Semivolatile organic compounds, organochlorine pesticides and heavy metals in sediments and risk assessment in Huaihe River of China

The concentrations of semivolatile organic compounds, organochlorine pesticides and heavy metals in sediments from Jiangsu reach of Huaihe River, China, were presented. The organic compounds were extracted by acetone： n-hexane using a Soxhlet apparatus and concentrations were performed using HP6890 gas chromatography coupled by FID and ECD detector. The total contents of 8 heavy metals by inductively coupled plasma atomic emission spectrometry or cold-vapor/atomic absorption spectrometry were developed. 30 semivolatile organic compounds were detected, including substituted benzenes, phenols, phthalates and polycyclic aromatic hydrocarbons, from 0.01 to 3.01 mg/kg. 16 organochlorine pesticides were almost detected and from 0.010 to 2.339 μg/kg. Concentrations of major metals were 50 mg/kg or less, mean level of mercury was only 0.055 mg/kg. Compared to sediment quality guidelines （SQGs）, concentrations of some semivolatilc organic compounds were high enough to cause possible toxic effects to living resources. The organochlorine pesticides presented relatively low, lower than threshold effect concentrations （TECs）, harmful effects on sediment-dwelling organisms were not expected. Chromium posed probable toxic effects to the living resources, other heavy metals had no threat temporarily according to SQGs.

Relationship Between Persistent Heavy Rain Events in the Huaihe River Valley and the Distribution Pattern of Convective Activities in the Tropical Western Pacific Warm Pool

Using daily outgoing long-wave radiation （OLR） data from the National Oceanic and Atmospheric Administration （NOAA） and the National Center for Environmental Prediction/National Center for Atmospheric Research （NCEP/NCAR） reanalysis data of geopotential height fields for 1979-2006, the relationship between persistent heavy rain events （PHREs） in the Huaihe River valley （HRV） and the distribution pattern of convective activity in the tropical western Pacific warm pool （WPWP） is investigated. Based on nine cases of PHREs in the HRV, common characteristics of the West Pacific subtropical high （WPSH） show that the northern edge of the WPSH continues to lie in the HRV and is associated with the persistent ＂north weak south strong＂ distribution pattern of convective activities in the WPWP. Composite analysis of OLR leading the circulation indicates that the response of the WPSH to OLR anomaly patterns lags by about 1-2 days. In order to explain the reason for the effects of the distribution pattern of convective activities in the WPWP on the persistent northern edge of the WPSH in the HRV, four typical persistent heavy and light rain events in the Yangtze River valley （YRV） are contrasted with the PHREs in the HRV. The comparison indicates that when the distribution pattern of the convective activities anomaly behaves in a weak （strong） manner across the whole WPWP, persistent heavy （light） rain tends to occur in the YRV. When the distribution pattern of the convective activities anomaly behaves according to the ＂north weak south strong＂ pattern in the WPWP, persistent heavy rain tends to occur in the HRV. The effects of the ＂north weak south strong＂ distribution pattern of convective activities on PHREs in the HRV are not obvious over the seasonal mean timescale, perhaps due to the non-extreme status of convective activities in the WPWP.

Characteristics of Heavy Metals and Their Evaluation in Sediments from Middle and Lower Reaches of the Huaihe River

We have collected 18 samples corresponding to 18 locations in the middle and lower reaches of the Huaihe River. The sediment samples were tested for their pH level,percentage of solids,organic matter and five heavy metals (Cr,Cu,Zn,Cd and Pb). The average concentrations of Cr,Cu,Zn,Cd and Pb of the 18 sampling locations were re-spectively 56.1,22.2,70.0,0.17 and 20.4 μg/g. Compared with their background values,the average concentrations of Zn and Cu in sediment samples from the Huaihe River were slightly higher,while the average concentrations of Cr and Pb were slightly lower. The concentration of Cd in all sediment samples was higher than its background value,while the average concentration of Cd in all sediment samples was about twice the amount of the background value. The concen-tration of the five heavy metals was lower than that of the Yangtze River. A correlation analysis revealed that heavy metals have similar geochemical feautures. The geo-accumulation index (Igeo) was used to evaluate the degree of pollu-tion of the Huaihe River sediments. The index reveals that the sediment samples are largely ranked from zero pollution to no to medium pollution.

