Suspended Particulate Matter Concentrations Research Articles

Insights into Mercury Source Identification and Bioaccumulation Using Stable Isotope Approaches in the Hannibal Pool of the Ohio River, USA.

Mercury contamination in river systems due to historic and current Hg releases is a persistent concern for both wildlife and human health. In larger rivers, like the Ohio River, USA, it is difficult to directly link Hg discharges to bioaccumulation due to the existence of multiple industrial Hg sources as well as the varied dietary and migratory habits of biota. To better understand how industrial effluent influences the cycling and bioaccumulation of Hg within the Ohio River, Hg stable isotope analysis was applied to various nonbiological and biological media. High Hg concentrations in suspended particulate matter suggest this vector was the largest contributor of Hg to the water column, and distinct Hg source signatures were observed in effluent particulates from different industrial processes, such as chlor-alkali activity (δ202 Hg = -0.52‰) and coal power plant discharge (δ202 Hg = -1.39‰). Despite this distinction, average sediments (δ202 Hg = -1.00 ± 0.23‰) showed intermediate isotopic signatures that suggest the accumulation of a mixed Hg source driven by multiple industrial discharges. Biota in the system were shown to have a conserved range of δ202 Hg and estimation approaches related these signatures back to particulate matter within Hannibal Pool. Mussels were found to conserve Hg isotopes signatures independently of food web drivers and served as ideal water column indicators of bioaccumulated Hg sources. This study highlights the complexity of Hg cycling within an industrialized river and shows that an isotope tracer approach can provide insight to water column sources of Hg. Integr Environ Assess Manag 2021;17:233-242. Published 2020. This article is a US Government work and is in the public domain in the USA.

Single tuned algorithm to estimate the SPM concentration in a cascade reservoir system using OLI/L8 images

Suspended particulate matter (SPM) affecting light propagation in the water column, which, in turn, affects primary production, is considered an important water quality indicator. Monitoring SPM in cascading reservoir system is of a particular challenge due to the widely differing optical properties. The Tietê River Cascade System (TRCS) is considered a representative case that comprises different water types with varying optical properties. At 1150 km long, the Tietê River crosses the State of São Paulo from East to West across a variety of land uses and land covers, which makes SPM monitoring of this system extremely challenging via traditional methods. This research aims to investigate the relationship between heterogeneous SPM configuration in the TRCS and the remote sensing reflectance (Rrs) by identifying the most suitable empirical model to quantify a wide range of SPM concentrations. Empirical models based on single-band and band ratios were tuned which is then applied to OLI/Landsat-8 images to estimate the SPM concentrations. We tested three approaches to obtain the best fit to retrieve the SPM concentration: the first approach (i) the dataset from the first fieldwork of each reservoir was used do calibrate and the others fieldworks data were used do validate the algorithm; the second (ii) all data from a single reservoir were selected for calibration and the others for validation and the third (iii) approach we used methods for randomly divide the calibration and validation dataset. The results showed that only approach (iii) returned significant results. The best algorithm to estimate the SPM concentration was based on the band ratio B3/B2 (SPM = 10.34 × [561 nm/482 nm]-12.32; with an r = 0.65). This algorithm resulted in the lowest error on average (RMSE = 6.5 mg/L, nRMSE = 32.97% and MAPE = 47.05%). The highest errors in retrieve the SPM were observed for reservoirs with dominance of phytoplankton; in fact, considering the dataset from all reservoirs the correlation between SPM and Chl-a was 0.95, proving that there are influence from the Chl-a pigment on the signal which increases the error. Therefore, a method to reduce the influence of phytoplankton on the remote sensing reflectance should be developed in order to reduce the error in retrieve the SPM concentration.

Spatial-temporal Variations and Driving of Nitrogen and Phosphorus Ratios in Lakes in the Middle and Lower Reaches of Yangtze River

