河口切变锋引起的滩槽泥沙交换效应

切变锋是河口湾锋系中最为常见和最易观察到的锋面类型。本文对长江口的切变锋进行现场观察和滩，槽同步水文资料分析，简述了长江口切变锋发生的部分和基本特性，提出了切变锋引起的滩，槽泥沙呈现螺旋形交换形式等论点。     

Levels of tin in core sediments along the Alexandria Coast, Egypt

Tin concentrations were determined in surface and core sediments from three hot spots along the Alexandria coast, namely: Abu-Qir Bay, Eastern Harbour, and Western Harbour. The mean concentrations in surface sediment were 2.434, 3.212, and 5.572 μg/g dry weight for Abu-Qir Bay, Eastern Harbour, and Western Harbour, respectively. A sharp decrease in tin level in core sediments with depth was observed in almost all locations except for core 4 in Abu-Qir Bay and core 17 in the Eastern Harbour, where the sub-sample at the 5 cm level recorded the highest tin concentrations.     

Biological Activity in a Heavily Organohalogen-Contaminated River Sediment (8 pp)

Background, Aims and Scope Sediments of the Spittelwasser creek are highly polluted with organic compounds and heavy metals due to the discharge of untreated waste waters from the industrial region of Bitterfeld-Wolfen, Germany over the course of more than one century. However, relatively few data have been published about the chloroorganic contamination of the sediment. This paper reports on the content of different (chloro)organic compounds with special emphasis on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), and chlorobenzenes. Existing concepts for the remediation of Spittelwasser sediment include the investigation of natural attenuation processes, which largely depend on the presence of an intact microbial food web. In order to gain more insight in terms of biological activity, we analyzed the capacity of sediment microflora to degrade organic matter by measuring the activities of extracellular hydrolytic enzymes involved in the biogeochemical cycling of carbon, nitrogen, phosphorus and sulfur. Furthermore, the detection of physiologically active bacteria in the sediment, particularly of those known for their capability to reductively dehalogenate organochlorine compounds, illustrates the potential for intrinsic bioremediation processes. Methods PCDD/F and chlorobenzenes were analyzed by gas chromatography(GC)/mass spectrometry and GC/flame ionization detection, respectively. The activities of hydrolytic enzymes were determined from freshly sampled sediment layers using 4-methylumbelliferyl (MUF) or 7-amino-4-methylcoumarin-conjugated model compounds and kinetic fluorescence measurements. Physiologically active bacteria from different sediment layers were microscopically visualized by fluorescence in situ hybridization (FISH). Specific bacteria were identified by 16S rRNA gene amplification and sequencing. Results and Discussion The PCDD/F congener profile was dominated by dibenzofurans. In addition, the presence of specific tetra and pentachlorinated dibenzofurans supported the assumption that extensive magnesium production was one possible source for the high contamination. A range of other chloroorganic compounds, including several isomers of chlorobenzenes, hexachlorocyclohexane and 1,1,1-trichloro-2,2-bis (p-chloro-phenyl)ethane (DDT), was present in the sediment. Activities of extracellular hydrolytic enzymes showed a strong decrease in those sediment layers that were characterized by high contents of absorbable organic halogen (AOX), indicating disturbed organic matter decay. Interestingly, an abnormal increase of cellulolytic enzyme activities below the organochlorine-rich layers was observed, possibly caused by residual cellulose from discharges of sulfite pulping wastes. FISH revealed physiologically active bacteria in most sediment layers from the surface down to the depth of about 60 cm, including members of Desulfitobacterium (D.) and Sulfurospirillum. The presence of D. dehalogenans was confirmed by its partial 16S rRNA gene sequence. Conclusions Results of chemical sediment analyses demonstrated high loads of organochlorine compounds, particularly of PCDD/F. Several years after stopping the waste water discharge to Spittelwasser creek, this sediment remains a main source for pollution of the downstream river system by way of the ongoing mobilization of sediment during high floods. As indicated by our enzyme activity measurements, the decomposition potential for organic matter is low in organochlorine-rich sediment layers. In contrast, the comparably higher enzyme activities in less organochlorine-polluted sediment layers as well as the presence of physiologically active bacteria suggest a considerable potential for natural attenuation. Recommendations and Perspectives From our data we strongly recommend to explore the degradative capacity of sediment microorganisms and the limits for in situ activity towards specific sediment pollutants in more detail. This will give a sound basis for the integration of bioremediation approaches into general concepts to reduce the risk that permanently radiates from this highly contaminated sediment. Submission Editor: Dr. Henner Hollert (Henner.Hollert@urz.uniheidelberg.de)     

