Suspended Soil Research Articles

Demonstration of the ability of the bacterial polysaccharide FucoPol to flocculate kaolin suspensions

ABSTRACTIn this study, the flocculation properties of FucoPol, a bacterial extracellular polysaccharide, were investigated. FucoPol is a high molecular weight polymer and negatively charged due to the presence of glucuronic acid and the acyl groups succinyl and pyruvyl. High flocculation rate values (>70%) were achieved with a low bioflocculant dosage of 1 mg/L, for pH values in the range 3–5 and temperature within 15–20°C. The bioflocculant was also shown to be stable after freezing/thawing and heating up to 100°C. Given the polymer’s anionic character, the size of flocs formed and their surface profile, bridging seems to be the main flocculation mechanism of FucoPol. This study demonstrated that FucoPol is a promising natural, biodegradable and biocompatible alternative to the currently used synthetic or inorganic hazardous products, with potential to be used as a novel flocculation agent in several applications, such as water treatment, food or mining. Further studies will involve evaluating the reduction of cation dosage on flocculation efficiency, as well as testing the applicability of FucoPol to flocculate different types of suspended solids, such as, for example, activated carbons, soil solids or yeast cells.

Study on optimization of co-digestion process parameters for enhancing biohydrogen production using response surface methodology

ABSTRACTIn the present study, batch anaerobic co-digestion experiment was conducted with dairy secondary clarifier waste activated sludge as substrate and anaerobic digested municipal waste activated sludge as seed sludge for enhancing biohydrogen rate. The statistical tools were used to study the effect of co-digestion process parameters (pH, seed sludge, temperature, and digestion time) on mixed liquor suspended soils (MLSS) reduction % and chemical oxygen demand (COD) solubilization %. The maximum of MLSS reduction and COD solubilization obtained at global optimal condition (pH 6, temperature 40°C, seed sludge 35 ml, and digestion time 30 days) determined, respectively, were 22.7 and 28.02%. Subsequently, the production data of cumulative biohydrogen were fitted with modified Gompertz equation and the biohydrogen kinetic parameters were determined.

Bacterial community dynamics involved in Reactive Orange M2R dye degradation using a real time quantitative PCR and scale up studies using sequence batch reactor

ABSTRACTBacterial consortium volatile suspended soil (VSS) (Vatva soil sample) with a capability of azo dye Reactive Orange M2R (ROM2R) decolorization and degradation (shown in our earlier studies using Fourier transform infrared spectroscopy (FTIR) and phytotoxicity studies) was isolated from industrial wastewaters by enrichment culture technique. The present study was carried out to study bacterial population dynamics in consortium Vatva soil sample (VSS) during azo dye ROM2R degradation and to identify the consortium members that were actively involved in the degradation process. To achieve this goal, a real-time Polymerase chain reaction (PCR) assay targeting species-specific region of 16S rDNA of each consortial bacteria was developed to provide quantitative information about the bacterial abundance during azo dye degradation. The real-time PCR assay indicated that Pseudomonas aeruginosa (VSS-6) dominated consortium bacterial community during the active continuous bioremediation process. Attempt has been made to scale up from 100 ml volume to 10 L operation volume with intermittent additions (batch fed loadings) in a Sequence batch reactor (SBR). The development of VSS consortium biomass (MLVSS), changes in COD and biochemical oxygen demand, and the dye degradation were studied under conditions simulating the operations of biological effluent treatment in an attempt to develop a commercially applicable dye effluent treatment process unit.

