Landscape patterns and water age are considered to play similar roles in influencing water quality, as human-caused landscape fragmentation usually leads to complex hydrological pathways and older water ages. The young streamflow fraction (Fyw), which can significantly alter water age, is believed to disproportionately impact water quality. Landscape and Fyw thus may play different roles in streamwater quality, but this assumption has not been examined. Here we examined the roles of Fyw (estimated by the amplitudes of seasonal cycles of oxygen isotope ratios in precipitation (Ap) and streamwater (As)) and landscape pattern (reflected by common landscape metrics) in streamwater quality over 7 forest-dominated catchments in eastern China. Landscape metrics, indicating land use arrangement, were closely related to multiple water quality parameters, suggesting a close association between stream water quality (sinks) and land use (sources). The Fyw had a positive relationship with ammonia nitrogen (R2 = 0.51, P = 0.044) and a negative relationship with nitrate nitrogen (R2 = 0.62, P = 0.022). The Fyw, determined by the heterogeneous-independent As/Ap, offers the possibility of modeling nitrogen compounds across multiple spatial scales. Importantly, the water quality parameters that significantly correlated with Fyw did not correlate with the landscape metrics. Differences in correlations of landscape and Fyw to water quality parameters imply that landscape and Fyw differed in their roles in water quality parameters, as well as the consideration for different water quality management strategies for different contaminants.

Base flow (BF) is harder to predict than other hydrological signatures. The lack of hydrologically relevant information or adequately broad spectrum of typically selected catchment attributes (particularly landscape and topography) hinders the explanatory power. Our goals were to identify the most influential controls on base flow spatially and temporally and to elucidate the response relationships. Base flow in 19 semi-arid sub-watersheds was separated by digital filtering. One hundred and fourteen sub-watershed attributes were related to base flow using random forest regression. The main results were as follows: (1) Annual BF significantly declined since 1999 due to decreased precipitation, increased air temperature, afforestation, urban expansion, and increasing water consumption. Annual base flow index (BFI), varying between 0.319 and 0.695, showed less noticeable temporal trends. (2) Precipitation (P) and underlying carbonate rocks primarily controlled the spatial variation of annual BF and total flow (TF), with the impacts being positive. Landscape was less influential. After the abrupt runoff decline, landscape composition rather than configuration exerted greater impacts on spatial BF and TF, and the importance of forest increased, whereas landscape configuration was decisive for BFI during the whole observation period. The absence of significant links between landscape configuration and water quantity may result from a scale issue. Concave profile curvatures were found to be topographic variables more important than slopes. The impact of soil was the least. This study would benefit the selection of catchment attributes and spatial extents to quantify these attributes in building BF predicting models in future studies.

利用博物馆资源开展跨学科实践活动,应充分发挥其实物性、科学性、基础性、综合性和情境性等特点.在进行活动设计时,要分析学科间的联系、重视行前教育,通过资源整合设计与学生生活经验及认知相联系的多种形式的体验活动,并注意进行有效评价.

Urban surface-deposited sediments (USDs) with different spatial positions and heights are a mixture of various pollutants with complex sources and are widely distributed in urban environments.