亚热带稻田土壤碳氮磷生态化学计量学特征

为了解稻田土壤中是否存在稳定的土壤有机碳(C)、氮(N)和磷(P)比值,基于亚热带区110个水稻土剖面和587个发生层的土壤调查数据库,在区域尺度上分析了典型水稻土C∶N∶P比值的生态化学计量学特征,并应用相关分析和冗余分析,研究水稻土C∶N∶P比值与土壤-环境因子(地形和母质、土壤发生层、土壤类型和土壤理化性质)的关系.结果显示,亚热带区稻田土壤C∶N、C∶P和N∶P的剖面加权平均值分别为12. 6、49和3. 9,C∶N∶P为38∶3. 2∶1.不同母质起源、不同土壤亚类和不同发生层的水稻土C∶N变异相对较小;但C∶P和N∶P的变异很大,两者均值也远低于全球(186和13. 1)和中国土壤(136和9. 3)的C∶P和N∶P的平均水平.尽管稻田土壤剖面的C∶N∶P相对不稳定,但由于稻田表土生物与环境相互作用强烈,表土C∶N相对稳定(14. 2).这反映长期水耕熟化作用下,稻田表土中C和N仍存在紧密的耦合作用.然而,在稻田土壤剖面上,C∶P和N∶P并不稳定,SOC与全P含量、全N与全P含量也无显著相关性,表明环境变化可能导致土壤C∶N∶P解耦.地形、土壤质地、氧化铁和容重是调控稻田土壤剖面C∶N∶P的关键土壤环境因子.     

基于两种再分析资料的一次四川盆地大气污染过程气象要素数值模拟研究

利用ECMWF-ERA5和NCEP-FNL再分析资料作为中尺度气象模式WRF（The Weather Research and Forecasting）初始场,对四川盆地2018年1月一次大气污染过程气象要素进行了模拟,对比分析了气温、风速、风向、相对湿度、边界层高度、温廓线的模拟效果,并结合大气超级站观测数据对模拟结果进行评估.结果表明：两种资料均能较好地模拟出气象要素的变化情况,但由于两套资料时空分辨率、采用的模式、同化方案、数据来源和质量控制方案存在一定区别,导致各要素模拟效果并不一致.与NCEP-FNL相比,ECMWF-ERA5模拟的平均相对湿度（59.23%）与观测值差异更小,且均方根误差、偏差较小,分别为9.83%和-0.83%,但NCEP-FNL模拟的平均气温（8.99℃）更接近观测值,且偏差值较小,为-0.04℃.两组模拟结果均显示盆地内部为模拟区域的低风速区,相对湿度模拟值在60%以上,气温高于西部山地地区.NCEP-FNL模拟的盆地内部气温、相对湿度、风速小于ECMWF-ERA5模拟值,但边界层高度模拟值较大.ECMWF-ERA5模拟的逆温强度相比较小,且温度露点差较小.此次污染过程PM_2.5和PM₁₀日均浓度最大值分别为190.1 μg·m^-3和261.0 μg·m^-3,相对湿度增大引发的颗粒物吸湿增长是导致PM_2.5和PM₁₀质量浓度突增的主要原因.     

石臼漾人工湿地冬夏季全程氨氧化微生物的分布、群落结构及其影响因素研究

湿地作为水体与陆地之间的过渡地带,具有独特的生态环境特性,是氮循环反应的关键区域.研究湿地生态系统中的全程氨氧化过程（complete ammonia oxidation,comammox）,解析该区域中comammox细菌的分布与群落结构特征,补充了此前该新型氨氧化微生物在湿地生态系统中分布特征的研究空白,对于完善comammox细菌在各种不同生态系统中分布情况的研究具有重要意义.本研究在石臼漾人工湿地中于冬夏两季分别采集了大沟中心、大沟边缘、小沟中心和小沟边缘的表层沉积物样品,利用PCR、荧光定量PCR和amoA功能基因高通量测序等方法,解析人工湿地中comammox细菌的时空分布与群落结构特征.主要研究结果如下：①所有样品中均检测到了comammox细菌,其丰度为1.77×10⁵~4.07×10⁷ copies·g^-1.冬季,comammox细菌丰度在大沟中高于氨氧化细菌（ammonia oxidizing bacteria,AOB）和氨氧化古菌（ammonia oxidizing archaea,AOA）,在小沟中高于AOB,但低于AOA;夏季,comammox细菌丰度在所有样点中均高于AOB和AOA.②冬夏两季样品中,comammox细菌丰度与底物NH₄⁺-N浓度均呈负相关关系,且夏季样品中呈显著性负相关.③主坐标分析（Principle Coordinate Analysis,PCoA）与多样性分析结果表明,comammox细菌群落结构具有空间异质性,且冬季物种多样性高于夏季.     