In spring and summer of 2018, 26 lakes in the middle and lower reaches of the Yangtze River were studied to determine the temporal and spatial characteristics of nitrogen and phosphorus ratios (TN/TP) and their influencing factors. The differences in nitrogen and phosphorus ratios in different types of lakes (including water-psaaing lakes, deep reservoirs and eutrophic lakes) and in different seasons were analyzed in terms of the sources of the lakes, lake depth, suspended particulate matter concentrations, and phytoplankton levels. The average TN/TP was 21.52±14.28 in spring and 21.73±23.78 in summer. The TN/TP varied significantly in different types of lakes. The TN/TP ratios in water-passing lakes, deep reservoirs and eutrophic lakes were 20.41±9.25, 40.97±33.37, and 14.38±7.40 during spring, and were 22.62±6.48, 96.38±45.91, and 10.91±4.44 during summer, respectively. The TN/TP of the water-passing lakes and deep reservoirs increased significantly in summer, while that of the eutrophic lakes decreased significantly, which indicates that TN/TP changes and lake nutritional status are closely related. The source of nutrients in lakes and reservoirs affects the TN/TP. The TN/TP of lakes and reservoirs had a significant correlation with the lake depth in both spring and summer, indicating that lake depth is a key factor affecting the ratio of nitrogen and phosphorus. In addition, in eutrophic lakes with higher absolute nutrient concentrations, TN/TP has less effect on phytoplankton, while in deep-water lakes with lower absolute nutrient concentrations, TN/TP can determine the growth of phytoplankton limited by phosphorus. Therefore, the governance strategy of lakes in the middle and lower reaches of the Yangtze River should prioritize phosphorus control. Local digging, controlling non-point source pollution, sediment dredging, and changing fishery production methods can be applied to improve the ecological quality of the eutrophic lakes.

In situ Measurements of the Characteristics of Suspended Particles in the Barents Sea by the LISST-Deep Laser Diffractometer

The key indicators of marine sediment genesis are the particle size distribution (PSD) and volume concentration of suspended particulate matter (SPM). However, their study is not widespread in ship oceanology research. This paper reviews experience in using the LISST-Deep laser particle size analyzer for the study of marine SPM in situ. We present the first data on the volume concentration and PSD of SPM in the Barents Sea obtained during the 75th cruise of the RV Akademik Mstislav Keldysh in June 2019. We carried out an assessment of the adequacy of information display on the polydisperse system composition of the Barents Sea water body, which contains particles of a wide particle size spectrum of differing genesis and shape. This paper gives a regression and correlation analysis of LISST-Deep data with a Wet Labs turbidity meter and Multisizer 3 Coulter Counter, as well as the SPM mass concentration measured by the membrane filtration technique. All of them demonstrated reliable correlations between characteristics of SPM of the Barents Sea. Their correlation and determination coefficients varied from 0.6 to 0.8. The laser diffractometer produces more detailed vertical distributions of marine SPM parameters than does a turbidity meter, especially for euphotic zones. We found a significant correlation of LISST-Deep data with the concentration of dissolved oxygen, which increases for coarse–silty and sandy fractions (47.7–92.6 and 92.6–250 µm, respectively). Also, there is a correlation with SPM composition between parameters as organic carbon concentration and phytoplankton pigments. These correlations give some indirect indications of SPM composition from laser diffractometer measurements.

Reduction of Atmospheric Suspended Particulate Matter Concentration and Influencing Factors of Green Space in Urban Forest Park

In the process of urbanization in China, the problem of atmospheric suspended particulate matter pollution is becoming increasingly serious. It has been impossible to completely rely on pollution source control measures to solve this problem for a long time due to the diversity and complexity of pollution sources. Therefore, there is an urgent need to explore alternate solutions to significantly improve air quality through increasing the capacity of green space in cities as these locations can provide multiple ecosystem services. In this study, a three-dimensional classification system was created by utilizing Beijing’s urban forest as a study area. Considering the meteorological factors, change of month and time and the characteristics of the forest itself, the significance and difference of reducing the concentration of atmospheric suspended particulate matter by the forest with different vegetation structures were tested. The results showed that meteorological factors such as wind velocity, temperature, and relative humidity all had a very significant effect on the concentration of atmospheric suspended particulate matter in the conditions of this study. The concentration was highest in winter, followed by spring and autumn, and lowest in summer. The concentration in the morning was the lowest of the day, increasing in the noon and afternoon with time. It was the lowest in the closed single-layered mixed forest, and the highest in the open lawn green space. By comparing the forest with gradient areas of 0.5 ha and 3.0 ha, it was found that with the increase in the area, the green space did not necessarily show a better dust retention effect, and the vegetation structure type of the green space often had more important influence. There was a very significant correlation between vegetation structure and plant diversity (Shannon–Wiener Diversity Index and Simpson Diversity Index). Biodiversity could significantly support and strengthen urban forest ecological service functions that improve air quality. Increasing the plant species diversity could lead to lower particulate matter concentration. The research conclusions could provide theoretical and practical bases for how to select the combination of vegetation structure in the planning and design of urban forest oriented to improve air quality.

