Physically-Based Particle Size Distribution Models of Urban Water Particulate Matter

Water, Air, & Soil Pollution - The aim of this study was to evaluate the effect of pretreatment on the phytotoxicity and leaching of nitrogen and phosphorus in biosolids from anaerobic...     

Concentration and Exposure Evaluation of Perchlorate in Size-Segregated Airborne Particulate Matter from Changsha,China

As a newly emerging persistent environmental contaminant, perchlorate (ClO₄ ^?) has adverse effects on thyroid function by inhibiting iodide uptake and could result in neurodevelopment deficits. Our study was performed to investigate the concentration of perchlorate in size-segregated airborne particulate matter (APM) and evaluate its human exposure for children and adults. In this study, 45 size-segregated APM samples were collected from Changsha, China, during July 20 to July 31, 2016. The total APM concentrations ranged from 93.367 to 253.271 μg/m³ (mean 154.651 ± 59.175 μg/m³), and a bimodal size distribution was observed during the sampling period. The concentrations of perchlorate in size-segregated APM were in the range of 0.05–4.99 ng/m³ (mean 2.03 ng/m³). Exposure evaluation indicated that the ingestion was the predominant exposure pathway for daily intake of perchlorate via size-segregated APM, and children are more likely to intake more perchlorate via APM than adults. We suggested that the risk of exposure to perchlorate for children is worthy of attention, and a further study is required, especially for seasonal variations.     

Particle Number Size Distribution and Weight Concentration of Background Urban Aerosol in a Po Valley Site

Measurements of particle size distributions and PM_2.5 from an urban background site in the Central Po Valley are analysed; the site is one of the medium–small-size cities in the central valley, without the direct influence of the metropolitan and industrial area of Milan and of the Adriatic Sea. The data comprise number concentration of particle with diameters ranging between 10 and 700 nm, PM_2.5 and main meteorological variables from February to August 2008. Daily cycles of the observed pollutants are analysed, along with auto-correlation function for particle number concentration and principal component analysis (PCA) of all the available variables; finally, the diurnal pattern of PM_2.5 low-, medium- and high-pollution events has been investigated. Total particle number concentration showed a daily pattern both in winter and summer, although different between weekdays and Sundays and with wider variations during the cold season. A daily cycle is present for the geometric mean diameter of nucleation mode particles in winter and of nucleation and Aitken mode particles in summer. PM_2.5 showed a slight daily pattern for weekdays and Sundays, similar, but lagged, to total particle count cycle. Mixing layer depth resulted the main process controlling PM_2.5, although also human activities contribute to PM_2.5 concentration and allow some deposition and (re-)mobilisation at the first hours of the day and morning rush hour, respectively, while particle number concentration responds immediately to anthropogenic sources. PCA confirmed the dependence of particle number concentration also on meteorological variables, e.g. mixing layer height, wind speed or atmospheric pressure, showing the important influence of regional meteorology on local pollution conditions. Modena can be considered a representative test area of the effect of the meteorological regime for the Central Po Valley on atmospheric particle concentration patterns, characterised by steady high-background concentration.     

Impact of Biomass Combustion on Urban Fine Particulate Matter in Central and Northern Europe