Spatial Variation and Risk Assessment of Arsenic and Heavy Metals in Surface Water and Suspended Particulate Matter in Tail Reaches of the Yellow River, China

To determine the pollution levels and potential toxic risks of arsenic(As) and heavy metals(Cr, Ni, Cu, Zn, Pb and Cd) in water and suspended particulate matter(SPM) in tail reaches(including freshwater reach and low-salinity reach) of the Yellow River as the Flow-Sediment Regulation Project(FSRP) has been carried out for approximately 15 yr, the surface water and SPM were sampled at pre-flood(April) and post-flood seasons(October). Results showed that similar changes of As and metal levels in water and SPM were observed along the tail reaches at pre-flood or post-flood season. Compared to pre-flood season, the levels of As, Cu, Cr and Ni in freshwater reach and the concentrations of Cr and Ni in low-salinity reach rose greatly at post-flood season. The levels of As and metals in SPM of freshwater reach or low-salinity reach at pre-flood season were significantly higher than those at post-flood season(P < 0.01).The pollutions of As and metals in surface water of tail reaches at pre-flood or post-flood season were not serious. The SPM in freshwater reach at pre-flood season were polluted by Cd, As, Cr, Cu and Ni while those in low-salinity reach were polluted by Cd and Cr. The SPM in freshwater reach at post-flood season were polluted by Cd and Pb while those in low-salinity reach were polluted by Cd and Cr.Cd was identified as heavy metal of primary concern at both pre-flood and post-flood seasons. Combined with the existed data reported in present research, this study found that the toxic risk of As and metals in SPM of tail reaches at pre-flood season was higher than that at post-flood season, implying that the implementation of FSRP during flooding season, to a great extent, reduced the toxic risk of these elements. With the long-term implementation of FSRP, the pollution levels of As and metals(particularly for Cd) in SPM of tail reaches might be elevated and the potential toxic risk primarily produced by Cr, Ni and As might be increased if effective measures were not taken in future.

Pollution status and potential ecological risk assessment in the surface sediments of the Yellow River estuary

Based on the ＂Project 908＂ survey data in 2006--2007 on surface sediments of the sea area adjacent to the Yellow River estuary, the research was conducted on the concentration distribution characteristics of heavy metals in surface sediments of the estuary, which show that the mean contents of seven heavy metals （Cu, Pb, Zn, Cd, Cr, Hg, As） in the Yellow River estuary and its surrounding areas all comply with the Level-I of National Marine Sediments Quality Standard of China. Statistically significant correlation between the elements Cu-Cd, Pb-Cr and Cr-As in sediments indicates that the two heavy metals in each group may respectively have similar geochemical properties and sources. By using the Potential Ecological Risk Index （PERI） proposed by Hakanson, the assessment shows that the potential ecological risks in the estuary surface sediments are mainly attributed to Cd and Hg. The biological toxicity effects are assessed with the biological effects of concentration method, resulting in a conclusion that the adverse effects of As on organisms in the estuary marine environment occasionally occur, in contrast, Cu, Pb, Zn, Cd, Cr and Hg will not generate adverse biological effects on a short and medium time scale.

Analysis on Formation Reason of a Squall Line Weather in the Yellow River and Huaihe River Basins

[Objective]The research aimed to analyze formation reason of the strong squall weather in the Yellow River and Huaihe River basins on June 3,2009.[Method]Using American NCEP 1°×1° reanalysis data,observation data at automatic weather station,conventional meteorological data,FY-2C satellite cloud image and Doppler weather radar data in Shangqiu,circulation background situation of a strong squall line case on June 3,2009 in the Yellow River and Huaihe River basins was conducted diagnostic analysis.Then,formation reason of the squall weather was discussed.[Result]Increasing convective instable stratification was the favorable situation.Translot in the rear of northeast cold vortex leaded cold air to go south.The rising airflow created by ground meso-scale convergence was as trigger mechanism of the convection.Water vapor from the south continuously supplied.Finally,squall line was formed,and developed.It was a high incidence zone of the thunderstorm and squall line near dry line.[Conclusion]The research provided reference for the future similar weather forecast.