Organic Compounds and Suspended Particulate Matter in Snow of High Latitude Areas (Arctic and Antarctic)

Long-term studies of suspended particulate matter (SPM) and organic compounds (OCs)—Corg, lipids, hydrocarbons (aliphatic—AHCs and polycyclic aromatic—PAHs), and chlorophyll a in the snow cover of the Arctic (Franz Victoria Trough, Mendeleev Rise, White Sea) and Antarctica (in the coastal waters on fast ice and on the mainland near Russian stations) were generalized. It was shown that in the Arctic, the influence of continental air masses leads to an increase in OCs in snow. Therefore, despite the fact that the Franz Victoria Trough and the Mendeleev Rise are at the same latitude (82° N), the OCs content in the snow in the region of the Mendeleev Rise was lower for aliphatic hydrocarbons 5 and 14–18 μg/L. In the White Sea, the AHC content in the snow and the upper layers of the ice in the mouth of the Severnaya Dvina River and in the Kandalaksha Bay was higher than that in the lower layers of the ice and sharply decreased with distance from the emission sources. As a result, the snow was supplied mainly by pyrogenic PAHs. In the Antarctica, the lowest OCs levels in atmosphere were found in areas where coastal hills are covered with snow. The maximum SPM and AHCs concentration was found in the sludge (SPM—to 4.37 mg/L, AHC—to 33 μg/L). An increase in the concentration of OCs and SPM in snow sampled on the continent took place in the areas of stations and oases (St. Novolazarevskaya) where the predominance of mineral particles in the SPM was registered. In the area of the operating stations, mainly low molecular weight PAHs with the dominance of petroleum PAHs were found in the SPM of snow and in mosses.

COVID-19 and its impact on environment: Improved pollution levels during the lockdown period – A case from Ahmedabad, India

The novel Coronavirus pandemic (COVID-19) hit the world severely in the first half of 2020 which forced several nations to impose severe restrictions on all sorts of activities involving human population. People were mainly advised to remain home quarantined to curb the virus spread. Industrial and vehicular movements were ceased as a result of lockdown, and therefore the rate of pollutants entering the ecosystem was also reduced in many places. Water and air pollution remained a major concern in the last few decades as these were gradually deteriorating in many spheres including the hydrosphere and atmosphere. As the nation-wide lockdown period in India completed more than two months, this study attempted to analyze the impact of lockdown on water and air quality to understand the short-term environmental changes. Using remote sensing data, this study demonstrated the improvements in ambient water quality in terms of decreased turbidity levels for a section of the Sabarmati River in the Ahmedabad region of India. The Suspended Particulate Matter (SPM) concentrations are evaluated to underline the turbidity levels in the study area before and during the lockdown period using the Landsat 8 OLI images. We noticed that the average SPM has significantly decreased by about 36.48% when compared with the pre-lockdown period; and a drop of 16.79% was observed from the previous year's average SPM. Overall, the average SPM concentration during the lockdown period (8.08 mg/l), was the lowest when compared with pre-lockdown average and long-term (2015–2019) April month average. The atmospheric pollution level (NO2, PM2.5, and PM10) data obtained from the Central Pollution Control Board for Ahmedabad city also shows a significant improvement during the study period, implying a positive response of COVID-19 imposed lockdown on the environmental fronts.

Suspended particulate matter for sediment accumulation on inundated anthropogenic marshland in the southern North Sea – Potential, thresholds and limitations

Determining the availability of suspension load, i.e. suspended particulate matter (SPM), in shallow marine tidal systems is necessary to estimate whether coastal lowlands may experience vertical accretion rates that keep pace with global sea level rise. In particular anthropogenic marshland areas are affected by limitations of SPM accumulation due to artificial structures such as dikes and revetments that act as transport barriers.With the use of an autonomously operating turbidity measuring network installed at and around the Hallig Langeness in the North Frisian Wadden Sea, we have analyzed eight individual inundations on this island-like marshland during harsh weather conditions. The results reveal that the majority of the available SPM could not accumulate on the marshland due to adjacent coastal protection measures. This reduction in SPM affects especially grain sizes within the very fine to fine sand range between 63 and 200 μm that can account for up to 70% of the sampled SPM during an inundation. Furthermore, we have determined a tidal average SPM concentration threshold of 0.15 g/l should be available on the tidal flat in order to allow sufficient vertical marshland accretion. Although this threshold is exceeded by the determined SPM on the tidal flats around Langeness, the available SPM on the marshland after passing the coastal protection measures is at most 20%. Hence, an optimized coastal management strategy has the potential to increase the sediment accumulation rate on the marshlands by a factor of five, which might allow for keeping pace with local sea level rise.