Partitioning of Ag and CeO2 nanoparticles versus Ag and Ce ions in soil suspensions and effect of natural organic matter on CeO2 nanoparticles stability

This study examined the solid-liquid distribution of 14.8-nm Ag and 6.2-nm CeO2 nanoparticles in soil suspensions and compared it to that of Ag+ and Ce3+ ions, to better understand their environmental behaviour and fate. After 24 h incubation, more than 51% or 29% of the spiked amounts of Ag or CeO2 nanoparticles, respectively, can be retrieved in the liquid phase of (re)suspended soils. The Ag or Ce concentration remaining in solution depends on the incubation time and was influenced by soil properties. Significant correlations are obtained between, on the one hand, the relative amounts of Ag or CeO2 nanoparticles in suspension and the soil-pH, CEC, texture, suspended matter, nitrogen, phosphorus, TOC and main and trace elements content on the other hand. The presence of dissolved natural organic matter stabilizes CeO2 nanoparticles in the aqueous phase. In soil suspensions, Ag+ and Ce3+ ions seemingly interact more strongly with soil constituents compared to their nanoparticle counterparts, rendering the Ag and CeO2 nanoparticles to be more stable and potentially bioavailable.

Humification and Humic Acid Composition of Suspended Soil in Oligotrophous Environments in South Vietnam

Humification is considered to be a global process that is implemented in soils and organic sediments and also in natural water and air. The term “suspended soils” has become increasingly common in recent years. Suspended soils are defined as the part of the organic matter that has not undergone the full decomposition process and has not turned into the humus of terrestrial soils. Suspended soils were shown to contain higher total nitrogen, phosphorus, and potassium contents than the forest soil, but the moisture content in suspended soils was significantly lower. Our study of the structural composition of humic substances in suspended soils was conducted with an aim of evaluating the humification rates and structural composition of humic acids in the suspended soil in tropical forests of South Vietnam. Soil samples from three selected areas were investigated: the soil under phorophytes (mineral soil presented by samples of topsoil of the typical dry savanna landscape) and two soils from epiphytous formations. Samples were collected from savanna-type sparse communities, located on oligotrophous plains in Phú Quốc Island (South Vietnam) in 2015. General properties of the soil and the elemental composition of suspended soils were determined, and the humic substance chemical composition was evaluated using solid state 13C-NMR. Data obtained showed that the pH of the soils under phorophytes was higher than in the suspended soils; basal respiration did not tend to change indices between soils under phorophytes and suspended soils, but the suspended soil was less enriched by nitrogen than the soil under phorophytes. This can be related to the total amount of organic matter exposed to humification in various soils and to the presence of an essential portion of mineral particles in the soil under phorophytes. Data on elemental composition of the humic acids (HAs) indicated that one method of humification is implemented in all three soils that were investigated. The humic acids of the phorophyte soil showed the same content of aromatic fraction as the suspended soil. The most comparable soil type in terms of humic substance composition is Cambisols from humid forests of subboreal and subtropical zones. The humification process implemented in suspended soils showed the absence of mineral compounds or mineral fine earth, which indicated that humification in conditions of pure organic substrates can result in formation of deep humified organic matter, as shown by humic acids with an essential aromatic fraction content.

Dissolved and suspended solids in aquaculture.

Abstract A few major ions contribute most of the weight of dissolved solids in water. Direct determination of total dissolved solids (TDS) concentration is tedious, and the electrical conductivity of freshwater and the salinity of saline water are common surrogates for TDS in aquaculture. The primary concern over dissolved solids is maintaining TDS concentration within a range that allows effective osmoregulation by culture species. There is usually more concern over TDS concentration in inland, saline water or brackishwater aquaculture than in freshwater aquaculture. The handheld salinity refractometer is used almost exclusively to measure the salinity of saline waters for aquaculture. Suspended solids comprise mineral soil particles, living microorganisms (especially phytoplankton) and decaying organic matter cause turbidity, and amount of suspended solids is usually assessed from water clarity as determined with a Secchi disk. Turbidity limits light penetration and restricts the depth to which photosynthesis may occur. Turbidity from suspended soil particles usually is a negative factor while plankton turbidity normally is a positive factor in fertilized ponds. Nevertheless, in fertilized ponds or un-aerated ponds with feeding, excessive plankton turbidity causes low nighttime dissolved oxygen concentrations. Turbidity from suspended soil particles may be beneficial by reducing light penetration for phytoplankton growth in mechanically-aerated ponds with feeding, but soil particles suspended by aeration settle creating zones of organically-enriched sediment. Such sediment may result in anaerobic areas from which microbial respiration releases toxic metabolites. Methods of managing dissolved and suspended solids and sediment are summarized.

