Assessing Settleability of Dry and Wet Weather Flows in an Urban Area Serviced by Combined Sewers

Settleability of dry and wet weather flow samples from a combined sewer system was examined by settling column tests, in order to improve understanding of settling processes and obtain information for design of settling tanks. In fact, these tests mimic the actual settling processes and allow evaluating total suspended solids (TSS) removal by settling. Therefore, it is also possible to assess, indirectly, removals of other pollutants, such as heavy metals, which are generally transported by solid particles in sewage. Towards this end, dry and wet weather flow samples were collected in the Liguori Channel catchment and analyzed in the laboratory for Water Supply and Sewerage (Acquedotti e Fognature) of the University of Calabria for TSS concentrations according to the Standard Methods. The settleability study revealed that removals of TSS in dry weather samples (i.e., sanitary sewage) were greater than in wet weather samples (WW), using the same experimental procedures. In particular, 65% of TSS was removed in dry weather samples at a depth of 3?m for a detention time of 40?min; while in wet weather samples the comparable removal efficiency was less than 60%.     

Polychlorinated biphenyls (PCBs) detection in food samples using an electrochemical immunosensor

In this work, a disposable electrochemical immunosensor, based on a competitive assay scheme, was applied to detect polychlorinated biphenyls (PCBs) in food. For this purpose, antibodies against PCBs were directly immobilized onto the carbon surface of a disposable screen-printed electrode. A competition between the PCBs present in the sample and a fixed concentration of an enzyme-labeled PCB was realized and evaluated by electrochemical detection. Alkaline phosphatase was used as the enzyme label, coupled with differential pulse voltammetry (DPV) as the electrochemical technique. The immunosensor was tested on aroclor mixture detection (1242 and 1248) and then on some typologies of food samples to evaluate the possible application for real sample analysis. Samples analyzed were from different matrixes, such as sheep milk, bovine adipose tissue, and bovine muscle. Results obtained were compared with the accredited results according to ISO 17025 methods for PCB detection (HRGC-LRMS) as a confirmatory analysis. Preliminary results show the possibility to use this device as a screening method in food sample analysis. The negligible matrix effect observed may lead to a simplified extraction procedure, and considerable time and consumable savings are the immediate benefits given by the proposed method.     

Comparison of the Effects of Wet N Deposition (NH4Cl) and Dry N Deposition (NH3) on UK Moorland Species

Increases in N deposition (wet and dry) have been associated with a decline in semi-natural plant communities, adapted for growth on nutrient poor soils in the UK and Europe. The impacts of N deposition applied as either wet NH₄ ⁺ or gaseous NH₃ on vegetation (7 species) from acid moorland in SE Scotland were compared in a dose-response study. Wet N deposition at 0, 8, 16, 32, 64, 128 kg N ha^?1 y^?1 was applied as NH₄Cl, and dry deposition as gaseous NH₃ (2, 6, 20, 50, 90 µg NH₃ m^?3) under controlled conditions in open-top chambers. A strong linear dose-response relationship (p<0.05) was found between foliar N content in all seven plant species and applied NH₄?N. However, in the NH₃ treatment, only C. vulgaris and P. commune showed a significant response to increasing N additions. NH₃ was found to increase the rate of water loss in Calluna in both autumn and winter by comparison with wet deposition. For Eriophorum vaginatum, the NH₃ and NH₄ ⁺ treatments showed significant N dose response relationships for biomass. A significant increase in above ground biomass, proportional to the added N, was found for Narthecium ossifragum when N was applied as NH₃ compared to NH₄ ⁺.     

Characterizing Dry Deposition of Mercury in Urban Runoff

Stormwater runoff from urban surfaces often contains elevated levels of toxic metals. When discharged directly into water bodies, these pollutants degrade water quality and impact aquatic life and human health. In this study, the composition of impervious surface runoff and associated rainfall was investigated for several storm events at an urban site in Orlando, Florida. Total mercury in runoff consisted of 58% particulate and 42% filtered forms. Concentration comparisons at the start and end of runoff events indicate that about 85% of particulate total mercury and 93% of particulate methylmercury were removed from the surface before runoff ended. Filtered mercury concentrations showed less than 50% reduction of both total and methylmercury from first flush to final flush. Direct comparison between rainfall and runoff at this urban site indicates dry deposition accounted for 22% of total inorganic mercury in runoff.     