The distribution of nonylphenol ethoxylates (NPEOn) and their derivatives of nonylphenol (NP) and nonylphenoxy ethoxy acetic acids (NPEnC) in the sediments of a relatively closed freshwater reservoir was investigated using sediment layers sliced from undisturbed sediment cores collected with a gravity core sampler at three sampling sites (St. 1, St. 2 and St. 3) along the water flow direction. The relationships between the bound content of these compounds and the sediment organic matter as well as the likely transformation pathways were evaluated. The total content of NPEOn (n?=?1–15) fell in 84.6–336.5, 59.9–135.5 and 77.0–623.4 μg/kg-dry for all sliced layers at St.1, St.2 and St.3, respectively, with the content of individual NPEOn species showing a general decreasing trend with the attached molar number of the ethoxy (EO) chain. Compared to each detected NPEOn species, the bound content of NP was much higher, falling in 73.2–248.4, 79.9–358.2 and 25.5–1,988.4 μg/kg-dry at St. 1, St. 2 and St. 3, respectively. A general increasing trend of the NP content along the water flow direction of the reservoir was revealed. NPEnC (n?=?1–10) varied in 1.93–4.12, 2.85–9.84 and 1.05–19.1 μg/kg-dry for sediment at the respective site of St. 1, St. 2 and St. 3, with the averaged values at these sites (2.91, 4.71 and 6.72 μg/kg-dry) showing an increasing trend from the upstream to the downstream. For NPEnC, a parametric trend of increases in the content of NPE₁C, NPE₂C and NPE₃C with the bound sediment organic matter (9.06–11.8%) seemed to be existent. Furthermore, the computed magnitudes of NPEO_1–2/NPEO_1–15, NP/NPEO_1–15 and NPEC_1–10/NPEO_1–15 suggested that non-oxidative hydrolytic transformation was probably prevailing within the sedimented mud phase of the reservoir, with the oxidative hydrolytic transformation pathway being less involved.     

Size Distribution of Trace Elements and Major Ions in the Eastern Mediterranean Atmosphere

Size distribution of trace elements is measured at the Mediterranean coast of Turkey, by analyzing hi-vol impactor samples collected between August 1993 and May 1994. Mass median diameters of marine elements are between 4.6 and 5.3 μm, and those of crustal elements are between 3.0 and 3.5 μm. Mass median diameters of crustal elements are 30% smaller in samples impacted by Saharan Dust. Pollution derived elements, As, Cd, Mo, Pb, Se, and Zn have MMD's between 1.25 and 1.01 μm. Although 70–90% of the masses of these elements were associated with particles smaller than 2.1 μm, 10–30% of their mass was associated with coarse particles. Coarse component in concentrations of Cd, Pb, Sb and particulate Hg are due to adsorption of fine anthropogenic particles on coarse crustal aerosol, whereas coarse fraction Zn, As, Se, In, Mo and Au are crustal at Al concentrations > 100 ng m^?3. Bromine, Cr, Ni, and V have bimodal distributions. The fine component, which account for approximately 30–40% of their masses are due to anthropogenic sources, whereas the coarse component, which accounts for 30–50% of their masses are due to sea salt for Br, and crustal particles for Cr, Ni, and V.     

Concentration Of Trace Elements in Airborne PM10 from Jobos Bay National Estuary, Puerto Rico

Atmospheric suspended particulate matter (PM₁₀) was sampled from the Jobos Bay estuary in Salinas and from a reference site (Fajardo) in the east coast of Puerto Rico. Salinas is a town in the south coast of Puerto Rico adjacent to a number of industries and to the only coal power plant on the island. It is important to study the air quality in this area since significant releases of metal to the environment due to energy production could represent a threat to local communities. This study evaluated the levels of PM₁₀, metals, and arsenic to set a reference point for future environmental studies in the area. Sampling was performed for periods of 72 h between August 2002 and May 2003 using a Partisol Plus Model 2025 sequential PM₁₀ air monitor. Seven metals were analyzed per sample (Cd, Cu, Fe, Ni, Hg, Pb and V) plus arsenic using Atomic Absorption. Average annuals levels for PM₁₀ in Salinas were 22.9 μg/m³ versus 20.7 μg/m³ in Fajardo. All metals analyzed were significantly higher in Salinas when compared to Fajardo (reference site). Statistical analyses showed strong relationships between the metal groups (Cu and Cd) and (As and Pb) at Salinas. Good relationship was also observed for Fe and PM₁₀. This analysis suggests two main sources for the elements: anthropogenic and metal flux from Saharan dust arriving to the island.     

