Transferral of HMs pollution from road-deposited sediments to stormwater runoff during transport processes

Ratio of turbidity and TSS (Tur/TSS) was used to characterize PSD of stormwater particles. Pb and Zn preferred to accumulate in finer RDS, while Cu, Cr and Ni in coarser RDS. HMs pollution in stormwater particles increased linearly with Tur/TSS. Dissolvability of HMs and PSD variations contribute to the differences between RDS and stormwater. Stormwater runoff, derived from the wash-off of road-deposited sediments (RDS), contains elevated heavy metal (HM) concentrations and, thus, imposes an increasing threat to urban aquatic ecosystems. In-depth understanding of the variations of HMs pollution from RDS to stormwater during transport processes facilitates the development of effective RDS and stormwater control strategies. Toward this end, the distribution of HMs (Cu, Pb, Zn, Cr, and Ni) in RDS and stormwater were investigated simultaneously. The results show a preferential accumulation of Pb and Zn in the finer (<38.5 μm) RDS, and Cu, Cr and Ni in the coarser (38.5–150 μm) RDS. For stormwater, n.d.~48.6% of HMs fractionated into the dissolved phase, and stormwater particles constitute the primary carriers of HMs. Furthermore, the accumulation of HMs in stormwater particles increased linearly with finer particle size distributions (PSD). Geoaccumulation index (I_geo) highlighted the predominant pollution of both RDS and stormwater particles by Cu, Pb and Zn. Nonetheless, Cu, Pb, and Ni mostly contributed the potential ecological risk of RDS, whereas Cu, Pb, and Zn mainly contributed that of stormwater particles. Moreover, contamination by Cu, Pb and Zn was significantly higher in stormwater particles than that in RDS. These differences are attributable to the solubility and size-dependent accumulation of HMs in RDS, as well as the PSD variations during transport processes. The study outcomes highlight the importance of very fine (nano- and submicron- scale) RDS in stormwater pollution and the necessity of control.     

城市污染河道沉积物有机质的氧化稳定性

为了研究城市河道沉积物有机质的氧化稳定性,以氧化稳定系数(Kos)和腐殖化程度(HA/FA)作为评价指标,在用H2O2处理沉积物的基础上,探讨城市污染河道有机质含量、有机质组成等对氧化稳定性的影响.结果显示,污染河道沉积物有机质含量明显高于自然水生态系统沉积物有机质含量;富里酸(FA)、胡敏酸(HA)、胡敏素(HM)是污染河道沉积物有机质主要赋存形式,其中胡敏素是主体,占全部有机质的65%以上;易氧化有机质(OMr)和难氧化有机质(OMd)与总有机质含量均显著正相关(P0.05);OMd的含量可以更直观地反映河道污染程度;重污染河道沉积物有机质去除量较高;随着有机质的去除,沉积物Kos在总体上有上升的趋势;不同形态有机组分其Kos差异性明显(P0.05),以HM为主的紧结态腐殖质的Kos值最高;用HA/FA和OMr可从大体上表征沉积物的氧化稳定性;HA、FA是影响城市河道沉积物氧化稳定性的主要因素.     

Mesoscale variability of organic matter composition in nw adriatic sediments

We investigated the spatial variability of sediment organic matter content and composition in three areas (A, B and C) of the Northwestern Adriatic Sea, subjected to a putative gradient of trophic state ( i.e. , increasing distance from the Po river outflow) in order to determine the appropriate sample size and replication. The analysis of the mesoscale variability was carried out comparing variability on the scale of meters ( i.e. among different deployments) with the variability observed on a scale of several kilometres ( i.e. among different sampling areas). Sediment samples, collected on April 1999, October 1999, April and October 2000, were analysed for chloropigment content (chlorophyll-a and phaeopygments) and protein, carbohydrate and lipid concentrations. Chloropigment, protein, carbohydrate and lipid concentrations were high, indicating that this system shares trophic conditions typical of highly productive environments. All organic matter components displayed a distribution independent from the increasing distance from the Po river outflow and a clear spatial variability, characterised by significant differences among different areas, but not among deployments. Carbohydrates were the biochemical compound displaying the highest spatial variability among the three areas. Chloropigment, protein, carbohydrate and lipid concentrations displayed also significant temporal changes. When spatial and temporal variability were compared, chlorophyll-a, phaeopigment and protein concentrations displayed a higher temporal than spatial variability. Conversely, for carbohydrates and lipids spatial and temporal variability was of the same order of magnitude. Organic matter composition displayed limited changes among areas, but a strong temporal variability. The results from the Adriatic sea suggest that analyses from sediments collected from a single deployment are sufficient for assessing organic matter concentration and composition over areas of several hundreds of square meters. However, for estimating organic matter composition over larger spatial scales ( i.e. miles) the identification of different sampling areas is needed.     