土壤微生物胞外酶活性及其化学计量比对土壤养分的有效性和微生物生长的限制因子具有良好的指示作用.然而,在解除氮抑制作用的情况下,微生物的生长策略会呈现何种转变,目前还不明确.在山西太岳山油松林内,按N0(CK)、N5(5 g m-2 a-1)、N10(10 g m-2 a-1)、N20(20 g m-2 a-1)、N40(40 g m-2 a-1)5种施氮量向土壤施撒硝酸铵,探讨无机氮添加对土壤酶活性及其化学计量特征的影响.钻取不同氮添加梯度的表层土壤样品,分析土壤的养分含量、微生物生物量和5种胞外酶的活性,并计算不同氮添加梯度下土壤酶的化学计量比、矢量长度和角度等生态学指标.结果表明:氮添加使土壤可溶性有机氮(DON)含量从10.64 mg/kg显著提高到55.94 mg/kg,增加了5.3倍;而氮添加使可溶性有机碳氮比值(DOC∶DON)显著降低了6.5倍;氮添加使β-1,4-葡萄糖苷酶(BG)活性和酸性磷酸酶(AP)活性分别提高了53.78％和32.12％,均在N40达到最大值;氮添加使酚氧化酶(PHO)和亮氨酸氨基肽酶(LAP)活性分别降低了55.30％和80.42％;氮添加提高了酶C∶N(EEAC∶N)、矢量长度和矢量角度,降低了酶N:P(EEAN∶P).其中,土壤pH值、可溶性有机碳氮比和微生物生物量的变化构成了氮添加改变土壤酶活性和触发微生物生长的磷限制性的关键解释因子综上所述,研究区域山西太岳山油松林土壤微生物的碳氮磷代谢对无机氮添加响应显著,微生物代谢呈现出一定的磷限制,高氮(N40)添加背景下微生物碳限制和磷限制加剧.

现有自然科学类博物馆科技教育活动的研究聚焦在受众视角,与活动的开发存在错位.开发视角应关注教育活动微观个体的具体开发过程,提出开发视角下的博物馆教育活动开发方略:起点、分析-联想、关联、整合、迁移和评价,并引申为以教育活动"基本单位"的形式发展博物馆教育活动结构体系,供以自然科学教育为主的社会教育资源参考.

Pre-mRNA splicing is an essential step during gene expression, which takes place in the spliceosome, a large dynamic ribonucleoprotein complex assembled in a stepwise manner. During the last decade, several spliceosomal mutants were functionally identified to cause a lengthened circadian period by introducing intron retention defects into circadian clock genes in Arabidopsis. However, the spliceosomal components that play opposite roles in the circadian period via alternative 3' splice site (Alt 3'ss) are largely unknown. Here, we demonstrated that XCT (XAP5 CIRCADIAN TIMEKEEPER) is a key spliceosomal component associated with multiple splicing factors. Moreover, genome-wide analysis revealed that inactivation of XCT particularly results in defects in Alt 3'ss recognition by RNA sequencing. Further analysis indicated that a strong alteration in the 3' splice sites of LHY and TIC partly accounts for the shortened circadian period of the xct mutant. Therefore, our results demonstrated that mutations in XCT shortened the circadian period partly by alternative splicing of LHY and TIC particularly in 3' splice site recognition, which provides new insight into the link between alternative splicing and the circadian clock.

Urban surface-deposited sediments (USDs) with different spatial positions and heights are a mixture of various pollutants with complex sources and are widely distributed in urban environments. However, the influence of urban surfaces on USDs vertical distribution pattern and associated pollution characteristics due to their spatial position and height is still unclear. We investigated USDs vertical distribution pattern and their heavy metals in the Haidian District of Beijing. There was an obvious gradient in mass per unit area (unit: g·m -2 ) for the bulk USDs as follows: low (platform, 3 m, 2.3±1.0; overbridge, 5 m, 4.0±3.2), medium (roof top, 20 m, 17.7±5.7), and high (road surface, 0 m, 28.0±17.7; sidewalk, 0 m, 38.3±25.3). Six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) concentrations in USDs on road surface, sidewalk, platforms, overbridge and roof tops were 3.4, 3.5, 7.1, 7.5 and 6.9 times, respectively, higher on average than in corresponding Beijing background soil. Potential heavy metal contribution loads per unit area for the bulk USDs were in the order: low (platform and overbridge), medium (road surface and sidewalk), and high (roof top), implying that flat roof top was the “hot spot” for metal contamination. Furthermore, particle size had an important effect on pollution distribution and their output. Particle sizes (<105 μm) in USDs accounted for about 40% of the bulk particle size on most urban surfaces, while it contributed about 60% to heavy metal load in USDs and about 80% to heavy metal load in TSS in surface runoff. Similarities between different USDs were analysed using discriminant analysis and we discuss the input-output relationships between them. Representative characterization of USDs sources, transport mechanisms and risk to the urban environment are important for regulatory decisions, best management practice performance and maintenance.

