Urban Land Use Influences on Heavy Metal Fluxes and Surface Sediment Concentrations of Small Lakes

To study urban land use influences on heavy metal (Cd, Cr, Cu, Hg, Ni, Pb and Zn) lake fluxes and sediment concentrations,ten headwater lakes and catchment areas in Stockholm, Sweden,were investigated. The catchment land use consisted of a gradient of urbanisation and was described on a detailed level,including all parts of the catchments, natural and urban. Covariation between catchment variables made interpretations difficult, however, and no detailed conclusions regarding metal sources could be drawn. Regression models for lake metalfluxes were calibrated using an urban status variable and a lake size variable (representing regional background sources).Hg showed no significant correlation with urban status, indicating a distribution pattern unaffected by local sources,mainly controlled by regional background sources. Cd showed aweak influence from urban land use. For Cu (and to some extent Cr) the urban status influences dominated. Pb, Ni andZn were in between these two groups and showed relations toboth urban land use and regional background.     

Estimating the Fate of De-icing Salt in a Roadside Environment by Combining Modelling and Field Observations

Predicting the environmental effects of de-icing salt requires knowledge of the pathways taken by salt from on-road application through spread to the surroundings to deposition and fate in the roadside environment. This study described differences in chloride deposition and distribution in soil with increasing distance from the road by means of field observations and modelling. The dynamic modelling approach successfully represented the spread of de-icing salt from road to surroundings, deposition in the roadside environment and the subsequent infiltration into roadside soil. The general decrease in soil chloride content with distance from the road was described by differences in salt deposition, soil physical properties, vegetation properties and snow characteristics. The uncertainty in model predictions was highest in areas close to the road due to a complex combination of high salt deposition, snow-ploughed masses and road runoff. The exponential decline in salt deposition with distance from the road could not be justified close to the road. Different types of field investigations were applied in a calibration procedure to establish reasonable ranges for the most influential model parameters. Measured electrical resistivity reflected well the changes in simulated chloride content in soil during winter and spring when chloride concentrations were high. However, during summer or periods with low chloride concentrations the measured resistivity was substantially lower than simulated values, as it reflected the total contamination level in soil.     

Study of How Salt Types Greatly Shape Soil Reflectance Spectra versus Salt Concentrations

In this study, a controlled experiment was designed to determine the potential impacts that salt types impose on soil reflectance spectra. Base soil from a typical inland river basin in China and 99% pure salts of three representive salt types as well as their combinations in different proportions were used to create composite soil samples. Seven levels of salt concentration were assigned for each saline soil treatment. The results revealed that salt concentration did not affect pattern parameters significantly (P > 0.5), where varying the salt concentrations only led to changes in the confined range that corresponded to salt types. Statistical parameter R_mean was sensitive to salt types but was limited to single-type salts. Therefore, salt types largely determined the overall shapes of soil reflectance spectra rather than salt concentrations. It is therefore necessary to identify salt type before retrival of salt concentration in saline soils by use of remote sensing data.     

Salinization of Mirror Lake by Road Salt

The salinization of Mirror Lake in the White Mountains of New Hampshire has been ongoing steadily since Interstate 93 (I-93) was built through the NE subcatchment of the lake in the fall and winter of 1969–1970. Salt added to I-93 during winter as a deicer has been transported to the lake by different quantified, hydrologic pathways, but primarily from the Northeast Tributary, which was intersected by I-93. Now, surprisingly, after the New Hampshire Department of Transportation has spent more than $500,000 on recent structural modifications to divert salt from I-93 away from the Northeast subcatchment of Mirror Lake, applications of salt to a small, town road traversing the other two subcatchments for the lake and servicing a new housing development, have become the major source of salt to the lake. Streamflow from these two subcatchments currently provides more than three times as much salt to the lake as from I-93, and the salt concentration in the lake continues to rise.     