Temporal variation of heavy metal pollution in urban stormwater runoff

Stormwater runoff from three types of urban surfaces, a parking lot, a street, and a building roof, was monitored during four rainfall events that occurred in the one-year period from June 2009 to June 2010. The event mean concentrations (EMC) of dissolved copper (Cu), lead (Pb), zinc (Zn), manganese (Mn), and iron (Fe) exceeded China’s National Water Quality Standards for Surface Water. The degree of heavy metal contamination was related to the type of underlying surfaces. Additionally, the concentration of dissolved heavy metals peaked shortly after the runoff began and then declined sharply as a result of adequate flushing. First flush effects of varying degrees were also observed during all of the monitored rainfall events based on the first flush ratio (FF₂₅). Redundancy analysis revealed that four environmental variables (rainfall depth, intensity, antecedent dry weather period and type of underlying surface) had significant effects on the strengths of the first flush effects, accounting for 72.9% of the variation in the FF₂₅. Dissolved metals presented varying first flush effects on different underlying surfaces that occurred in the following relative order: parking lot>roof>road for low intensity and high runoff volume rainfall events; parking lot>road>roof for high intensity and low runoff volume events. The relative strength of the first flush for dissolved heavy metals was Fe, Mn>Cu, Zn>Pb.     

建筑垃圾对雨水径流中磷的吸附特性

以经过筛分、破碎等预处理后的砖砼建筑垃圾为研究对象,采用人工模拟雨水径流,通过静态吸附、动态吸附和脱附实验,研究了不同粒径粒级建筑垃圾对雨水径流中磷酸根的吸附效果和脱附特征.结果表明,建筑垃圾对磷酸根的吸附过程更符合准二级动力学模型,Langmuir等温模型能较好地描述其等温吸附过程;粒径粒级对建筑垃圾吸附磷酸根的效果具有重要影响,粒径粒级越小,对磷的去除效率越高,1—2.5 mm粒径的建筑垃圾对磷酸根去除率最大,其值为55%,建筑垃圾的粒径对磷的吸附平衡时间、吸附速率和吸附量也具有较大影响,粒径粒级1—2.5 mm的建筑垃圾对磷酸根的平衡吸附量最大值为7.8μg·g~(-1).建筑垃圾吸附的磷酸根在雨水径流pH值为5—9的范围内溶出风险较小.     

不同生态类型富营养化湖泊沉积物中有机质赋存形态

以藻型湖泊(太湖)、草藻型湖泊(南四湖)、草型湖泊(白洋淀)湖泊沉积物为研究对象,采集了11个表层沉积物样品,测定沉积物中总氮(TN)和总磷(TP)含量并利用物理分组方法,研究了3种不同生态型湖及同一湖泊不同区域沉积物中总有机质(OM)、轻组有机质(LFOM)和重组有机质(HFOM)的赋存特征.结果表明,南四湖沉积物中总氮、总磷和总有机质含量显著高于太湖和白洋淀;尽管太湖、南四湖和白洋淀沉积物中总有机质含量较高,但是轻组有机质(LFOM)含量较低,分别占总有机质的0.95%—1.08%、0.21%—1.37%和1.4%—1.78%;重组有机质(HFOM)含量较高,分别占总有机质的83.83%—87.4%、94%—98.98%和88.2%—98.3%,表明3种不同生态型湖泊沉积物中所含有机质绝大部分为难分解的重组有机质,轻组有机质基本矿化分解.相关性分析表明,轻组有机质(LFOM)、重组有机质(HFOM)与总有机质(OM)之间均呈现显著正相关关系.     

Effect of natural organic matter on arsenic release from soils and sediments into groundwater

Arsenic (As) contamination in groundwater has received significant attention recently. Natural and anthropogenic sources contribute to the worldwide occurrence of As contamination. As speciation is an important factor related to its toxic and mobile behavior. The release of As from soils and sediments into groundwater is governed by several geophysicochemical processes, of which, As sorption behavior is of principle significance. This review paper summarizes existing information regarding the effects of natural organic matter (NOM) on the fate and mobility of As species in the environment. NOM may enhance the release of As from soils and sediments into the soil solution, thereby facilitating As leaching into the groundwater. The main influencing mechanisms include competition for available adsorption sites, formation of aqueous complexes, and/or changes in the redox potential of site surfaces and As redox speciation. NOM may also serve as binding agents, thereby reducing As mobility. However, comparably little research has been performed on this aspect. Since most investigations have been done on purified minerals under laboratory conditions, further research involving various geological materials under natural environmental conditions is required. Development of proper geochemical conceptual models may provide means of predicting the role of NOM in arsenic leaching and/or immobilization.     