Measuring hydrological connectivity inside a soil by low field nuclear magnetic resonance relaxometry

AbstractHydrological connectivity inside the soil is related to the spatial patterns inside the soil (i.e., the structural connectivity). This, in turn, is directly associated with the physical and the chemical processes at a molecular level (i.e., the functional connectivity). Nuclear magnetic resonance (NMR) relaxometry can be successfully applied to reveal both structural and functional components of soil hydrological connectivity. In the present study, the low field NMR relaxometry was applied on water suspended soils sampled at the upstream‐ and downstream‐end of three different length plots. Also the sediments collected from the storage tanks at the end of each plot were water suspended and monitored by NMR relaxometry. The results from the NMR investigations were elaborated by using a mathematical approach in order to quantify both the functional and structural connectivity components. In particular, following integration of the T1 distribution curve, an S‐shaped curve was obtained. It revealed two plateaus corresponding to the shortest (low component) and the longest (high component) intervals of relaxation times, respectively. According to relaxometry theory, the two T1 intervals, associated to the different plateaus, were attributed to micro and macro soil pores, respectively. The two T1 intervals were used to define a functional connectivity index, while the central part of the S‐shaped distribution was used to define a structural connectivity index. Here we provide the physical meaning of the our mathematical approach, thereby revealing that functional connectivity index increases with plot length, as a result of a selective eroded particle transport. Moreover, the relationship structural connectivity index versus plot length resulted quasi‐independent of grainsize distribution, whereas the values of the structural connectivity index for the sediment samples resulted lower than those obtained for the corresponding soils.

Physical Conditions Regulate the Fungal to Bacterial Ratios of a Tropical Suspended Soil

As a source of ‘suspended soils’, epiphytes contribute large amounts of organic matter to the canopy of tropical rain forests. Microbes associated with epiphytes are responsible for much of the nutrient cycling taking place in rain forest canopies. However, soils suspended far above the ground in living organisms differ from soil on the forest floor, and traditional predictors of soil microbial community composition and functioning (nutrient availability and the activity of soil organisms) are likely to be less important. We conducted an experiment in the rain forest biome at the Eden Project in the U.K. to explore how biotic and abiotic conditions determine microbial community composition and functioning in a suspended soil. To simulate their natural epiphytic lifestyle, bird’s nest ferns (Asplenium nidus) were placed on a custom-built canopy platform suspended 8 m above the ground. Ammonium nitrate and earthworm treatments were applied to ferns in a factorial design. Extracellular enzyme activity and Phospholipid Fatty Acid (PLFA) profiles were determined at zero, three and six months. We observed no significant differences in either enzyme activity or PLFA profiles between any of the treatments. Instead, we observed decreases in β-glucosidase and N-acetyl-glucosaminidase activity, and an increase in phenol oxidase activity across all treatments and controls over time. An increase in the relative abundance of fungi during the experiment meant that the microbial communities in the Eden Project ferns after six months were comparable with ferns sampled from primary tropical rain forest in Borneo.