Size Distribution of Wet Weather and Dry Weather Particulate Matter Entrained in Combined Flows from an Urbanizing Sewershed

Urban drainage transports a complex and heterogeneous mixture of aqueous-phase chemicals and also solid-phase particulate matter (PM). In this study, event-scale particle size distribution (PSD) of wet and dry weather flows are measured, modeled, and compared. The flows are generated from a complex urbanizing sewershed (Liguori catchment) in Cosenza, Italy. Results indicate PSDs are heterodisperse, ranging from colloidal to sand-size PM. On an event scale, dry weather PSDs are coarser than wet weather flows, yet within each flow class results indicate flow-limited behavior and only nominal variability during and between events. PSDs from each event and flow category are modeled with a cumulative gamma distribution. Results produced nonparametric distributions of shape (γ) and scaling (α) parameters as well as a d ₅₀ index. Wet weather flows generated statistically significantly higher distributions of γ and α and statistically significantly lower d ₅₀. Nonparametric parameter distributions illustrate greater, yet still nominal variability for wet weather flows.     

Trace Elements in Soils of Urban Areas

Urban soils are an essential element of the city environment. However, studies on urban soils are scattered in terms of geographical distribution, sampling pattern, analytical dataset, etc. One of the major issues arising from the studies on this ecosystem is the diffusion of its contamination. In cities, in fact, the proximity to humans may cause a serious danger for citizens. In the present study, results from the literature about trace elements in urban soils are presented to compare methodologies and results and to offer a basis for the harmonization of investigation approaches and establishment of remediation thresholds. A total of 153 studies on the urban ecosystem published in the last 10 years were collected and data on trace elements in soils of 94 world cities were compared and discussed. Data highlights the discrepancies among different studies (sampling strategies, analytical procedures) and the extreme variability of urban soils. Most cities are contaminated by one or more trace elements, revealing the environmental relevance of the urban soil system. While Pb is still one of the major concerns in many locations, new contaminants are on the rise and would deserve more attention from the researchers. While in fact some contaminants are almost ubiquitous in world cities and could be used as tracers for urban contamination, some traffic-related elements such as platinum, rhodium, and palladium, whose reactivity and toxicity is still unknown, are becoming of concern. Collation of literature data highlights the need for the harmonization of sampling, analytical, and rendering procedures for regulatory purposes and provides a useful dataset for environmental scientists dealing with the urban ecosystem and for city planners. A sampling design adapted to local urban patterns, a prescribed sampling depth, and a minimum set of elements that deserve to be measured could be the core of a common methodology.     

Influence of Acidification and Liming on the Distribution of Trace Elements in Surface Waters

Metals in water have been monitored for up to 18 years in acidified regions of Sweden. The concentrations of metals (Al, Cd, Cu, Fe, Mn, Mo, Pb, Zn) were determined by AAS and ICP-MS, the dissolved fractions after separation by in-situ dialysis. Elements showing negative pH-correlation were primarily Al, Zn, Cd, Mn, and Pb, while Mo was positively correlated to pH, indicating a predominance of negatively charged ionic forms. Zn, Cd, and Mn occurred primarily in the dissolved fractions, especially at the lower pH levels. Fe, Al, Pb and Mn were further enriched in humic waters. During the study period, some of the sites were subject to lime treatment, which had a marked influence on most elements, causing the mean levels and the seasonal fluctuations to decrease. Treatment on the lake surface was less effective than wetland liming to reduce seasonal fluctuations, especially for metals mainly originating from the catchments, as Fe and Al.     

Spatial Distribution of Gaseous And Particulate Matter Emissions in Greece

The quantification of air pollutant emissions to theatmosphere, from anthropogenic and natural sources, in Greece is the main focus of the current work. Emissions are spatially and temporally disaggregated in a high resolution grid based on a methodology given in Atmospheric Emissions Inventory Guidebook, CORINAIR. The anthropogenic emissions are equal to those given by UNECE through the EMEP program and an estimation of their spatial distribution in a 5 × 5 km² grid is performed. Furthermore, natural emissions are calculated using the bottom-up approach and are distributed to the 5 × 5 km² grid. The methodology used for the estimation of the spatial and temporal distribution of the emissions is presented as well as the contribution of each individual source in the distribution of gaseous and particulate matter emissions in Greece. Energy production, agriculture and road transport have been recognized as the activities in Greece mainly contributing to the anthropogenic emissions. Other important sources include biogenic VOC and resuspended dust.     