Ion Fluxes with Bulk and Throughfall Deposition along an Urban–Suburban–Rural Gradient

Fluxes of principal anions and cations with bulk and throughfall deposition during the growing period (April–September) were investigated for three years (2001–2003) at three sites differently exposed to the second biggest Lithuanian city – Kaunas. Fluxes of all investigated anions (SO₄ ^2?, NO₃ ^? and Cl^?) and most cations were found to be the highest in suburban area to compare with both – Rural and urban sites. The highest seasonal variability of monthly ion fluxes and the highest differences between throughfall and bulk fluxes (net throughfall) were recorded in suburban area. The highest throughfall enrichment by sulphur was detected in spring and the beginning of summer (April, May) in urban and especially in suburban sites. For nitrogen compounds (NO₃ ^?, NH₄ ⁺) positive net throughfall values were characteristic for urban and suburban sites and negative for rural site almost during the entire growing period. Uptake of NH₄ ⁺ ions was detected to be much higher of that for nitrates in rural area (46% vs. 22%). The most intensive enrichment of throughfall fluxes by K⁺ ions took place during the summer time (May, June, July), however, intensity of potassium leaching at the same amount of precipitation was the highest in suburban area.     

Fine and Coarse Ionic Aerosol Components in Relation to Wet and Dry Deposition

The distribution of acidic andalkaline constituents (SO₄ ^2-,NO₃ ^-, Cl^-, NH₄ ⁺, Na⁺,K⁺, Ca²⁺) between the fine and coarseparticle range has been examined in an urban locationin Thessaloniki, N. Greece over an 8-month period. The chemistry of wet and dry deposition collected overthe same period was also examined. Statisticalassociations between species within each environmentalphase were investigated using correlation analysis.Use of principal component analysis was made toinvestigate compositional similarities betweenaerosol, deposited dust and rain. It was found thatSO₄ followed by NO₃, NH₄ and Caprevailed in fine aerosol. Sulphates and Ca were alsothe prevailing ions in the coarse particle fraction.Wet deposition was found to be the dominant depositionmechanism for all species. The high dry depositionrates observed for Ca and SO₄ suggest that mostof the dry deposited sulphate is in the form ofCaSO₄. Scavenging ratios of ionic speciesassociated with coarse aerosol were higher than thecorresponding ratios for fine particles. Principalcomponent analysis suggested that variations in ioniccomposition of fine aerosol could be interpretedprimarily by gas-to-particle neutralization reactionsinvolving atmospheric ammonia. In contrast, theinteraction between SO₂ and HNO₃ with Cacompounds seems to be the most likely factor that canexplain variations in wet and dry deposition ioniccontents.     

Chemical Composition of Urban Wet Deposition in Amman,Jordan

Precipitation events were collected during the period from October 1996 to April 1997 from two sites in the city of Amman, Jordan. The samples were analyzed for major cations (Na+, K+, Ca2+, Mg2+ and NH4+), major anions (F-, Cl-, NO3- and SO42-), in addition to heavy metals (Cu2+, Cd2+, Zn2+, and Pb2+). High levels of Ca2+ and SO42- were observed. The results were comparable with some regional values and they indicate that about 58% of Na+ and Cl- are of marine origin, while Ca2+, K+ and a large fraction of SO42- are of soil dust origin. Heavy metals were detectable in most of the samples, zinc showed the highest concentrations. Significant correlation was obtained between zinc and lead, which may indicate automobile emission source.     

Wet Deposition to an Upland Area of England in 1988 and 1999: Measurements and Modelling

Fine spatial-scale measurements of acidic deposition have been made over two time frames: 1987/1988 and 1999/2000. Over this period, dramatic reductions in precursor emissions have occurred. The two sets of data are compared in order to quantify deposition reductions. Orographic enhancement of wet deposition from the seeder-feeder mechanism is important in the UK at high-elevation sites such as these and the measurements were corrected for this process using a standard methodology. The data were also modelled using a simple long-term Lagrangian acid deposition model and comparisons made with both sets of observations at a resolution of 5 km_5 km. Future scenarios (2010) of emissions were modelled to examine the impact of UK and other European sources in order to determine optimal protection of ecosystems in this region.     

土壤中多氯联苯的生物有效性及其影响机制研究

多氯联苯(PCBs)属于环境中广泛存在的持久性有机污染物(POPs),威胁生态系统安全与人体健康。为评价典型土壤中PCBs的生态风险,揭示其生物有效性以及影响生物有效性的分子机制将具有重要科学意义。本文以赤子爱胜蚓(Eisenia fetida)为土壤模式生物,模拟土壤中6种典型PCBs化合物(PCB-18、PCB-20、PCB-28、PCB-101、PCB-105、PCB-114)的富集动力学过程,并分析了蚯蚓吸收累积对土壤中PCBs总量的影响。结果表明,对于PCB-18、PCB-20和PCB-28,蚯蚓富集15天能够达到动力学过程的近平衡状态,而PCB-101、PCB-105和PCB-114则在30天达到近平衡状态,这可能是由于分子体积增大致使PCBs自由穿越生物膜并为生物体有机脂相富集的过程受到一定程度的限制,吸收速率变慢。PCBs生物有效性与典型分子性质(α、Kow)之间高度线性相关,从微观层面上揭示了影响生物有效性的分子机制,进一步表明PCBs分子体积、分子极化率及其疏水作用是影响生物有效性的主要因子,为典型土壤中PCBs污染物的生态风险预测与评价提供科学依据。     