Human impact on suspended particulate matter in the Yellow River Estuary, China: Evidence from remote sensing data fusion using an improved spatiotemporal fusion method

Transport of suspended particulate matter (SPM) in estuarine waters plays an important role in regulating erosion-accretion and biogeochemical processes. In the Yellow River Estuary (YRE), artificial water and sediment regulation scheme (WSRS) and coastal engineering structures are the 2 typical anthropogenic activities affecting the spatiotemporal dynamics of estuarine SPM. The monitoring of SPM transport affected by such human activities requires SPM mapping at both high spatial and high temporal resolutions. In this study, we presented an improved Flexible Spatiotemporal Data Fusion (FSDAF) strategy with consideration of highly dynamic SPM variations in estuarine waters, and generated 30-m hourly SPM concentrations based on Landsat 8 OLI and GOCI datasets. The new strategy produced higher SPM estimation accuracy than the original FSDAF, with the relative percentage difference (RPD) decreasing from 29.75% to 5.31% using GOCI-derived hourly SPM as reference. With in situ SPM measurements as reference, the fused SPM concentrations had an RMSE of 12.09 mg/L and an RPD of 27.17%. Investigation of interday SPM variations before, during, and after the WSRS in 2018 revealed that the first WSRS significantly increased the SPM concentration and plume extent; new wetland with an area of 12.56 km2 was formed due to sediment accretion near the river mouth. The two groins offshore from the coastlines on the north and south sides of YRE exhibited obvious sediment trapping effects in that higher SPM concentrations on one side of each groin were found regardless of the turbidity modes and diurnal SPM variations; the trapping effects were associated with the number of groins and groin length. Intraday variations of SPM were influenced by tidal currents, with plume direction following the ebb and flooding tidal current direction. The inter- and intraday characteristics of the 30-m hourly SPM dynamics facilitate the detailed analysis of the sediment transport associated with human activities.

Size‐Fractionated Compositions of Marine Suspended Particles in the Western Arctic Ocean: Lateral and Vertical Sources

AbstractWe present full water depth sections of size‐fractionated (1–51 μm; >51 μm) concentrations of suspended particulate matter and major particle phase composition (particulate organic matter [POM], including its carbon isotopic composition [POC‐δ13C] and C:N ratio, calcium carbonate [CaCO3], opal, lithogenic particles, and iron and manganese [oxyhydr]oxides) from the U.S. GEOTRACES Arctic Cruise (GN01) in the western Arctic in 2015. Whereas biogenic particles (POM and opal) dominate the upper 1,000 m, lithogenic particles are the most abundant particle type at depth. Minor phases such as manganese (Mn) oxides are higher in GN01 than in any other U.S. GEOTRACES cruises so far. Extremely depleted POC‐δ13C, as low as ~ −32‰, is ubiquitous at the surface of the western Arctic Ocean as a result of different growth rates of phytoplankton. Moderate penetration of depleted POC‐δ13C to depth indicates active sinking of large particles in the central basin. Lateral transport from the Chukchi shelf is also of significance in the western Arctic, as is evident from increases in biogenic silica to POC ratios and Mn oxide concentrations in the halocline, as well as lithogenic element contents in the deep waters. Our study supports previous suggestions of the near absence of CaCO3 in the Arctic Basin. This study presents the first data set of concentration and composition of suspended particles in the western Arctic Ocean and sheds new light on the vertical and lateral processes that govern particle distribution in this enclosed ocean basin.