Landscape patterns significantly affect urban runoff pollution, and a reasonable arrangement of pervious patches in urban catchments is critical to control urban non-point-source pollution. Low impact development (LID) can be recognized as a pervious surface type, and many previous studies have analyzed the LID performance at a system scale. However, the influence of the LID spatial distribution on runoff pollutant transport at a catchment scale remains unclear. This study analyzed the influence of pervious/impervious patterns on runoff pollution within two urban catchments constructed with LID. It was found that the runoff pollution was influenced by the area ratio, circumference, shape, and pervious patch connectivity of pervious surfaces (i.e., LID). Catchments with high perviousness ratios are more efficient in reducing the runoff volume and suspended solids, and LID should focus on removing runoff pollutants at catchments with high imperviousness ratios. Six typical landscape metrics that represented the fragmentation, complexity and vergence of pervious surfaces were selected to investigate the influence of pervious/impervious patterns on runoff pollution. The results show that larger fragmentation, smaller complexity and smaller vergence of pervious patches result in larger runoff volumes and more pollutants. Therefore, it is recommended that large pervious areas should be retained and close to one another to enhance the retention capacity of LID, and the outline of pervious patches should be long and irregular to reduce pollution confluence. The results of this study are helpful in arranging LID structures for efficient runoff regulation and pollution control at an urban catchment scale.

为了解决远海工程中混凝土用细骨料和用水等资源的就地取材问题,进行了海水拌制珊瑚礁砂混凝土制备关键技术试验.在配合比正交试验优化的基础上,开展了立方体抗压强度、劈裂抗拉强度、抗折强度、轴心抗压强度以及弹性模量等基本力学性能试验研究.结果表明,不同龄期海水拌制珊瑚礁砂混凝土的基本强度均高于相应龄期普通混凝土的强度,可以满足一般混凝土工程对基本力学性能的要求,具有显著的经济价值和社会效益.

以南方丘陵红壤区典型小流域为例,构建了基于R语言的流域非点源颗粒态磷污染指数并进行应用.结果表明,(1)流域土壤侵蚀模数在0.7～15244.2t/(km2·a)之间,超出南方丘陵红壤区容许土壤侵蚀量的区域占流域面积59％;平均非点源颗粒态磷产生强度为0.86kg/hm2,超出非点源磷流失阈值的区域占流域面积14％.流域侵蚀等级以微、轻度为主,但中度及以上强度区域以较小的面积(7.2％)贡献了较大比例的流域侵蚀产生量(35％)和输出量(43％)、以及非点源颗粒态磷输出量(31％).(2)识别的关键源区占流域面积14％,贡献了65％和58％的侵蚀土壤和颗粒态磷输出负荷;主要分布在近河道的坡地(＜25°,水文距离≤800m),林地、耕地、园地是主要土地利用类型组成.(3)过量施肥导致的土壤磷素富集、强降雨条件下低丘缓坡地带的高易蚀性是关键源区形成的主因.研究进一步对关键源区进行分类分区,提出了以水土保持、配方施肥、工程治理为核心的非点源颗粒态磷污染治理组合措施.研究为丘陵红壤区流域非点源颗粒态磷污染的防治提供了较为系统完善的思路.

深入了解不同下垫面非点源污染物的输出特征是小流域综合治理的前提之一.以红壤丘陵地区的典型小流域为例,实地对比观测了降雨条件下林地、农业种植用地(园地和耕地)和建设用地(村镇道路和屋顶)的主要下垫面非点源磷污染物输出过程后发现,典型降雨事件中5种主要下垫面总磷(TP)的场降雨平均浓度为:耕地(0.75 mg.L-1)＞园地(0.59 mg·L-1)＞村镇道路(0.38 mg.L-1)＞林地(0.25 mg·L-1)＞屋顶(0.08 mg·L-1);而 TP 输出强度依次为:村镇道路(0.07 kg.hm-2)＞耕地(0.06 kg·hm-2)＞园地(0.04 kg·hm-2)＞屋顶(0.021 kg·hm-2)＞林地(0.019 kg,hm-2).下垫面类型影响着非点源磷的输出形态,建设用地溶解态磷占比最高(51％～71％),林地溶解态磷次之(44％),而种植用地溶解态磷占比最低(25％).整个小流域土地利用面积占比和磷污染负荷贡献比分别为:林地(87％;55％)＞种植用地(9％;42％)＞建设用地(1％;3％).以上结果再结合当地降雨特征及水土流失现状,可为我国红壤丘陵地区小流域非点源污染治理提供参考.