Polychlorinated biphenyls (PCBs) in bulk soil and particle size separates of soils in a rural community

In a rural community (Stephanskirchen, Southern Germany) situated near a waste incineration plant six A horizons were sampled to determine 14 polychlorinated biphenyls (PCBs) in bulk soil and particle size separates (clay, silt, fine and coarse sand) and to test the suitability of alkaline saponification for PCB extraction. The PCB concentrations were higher in alkaline saponification extracts than in Soxhlet extracts. However, the extraction efficiency of up to fourfold chlorinated PCBs was lower and more than sevenfold chlorinated PCBs were destroyed. Nevertheless, alkaline saponification was suitable to determine the indicator congeners 28, 52, 101, 138, 152, and 180. The sum of the PCB concentrations ranged from 8.4 to 59.5 μg kg^?1 which was as high as in soils of big cities. However, the concentrations did not reach the threshold value for agricultural purposes of 200 μg kg^?1 as proposed in literature for the sum of the six indicator congeners. The hexachlorinated PCBs 138 and 153 were the most abundant (together > 50% in all samples) whereas PCB 1 could not be detected in any sample. On the average, PCB concentrations increased as particle size decreased. When normalized to C_org, however, the fine sand fraction had the highest PCB concentrations. A slight decrease of lower chlorinated PCBs as particle size decreased indicated an increasing state of degradation. The PCB compositions in the emissions of a comparable waste incineration plant (Bamberg, Bavaria) and in Stephanskirchen soils differed markedly. Therefore, we did not get any indications that waste incineration was a main source of PCBs in the examined soils. Instead, higher chlorinated technical PCB mixtures such as Clophen A 60 or Aroclor 1260 may be the most important sources.     

东平湖表层沉积物中多氯联苯的污染特征

[目的]查明东平湖表层沉积物多氯联苯(PCBs)的污染特征,为东平湖沉积物的污染控制及风险评价提供科学依据。[方法]于2015年7月对东平湖16个不同点位的表层沉积物进行采样,使用GC-ECD检测了PCBs(PCB28,PCB52,PCB101,PCB118,PCB153,PCB138,PCB180)的含量,对东平湖PCBs的空间分布进行分析。运用EPA法对东平湖表层沉积物中多氯联苯进行生态风险评价。[结果]东平湖表层沉积PCBs总的含量范围为nd～605.9ng/kg,均值为126ng/kg,标准差为153。在空间分布上,湖区中部(184.5ng/kg)入湖口(149.9ng/kg)湖区西南部(101.4ng/kg)湖区北部(46.7ng/kg)。研究区PCBs同系物组成以七氯联苯为主,占总量的66.72%。与其他地区的沉积物相比较,东平湖表层沉积物中PCBs处于较低水平,风险评价表明该研究区域生物毒性效应概率远远小于10%。[结论]由于水文因素的影响,东平湖表层沉积物中多氯联苯(PCBs)呈现出由大汶河入湖口向西北方向递减的空间分布趋势;东平湖表层沉积物中的多氯联苯属于轻微污染水平,未对水体环境安全造成严重影响,沉积物中PCBs的浓度水平对大多数底栖生物无毒性影响。     

多氯联苯复合污染土壤的土著微生物修复强化措施研究

通过室内模拟试验,以不同C源、C/N比、水分及通透性为调控因子,对多氯联苯(PCBs)长期复合污染土壤的土著微生物强化修复进行了初步研究。结果表明,PCBs长期复合污染土壤中,在土壤水分含量为田间持水量的60%时,加入淀粉、葡萄糖和琥珀酸钠均在一定程度上增加了细菌和真菌数量,从而促进土壤中PCBs的土著微生物降解。不同种类的C源对PCBs污染土壤的土著微生物降解效果存在明显差异,且其降解效果与C源的施用剂量密切相关。当淀粉加入量为C1.0g/kg土时,土壤中PCBs的降解效果较好,而葡萄糖和琥珀酸钠加入量为C0.2g/kg土时,PCBs的降解效果明显。土壤C/N比为10:1的处理效果优于C/N比为25:1和40:1。土壤人为翻动有利于PCBs污染土壤中细菌和真菌的生长,提高土著微生物的代谢活性,从而促进土壤中PCBs的自然降解。这为进一步探讨加速土壤中PCBs降解的最适条件和研发POPs污染土壤的生物修复技术提供了科学依据。     