Geochemical characteristics and organic carbon sources within the upper reaches of the Xi River, southwest China during high flow

Carbon (POC, DOC) and carbon isotopes (δ13C) within two headwater tributaries to the Xi River Basin, southwest China were analyzed to document the geochemical characteristics and sources of organic carbon (C) within basins characterized by a monsoonal climate and karst landforms. δ13 C POC value and C/N ratio data indicate that suspended soil organic carbon (SOC) was an important source of POC in both the Nanpan and Beipan rivers (i.e., the studied tributaries). However, differences in C sources exist between the Nanpan and Beipan River Basins. Higher terrestrial plants supplied a portion of the POC within the Beipan River. In contrast, the Nanpan River was characterized by an inverse correlation between POC and DOC, and a positive relationship between the δ13C values. These trends indicate that DOC within the Nanpan River was partly derived from the degradation of soil C within the water column. In addition, the interception of C by hydrological projects (e.g., dams) positioned along the Nanpan River led to higher DOC/POC ratios. In contrast, within the Beipan River δ13C DOC values range from −20 to −25.2 ‰ and are consistent with ratios associated with soil C, suggesting that leaching of C from catchment soil was the dominant source of DOC. Organic C in tributaries to the Beipan River may also have been derived from intense upland soil erosion, a process that resulted in the lowest DOC/POC ratios. The collected data indicate that land-use changes have potentially influenced regional- to local-scale organic C budgets within subtropical basins subjected to karstification.

Sources and cancer risks assessment of polycyclic aromatic hydrocarbons in particulate matter and surface soils in Kunming, China

The concentrations, possible sources and cancer risks of polycyclic aromatic hydrocarbons (PAHs) in fine particulate matter (PM2.5), total suspended particles (TSP) and surface soils collected from the same sampling spots were analysed in Kunming, China. The total PAH concentrations in PM2.5, TSP and surface soil were 7.44-25.64 ng/m3, 17.73-48.35 ng/m3 and 72.16-442.40 ng/g dry weight, respectively. Pyrogenic origins (especially coal, wood and fossil fuel combustion) were identified as the main sources of PAHs in particulate matter (PM) and surface soils based on the diagnostic ratios and principal component analysis (PCA). The values of incremental lifetime cancer risk (ILCRs) that exposed to PAHs in PM2.5 were slightly larger than 10−4, indicating high potential of carcinogenic risk. And the values of ILCRs showed that particle-bound PAHs with higher potential carcinogenic ability than soil PAHs. Moreover, compared with adults, the values of cancer risk among children were always higher.

Стадії ґрунтотворення підвісних ґрунтів Верховинського вододільного хребта Українських Карпат

It was found out that suspended soils in Verkhovyna Dividing Range in Ukrainian Carpathians are intrazonal ones and are formed near dense sandstones outcrops in Krosnenska zone provided excess moisture of flushing type of water regime. Suspended soils are located within the mountain-forest and subalpine zones under moss lichen communities. They form habitats ranging from 0.1 to 1.0 square meter, oval and oblong shaped with the highest capacity of organic horizon in the central part with gradual reduction to the periphery. Suspended soils in Ukrainian Carpathians were mentioned for the first time in writings of Professor A. Zrazhevskyi. Formation of suspended soils in dense sandstones within Verkhovyna Dividing Range can occur in two ways: initial (primary) soil development and settlement of moss lichen communities from adjacent soil areas. Main stages of formation of soils under research are detected analyzing the succession of plant communities and morphological features of each section. Initial stage begins with the settlement of alga, bacteria, fungi, actinomyces, lichens (crustose and foliose) in centres of soil formation and formation of humified layer of dark gray colour up to 2 cm thick. Moss settlement on the developed organo-mineral layer and formation of organic (peat) horizon marks the beginning of development stage. Soils under research with formed organic horizon up to 10 cm thick are to be classified as initial suspended soils. The development stage is accompanied by accumulation of defunct organic remains (peat formation) and expansion of organic horizon (Td+T). Soils formed in Krosnenska zone in mild wind-blown sandstones with organic horizon more than 10 cm thick are at the stage of equilibrium functioning. It is advisable to define these soils as peat-suspended soils. Suspended soils are not represented in the nomenclature list of soils of Ukraine, that encourages conducting more detailed research on their classification. Patterns of distribution of soils under research and stages of soil formation were found out. Key words: Verkhovyna Diving range, suspended soils, the formation of peat, genesis, stages of soil formation.