Scientific identification of runoff output characteristics of different land use patterns is the premise of controlling non-point source pollution in watersheds. The hydrology and output process of non-point source pollutants of forest, planting, and construction land with different rainfall characteristics were observed using a micro-watershed in a low mountain and hilly region of Southern China. The results showed that land use affected the hydrological characteristics and water quality processes of runoff. The characteristics of runoff generation time and cumulative rainfall under typical rainfall conditions were as follows:construction land(9 min, 2.0 mm), planting land(35 min, 11.4 mm), and forest land(108 min, 24 mm). There were significant differences in the three land use types in the pollution output process characteristics, such as pollutant concentration of total suspended matter(TSS), total nitrogen(TN) and phosphorus(TP), their components, N/P ratio change, and output intensity. Under typical rainfall, different land use types had similar pollution output stages, the mass concentrations of TSS, TN, and TP in the initial runoff were high, and then gradually stabilized. In addition, the first 30 min of the flow generation process contributed to the TSS, TN, and TP loads within the 23%-43% range. At the annual scale, there were significant differences between the contribution rate of each land use type to TN and TP load and ratio per unit area; the highest contribution to total pollution load was planting land(57% and 45%), while the highest in pollution load per unit area was construction land(9.50-12.50). The results also showed that the distribution of key non-point source areas had different spatial and temporal dynamics, which was comprehensively determined by the land use types in catchment units, the characteristics of annual rainfall, among other factors. With the increase in rainfall, the main contribution non-point source pollution in the micro-watershed changed from construction land to planting land. Targeted ecological interception strategies should be implemented based on the distribution characteristics of key source areas and characteristics of underlying surface runoff production process.

At present, there are few reports about how impervious surface microstructure characteristics affect the runoff output process of street dust. Based on field observations of 12 rainfall events, this study quantified the microstructure characteristics of impervious surfaces by structural depth (roughness) and analyzed the correlation between roughness and accumulation characteristics of street dust on sunny days as well as scouring characteristics in rainy days. The results show that the roughness of the underlying surface notably affects dust accumulation on sunny days and scouring in rainy days. The correlation between roughness and street dust accumulation (r=0.664, P<0.01) was enhanced on sunny days, and the correlation between roughness and street dust erosion (r=0.527, P<0.01) was enhanced by rainfall. The correlation of street dust accumulation and roughness of each particle size segment increased as particle size increased (0.529 ≤ r<0.757), and the correlation between street dust scouring amount and roughness decreased as particle size increased (0.603 > R > 0.209). By establishing the linear regression model of roughness and rainfall, the cumulative pollution load of TSS in rainfall runoff can be well predicted. The effects of roughness and rainfall on the cumulative load of grain sizes<20 μm and >250 μm are significant. These results elucidate the role of roughness and rainfall analysis in predicting surface runoff pollution load characteristics, which can provide new information for predicting and evaluating urban non-point source pollution.

我国海绵城市工程设施的运行维护管理是当前亟需重视的问题.针对国内现有的不同雨水设施的运行维护需求,提出了科学运行维护管理的技术体系,如日常巡护制度、运行效能监测和衰减性能监测.其中,运行效能监测主要是观测雨水设施运行过程中对径流峰值和污染物总量的调控.当雨水设施运行效果不达标时,应及时进行设施的衰减性监测.通过对雨水设施的介质土表征测试、沉积物积累测试和表面渗透性测试等步骤,评估雨水设施当前的衰减程度,并根据设施的衰减程度进行针对性维护.同时,运用物联网等技术建立智慧海绵动态管控系统,保证雨水设施持久有效运行,由此实现了运行维护指标体系的系统化,以期为今后我国海绵城市运行维护提供有力的技术支撑.