Mineralization of particulate organic matter derived from coral-reef organisms in reef sediments of the Gulf of Aqaba

In situ and laboratory incubation experiments in a fringing reef in the Gulf of Aqaba were performed to study degradation rates of particulate organic matter in reef sediments. Coral mucus, clam eggs, and zooxanthellae were used as model particulate organic compounds for these experiments. Aerobic and anaerobic mineralization rates were calculated by dissolved inorganic carbon (DIC) and O₂ fluxes from the sediments under different particulate organic matter additions. Fast enhancement (approximately twofold) of O₂ and DIC fluxes were found with the addition of coral mucus and clam eggs compared with control incubations without addition. Most of the degradation is believed to have occurred anaerobically rather than aerobically (DIC:O₂ ratios were 4.3–28.1). Higher degradation rates of coral mucus and clam eggs were estimated in carbonate sediment than in silicate sediment (1.2–1.6-fold), which was attributed to the different physical and chemical properties of both sediments. Our study shows the significance of the reef sediment as a suitable site for microbial degradation of particulate organic material excreted from different reef community organisms. This may increase the regeneration of nutrients in the reef environment necessary to sustain high biological productivity.     

Mineralization of particulate organic matter derived from coral-reef organisms in reef sediments of the Gulf of Aqaba

In situ and laboratory incubation experiments in a fringing reef in the Gulf of Aqaba were performed to study degradation rates of particulate organic matter in reef sediments. Coral mucus, clam eggs, and zooxanthellae were used as model particulate organic compounds for these experiments. Aerobic and anaerobic mineralization rates were calculated by dissolved inorganic carbon (DIC) and O₂ fluxes from the sediments under different particulate organic matter additions. Fast enhancement (approximately twofold) of O₂ and DIC fluxes were found with the addition of coral mucus and clam eggs compared with control incubations without addition. Most of the degradation is believed to have occurred anaerobically rather than aerobically (DIC:O₂ ratios were 4.3-28.1). Higher degradation rates of coral mucus and clam eggs were estimated in carbonate sediment than in silicate sediment (1.2-1.6-fold), which was attributed to the different physical and chemical properties of both sediments. Our study shows the significance of the reef sediment as a suitable site for microbial degradation of particulate organic material excreted from different reef community organisms. This may increase the regeneration of nutrients in the reef environment necessary to sustain high biological productivity.     

High Cu and Cd pollution in sediments from Sisimiut, Greenland. Adsorption to organic matter and fine particles

High concentrations of Cu of up to 200 mg/kg, and Cd of up to 4.0 mg/kg, were found in sediments from the aquatic environment around Sisimiut, Greenland. These concentrations are four times higher than the limiting concentration where toxicological effects are expected. The pollution could be linked to human activities in Sisimiut, a link that have not been investigated previously in Greenland. Except from the most polluted samples there was good correlation between heavy metal concentration and organic matter. Also some relationship between fine fraction and heavy metal concentration was observed.     

Organic matter composition in sediments of the Oman Margin

The quantity and biochemical composition of organic matter (OM) in the sediments underlying and below oxygen minimum zone (OMZ) in the Arabian Sea were studied to provide information on the diagenetic processes of organic carbon under different environmental conditions. Concentrations of total organic carbon (TOC), total nitrogen (TN) and total hydrolysable amino acids (THAA) were significantly higher in sediments within rather than below OMZ, while those of total carbohydrates (TCHO) were slightly lower in the latter, suggesting the presence of a larger supply of labile compounds into the sea bottom at the shallower site (i.e. within OMZ). Hydrolysable amino acid and carbohydrate contribution to TOC were even lower (about 10% in surficial sediments) than the values obtained from the abyssal oligotrophic North Pacific, suggesting that OM food availability in the Oman Margin sediments within OMZ was lower than that observed at abyssal depths. The presence of the highest THAA and TCHO concentrations in the top 40?mm of the sediment core at both sites reflected the presence of bioturbation processes. In contrast with the general view of the deep sea as a stable and constant system, below OMZ in the Arabian Sea sediments, some differences were observed in the two investigated cores indicating the presence of a certain spatial variability in OM content and diagenesis.     