Effectiveness in the Removal of Organic Compounds from Municipal Landfill Leachate in Integrated Membrane Systems: Coagulation – NF/RO

ABSTRACTThe article presents the results of studies concerning the hydraulic permeability of integrated membrane systems during the treatment of municipal landfill leachate. The laboratory-scale experiments were conducted to determine the effectiveness of coagulation as a pretreatment option for treating stabilized landfill leachate and effectiveness of nanofiltration (NF) and reverse osmosis (RO) processes. The municipal landfill leachates were analyzed for the concentration of the following: polycyclic aromatic hydrocarbons (PAHs), nitrate nitrogen, ammonium nitrogen, chemical oxygen demand (COD), total organic carbon (TOC), total carbon (TC), suspended soils (SS), turbidity, pH. The commercially available coagulant – aluminum sulfate Al2(SO4)3·18H2O (alum) was used as a coagulant. The NF process was carried out at the transmembrane pressure of 1.5 MPa. The membrane separation process was based on a thin film membrane (DK). The transmembrane pressure of the RO stood at 2 MPa and for this process one polyamide membrane (AG) was used. The level of leachate treatment was defined for raw and cleaned wastewater indicators. Both NF and RO membranes allowed obtaining the high level of pollutants removal. In the coagulation–NF system, the removal efficiency was equal to 77% for PAHs, 88% for COD, 72% for ammonium nitrogen, 80% for nitrate nitrogen, 67% for TOC, 80% for TC, 96% for SS and during the RO – 86% for PAHs, 98% for COD, 93% for ammonium nitrogen, 87% for nitrate nitrogen, 89% for TOC, 100% for TC, 98% for SS. The calculations based on the assumptions of the mathematical filtration model (relaxation) made it possible to predict the efficiency of commercial filtration membranes used for leachate treatment.

Radioactive Cs in the estuary sediments near Fukushima Daiichi Nuclear Power Plant

The migration and dispersion of radioactive Cs (mainly 134Cs and 137Cs) are of critical concern in the area surrounding the Fukushima Daiichi Nuclear Power Plant (FDNPP). Considerable uncertainty remains in understanding the properties and dynamics of radioactive Cs transport by surface water, particularly during rainfall-induced flood events to the ocean. Physical and chemical properties of unique estuary sediments, collected from the Kuma River, 4.0km south of the FDNPP, were quantified in this study. These were deposited after storm events and now occur as dried platy sediments on beach sand. The platy sediments exhibit median particle sizes ranging from 28 to 32μm. There is increasing radioactivity towards the bottom of the layers deposited; approximately 28 and 38Bqg−1 in the upper and lower layers, respectively. The difference in the radioactivity is attributed to a larger number of particles associated with radioactive Cs in the lower part of the section, suggesting that radioactive Cs in the suspended soils transported by surface water has decreased over time.Sequential chemical extractions showed that ~90% of 137Cs was strongly bound to the residual fraction in the estuary samples, whereas 60~80% of 137Cs was bound to clays in the six paddy soils. This high concentration in the residual fraction facilitates ease of transport of clay and silt size particles through the river system. Estuary sediments consist of particles <100μm. Radioactive Cs desorption experiments using the estuary samples in artificial seawater revealed that 3.4±0.6% of 137Cs was desorbed within 8h. More than 96% of 137Cs remained strongly bound to clays. Hence, particle size is a key factor that determines the travel time and distance during the dispersion of 137Cs in the ocean.