Flood Risk Forecasting and Early Warning Technology for Medium and Small Rivers in the Yellow River Basin Induced by Heavy Rain

The Yellow River Basin is one of the important sand-producing and sediment-transporting areas in China,and one of the three most important sand-producing areas in the world.The amount of sand and dust days in the“Three Norths”(Dongbei,Xibei,and Huabei)area has increased,and regional sand and dust storms have occurred frequently.There are generally more serious hidden danger points of debris flow geological disasters in small and medium-sized river basins.The technical achievements of flood risk forecasting and early warning for medium and small rivers in the Yellow River Basin based on rainstorm-induced floods are important technical supports for flood forecasting and early warning for medium and small rivers.Based on this,a case study was carried out on the problems such as the weak forecasting and early warning ability of flood disasters induced by heavy rain and the low accuracy of flood disaster loss assessment in the flood disasters of medium and small rivers,for the reference of relevant personnel.

The distribution and variation of elements in sediments off the Huanghe (Yellow) River mouth

Surface sediment samples collected off the Huanghe （Yellow） River mouth during the period 2007-2009 were analyzed for major and trace element concentrations. Concentrations of 16 elements were measured using X-ray fluorescence spectrometry. Results demonstrate that sediment grain size is the dominant factor controlling the spatial variations of elemental concentrations. Correlation and cluster analyses allowed classification of the study area into four geochemical regions： Regions Ⅰ and Ⅲare characterized by high concentrations ofAl2O3, Fe2O3, MgO, Na2O, K2O, Cr, Cu, Mn, Ni, Pb, V, and Zn, and contain fine-grained sediments with mean grain size （Mz）〈22 μm; and; Regions Ⅱ and Ⅳcontain mostly coarse-grained sediments, and are characterized by high concentrations of SiO2, Na2O, and Zr. The sediment entering the sea from the Huanghe River and its tributaries is enriched in Ca. Thus, the Ca/Al ratio was used as an indicator of the proportion of sediments in the study area that originated from the Huanghe River. Ca/Al ratios decrease from Regions Ⅰ and Ⅱ（located in the nearshore zone of the Huanghe River delta） to Regions Ⅲand Ⅳ（distributed in the offshore zone of the northern Huanghe River delta, southern and southeastern Laizhou Bay area）.

Analysis on the Climate Characteristics of Rainstorm Weather over Huaihe River Basin and Its Influence on Agriculture Production

By the daily precipitation data at 18 meteorological stations of Huaihe River basin in recent 50 years,the temporal-spatial distribution features of the rainstorm over Huaihe River basin during 1958- 2007 and its influence on agriculture production were analyzed. The results showed that the interannual change magnitudes of the rainstorm days and rainstorm amount from 1958 to 2007 were fierce. Especially in the late 1990 s,rainstorm days and rainstorm amount increased obviously. As a result of interannual variability of East Asian summer monsoon and East Asian circulation system,rainstorm had significant quasi-2-year periodic oscillation in summer. Because of water vapor and terrain,rainstorm mainly concentrated in the southwest over the Huaihe River basin,but was less in the north.

Distribution characteristics and controlling factors of typical heavy metals in Huanghe River estuary,China

The geochemical characteristics and potential controlling factors of colloidal Zn,Cd,and Pb in Huanghe(Yellow)River estuary(HRE),China were investigated.The three metals were highly variable over a range of spatiotemporal scales,comprehensively forced by various physical and biological processes.Total dissolved Zn,Cd,and Pb varied from 200.1 to 321.7,2.6 to 4.1,and 0.5 to 1.0 nmol/L,respectively.Only one near-estuarine station of Zn had contamination factor values>1,which indicate the lower contaminant levels.Five dissolved species of Zn,Cd and Pb were fractionated,namely<1 kDa,1-3 kDa,3-10 kDa,10-100 kDa,and 100 kDa-0.45μm.The<1 kDa truly dissolved phase was the main fraction of the three dissolved metals(50%-62%),while the 100-kDa-0.45-μm high molecular weight colloidal fraction was dominant in their respective colloidal phase.Territorial input and sediment acted as important sources of strong ligands and natural colloids for the HRE water system.<3-kDa Zn and Pb were susceptible to the dissolved oxygen,the behaviors of colloidal Zn and 3-10-kDa Pb were related to dissolved organic carbon(DOC).However,no significant correlation between each dissolved fraction of Cd and salinity,pH,temperature,colloidal organic carbon,and DOC was found in this study.Overall,these findings,completed by the evaluation of the dissolved species of Zn,Cd,and Pb at 10 sites over the river-sea mixing zone,provided new insights into the colloidal heterogeneity that affect metals geochemical features,migration and fate in estuaries.