The Effect of Precipitation Amount and Atmospheric Concentrations on Wet Deposition Fluxes of Oxidized and Reduced Nitrogen Species in Connecticut

The effects of precipitation amount and atmospheric concentrations of inorganic nitrogen species on precipitationconcentrations and wet fluxes of oxidized and reduced nitrogen inConnecticut were studied for a period of 152 weeks (7 February,1997 through 31 December, 1999). The annual volume weighted mean(VWM) concentration in precipitation of oxidized and reducednitrogen varied with precipitation amount between sites andyears. To investigate the effect of varying precipitation amountand mean monthly temperatures on concentrations of inorganicnitrogen species in precipitation, the precipitation events wereclassified into seven groups and each year was divided into twowarm and cold sampling periods. Increasing precipitation amounthad a substantial decreasing effect on the VWM concentration ofnitrate and ammonium ions in precipitation. The highest VWMconcentrations of oxidized and reduced nitrogen in precipitationwere found in the lower weekly precipitation range of 0 to 0.5 cm. The results of this study indicated that precipitationamount was one of the main factors affecting volume weighted meanconcentrations and fluxes of oxidized and reduced nitrogen. Chemical composition of inorganic nitrogen species in theatmosphere showed that during warm and cold sampling periodsreduced nitrogen was the predominant atmospheric specie, andoxidized nitrogen was the predominant wet specie in precipitationat all sampling sites.     

Seasonal Deposition Fluxes of Polycyclic Aromatic Hydrocarbons (PAHs) in Lake Biwa,Japan

Water, Air, & Soil Pollution - The concentrations of Cd, Cu, Fe, Ni, Pb and Zn in the different parts of six bivalves species were determined. From the study conducted, it was found that the...     

上海农村及郊区土壤中PCBs污染特征及来源研究

2007年3月采集上海市农村及郊区36个表层土壤样品,采用气相色谱法对土壤中的多氯联苯（PCBs）残留进行了分析,揭示了土壤中PCBs的残留水平、分布、组成特征及来源。结果表明,试区土壤中共检出62种PCB,总浓度最高2530ng·kg-1,最低71.7ng·kg-1,平均含量534ng·kg-1。较高污染浓度主要是编号为BS2、SJ6、JS4和FX4的土壤样品,但从整体采样区域来看,其污染可能主要来源于城区污染导致的区域大气沉降或是全球大气传输所致。上海农村及郊区土壤PCBs污染物以Tri-CBs和Tetra-CBs为主,主要以工业Aroclor1242来源为主。相关性分析显示,土壤中PCBs与TOC具有显著相关性,尤其是对于挥发性较强的低氯代PCBs,表明TOC是影响上海市土壤中PCBs持留的重要因素之一。聚类分析显示,部分采样点PCBs污染与工业品使用有关,但可能还存在其他来源。     

Enhanced Reduction of Extractable Polychlorinated Biphenyls and Toxicity in Sediment by Organic Matter

Water, Air, & Soil Pollution - Aquatic system contamination is a subject of concern due to the high number of contaminants with the potential to be hazardous for plant and animal species,...     

Dry and Wet Deposition of Nitrogen Emitted in Buenos Aires City to Waters of de la Plata River

Dry and wet deposition of atmospheric nitrogen species (NO₂ and HNO₃) coming from nitrogen oxides emissions in Buenos Aires city to surface waters of de la Plata River were estimated. Atmospheric dispersion models DAUMOD-RD (v.2) and CALPUFF were applied to area and point sources, respectively. These models were run considering 1 year of hourly meteorological data. Emission information included a typical diurnal variation of area source emissions. Annual atmospheric nitrogen (N–NO₂?+?N–HNO₃) deposition to 1,763 km² of the river was 35,600 kg-N year^?1. Dry deposition processes accounted for 89% of this value. The small contribution of wet deposition was a consequence of the very few cases (5%) of rain events during offshore wind conditions. Monthly dry deposition to 1,763 km² of the river varied from 1,628 kg-N month^?1 in February to 3,799 kg-N month^?1 in December, following the monthly occurrence of offshore winds. Monthly wet deposition varied from 1 kg-N month^?1 in June to 1,162 kg-N month^?1 in February. These results came from the combination of favorable conditions for formation of HNO₃ and the occurrence of precipitation during offshore wind situations. Spatial distribution of annual atmospheric N deposition showed a strong coastal gradient. Deposition values reached a maximum of 137.1 kg-N km^?2 year^?1 near the shoreline, which was reduced to the half at 4 km from the coast.     