Organic matter composition in sediments of the Oman Margin

The quantity and biochemical composition of organic matter (OM) in the sediments underlying and below oxygen minimum zone (OMZ) in the Arabian Sea were studied to provide information on the diagenetic processes of organic carbon under different environmental conditions. Concentrations of total organic carbon (TOC), total nitrogen (TN) and total hydrolysable amino acids (THAA) were significantly higher in sediments within rather than below OMZ, while those of total carbohydrates (TCHO) were slightly lower in the latter, suggesting the presence of a larger supply of labile compounds into the sea bottom at the shallower site (i.e. within OMZ). Hydrolysable amino acid and carbohydrate contribution to TOC were even lower (about 10% in surficial sediments) than the values obtained from the abyssal oligotrophic North Pacific, suggesting that OM food availability in the Oman Margin sediments within OMZ was lower than that observed at abyssal depths. The presence of the highest THAA and TCHO concentrations in the top 40 mm of the sediment core at both sites reflected the presence of bioturbation processes. In contrast with the general view of the deep sea as a stable and constant system, below OMZ in the Arabian Sea sediments, some differences were observed in the two investigated cores indicating the presence of a certain spatial variability in OM content and diagenesis.     

Relationships between microbial distributions and the anaerobic decomposition of organic matter in surface sediments of long Island Sound,USA

Relative rates of the anaerobic decomposition of organic matter in the upper 10 cm of sediment from two stations in central Long Island Sound, USA, were compared. Sediment samples from discrete depth intervas were incubated anoxically and changes in SO ₄ ⁼ , NH ₄ ⁺ , bacterial numbers, extractable adenosine triphosphate (ATP), organic matter, and organic carbon were measured as a function of time and temperature. At both stations (15 and 34 m water-depths, respectively), the calculated rates of SO ₄ ⁼ reduction and NH ₄ ⁺ production decreased exponentially (approximately) with depth below the sediment-water interface. Over the same depth interval, ATP concentrations dropped by a factor of 6 to 7 and bacterial numbers were lower by a factor of 2 to 3. These decreases in SO ₄ ⁼ reduction, NH ₄ ⁺ production, bacterial numbers, and ATP, reflect a change in the physiological state of microbial populations with depth in the sediment and are consistent with the conclusions that the quantity of easily utilizable organic matter changes rapidly below the sediment surface and that food limitation controls the basic depth distribution of microbial activity. The average rates of SO ₄ ⁼ reduction, 29 to 39 mM year^-1 (22°C), in the top 10 cm are similar at both stations studied here, as well as at an additional station from a previous study. In contrast, average NH ₄ ⁺ production differs by a factor of 2 at the two stations, reflecting differences in the C:N ratio of the organic matter supplied to the sediment surface and differences in particle reworking by macrofauna at each site. The apparent activation energy of SO ₄ ⁼ reduction was 19±1 kcal mole^-1 and that of NH ₄ ⁺ production, 18±3 kcal mole^-1. The overall quantity of carbon required to support the calculated average SO ₄ ⁼ reduction rate in the top 10 cm is 23 g C m^-2 year^-1 and represents 36% of all the carbon available to the benthos annually and 11% of the net primary production in the water column. Directly measured fluxes of NH ₄ ⁺ from sediments to overlying water at both stations agree well with those predicted from production rates obtained by the incubation techniques.     

Biochemical composition and early diagenesis of organic matter in coastal sediments of the NW Adriatic Sea influenced by riverine inputs

River inputs influence trophodynamic and biogeochemical processes of adjacent continental shelves. In order to provide new insights on the influence of continental inputs on the benthic trophic state and early diagenesis of sediment organic matter we collected surface sediments in the NW Adriatic Sea at three stations located at increasing distance from the Po River. Sediment samples were collected in four periods characterized by different river outflows and analysed for chloropigment content (chlorophyll-a and phaeopygments), protein, carbohydrate and lipid concentrations, prokaryote abundance and aminopeptidase activity. Sediments of the NW Adriatic Sea displayed high organic loads, tightly coupled with the outflow dynamics of the Po River. A major flooding event was responsible of an enhanced accumulation of organic material on the sea bottom. The resulting increased nutrient load in the sediment impaired organic matter degradation processes. The results of the present study suggest that the enhanced trophic state of marine coastal sediments subjected to riverine inputs are related not only to the increased nutrient inputs, but that they may be amplified by impaired degradation processes.     