Analysis and Zoning of Rainstorm Flood Disaster Risk in Huaihe River Basin

Taking the rainstorm flood disaster of Huaihe River basin as the research object,according to the principles of risk assessment for natural disasters,starting from the fatalness of inducing factors and the vulnerability of hazard bearing body,the weight of each impact factor was calculated by using AHP. By using spatial analysis and statistical function of GIS,the integrated risk chart of rainstorm flood disaster in Huaihe River basin was obtained. The results showed that the high risk areas of rainstorm flood disaster in Huaihe River basin mainly distributed in the southern part of Henan,the central northern part of Anhui and eastern part of Jiangsu Province. Due to higher fatalness of inducing factors in southern Henan,there was high risk in the region. Central Anhui and east Jiangsu were not only high-fatalness zones but also high vulnerability zones of population and economy.

Analysis of Soil Heavy Metal Pollution in Hechuan Wetland

Soil samples were collected from Hechuan wetland and digested by the national standard method. The contents of Pb, Cd, Cr, Cu, Zn and Mn in the wetland soil were determined, and the degree of soil heavy metal pollution was estimated by single-factor pollution index, root-mean-square comprehensive pollution index and geo-accumulation pollution index methods. The results showed that the wetland in the sampling range was seriously polluted by heavy metals, mainly by heavy metal Cd, while the effects from other heavy metals were relatively less.

Spatial Distribution Characteristics of Heavy Metals Cu and Zn in Coastal Wetland Sediments

The content of Cu,Zn in the sediments from coastal wetlands of the Yellow River Delta was determined.The results showed that:(i)The content of Cu,Zn range was 16.70-50.40 mg/kg,18.15-48.80 mg/kg,respectively.The mean content of Cu,Zn was 31.12mg/kg,36.74 mg/kg,respectively.Compared with the soil environmental background values of Shandong Province,the content of Cu was excessive,while the content of Zn was below the background.(ii)The concentrations of Cu,Zn in sediment in the coast of the Yellow River Delta were higher than in the other two areas.(iii)Vertical distribution characteristics of the concentrations of Cu,Zn were increasing with depth.The maximum content of Cu,Zn was 80-100 cm,in general,the content of Cu,Zn in the bottom sediments was higher than that in the surface sediments.The growth and decline trends of Zn in Tamarix and Suaeda areas were much the same and all higher than in the Phragmites communis area.(iv)The distribution characteristics of Cu concentration in different vegetation cover in sediment is Suaeda>Phragmites communis>Tamarix,which reflected different effects on retention of Cu in the sediments because of the different vegetation types.The highest content of Zn in the 0-20 cm sediments in Tamarix area was 44.07 mg/kg.

Succession of bacterial community along with the removal of heavy crude oil pollutants by multiple biostimulation treatments in the Yellow River Delta,China

Multiple biostimulation treatments were applied to enhance the removal of heavy crude oil pollutants in the saline soil of Yellow River Delta.Changes of the soil bacterial community were monitored using the terminal restriction fragment length polymorphism （T-RFLP） and clone library analyses.The 140-day microcosm experiments showed that low C：N：P ratio,high availability of surfactant and addition of bulking agent significantly enhanced the performance,leading to the highest total petroleum hydrocarbon removal.Meanwhile,the bacterial community was remarkably changed by the multiple biostimulation treatments,with the Deltaproteobacteria,Firmicutes,Actinobacteria,Acidobacteria and Planctomycetes being inhibited and the Alphaand Beta-proteobacteria and some unknown Gammaproteobacteria bacteria being enriched.In addition,different hydrocarbon-degraders came to power in the following turn.At the first stage,the Alcanivorax-related Gammaproteobacteria bacteria dominated in the biostimulated soil and contributed mainly to the biodegradation of easily degradable portion of the heavy crude oil.Then the bacteria belonging to Alphaproteobacteria,followed by bacteria belonging to Candidate division OD1,became the dominant oil-degraders to degrade the remaining recalcitrant constituents of the heavy crude oil.