To investigate the effects of Spartina alterniflora invasion on soil phosphorus(P) cycling in coastal wetlands, we selected a S. alterniflora zone(SA zone) and mudflat zone(MF zone) in the Jiaozhou Bay as the target areas for the study. The variability of total phosphorus(TP), inorganic phosphorus(IP), and their component contents in wetland soils after S. alterniflora invasion and their influencing factors was evaluated. The results showed that the average contents of TP(472.70 mg·kg-1) and IP(239.00 mg·kg-1) in the soils were significantly higher than those of TP(386.19 mg·kg-1) and IP(212.68 mg·kg-1) in the pre-invasion area, with an increase of 22.40% and 12.38%, respectively. The IP fractions in the study area were dominated by calcium-phosphorus(Ca-P) and iron-phosphorus(Fe-P), accounting for 45%-61% and 31%-49% of IP, respectively. The Ca-P content of the soil in the 10-30 cm layer decreased significantly(P<0.05) after S. alterniflora invasion, which was especially significant in July. The Fe-P content increased significantly(P<0.05); in the 0-40 cm soil layer, Fe-P was higher than that in the 40-60 cm layer(P<0.05), and showed significant enrichment in the 10-40 cm soil in July. The structural equation model showed that organic matter(OM) had a significant positive effect on TP and Fe-P after S. alterniflora invasion(P<0.01), and the normalized path coefficients were 0.775 and 0.724, respectively. Fe-P had a significant negative effect on Ca-P after invasion(P<0.01) with a normalised throughput coefficient of -0.435. The study found that S. alterniflora invasion generally increased wetland soil P content, while promoting the conversion of Ca-P to Fe-P, improving wetland P bioavailability.

[目的]分析不同林龄油松林土壤有机碳及其组分的变化特征,为揭示维持油松林土壤有机碳稳定性的生物学机理提供理论依据.[方法]以山西太岳山林区40,80和110年生的油松林为研究对象,测定不同林龄油松林土壤有机碳及其组分(高氧化活性有机碳(F1)、中氧化活性有机碳(F2)、低氧化活性有机碳(F3)、稳定有机碳(F4))含量、pH、全氮含量、全磷含量、阳离子交换量、土壤酶活性和土壤粒径分布,分析不同林龄油松林土壤有机碳的稳定性和土壤理化性质的变化特征.[结果]土壤有机碳含量随林龄的增加而增大.难被氧化分解的有机碳组分(F3和F4)占总有机碳的70％以上,且所占比例随林龄的增大而增高;易被氧化分解的有机碳组分(F1和F2)占总有机碳的30％以下,随林龄的增大占比总体降低.40,80和110年生油松林在0～1o cm土层土壤有机碳的稳定系数分别为2.69,5.77和6.60,在10～20 cm土层分别为3.42,5.90和6.36.随着林龄的增加,土壤全氮含量、阳离子交换量、β-1,4-葡萄糖苷酶和纤维二糖水解酶活性呈增大趋势;在0～10 cm土层,土壤黏粒和粉粒含量呈降低趋势,土壤砂粒含量呈增大趋势.地表凋落物现存量与土壤有机碳含量呈显著的正相关关系,与F4呈极显著正相关关系,影响土壤总有机碳的积累与稳定.逐步回归分析结果显示,F1主要受全氮、阳离子交换量、粉粒含量、砂粒含量和β-1,4-葡萄糖苷酶活性的综合影响;F2主要受pH和β-1,4-葡萄糖苷酶活性的综合影响;F3主要受粉粒含量、β-1,4-葡萄糖苷酶活性和纤维二糖水解酶活性的综合影响;F4主要受pH、全氮、黏粒含量、粉粒含量和砂粒含量的综合影响;总有机碳主要受pH、全氮、全磷和阳离子交换量的综合影响.[结论]当油松林林龄为40～110年时,随林龄的增加,土壤理化性状和生物学性状均得到改善,林龄越高,土壤有机碳固持能力越强,土壤有机碳库越稳定.