Polycyclic Aromatic Hydrocarbons, Polychlorinated Biphenyls and Trace Metals in Sediments from a Coastal Lagoon (Northern Adriatic, Italy)

Surface sediments (0–5 cm) were analysed to provide information on levels, spatial trends and sources of the 16 USEPA polycyclic aromatic hydrocarbons (PAH), 15 polychlorinated biphenyls (PCBs) and trace metals (copper, chromium, mercury, nickel and zinc) in channel and wetland habitats of Pialassa Baiona lagoon (Italy). The highest levels of PAHs, PCBs and Hg (3,032–87,150, n.d.–3,908 and 1.3–191 mg kg⁻¹) were mainly found at channel habitats close to industrial sources. Pyrogenic PAH inputs were significant, with a predominance of four-ring PAHs and combustion-related PAHs in both channel and wetland habitats. Among PCB congeners, chlorination class profiles show that penta- and hexachlorinated PCBs are the most prevalent homologues accounting for approximately 33% and 47% of the total PCB concentrations in channel sediments. Total toxicity equivalent factors (TEQs) of potentially carcinogenic PAHs varied from 348 to 7,879 μg kg⁻¹ and from 4.3 to 235 μg kg⁻¹ in channel and wetland sediments; calculated TEQs for dioxin-like PCB congeners at channel habitats ranged from n.d. to 86.7 μg kg⁻¹. Comparison of PAHs, PCBs and metal levels with Sediment Quality Guidelines suggests that more concern should be given to the southern area of the lagoon for potential risks of carcinogenic PAHs, dioxin-like PCBs and mercury.     

Fluxes of Suspended Materials in the North Adriatic Sea (PO Prodelta Area)

Two time-series sediment traps were deployed south-east of the Po River delta (North Adriatic Sea) in 23m of water at 12 meters and 21 meters depths from 12/20/89 to 06/26/90. Temperature, conductivity, salinity, pH, Eh, O₂, transmittance profiles, wave height, speed and direction of currents were measured. Bottom sediments and river suspended matter were periodically collected during the same period. Organic carbon, Al, Fe and Mn concentrations and partitioning of Phosphorous on the solid phase in sediment samples were determined. This made it possible to calculate vertical fluxes at two water levels, and then to quantify and separate veritical fluxes of sinking particles into fluxes of lateral transports (river input), primary production and resuspension. To do so, the approach was based on the identification, comparison and integration of two different label substances (POC and Mn). This led to the finding that sediment fluxes and biogeochemical characters of suspended matter are in good agreement with seasonal differences and short-term events such as river floods, algal blooms and marine storms. A decrease in organic carbon along the water column (5.13% mean value at 12 in, 2.84% mean value at 21 m) with minimal values in the bottom sediment (1.49% mean value) was detected. Resuspension and reoxygenation increase the mineralization of organic matter (occurring already in water column). Differences in adsorption and desorption in the fine particulates of fundamental elements for primary production such as phosphorous were detected at different levels in the water column and in the bottom sediments.     

Wet Deposition of Trace Metals in Singapore

The concentrations of 12 trace metals (Al, Cd, Cr, Cu, Co, Fe,Mn, Ni, Pb, Zn, V, and Ti) in wet depositions are reported. Eighty four rainwater samples were collected using an automated wet-only sampler in Singapore for one year (2000) and subjected to chemical analysis using ICP-MS. Based on the volume-weighted meanconcentrations measured, the trace metals were classified into three groups: Al and Fe with an average concentration of largerthan 15 μg L^-1, Cr, Cu, Mn, Ni, Pb, Zn, V, and Ti withconcentrations between 1 and 10 μg L^-1, and finally Co and Cd with concentrations lower than 1 μg L^-1. Elementenrichment factors were calculated to distinguish between naturaland anthropogenic sources. The calculation of crustal enrichmentfactors with Al as the reference element indicated that while Ti,Fe and Mn originated from crustal sources, the remaining trace metals (Cd, Cr, Co, Cu, Ni, Pb, Zn and V) were mainly derived from anthropogenic sources. The removal of the trace metals from the atmosphere by precipitation was influenced by the rainfall amount as well as pH. The magnitude of the measured average annual wet deposition fluxes of Al, Fe, and combustion-generatedelements such as V, Ni, and Cu is higher than that reportedfor other sites outside Singapore, owing to abundant rainfallthroughout the year in this region.