城市景观湖泊水体总有机碳的研究

利用总有机碳分析仪测定了芜湖市区几种典型地面水体总有机碳(TOC)含量。结果表明:市区景观水体镜湖和九连塘湖水中TOC平均含量分别为16.911 mg/L和23.207 mg/L,市郊自然河塘水中TOC平均含量在晴天和降雨后分别为35.867 mg/L和24.533 mg/L;两类水体中TOC含量的影响因素分别是市政绿化冲洗水及田间沟渠漫溢水的排入,降雨对河塘水TOC有明显的稀释作用。     

Mechanisms of Phosphorus Control in Urban Streams Receiving Sewage Effluent

Urban streams often are a major source of phosphorus (P) to rivers, primarily due to large inputs of sewage effluent. A good example of this is Chicago (Illinois, USA) area streams, which make up most of the flow of the upper Illinois River. Even though streams in this section of the Mississippi River basin are characteristic hard-water systems and exhibit high calcium and carbonate concentrations, the precipitation of Ca–P minerals is minimal and phosphate is not removed from the water column. The objective of this study was to determine the chemical mechanisms controlling P activity in Chicago area streams. Measurement of dissolved ion activities on filtered surface water samples demonstrated that an average of 79% of P in the study streams was dissolved and the remaining was particulate (<0.05 μm and >1.0 μm in diameter, respectively). Neither a P colloidal-size fraction nor a correlation between dissolved and particulate Fe and P was observed. Thermodynamic modeling and SEM-EDS analysis of particulate matter in filter residues indicated that dissolved P may adsorb and co-precipitate on the surface of calcite rather than precipitating in a pure Ca–P mineral phase. Although SEM-EDS results also suggested that P was adsorbed to silicate minerals, organic residues likely dominated the P-containing particulate fraction. Sediment extraction results indicated that organic P was one of two major P components in the stream bottom. The Fe-associated P fraction represented the largest sediment-P fraction, and with little association between Fe and P in the overlying water, dissolved inorganic P may have aided in the authigenic formation of an Fe–P sediment phase. Overall, results suggest that pH combined with Ca and Mg activity are the dominant chemical controls on P chemistry in this P enriched system.     

Ultrasonic Characterization of Unyeasted Bread Dough of Different Sodium Chloride Concentrations

Altering the properties of dough by reducing sodium chloride (NaCl) content affects aeration processes during mixing. The effect of NaCl concentration on the bubble size distribution (BSD) in unyeasted doughs was investigated by an ultrasonic transmission technique through analysis of frequency‐dependent ultrasonic phase velocity and attenuation coefficient. As NaCl concentration was decreased, the volume fraction of gas in the dough increased, resulting in a larger attenuation coefficient for the dough. From the peak in attenuation coefficient, estimates of the median radius and the width of the lognormal BSD in the dough were extracted, both of which were sensitive to the dough's NaCl concentration. As NaCl concentration was reduced, the bubble radius decreased and the width of the distribution increased, in accordance with expectations arising from changes in the dough's consistency. Over the course of 150 min, the radius increased (40–50%) and the width decreased (4–8%) for all dough formulations, consistent with changes in the BSD arising from disproportionation. These dynamic changes demonstrate that dough is an interesting soft material whose formulation can be manipulated to enable it to possess different BSDs; the diffusively driven evolution in these bubble sizes can be investigated noninvasively with ultrasound.     

Soil and Atmospheric Inputs to PAH Concentrations in Salt Marsh Plants

Polycyclic aromatic hydrocarbons (PAHs) were measured in two wetland plant species grown outdoors in pots of sediment contaminated with up to 730,000 μg/kg total PAHs. After approximately 3 months, the plants were harvested, cleaned, and analyzed for an expanded suite of PAHs which included both the 16 priority PAHs and 22 alkyl PAH homologs. Sediment and air samples were also collected and analyzed. PAH compounds were detected in all of the samples, with the highest concentrations in the contaminated sediment. The root sample concentrations were generally about one order of magnitude lower than that of the sediment, and were strongly correlated with the concentration in the sediment in which they were grown. The concentrations in foliage were much lower and did not correlate with sediment concentration. Concentrations of low molecular weight PAH compounds detected in the foliage were not significantly lower in plants grown in control sediments, suggesting that the sediment is not the primary source of these PAHs. Several high molecular weight PAHs were detected only in plants grown in contaminated sediment. Plants of both species grown in control sediment were larger than plants grown in contaminated sediment.     