Efficiently evaluating the risk of urban non-point source pollution (urban-NPS) using only a few parameters is crucial to its management and control, especially in engineering. However, the huge spatial heterogeneity of urban-NPS induced by the high spatial heterogeneity in land use, surface infiltration and surface micro-topography, make it difficult. A new index model composed of transport and source factors was proposed to evaluate the urban-NPS risk. An urban catchment in southern China served to demonstrate the proposed method. The ability of runoff output was characterized by the transport factor in which the impervious-pervious surface spatial pattern, imperviousness ratio and rainfall were taken into account. The pollutants output capacity was represented by source factor where the imperviousness ratio and source-sink transformation resulting from rainfall were considered. Results show the proposed index can identify and evaluate the risk of urban-NPS at both urban parcel scale and catchment scale. The percent bias (PBIAS) of runoff volume helped to assess the performance of the index. PBIAS (1–86%) between the proposed method and the observed runoff was much lower than that (27–448%) between the traditional runoff coefficient method and the observed runoff. These suggest that the proposed index offers a new way of assessing urban-NPS risk.

义乌市的"五水共治"行动已开展了8年.尽管耗氧物质已得到全面管控,但仍面临水质型饮用水短缺和水系统功能受损的挑战.为助力该市经济与生态环境保护的协调发展,中国科学院生态环境研究中心(义乌)长三角中心提出了水生态可持续发展的战略举措:建议义乌市以生态资源经济化与经济发展生态化的发展模式,实行多水源开发与风险防控;将初期雨水治理、雨污分流处置、管网系统优化、水质质量保障、内外污染防控与生态环境品质提升作为工作重心;增设智慧化管理平台保障监测与控制;实行国内生产总值(GDP)和生态系统生产总值(GEP)双核算制度.以上举措有望协助义乌市走出一条集约化发展模式下的绿色流域构建道路.

Most sponge city constructions in China are carried out in urban parcel-based catchments, and the quality and quantity of surface runoff can be controlled by several low impact development (LID) facilities. However, there are few reports on the generation and control of urban diffuse pollution. In this study, two areas with different hardening rates were compared to analyze the load conditions during the accumulation-wash-off-transport process of particulate pollutants. The results showed that the road surface in the catchment was the main underlying surface that the particulate pollutants contributed to. The road dust accumulation in the medium hardening rate (61.1%) and high hardening rate (73.6%) plots accounted for 88.4% (2.22-12.51 g ·m-2) and 90.1% (4.99-33.43 g ·m-2) of the catchment area unit, respectively. The contribution to the suspended solids (SS) load of runoff was 91.7% (0.97-7.34 g ·m-2) and 90.5% (0.92-18.77 g ·m-2), respectively. The SS load of road runoff accounted for approximately 95.2% and 83.1%, respectively. The pollution load (SS) after treatment by the LID facilities was approximately 24.0% and 40.2% of the surface runoff, respectively. The particle size distribution of road dust during the accumulation and wash-off processes was>150 μm, while that in surface and output runoff was <50 μm. With the increase in the impervious area, the distribution of finer particles (<105 μm) in the process of accumulation and wash-off increased (24.4%, 106.4%), while the distribution of particles <50 μm in road runoff decreased (12.4%). The particle size distribution of the accumulated, washed dust, and the rain runoff on the roof were roughly similar to those on the road. However, compared to the particle size distribution of road dust, in the accumulation and wash-off processes, the coarser particles (>1000 μm) of the medium hardening rate plot and the particles of size 250-450 μm and <45 μm of the high hardening rate plot increased significantly (>1000 μm: 58.1%, 108.5%; 250-450 μm: 72.9%, 41.8%; <45 μm: 59.2%, 64.8%). The results revealed the entire distribution process (accumulation-wash-off-transport) of particulate pollutants and the effect of LID facilities on the total SS pollution load of the catchment, which can provide an important reference for the scientific assessment of the project performance of LID installation in urban parcel-based catchments.