Distribution, compositional pattern and sources of polycyclic aromatic hydrocarbons in urban soils of an industrial city, Lanzhou, China

The level, distribution, compositional pattern and possible sources of polycyclic aromatic hydrocarbons (PAHs) in Lanzhou urban soil of Northwest China were investigated in this study. The total level of 22 PAHs ranged from 115 to 12,100µgkg−1 and that of 16 priority PAHs from 82.4 to 10,900µgkg−1. Seven carcinogenic PAHs generally accounted for 6.18–57.4% of total 22 PAHs. Compared with data from those reported about urban areas, PAH contamination in Lanzhou urban soils was moderate. Among different functional areas, higher level of PAHs was found along roadsides and in the industrial district (p<0.01), while lower levels were detected in the commercial, park and residential districts. The composition of PAHs was characterized by high molecular weight PAHs (≥4 rings), among which fluoranthene, benz[a]anthracene and phenanthrene were the most dominant components. Correlation analysis suggested that low molecular weight PAHs and high molecular weight PAHs originated from different sources and further corroborated that TOC was an important factor in the accumulation of PAHs in soil. Isomer ratios and principal component analysis indicated that PAHs in urban soil derived primarily from emissions resulting from the combustion of biomass, coal and petroleum products. Toxic equivalent concentrations (BaPeq) of soil PAHs ranged from 6.12 to 1302µgBaPeqkg−1, with a mean of 138µgBaPeqkg−1. The results suggested that human exposure to those soils which polluted by high concentrations of PAHs through direct ingestion or inhalation of suspended soil particles probably poses a significant risk to human health from the carcinogenic effects of PAHs.

MORPHOLOGICAL EFFECT OF FLOOD WATER PATHWAY IN RESERVOIRS ON THE DISTRIBUTION OF SEDIMENTATION

In the North Africa countries, sediments deposition in the reservoir dams reduces the available surface water resources by 2 to 5% per year. In Tunisia, even many efforts are made to protect reservoir dams against soil erosion, the sedimentation still very important and constitute a limitation their time duration. In order to better understand these phenomena, bathymetry, turbidity, suspended soil particles and sediments were monitored for two reservoir dams in Tunisia: Joumine and Sejnane. These data will be interpreted in order to better characterize the sedimentation process and identify the determinant factors. Geostatistical Technics are applied to the bathymetric data in order to simulate the evolution, in time and in space, of the morphology of the reservoir dams and to estimate the distribution of the sediments deposits. The results for the two dams will permit to better understand the influence of the initial geometry of the reservoir dams on the sedimentation process and to deduce the main water flow path lines. Turbidity, suspended particles and sediments particles size profiles established for fixed stations in the reservoir dams will be interpreted in order to better understand the sedimentation process in the reservoirs dams and to characterize the influence of the initial reservoir geometry.

MORPHOLOGICAL EFFECT OF FLOOD WATER PATHWAY IN RESERVOIRS ON THE DISTRIBUTION OF SEDIMENTATION

In the North Africa countries, sediments deposition in the reservoir dams reduces the available surface water resources by 2 to 5% per year. In Tunisia, even many efforts are made to protect reservoir dams against soil erosion, the sedimentation still very important and constitute a limitation their time duration. In order to better understand these phenomena, bathymetry, turbidity, suspended soil particles and sediments were monitored for two reservoir dams in Tunisia: Joumine and Sejnane. These data will be interpreted in order to better characterize the sedimentation process and identify the determinant factors. Geostatistical Technics are applied to the bathymetric data in order to simulate the evolution, in time and in space, of the morphology of the reservoir dams and to estimate the distribution of the sediments deposits. The results for the two dams will permit to better understand the influence of the initial geometry of the reservoir dams on the sedimentation process and to deduce the main water flow path lines. Turbidity, suspended particles and sediments particles size profiles established for fixed stations in the reservoir dams will be interpreted in order to better understand the sedimentation process in the reservoirs dams and to characterize the influence of the initial reservoir geometry.