Systematic evaluation framework and empirical study of the impacts of building construction dust on the surrounding environment

Dust generated by construction activities profoundly affects ambient air quality and could adversely affect the health of individuals living close to construction sites. However, there is no systematic evaluation framework for assessing its impact on the surrounding environment, making it difficult to meaningfully compare results for different construction projects, hindering comprehensive assessment and effective impact reduction decisions. Therefore, this paper proposes a systematic framework for evaluating and decision-making regarding the impact of building construction dust on the surrounding environment. To produce multi-angled and comprehensive evaluations, the framework uses three methods for measuring dust concentrations: with-without comparison assessment (WCA), dust incremental concentration assessment (DICA), and horizontal distance assessment (HDA). The framework is applied in an empirical case study examining six representative construction projects. The results show that the concentration of particulate matter (PM) in the surrounding environment is significantly affected by the state of construction; this effect is particularly visible in the concentration of total suspended particulate matter (TSP). During the monitoring period, the mean absolute concentrations of TSP, PM10 and PM2.5 downwind of the construction sites increased by 58.33 μg/m3, 15.83 μg/m3 and 6.50 μg/m3, respectively, corresponding to increases of 28.23%, 14.83% and 10.60% per day relative to the basis environment. With an average wind speed of 1.5 m/s, the influencing distances of building construction dust on downwind TSP, PM10 and PM2.5 concentrations are about 100 m, 50–100 m and 20–50 m respectively. The empirical study validates the proposed framework as a reliable guideline for evaluations and making reduction decision of the impact of construction dust on the surrounding environment.

The effects of a tailing dam failure on the sedimentation of the eastern Brazilian inner shelf

In the past several decades, anthropogenic changes throughout drainage basins have threatened physical, hydrological and ecological river-to-ocean continuum balances. Dams are one of these anthropogenic influences that can seriously affect sediment fluxes to the ocean. Here, we investigate the formation and dispersion of a high-concentration mud suspension (HCMS) at a river mouth due to a tailing dam failure. In November 2015, the Fundão dam (Mariana-MG, Southeast Brazil) failure released approximately 39.2 million m3 of tailings into the Doce River system. The slurry travelled 660 km down to the river mouth, reaching the Atlantic Ocean. Pre- and Post-dam failure surveys were used to investigate temporal and spatial changes in Suspended Particulate Matter (SPM) concentration, seabed sediment grain size and seabed sediment bulk density along the inner shelf. Results indicate that the combination of the tailing dam failure with an extremely dry seasonal condition led to the formation of a HCMS, altering, at least in a short term, the sedimentary processes along the inner shelf, leading to high sedimentation rates and low seabed sediment bulk density. Changes in particle size defined by an increase in clay content, a significant increase in SPM concentration in the inner shelf and a decrease in seabed sediment bulk density were observed as a result of the dam failure. SPM concentrations were higher near the seabed than at the surface, reaching up to 9000 mg/l. The highest SPM concentration measured during a major flood in January 2014 reached around 100 mg/l, The combination of a HCMS with tailings high clay content resulted in low values of seabed sediment bulk density and the formation of fluid mud along the inner shelf. In the first week after the tailings arrival, a 5 cm thick tailing fluid mud was observed. In this stage of bed formation, bed strength is lower, easing particle reentrainment by waves or currents. Thus, tailings could be advected, spreading the impact along the coast.

Particle–Seawater Interaction of Neodymium in the North Atlantic

Dissolved neodymium (Nd) isotopes (expressed as εNd) have been widely used as a water mass tracer in paleoceanography. However, one aspect of the modern biogeochemical cycle of Nd that has been sparsely investigated is the interplay between dissolved and particulate phases in seawater. We here present the first regional data set on particulate Nd isotope compositions (εNdp) and concentrations ([Nd]p) from five stations in the western North Atlantic Ocean along the GEOTRACES GA02 transect, in conjunction with previously published dissolved Nd isotope compositions (εNdd) and concentrations ([Nd]d)1. Key observations and interpretations from our new particulate data set include the following: (1) Low fractional contributions of [Nd]p to the total Nd inventory per volume unit of seawater (∼5%), with significant increases of up to 45% in benthic boundary layers. (2) Increasing Nd concentrations in suspended particulate matter ([Nd]SPM) and fractions of lithogenic material with water depth, suggesting the removal of Nd poor phases. (3) Different provenances of particulates in the subpolar and subtropical gyres as evidenced by their Nd isotope fingerprints reaching from εNdp ≈ −20 near the Labrador Basin (old continental crust), over εNdp ≈ −4 between Iceland and Greenland (young mafic provenance), to values of εNdp ≈ −13 in the subtropics (similar to African dust signal). (4) Vertical heterogeneity of εNdp as well as large deviations from ambient seawater values in the subpolar gyre indicate advection of lithogenic particles in this area. (5) Vertically homogeneous εNdp values in the subtropical gyre, indistinguishable from εNdd values, are indicative of predominance of vertical particulate supply. The process of reversible scavenging only seems to influence particulate signatures below 3 km. Overall, we do not find evidence on enhanced particle dissolution, often invoked to explain the observed increase in dissolved Nd in the North Atlantic.