Impact of Soil Sorption Characteristics and Bedrock Composition on Phosphorus Concentrations in two Bohemian Forest Lakes

Phosphate (PO₄-P) sorption characteristics of soils and bedrock composition were determined in catchments of two mountain lakes, Ple?né Lake (PL) and ?ertovo Lake (CT), situated in the Bohemian Forest (Czech Republic). The aim was to explain higher terrestrial P export to mesotrophic PL compared to oligotrophic CT. Concentrations of Al and Fe oxides were the dominant parameters affecting soil ability to adsorb PO₄-P. Depending on concentrations of Al and Fe oxides, P sorption maxima varied from 9.7 to 70.5 mmol kg^?1 and from 7.4 to 121 mmol kg^?1 in organic and mineral soil horizons, respectively. The catchment weighted mean PO₄-P sorption capacity was 3.4 mol m^?2 and 11.9 mol m^?2 in the PL and CT soils, respectively. The higher PO₄-P sorption capacity in the CT catchment was predominantly associated with higher pools of soil and Fe oxides. The CT bedrock (mica schist) released one order of magnitude less P than the PL bedrock (granite) within a pH range of catchment soils (pH_CaCl2 of 2.5–4.5). The higher ability of PL bedrock to release P and the lower ability of PL soils to adsorb PO₄-P thus contributed to the higher terrestrial P loading of this lake.     

Urban Runoff Impacts on Particulate Metal Concentrations in River Seine

Metallic contents (Cd, Cu, Pb, Zn) of suspended solids (SS) were measured in two sites (Suresnes and Chatou) in the river Seine, downstream Paris, during three summer periods. These two sites, which are respectively located downstream and upstream two of the most important combined sewer overflows (CSO's) of the Parisian sewer system (Clichy and La Briche), allow us to assess these CSO immediate impacts. Samples were collected using sediment traps, weekly during dry weather and daily during the week following the major CSO's events. The heavy metal concentrations, relatively large but stable during summer periods, were shown to further increase downstream Paris after main rain discharges occurred. Metal concentrations measured within the Seine SS during rain events, allowed us to establish that the observable immediate impact of Clichy overflows is only 5% of what it could be. The general principle demonstrated through this work is that most SS originating from CSO's rapidly settle once they reach the river. These polluted particles greatly contribute to the SS chronic pollution downstream Paris during dry weather, through a slow resuspension mechanism of the deposited sediments.     

A Model of the Impact of Winter Ice Cover on Pollutant Concentrations and Fluxes in Mountain Lakes

High mountain lakes have been used in a number of recentstudies concerned with measuring and modelling the dynamicresponse of remote ecosystems to environmental change (theAL:PE, MOLAR and EMERGE projects). One of the importantfeatures that distinguishes these lakes from lowland lakes atsimilar latitudes is fact that they may be isolated from theatmosphere for six months or more during the winter by a thickice cover. Pollutants deposited during the winter are lockedup in the ice and snow and released only during the springthaw. These processes generate a very strong seasonalvariation of pollutant concentrations in the water column, andfluxes through the water column to the sediment record. Thisarticle presents a mathematical model of these processes, anduses the model to assess data on fluxes and concentrations offallout radionuclides in the water column of Redó Lake in theSpanish Pyrenees. Using fallout ²¹⁰Pb as a tracer, themodel results show that concentrations in the water columnimmediately after ice melt are enhanced by a factor of up to70%. Fluxes through the watercolumn show a similar patternto the empirical results, though the theoretical values tendto be a little more conservative. By comparing fluxes throughthe water column with the measured atmospheric flux it isestimated that between 4–6% of annual fallout of ²¹⁰Pbonto the catchment of Redó is delivered to the lake, and that the mean ²¹⁰Pb residence time in the catchment is between 500–750 yr.     

