及杯状细胞脱落等,而相对应浓度Zn²⁺组的毒性较弱.电子显微镜下对大型溞肠道组织亚显微结构观察发现,0.3 mg·L^-1 ZnONP处理组大型溞肠道上皮细胞组织出现微绒毛排列紊乱、脱落、溶解,上皮细胞松散,线粒体双层膜结构不完整,嵴溶解消失,核糖体增多等现象.0.3 mg·L^-1-Zn²⁺组大型溞肠道组织上皮细胞有损伤,但整体结构基本完整.从ZnONP和对应的Zn²⁺所产生的毒性效应特征和各组大型溞机体中Zn元素含量的测定分析,ZnONP对大型溞造成的肠道组织损伤不仅与其释放的Zn²⁺引起的毒性有关,更可能与大型溞对颗粒物摄取的方式或ZnONP在体内的积累量、排泄速率和作用的细胞器等有关.因此,ZnONP对肠道组织毒性效应产生的分子机制还需要 进一步研究.     

流域开发的外部性及其内部化

流域是地表水的集水区域。流域问题的本质是水。水是可持续发展的基础和条件，是环境与发展问题的核心。流域开发是以水资源为先导和主体的综合资源开发。实现流域经济可持续发展实质就是实现流域水资源可持续开发和利用。外部性是流域开发的基本特征，水资源的特性决定了流域开发的外部性。实现流域开发的外部性内部化是流域经济可持续发展的关键。实现流域开发外部性内部化，必须界定流域资源产权，明确流域开发主体；建立税收－补贴体系，对水资源合理定价；坚持“排污者付费原则”；建立流域水资源市场，实现水资源资产化管理。同时，政府要加强流域的管理；建立健全水资源保护与流域开发的法律体系；普及保护环境和水资源的教育，建立节水观念；支持和鼓励流域开发企业实行外部成本内部化措施；调整产业结构，深化国有企业改革。     

历史抗生素胁迫改变磺胺甲唑和甲氧苄啶对活性污泥的影响:ARGs及其潜在宿主

抗生素共暴露对污水处理厂抗生素抗性基因（ARGs）及微生物群落聚集过程有着重要影响.然而,历史抗生素接触胁迫差异（遗留效应）是否能决定微生物和ARGs对抗生素复合污染的响应尚不清楚.通过选择高浓度（30 mg ·L^-1）磺胺甲唑（SMX）和甲氧苄啶（TMP）作为历史接触胁迫条件,探究SMX和TMP复合污染对ARGs、细菌群落及其交互作用的短期影响.基于高通量荧光定量PCR,共检测出13种ARGs,它们的绝对丰度介于2.21~5.42 copies ·μL^-1（对数值,以DNA计,下同）,其中sul2、ermB、mefA和tetM-01是样品中最主要的亚型,绝对丰度在2.95~5.40 copies ·μL^-1之间;SMX和TMP复合污染会引起ARGs和可移动基因元件（MGEs）的富集,但其对各亚型的影响不同,且SMX的历史遗留效应高于TMP;不同接触史的复合污染下,ARGs间的共现与互斥模式均存在;MGEs （尤其是intI-1）与磺胺类（sul1、sul2）、四环素类［tet （32）］和大环内酯-林可酰胺-链霉菌素类抗性基因（ermB）均呈显著正相关性;基于微生物全尺度分类发现各类群微生物群落结构对复合污染的响应不同,且条件丰富菌属（CAT）得到了显著富集;陶厄氏菌属（Thauera）、假黄单胞菌属（Pseudoxanthomonas）和副球菌属（Paracoccus）是优势的抗性菌属;网络分析共发现31个ARGs的潜在宿主,以条件稀有菌属（CRT）为主,尤其是Candidatus_Alysiosphaera和纺锤状菌属（Fusibacter）与多种ARGs呈现正相关,是多种ARGs的潜在公共细菌宿主;部分稀有菌属［RT,变异杆菌属（Variibacter）、气单胞菌属（Aeromonas）和管道杆菌属（Cloacibacterium）等］是转座子IS 613的潜在宿主,在ARGs的增殖传播中发挥重要作用.综上,研究揭示了污水处理系统中抗生素历史胁迫对ARGs赋存特征和及其宿主细胞的遗留效应,可为削减抗生素复合污染引起的ARGs污染提供新思路与理论依据.