A Study of Airborne Selected Metals and Particle Size Distribution in Relation to Climatic Variables and their Source Identification

Ten selected metals (Na, K, Fe, Zn, Pb, Mn, Cr, Co, Ni & Cd) were estimated in total suspended particulate (TSP) samples collected on glass fibre filters in urban Islamabad, Pakistan, from October 2002 to May 2003, using a high volume sampling technique. The wet digestion method (HNO₃/HClO₄) was used for metal analysis by the flame atomic absorption spectrophotometry (FAAS) method. Maximum mean contribution was noted for Na (1.949 μg m^?3), followed by K (0.900 μg m^?3), Zn (0.603 μg m^?3), Fe (0.584 μg m^?3) and Pb (0.214 μg m^?3). The particle size determination on % volume basis for four fractions (PM_{< 2.5}, PM_2.5–10, PM_10–100& PM_{> 100}) was also carried out. PM_10–100 were found to be the most abundant in the local atmosphere followed by PM_2.5–10, while the respirable fraction (PM_{< 2.5}) and giant fraction (PM_{> 100}) showed comparable and lower levels. The trace metals were found to be mainly associated with PM_{< 2.5} and PM_2.5–10. The influence of climatic variables on toxic trace metals and particle size fractions was also investigated statistically and it was revealed that temperature has a significant correlation with fine particle fractions and airborne trace metal levels. The source identification was carried out by Principal Component Analysis and Cluster Analysis. Four metal sources were identified: industrial (32.6%), soil-derived dust (21.9%), traffic/road dust (19.8%), and metallurgical/garbage incineration (12.4%). The metal levels were also compared with those reported for other parts around the world.     

Influence of Particle Size Distribution and Content of Organic Matter on the Toxicity of Copper in Sediment Bioassays Using Caenorhabditis Elegans (Nematoda)

The influence of particle size distribution and organic matter on the toxicity of copper was investigated using the nematodeCaenorhabditis elegans as testorganism. Sediments taken at various depths from three lakes of different trophic status and artificial sediments were spiked with sublethal concentrations of CuSO₄. After an exposure of 72 h to spiked sediment or liquid medium, body length of the nematodes was determined. Both artificial and natural sediments reduced the effect of copper, with natural sediments being more effective. In natural sediments worms grew normally at concentrations of copper up to 63.5 mg/L, whereas in artificial sediments body length was reduced at concentrations of 11.3 mg Cu/L or higher. Body length was positively correlated with content of fine particles and organic matter, indicating that particle size distribution and organic matter are determinant factors for the ecotoxicology of sediments.     

沙棘柔性坝对砒砂岩沟道泥沙粒径分布及有机质影响

为了进一步研究沙棘柔性坝对砒砂岩沟道泥沙的影响,基于内蒙古砒砂岩地区沙棘柔性坝野外试验,根据单座沙棘柔性坝一次降雨淤积后的试验数据,运用对比分析的方法,研究了沙棘柔性坝对砒砂岩沟道泥沙粒径分布及有机质的影响及其拦沙效果。结果表明:单座沙棘柔性坝能够提高砒砂岩沟道泥沙有机质含量,具有淤粗排细的分选功能和良好的拦沙效果。泥沙有机质从沙棘柔性坝上游到下游逐渐增加,沿泥沙剖面表现出先增后减的趋势;泥沙粒径从沟道上游到下游先增大后减小,沿一次降雨淤积的泥沙剖面也表现出先增后减的趋势;暴雨后沙棘柔性坝单位面积淤积泥沙的平均厚度为0.369m,与对比沟相比,淤积的泥沙厚度明显较高。     