Movement of Road Salt to a Small New Hampshire Lake

Runoff of road salt from an interstate highway in New Hampshire has led to contamination of a lake and a stream that flows into the lake, in spite of the construction of a diversion berm to divert road salt runoff out of the lake drainage basin. Chloride concentration in the stream has increased by over an order of magnitude during the 23 yr since the highway was opened, and chloride concentration in the lake has tripled. Road salt moves to the lake primarily via the contaminated stream, which provides 53% of all the chloride to the lake and only 3% of the total streamflow to the lake. The stream receives discharge of salty water from leakage through the diversion berm. Uncontaminated ground water dilutes the stream downstream of the berm. However, reversals of gradient during summer months, likely caused by transpiration from deciduous trees, result in flow of contaminated stream water into the adjacent ground water along the lowest 40-m reach of the stream. This contaminated ground water then discharges into the lake along a 70-m-wide segment of lake shore. Road salt is pervasive in the bedrock between the highway and the lake, but was not detected at all of the wells in the glacial overburden. Of the 500 m of shoreline that could receive discharge of saly ground water directly from the highway, only a 50-m-long segment appears to be contaminated.     

Concentrations of Free and Conjugated Estrogens at Different Landscape Positions in an Agricultural Watershed Receiving Poultry Litter

Animal hormones can enter the aquatic environment along with runoff as a result of manure or litter application on agricultural landscapes. Our understanding of the transport of these hormones and their concentrations at various points along the watershed drainage is however limited. We investigated the transport of naturally produced poultry hormones in an agricultural watershed located on coastal plain soils of Delaware receiving land application of raw poultry manure. The objective of this study was to determine the concentrations of free and conjugated forms of estrogens in agricultural runoff at selected landscape positions in the agricultural watershed. Estrogen concentrations were determined for surface water, soil water, and runoff sediment. Estrogen forms that were analyzed were: Estrone (E1), Estradiol (E2?? and E2??), Estriol (E3), and their sulfate and glucuronide conjugates. Poultry litter application occurred at a rate of 9 Mg ha^?1 in early spring (April 2010). Sampling was performed for surface runoff, subsurface drainage, and sediment for nine storm events extending over 187 days before and after manure application (March?COctober 2010). Runoff was collected from the field edge, upland and lowland riparian positions and from the stream. Samples were analyzed by for liquid chromatography with tandem mass spectrometry (LC-MS/MS). Concentrations of estrogens were low (<20 ng l^?1) for most of the samples and decreased from the field edge into the riparian zone. Estrogens were not detected in soil water and runoff sediments. Overall, this study suggests that manure application practices at our sites in Delaware such as incorporation of litter into the soil likely reduced the concentrations of estrogens in runoff and reduced the threat posed to aquatic ecosystems.     

上海市区公园土壤重金属含量及其污染评价

通过对上海市区44个公园土壤重金属含量的调查,发现市区公园表层土壤Pb、Zn、Cu和Cr的平均含量分别为55.1mg kg-1,198.5 mg kg-1、44.6 mg kg-1、77.0 mg kg-1。以上海土壤背景值为标准,用内梅罗指数法综合评价上海市区公园土壤重金属污染状况为:绝大部分公园为轻污染,9个为中度污染,7个达重度污染。通过对公园土壤重金属含量的空间分析发现:内环线附近公园土壤Pb、Zn和Cu的平均含量最高,Cr的平均含量以内外环线之间公园为最高。上海市区公园较严重的重金属污染可能来源于交通和工业污染,与公园建成时间无显著性相关。     

Field Data of Hydrogen Peroxide Concentrations in Urban and Mountain Air in Southwestern Poland

The concentrations of ambient gas-phase hydrogen peroxide were measured during the summer of 1998, 1999 and 2000. The experiments were performed in the city of Wroclaw and in the vicinity of Mount Szrenica, 1362 m a.s.l., Poland. Analysis was carried out by the chemiluminescence method. Typical mean ranges of 30 min H₂O₂ concentrations measured were 1.4–6.0 μg m^-3 at Mount Szrenica, whereas in the urban atmosphere H₂O₂ concentrations were in the range of 2.7–11.7 μg m^-3. In the case of the urban atmosphere, H₂O₂ concentrations were well correlated only with solar radiation and temperature. In the mountain air, H₂O₂ concentrations increased along with the increase of temperature, O₃, CO and the decrease of humidity. The diurnal variation was not only caused by photochemicalprocesses.     