Some respite for India's dirtiest river? Examining the Yamuna's water quality at Delhi during the COVID-19 lockdown period

The Yamuna's stretch within Delhi is considered as the dirtiest river reach in India and despite numerous restoration plans, pollution levels have risen unabated. However, the enforcement of a nationwide lockdown due to the ongoing COVID-19 pandemic can possibly provide a ray of hope. We analyze the lockdown's impact on the water quality status of this stretch using a combination of measured parameters and satellite image derived indices. Class C Water Quality Index estimates of nine stations indicate an improvement of 37% during the lockdown period. The Biological Oxygen Demand and Chemical Oxygen Demand values reduced by 42.83% and 39.25%, respectively, compared to the pre-lockdown phase, while Faecal Coliform declined by over 40%. Similar analysis of 20 major drains that meet the Yamuna revealed declining effluent loads and discernable improvements in drain contaminant status were ascertained via a hierarchical cluster analysis. Reach-wise suspended particulate matter content, turbidity and algal signatures were derived from multi-temporal Landsat-8 images of prior and ongoing lockdown periods for 117 channel segment zones. These parameters also declined notably within most stretches, although their extents were spatially varied. While the partial/non-operational status of most industries during the lockdown enabled significant reduction in effluent loads and a consequent betterment in the river water quality, its spatial variations and even deterioration in some locations resulted from the largely undiminished inflow of domestic sewage through multiple drains. This study provides an estimate of possible river recovery extents and degree of improvement if deleterious polluting activities and contaminants are regulated properly.

Assessment of Ventilation Efficiency in School Classrooms Based on Indoor–Outdoor Particulate Matter and Carbon Dioxide Measurements

The concentration of indoor suspended particulate matter is considered to be one of the main factors that affect health and quality of life. In Poland, in response to the pressure of public opinion, a few thousand air purifiers have been installed in public buildings where children spend time. However, another factor that also impacts upon the quality of indoor air, namely increased CO2 mixing ratios, is frequently overlooked. The only way to remove CO2 excess from interiors is through intensive ventilation. This is often an action at odds with the need to maintain low concentrations of particulate matter in indoor air. Two methods are presented to assess the rate of air exchange using CO2 or particulate matter as a tracer. One of the methods using indoor/outdoor PM (particulate matter) concentrations is based on the use of box models for analysis. The second one uses indoor CO2 concentration change analysis. At the tested locations, they showed large deviations of the determined values of the air exchange coefficients from its limits. Both methods showed consistent ventilation parameters estimation.

Long-Term Exposure to Particulate Matter and Mortality from Cardiovascular Diseases in Japan: The Ibaraki Prefectural Health Study (IPHS).

Aim: To examine the association between long-term exposure to suspended particulate matter (SPM) and cardiovascular mortality in Japan after controlling for known major confounding factors among a large middle and elderly cohort study in Ibaraki Prefecture, Japan.Methods: We followed 91,808 residents (men 34%) who undertook a national health check-up at age 40–79 years for 17 years (1993–2010). Two different exposure indices were adopted: baseline SPM concentration (in the year 1990) and average SPM concentration for the first (average of 1990 and 1995) and the second half (average of 2005 to 2009) of the study period. Sex-specific adjusted risk ratios (RRs) for cardiovascular mortality were calculated using general mixed Poisson regression models after adjusting the age, BMI, history of diabetes mellitus and hypertension, creatinine, glutamic pyruvic transaminase, total cholesterol, high-density lipoprotein cholesterol, smoking, alcohol, and temperature. The variation between seven medical administration areas was also taken into account as a random effect.Results: Baseline SPM concentration was associated with an increased risk of mortality from all cardiovascular diseases, coronary artery disease, and stroke. The adjusted RRs (95% confidence interval [CI]) per 10 µg/m3 increase in SPM concentration for all cardiovascular mortality were 1.147 (1.014–1.300) for men and 1.097 (0.985–1.222) for women. The point estimate of RR was highest for non-hemorrhagic stroke in men (1.248 [0.991–1.571]), although CI overlapped the unity. The RRs seemed slightly lower in the second half than in the first half, though the CIs widened in the second half.Conclusion: Our results suggest that long-term exposure to SPM is associated with an increased risk of all cardiovascular mortality for men in Ibaraki, Japan.