不同类型生物滞留介质对雨水径流中多环芳烃的去除效果

生物滞留设施是目前城市雨水控制利用中应用最广泛的措施之一,其中填料类型对雨水径流净化效果具有重要影响.通过实验室模拟实验,研究了不同类型填料生物滞留设施对雨水径流中多环芳烃(PAHs)的去除效果,并以炉渣为例研究了填料内部累积的PAHs降解特征.结果表明,不同类型填料对PAHs的去除效果从高到低依次为:炉渣砂土陶粒沸石,填料类型对PAHs的净化效果具有一定选择性;PAHs不同组分在不同填料中净化效果也不同,4种填料对2环PAHs净化效率均较高,约为70%,对56环的净化效率也均在50%以上,对4环PAHs的净化效率较低,约为40%.因此,生物滞留设施中填料类型对PAHs净化效果具有重要影响,实际工程中应根据PAHs的净化需求选择合适的填料.     

Source identification and groundwater health risk assessment of PTEs in the stormwater runoff in an abandoned mining area

Environmental Geochemistry and Health - Xikuangshan antimony mine in Lengshuijiang, China, has been developed for many years, and stormwater runoff contains high levels of potentially toxic...     

基于场降雨的北京某高架桥雨水径流中多环芳烃污染特征

以北京市某高架桥的典型场次雨水径流作为研究对象,通过对多场雨水径流中多环芳烃(PAHs)的监测,研究了高架桥雨水径流中PAHs的污染特性以及冲刷规律.结果表明,随着降雨历时的增加,雨水径流中PAHs浓度呈现先增加后减小的变化趋势,实验均值中w(Flu)/w(Pyr)为0.94,因此,高架桥雨水径流中溶解态PAHs主要来源于石油燃料的不完全燃烧.雨水径流中溶解态PAHs以三环、四环组分为主,五和六环次之,二环组分最少.高架桥雨水径流中PAHs存在浓度和质量初期冲刷现象,∑_(16)PAHs和四环组分在不同降雨事件中均存在浓度初期冲刷现象,∑_(16)PAHs及各环组分在降雨强度大、降雨历时长的场降雨存在明显的质量初期冲刷现象,而降雨强度小的场降雨质量初期冲刷不明显.     

Extraction of anthropogenic heavy metals from reduced sediments: Indeterminations due to authigenic sulphides and clay minerals

A mineralogical and micro‐chemical study was performed by X‐ray diffraction and SEM/EDS techniques in a reduced sediment sample from the Venice Lagoon to investigate selectivity and significance of two widely used acid extractions (cold IN HCl and hot 8N HNO₃) for the evaluation of anthropogenic metal concentrations. Hydrochloric acid determines an incomplete and variable solubilization of authigenic iron sulphides, yielding a partial extraction of the associated metals (Hg, Mn, Zn and less Ni and Cu). Nitric acid is effective in solubilizing all sulphides, however, it leads to an overestimate of the anthropogenic metal content since it partially dissolves the lattice of some clay‐minerals, particularly chlorites. When these acid extractions are used to asses metal pollution in aquatic ecosystems, the possible over or under‐estimate of the anthropogenic concentration must be taken into account, considering the mineralogical composition of the sediment.     

Role of salps in the flux of organic matter to the bottom of the Ligurian Sea

Sediment-trap samples were collected during and after the occurrence of a salp (Salpa fusiformis) bloom in the Bay of Villefranche, Mediterranean Sea, in April/May 1985. Large amounts of organic aggregates and faecal pellets were collected during the bloom. The aggregates were rich in carbohydrates and mineral grains and had similar rates of sedimentation (900 to 2 100 m d^-1) to those of the faecal pellets (1 000 to 2 000 m d^-1). The results of mineralogical and organic chemical analyses indicate the potential effect of these mucus-rich aggregates on local biogeochemical fluxes.     

Correlation of the methylating capacity of river and marine sediments to their organic sediment index

Methylation experiments of the metals Sn, Pb and Hg were carried out using representative terrestrial and marine sediment samples from the Axios river and Thermaikos Gulf in northern Greece. GC-FID, GC-TCD and GC-MS were used. The experiments were carried out on sterilised and bioactive samples by adding pure metals and metal salts (chloride, nitrate, oxalate, acetic, penicillaminic, methioninic and cysteinic). Except for sterilised HgCl2, methylated derivatives of Sn, Pb and Hg were produced only from bioactive sediments, and therefore higher yields were measured when nutrients were added to the sediments. Volatile products (CH4, CO2, H2S) of biological activity range between 35 and 250 mg l-. The correlation of methylation yield with organic sediment index (OSI), determined as the wt% product of [organic carbon] × [organic nitrogen], is positive for all the metals and metal salts added in the sediments. Methylation yields for Hg are found to be four orders of magnitude higher than those of Pb and Sn. In low OSI (terrestrial) sediments, the rate of Hg-methylation is higher than those of Pb and Sn. In high OSI (marine) sediments, where methylation of most of the contained Hg has taken place, methylation of Pb is slightly faster than Sn.