Distribution of Trace Elements in Meromictic Pit Lake

Studies were conducted at the deepest location of the meromictic Piaseczno pit lake, southern Poland, which was created in abandoned sulphur opencast. Pearson correlation and PCA were used to established the relationship between the elements and physico-chemical parameters of the water, whereas discriminant test to study vertical and time differentiation of Cd, Pb, Sr, Cu, Zn, Mn, and Fe concentrations. The results indicated both vertical (except Cu and Zn) and time differentiations of studied elements in the lake water. The highest concentrations of Cd, Pb, and Sr were found in the monimolimnion, that of Mn and Fe in the anoxic water. Depth profiles of Cu and Zn did not show any pronounced trend. Pb and Sr distributions in the water were related to alkalinity, Cl^? and COD, Cd to alkalinity and Cl^?, Mn and Fe to the redox conditions, Mn to water pH, and Fe to the alkalinity. The upper (0–15 cm) layer of the sediment consisted mainly of S (24.2 Atom%), Fe (21.62%), Ca (18.4%), Si (14.3%), and (Al 6.3%) and reflected mainly processes proceeded in the anoxic water-sediment interface. Calculated accumulation coefficients (K _d) of the elements in the sediment are discussed.     

不同形态河谷沉积物中稀土元素的粒径分布特征

稀土元素（REE）作为一种重要的土壤侵蚀示踪元素，明确其含量随土壤颗粒粒径的变化特征，对准确量化土壤侵蚀速率具有重要意义。本研究基于Samonova等采样测定的不同粒径范围（<1、1~10、10~50、50~250和250~1 000 μm）土壤/沉积物颗粒中的REE含量，分析了俄罗斯普罗特瓦河左岸河谷形态（“U”和“V”形谷）、地貌部位（坡面、沟坡/沟壁、沟道底部和洪积扇）、侵蚀（坡面、沟坡/沟壁）和沉积（沟道底部和洪积扇）环境对土壤/沉积物REE含量、富集系数等的影响。结果表明：（1）“U”和“V”形谷四类地貌下，轻稀土（LREE）、重稀土（HREE）和总稀土（?REE）含量均随颗粒粒径变粗呈降低趋势。在相同地貌部位，“U”形谷细颗粒中（<50 μm）中LREE、HREE和?REE含量较“V”形谷分别低14.6%~24.7%、10.0%~33.5%和14.2%~21.1%。（2）无论河谷形态和地貌部位，LREE和HREE均明显富集在细颗粒中，尤其是“V”形谷，LREE和HREE主要富集在<10 μm的颗粒中。（3）对比侵蚀和沉积区，“U”和“V”形谷沉积区细颗粒中LREE和HREE的富集程度均显著（P<0.05）大于侵蚀区。可见，无论河谷形态、地貌部位和侵蚀沉积区，REE均主要富集在细颗粒中；但河谷形态和侵蚀、沉积对REE含量的粒径分布有重要影响。     

秸秆覆盖对农田土壤风蚀及细颗粒物释放的影响

为了确定保护性耕作措施对北京周边农田土壤风蚀及颗粒物释放的影响,通过风洞模拟试验,对比不同风速和不同覆盖度下农田土壤风蚀速率及TSP、PM_(10)、PM_(2.5)、PM_1的释放差异,并分析了4种细颗粒物在风蚀物中的占比。结果表明:(1)当风速12 m/s时,秸秆覆盖度达到20%能显著降低风蚀速率,当风速16 m/s时,秸秆覆盖度需达到40%才能达到理想的防风蚀效果。(2)TSP、PM_(10)、PM_(2.5)、PM_1 4种细颗粒物的释放量与风速呈正指数函数关系,与覆盖度呈负指数函数关系;随风速的增加,4种细颗粒物的释放能力为AB1B2B3B4B5,当覆盖度10%或60%时,细颗粒物的释放量随风速增大差异逐渐减小;覆盖度达60%以上时,细颗粒物的释放量基本达到稳定值。(3)TSP、PM_(10)、PM_(2.5)、PM_1 4种细颗粒物在风蚀物中的占比随风速的增加而降低,当覆盖度60%时占比接近稳定。     