Energy Budgets on the Interactions between the Mean and Eddy Flows during a Persistent Heavy Rainfall Event over the Yangtze River Valley in Summer 2010

In this study,a persistent heavy rainfall event（PHRE） that lasted for around 9 days（from 0000 UTC 17 to0000 UTC 26 June 2010） and caused accumulated precipitation above 600 mm over the Yangtze River valley,was reasonably reproduced by the advanced research WRF model.Based on the simulation,a set of energy budget equations that divided the real meteorological field into the mean and eddy flows were calculated so as to understand the interactions between the precipitation-related eddy flows and their background circulations（BCs）.The results indicated that the precipitation-related eddy flows interacted with their BCs intensely during the PHRE.At different layers,the energy cycles showed distinct characteristics.In the upper troposphere,downscaled energy cascade processes appeared,which favored the maintenance of upper-level eddy flows;whereas,a baroclinic energy conversion,which reduced the upper-level jet,also occurred.In the middle troposphere,significant upscaled energy cascade processes,which reflect the eddy flows＇ reactionary effects on their BCs,appeared.These effects cannot be ignored with respect to the BCs＇ evolution,and the reactionary effects were stronger in the dynamical field than in the thermodynamical field.In the lower troposphere,a long-lived quasi-stationary lower-level shear line was the direct trigger for the PHRE.The corresponding eddy flows were sustained mainly through the baroclinic energy conversion associated with convection activities.Alongside this,the downscaled energy cascade processes of kinetic energy,which reflect the direct influences of BCs on the precipitation-related eddy flows,were also favorable.A downscaled energy cascade of exergy also appeared in the lower troposphere,which favored the precipitation-related eddy flow indirectly via the baroclinic energy conversion.

水土保持生态建设下的黄土高原典型流域水沙响应

为探讨黄土高原多沙粗沙区流域水沙关系演变特征及其对水土流失治理的响应,以黄河中游无定河流域为研究对象,综合采用水沙关系曲线、数理统计等多种方法,系统分析1956—2019年间无定河流域水沙关系多时间尺度演变特征及其与水土流失治理的协同响应。研究结果表明:1)研究时段内,无定河流域年径流及年输沙量呈锐减趋势(P<0.05),且均在1970年左右发生减少突变;2)流域水沙关系在年际和场次洪水尺度上均发生深刻变化。2010年以后,暴雨频发导致流域内侵蚀物源头供应明显增加,流域河道泥沙输送能力小幅提高;3)水土保持措施实施对流域水沙锐减影响较大。2000年前后在相似降雨条件下,单位降雨量径流量和单位降雨量输沙量较20世纪70年代减少47%和62%。水土保持措施面积增加与流域径流输沙减少呈现较好的一致性,流域水土流失治理在提高黄河多沙粗沙区流域下垫面抗侵蚀能力等方面发挥重要作用。研究结果可为科学认知区域水土流失治理成效及入黄泥沙锐减成因提供参考。

城市新区极端雨洪汇流淹没特性与致灾机理调查研究——以郑州“7.20”特大暴雨(郑东新区)为例

近年来全球极端暴雨发生的可能性与不确定性提高,增加了城市遭遇特大洪涝灾害的风险。城市雨洪与河道洪水有显著差异,灾后雨洪信息快速采集与调研对认清雨洪特性与致灾机理尤显重要。本文以郑州2021年“7.20”特大暴雨为例,结合郑东新区地理与社会环境特点,采用野外调查测量、口述记录、多源数据分析、数值模拟对比相结合的方法开展了城市雨洪汇流淹没特性及致灾机理的调查研究。针对城市雨洪洪痕特征,拟定调查基本方法与适宜工作程序,根据调查区93处洪痕数据绘制了区域雨洪淹没分布图,分析了城市雨洪峰值水位分布特征及调查区汇流特性,探索了道路雨洪汇流流速及行洪道路阻力参数的确定方法。研究表明,城市雨洪地表主要泄流通道是街区道路,汇流方向受连续阻水、导水建筑与路网布局影响,雨洪淹没深度分布与下垫面条件和雨洪汇流特性有关。致灾机理研究分析表明,极端暴雨汇流远超城市排水管网泄流能力,雨洪选择阻力小的街道快速行洪,街道交汇处壅阻引起局部积水严重,这是极端暴雨致灾的直接诱因;而城市新区水系泄洪排涝关系不协调以及清障不力,导致城区河流行洪不畅,干支流异常高水位的顶托,严重降低了管网排涝功能,则是城市雨洪严重积涝致灾的深层原因。研究成果可为城市雨洪调查标准方法的建立与城市新区防洪排涝体系规划提供技术参考。