生态滤沟对城市路面径流的净化效果

随着城市化进程的加快,城市路面径流污染问题日益严重,运用工程措施对其实施控制具有重要意义。在西安理工大学露天试验场设计和建设了6条不同配置方式的生态滤沟,通过试验分析生态滤沟对城市路面径流中污染物的净化效果及其影响因素。结果表明:在所选的基质中粉煤灰的净化效果较好,其对铵氮、总氮、可溶性正磷酸盐、总磷的去除率可分别达到30%～45%,25%～30%,90%～95%,60%～90%;较无植被情况,在有植被条件下生态滤沟对总氮的去除率可提高5%～30%,而对磷的净化效果相差不大;随着入流水力负荷的增大,生态滤沟对污染物的去除率会降低,铵氮和总氮的去除率在高水力负荷和低水力负荷时相差10%左右,可溶解性正磷酸盐和总磷的去除率在高负荷和低负荷时相差可达30%左右;随着进水污染物浓度的增大,COD、可溶解性正磷酸盐、总磷的去除率呈现先增大后减小趋势,铵氮去除率呈现增大趋势,总氮去除率呈现先减小后增大的趋势。随着入流时间的延续,生态滤沟对入流流量、入流水量、入流污染负荷的削减能力减弱。     

昆明市道路绿地信息管理系统

数字化管理是适应时代需求而发展起来的一种新的管理手段。从城市绿化植物档案管理计算机化的要求出发,以昆明市主干道路为调查对象,利用现代数码照相技术,将道路绿地植物相关资料及配置模式搜集回来,利用文字和图片处理软件对其进行美化处理。根据园林植物配置原则,对环境适应度和景观丰富度较高的道路进行了3D建模并绘出平面效果图输入到计算机,最终实现昆明市绿化植物档案管理的计算机化。     

上海市区公园表层土壤铅含量及其污染评价

通过对上海市区44个公园土壤中Pb含量的调查,发现表层土壤中Pb的平均含量为55．06 mg/kg, 变幅为26．39-174．35 mg/kg,为上海市土壤环境背景值的1．04-6．85倍。运用地积累指数法对公园表层土壤Pb 污染进行评价,结果表明:超过半数的公园为轻度污染至中等污染,近1/3的公园无污染, 6个公园达到中等污染和中等污染至强污染水平。通过对土壤Pb含量的空间分布分析发现,上海市区公园土壤中Pb主要来源于交通和工业污染,土壤Pb含量与公园建成时间无显著性相关。     

干旱区施不同浓度硝酸钾对后备耕地土壤水盐的影响

采用野外试验和室内分析相结合的方法,研究施用不同量硝酸钾对新疆盐碱土水盐及离子分布的影响.结果表明:(1)随着外源硝酸钾施入土壤,土壤上层含水率增加,下层减少.(2)土壤上层的全盐含量增大,并且施钾浓度越高含盐量也越高.(3)施钾样地整个土层的Ca2+、Mg2+、SO42-浓度相对于对照地(非施钾样地)有所增加,而Na+和Cl-浓度降低.当施钾浓度为400mg/L时上层Na+浓度显著增加,可能对作物造成危害;施钾浓度达到1 000mg/L时Na+浓度变化不大,即施钾浓度越高Na+浓度越低.(4)施钾浓度为1 000 mg/L时,土壤上层钠吸附比(SAR)、Cl-/SO42-大大降低.施用硝酸钾可增加后备耕地土壤上层的含水量,减少钠吸附比(SAR)、Cl-/SO42-,有利于农作物的生长,但也增加了土壤上层的含盐量.     

Comparative Analysis of Metal Concentrations and Sediment Accumulation Rates in Two Virginian Reservoirs,USA: Lakes Moomaw and Pelham

Water, Air, &; Soil Pollution - Agricultural chemicals from nonpoint sources in groundwater are present in the major provinces of the High Plains aquifer in Nebraska. Nitrate and...