Representation of Particulate Matter COD in Rainfall Runoff from Paved Urban Watersheds

For a half century, total suspended solids (TSS) has been the most commonly utilized particulate matter (PM) gravimetric index for wastewater. While TSS has been extended to urban runoff, runoff phenomena are unique. Runoff is unsteady and transports heterodisperse inorganic granulometry, giving rise to the PM index, suspended sediment concentration (SSC). With respect to PM-associated chemical oxygen demand (COD_p) in runoff, it is hypothesized that, while the TSS method can represent effluent COD_p, the SSC method is required to represent influent COD_p. COD_p and PM indices (TSS and SSC) for runoff events with mass balances and manual sampling are analyzed to investigate this hypothesis. This study examined a series of rainfall-runoff events captured from an instrumented fully paved urban catchment subject to traffic loadings in Baton Rouge, LA. Results indicate TSS generated substantial event-based mass balance errors for COD_p and Δm _p (mg/g) across a hydrodynamic separator (HS) as compared to SSC. TSS underestimates sediment-bound COD (>75 µm), a significant portion (maximum of 63% and median of 50%) of influent load. Negative bias by the TSS method for influent COD_p load increases as the heterodisperse particle size distribution becomes coarser. Above a PM of 250 mg/L, underestimation of COD_p by the TSS method is statistically significant. Utilizing the SSC method, COD_p reduction by a HS upstream of a batch clarifier (BC) indicates that a HS does not provide COD_p reduction, compared to a BC with 60 min of residence time. Representative PM and COD_P assessment suggests frequent BMP and drainage system maintenance to ensure proper operation and reduce pollutant elution.     

Human Health Impact of Exposure to Airborne Particulate Matter in Pearl River Delta, China

To evaluate the potential public health impact of exposure to airborne particulate matter, concentrations of PM₁₀ and PM_2.5 were measured at 16 monitoring stations in Pearl River Delta. Epidemiological studies were collected, and meta-analysis method was used to get the exposure-response functions for health effects on mortality of residents in China. Chinese studies reported somewhat lower exposure-response coefficients as compared with studies abroad. Both Poisson model and life-table approach were used to estimate the health effects including acute effects and chronic effects. For short-term exposure, 2,700 (95% confidence interval (CI), 2,200?C3,400) premature deaths would be prevented annually if PM₁₀ daily concentrations reduced to below World Health Organization (WHO) guideline value. Much more benefits would be gained for long-term exposure. The annual avoidable deaths would be 42,000 (95% CI, 28,000?C55,000) and 40,000 (95% CI, 23,000?C54,000) for PM₁₀ and PM_2.5, respectively, if the particulate matter annual concentrations were reduced to below WHO guideline values. And the average lifespan of residents would prolong 2.57?years for PM₁₀ and 2.38?years for PM_2.5 if reducing the PM annual concentrations. The benefits varied greatly in different areas and different manage strategies should be carried out to protect human health effectively.     

Bran Particle Size Influence on Pasta Microstructure,Water Distribution,and Sensory Properties

Whole wheat pasta offers improved nutritional value compared with regular pasta but lacks appeal to many consumers owing to its negative organoleptic properties, such as texture and taste. Various approaches have been studied to improve these properties in whole wheat products. Optimizing bran particle size showed its potential in noodles, but studies of its effects in pasta are scarce. Therefore, we produced spaghetti enriched with bran fractions similar in chemical composition but with varying median particle sizes of 90, 160, 370, and 440 µm. The effect of bran particles and their median size on dried and cooked pasta was studied by light microscopy and three‐dimensional magnetic resonance imaging. In general, bran particle size did not influence the macrostructure in cooked spaghetti. However, larger bran particles created a more heterogeneous microstructure in contrast to smaller particles and affected starch granule swelling. Sensory analysis indicated a preference for pasta containing smaller particles. Our results give new insight into the microstructural features responsible for the negative consumer appeal, and they could be used to guide future efforts in designing improved pasta formulations.