岷沱江、嘉陵江流域致宜昌大洪水暴雨过程的特征及天气成因

为揭示岷沱江、嘉陵江流域致大洪水暴雨过程的天气成因及宜昌控制站雨洪规律,加深对宜昌站大洪水发生发展机制的研究,基于NCEP/NCAR再分析资料及常规气象水文观测资料,采用统计学、天气学等方法分析研究了1980—2020年发生在岷沱江、嘉陵江流域的19例致洪暴雨过程特征、雨洪关系、致洪暴雨源地及下垫面特征、天气系统配置等。结果表明:宜昌作为长江流域主要控制站,当前期起始入库流量达到19000 m^(3)·s^(-1)以上,且刚好遭遇连续性暴雨过程,则发生大洪水概率会显著提高。从岷沱江或嘉陵江的连续性暴雨过程开始至洪峰产生所需时长平均在6 d左右。暴雨持续时间和累计面雨量与洪峰有较好的对应关系,每次大洪水的形成都需要一次持续3 d以上的暴雨过程,多数在4~6 d。大洪水过程全部发生在7—9月。致洪暴雨过程以准静止类雨带为主,其次是东移类和转向类。89%的过程雨带呈东北—西南向的带状分布。强降水中心源地与特殊地形关系密切,主要分布于3处:岷江下游与青衣江交汇处,转向类降水多发;嘉陵江中下游、涪江流域及渠江流域,多以准静止类为主;涪江中游及渠江流域北部,东移类暴雨过程多发。孟加拉湾热带低压系统的存在对上游产生连续性暴雨至关重要,其次是南海地区的低值系统,两者参与过程占比达68%。低压系统不仅为岷沱江、嘉陵江流域带来充足能量和水汽,其东侧水汽的卷入容易在岷沱江、嘉陵江流域触发低涡,再配合特殊地形,产生强的上升运动。降水过程分为准静止持续性降水和移动性持续降水2类。易发大洪水的天气概念模型有3类:Ⅰ型为西太平洋副热带高压边缘、西风短波东移触发暴雨型,Ⅱ型为青藏高原低值系统东移触发暴雨型,Ⅲ型为低层偏东气流暴雨型。

宁夏沿黄城市带土壤重金属分布特征及其生态风险评价

宁夏沿黄城市带是黄河中上游重要的产业聚集区,其土壤健康状况对黄河流域生态保护和高质量发展先行区建设具有重要意义。为摸清沿黄城市带土壤重金属现状及生态风险,该研究取样检测了该区域682个样点的土壤重金属元素含量,分析了其生态风险,并进行了溯源。研究结果表明:(1)宁夏沿黄城市带0~20 cm土壤砷(As)、铬(Cr)、铜(Cu)、锰(Mn)、铅(Pb)、锌(Zn)、镍(Ni)和镉(Cd)8种重金属元素平均值分别为(3.11±1.88)、(60.66±15.64)、(17.86±6.10)、(509.92±186.74)、(17.62±11.10)、(57.36±25.33)、(25.23±4.95)和(0.77±0.49) mg/kg。0~20 cm土层重金属元素平均含量均低于土壤背景值,也低于农用地土壤污染风险筛选值。0~5 cm土层重金属元素含量高于0~20 cm土层,且Cr、Mn、Zn和Cd 4种元素含量超过了土壤背景值。(2)沿黄城市带中As、Cr、Cu、Mn、Pb、Zn和Ni这7种元素对环境污染风险极低。大部分区域土壤Cd含量明显高于背景值,污染风险较高。(3)沿黄城市带重金属元素有5种来源,其中母质源对重金属来源贡献率最高,其次为农业和工业复合源、交通运输源,农业源和工业源对重金属元素贡献小。研究结果表明宁夏沿黄城市带土壤重金属有较高等级的Cd生态风险,值得关注。