深圳市秋季大气臭氧立体分布特征

利用大气O₃探测激光雷达在深圳市东部生态区和西部城区同步开展垂直观测,探究了2018年深圳市O₃立体分布在秋季光化学污染活跃期至冬季非活跃期的演变过程.结果表明：光化学反应活跃的10月,东部地面O₃浓度相对于西部地面高出约128%;地面向上至450m,O₃浓度在东部生态区发生快速降低,而在西部城区由于存在“滴定效应”,O₃浓度随高度升高而升高;450m~2km,东、西部O₃浓度均随高度升高而降低,西部城区O₃浓度水平超过东部生态区约30%;2km以上高空,东、西部O₃浓度趋同（70μg/m³）,并保持稳定,为具深圳市秋季O₃污染过程提供了较高的大气背景浓度.高污染期间,深圳市大气边界层内O₃浓度变化较为一致,西部高空的O₃区域传输作用更加显著.秋季至冬季光化学反应逐渐减弱,深圳市O₃浓度的水平和垂直空间差异逐渐减小,冬季的深圳市O₃污染基本受大气背景控制.     

大辽河沉积物中微塑料的污染特征

以大辽河为研究对象,选取8个典型区域的沉积物,采用密度浮选法,结合体视显微镜及μ-FTIR,进行大辽河沉积物中微塑料的组成及分布特征研究.结果表明,大辽河沉积物微塑料平均丰度为（66.67±79.93）个/kg;其中位于鞍山海城市的DL5丰度最高,为（193.33±172.43）个/kg,辽阳县柳壕镇的DL6丰度最低,为（20.00±34.64）个/kg;微塑料颜色以白色、黑色、黄色为主（83.75%）,形状以纤维、薄膜、碎片为主（91.25%）,粒径以（1000~2000）μm为主（33.75%）.通过红外光谱分析可得出,大辽河沉积物中薄膜类微塑料的主要成分是聚酰胺（PA）、聚丙烯（PP）和聚乙烯（PE）,碎片类的主要成分是聚乙烯（PE）和聚丙烯（PP）,泡沫类和颗粒类的主要成分是聚苯乙烯（PS）,纤维类的主要成分是人造丝（RY）及聚对苯二甲酸乙二醇酯（PET）.总体上,该研究区域沉积物中微塑料的丰度处于中等偏低水平.本研究可为我国淡水河流沉积物中微塑料的污染分布研究提供基础科学数据.     

浙江典型海湾潮间带沉积物污染及生态风险评价

基于浙江4个典型海湾潮间带表层沉积物重金属元素Cu、Zn、Pb、Cr、Cd、Hg、As和多氯联苯（PCB）的调查结果,探究其污染特征、潜在生态风险和来源.结果表明,海湾潮间带表层沉积物Cd、Hg、As、PCB含量均符合国家海洋沉积物质量Ⅰ类标准;42%、9%、3%、12%站位的Cu、Zn、Pb、Cr符合国家海洋沉积物质量II类标准,1%站位的Cu和Zn符合国家海洋沉积物质量III类标准.区域污染程度（PLI_zone）依次为乐清湾 > 三门湾 > 象山港 > 杭州湾,乐清湾潮间带沉积环境为中等污染,杭州湾、象山港和三门湾潮间带沉积环境无污染.区域生态风险（RI）依次为乐清湾 > 杭州湾 > 三门湾 > 象山港,乐清湾和杭州湾潮间带沉积物为中潜在生态风险,三门湾和象山港潮间带沉积物为低潜在生态风险.Cd是首要的潜在生态风险因子,Cd对杭州湾、象山港、三门湾、乐清湾潜在生态风险指数（RI）的贡献分别为63%、54%、58%和55%.生活污水、工农业和交通污染是浙江典型海湾潮间带重金属和PCB的主要来源.     

陆浑水库沉积物重金属空间分布特征及风险评价

为了解洛阳市饮用水水源地陆浑水库沉积物中重金属污染程度,采集32个点位的表层沉积物,分析6种重金属（Cd、Cr、Cu、Ni、Pb和Zn）的空间分布特征,并运用地累积指数法、潜在生态风险指数和聚类分析等方法对研究区重金属污染程度进行评价、生态风险评价及源解析.结果表明：Cd、Cu、Pb和Zn含量超过黄河流域河南段重金属土壤背景值,分别是其8.8、2.0、6.5、2.3倍,重金属存在明显富集,且主要污染集中于坝前区域.地累积指数法评价结果显示,Cd为强污染,Pb为中-强污染.潜在生态风险指数表明,陆浑水库沉积物重金属风险呈自上游至下游逐渐增强的趋势,总体处于高度生态危害,潜在生态风险指数均值达到312.94,其中Cd为主要贡献因子.富集系数法和聚类分析结果显示：Cd、Cu、Pb和Zn主要为人为源,Cr和Pb以自然源为主.总体而言,陆浑水库沉积物中重金属Cd和Pb污染相对较重,可能会对水库水环境构成威胁.