MORPHOLOGICAL EFFECT OF FLOOD WATER PATHWAY IN RESERVOIRS ON THE DISTRIBUTION OF SEDIMENTATION

In the North Africa countries, sediments deposition in the reservoir dams reduces the available surface water resources by 2 to 5% per year. In Tunisia, even many efforts are made to protect reservoir dams against soil erosion, the sedimentation still very important and constitute a limitation their time duration. In order to better understand these phenomena, bathymetry, turbidity, suspended soil particles and sediments were monitored for two reservoir dams in Tunisia: Joumine and Sejnane. These data will be interpreted in order to better characterize the sedimentation process and identify the determinant factors. Geostatistical Technics are applied to the bathymetric data in order to simulate the evolution, in time and in space, of the morphology of the reservoir dams and to estimate the distribution of the sediments deposits. The results for the two dams will permit to better understand the influence of the initial geometry of the reservoir dams on the sedimentation process and to deduce the main water flow path lines. Turbidity, suspended particles and sediments particles size profiles established for fixed stations in the reservoir dams will be interpreted in order to better understand the sedimentation process in the reservoirs dams and to characterize the influence of the initial reservoir geometry.

Construction techniques for bored piling in sand using polymer fluids

This paper is concerned with the use of polymer fluids for the construction of bored piles in silty fine sand, a situation which has been found to significantly increase the risk of ‘soft toes' and concrete contamination due to the settling of the suspended soil particles in the fluid. To illustrate how these problems can be avoided by adopting a simple fluid-testing regime and improved construction practice, this paper presents a case history of polymer use at a site in Glasgow where the ground conditions consist of silty fine sand. Fluid testing showed that the used polymer fluid was heavily laden with soil particles and that cleaning using chemical additives alone was not sufficient to reduce the amount of suspended solids to an acceptable level. The pile bores were therefore left open overnight to allow the particles to settle out of suspension, the effect of which was confirmed by further fluid testing. The settled solids were removed with a base cleaning bucket. Structural integrity tests conducted on over 50 working piles constructed using this method showed no sign of defects. High-strain dynamic loading tests on two completed piles also confirmed their performance despite the extended pile bore open period.

A new simple, low-cost approach for generation of the PM10 fraction from soil and related materials: Application to human health risk assessment

A new simple, robust and low-cost wet laboratory method for the generation of the <10μm (PM10) particle size fraction is reported. A sedimentation method is directly compared with a centrifugation method for generation of the PM10 fraction. Both approaches are based on an integrated form of Stokes’ law. Subsequently the sedimentation method was adopted. The results from the sedimentation method were corroborated using particle size distribution measurements. This approach for the generation of the PM10 fraction was applied to soil and mine waste samples from Mitrovica, Kosovo as part of an investigation in to the human risk assessment from inhalation of the PM10 fraction containing potentially harmful elements (PHEs). The average daily dose for Cd from the inhalation of suspended soil particles was calculated to be 0.021 and 0.010μgkg−1BWd−1 for a child and an adult, respectively. This corresponded to an inhalation dose of 0.50 and 0.70μg Cdd−1 for a child (20kg) and an adult (70kg), respectively.

Deposition and Mineralogical Characteristics of Atmospheric Dust in relation to Land Use and Land Cover Change in Delhi (India)

This study highlights that the increasing urbanization and industrialization in Delhi are responsible for higher fluxes of atmospheric dust and its chemical constituents. Delhi has experienced a drastic change in land use and land cover area during the past two decades. Road lengths of the city have increased by 76% from 1985 to 2011. The number of mobile vehicles has reached 80,52,508 in 2014 from 24,32,295 in 1994. The industrial units in Delhi have increased by 39.54% in 2011 as compared to 1994 value. Atmospheric dust which is originated from soil in this region becomes carbon rich due to interaction of suspended soil with atmospheric pollutants. Emissions of carbonaceous aerosols from coal and petroleum combustions are mainly responsible for silica dominated soil dust transforming into carbon rich particulate matter. Such dust may play very important role in the atmosphere having significant influence on human health, global warming, climate change, radiative forcing, visibility, and cloud formation. It is expected that if the rate of development remains the same, green cover of the city invariably will be sized down in order to meet the demand of housing, transportation, industries, and so forth in proportion to the rising population.