Intratidal and spatial variability over a slope in the Ems estuary: Robust along-channel SPM transport versus episodic events

Results from measurements are presented that were collected during a full tidal cycle in the Ems estuary, involving two landers and an anchored research vessel. The conditions were characterized by very weak winds, no wave effects, and low river run-off, so that the state was close to tide-only. We find that the lateral (i.e., cross-slope) transport of water and suspended particulate matter (SPM) much of the time shows a vertically layered structure, which is however subject to sudden transitions. Moreover, even on the small spatial scale of these measurements (i.e., within a distance of 200 m), a strong lateral variability is observed in the circulation patterns. We analyze its dynamics by means of dimensionless parameters. In addition, near-bottom peaks in SPM concentration are observed, notably during early flood. However, these episodic events have little effect on the overall transport of SPM, which involves the whole water column: the measurements show a high vertically integrated SPM signal during late ebb, resulting in an ebb-dominance in the transport at this position in the tidal channel.

An Algorithm to Estimate Suspended Particulate Matter Concentrations and Associated Uncertainties from Remote Sensing Reflectance in Coastal Environments

Suspended Particulate Matter (SPM) is a major constituent in coastal waters, involved in processes such as light attenuation, pollutant propagation, and waterways blockage. The spatial distribution of SPM is an indicator of deposition and erosion patterns in estuaries and coastal zones and a necessary input to estimate the material fluxes from the land through rivers to the sea. In-situ methods to estimate SPM provide limited spatial data in comparison to the coverage that can be obtained remotely. Ocean color remote sensing complements field measurements by providing estimates of the spatial distributions of surface SPM concentration in natural waters, with high spatial and temporal resolution. Existing methods to obtain SPM from remote sensing vary between purely empirical ones to those that are based on radiative transfer theory together with empirical inputs regarding the optical properties of SPM. Most algorithms use a single satellite band that is switched to other bands for different ranges of turbidity. The necessity to switch bands is due to the saturation of reflectance as SPM concentration increases. Here we propose a multi-band approach for SPM retrievals that also provides an estimate of uncertainty, where the latter is based on both uncertainties in reflectance and in the assumed optical properties of SPM. The approach proposed is general and can be applied to any ocean color sensor or in-situ radiometer system with red and near-infra-red bands. We apply it to six globally distributed in-situ datasets of spectral water reflectance and SPM measurements over a wide range of SPM concentrations collected in estuaries and coastal environments (the focus regions of our study). Results show good performance for SPM retrieval at all ranges of concentration. As with all algorithms, better performance may be achieved by constraining empirical assumptions to specific environments. To demonstrate the flexibility of the algorithm we apply it to a remote sensing scene from an environment with highly variable sediment concentrations.

Sphagnum: a promising indoor air purifier

In the present era, where pollution levels are alarmingly high and mankind is facing newer and newer diseases due to high levels of pollution, suspended particulate matter (SPM) leads to many respiratory diseases. In this work, the effectiveness of Sphagnum cymbifolium on indoor SPM concentration levels was studied under different conditions – namely, dark, sunlight and smoky conditions. S. cymbifolium was found effective in reducing the concentration of SPM in the environment, particularly indoors and in indoor smoky environments. Some further research areas are also proposed.

Observations of the distribution and flocculation of suspended particulate matter in the North Yellow Sea cold water mass

Flocculation has a great influence on the biogeochemical cycle by altering the particle size, density and settling velocity of suspended particulate matter (SPM) from coastal to shelf sea areas. However, the flocculation process in the shelf sea areas of China has not been systematically studied. In this study, the influencing mechanism of the North Yellow Sea cold water mass (NYSCWM) on the distribution and flocculation process of SPM is studied based on a comprehensive investigation during the summer of 2016. The results revealed that the mass concentration and turbidity of SPM showed a decreasing trend from coastal to offshore areas and an increasing trend from surface to near-benthic layers. Sediments from the Shandong subaqueous clinoform that were resuspended by the tidal mixing effect were the main source of inorganic SPM in the North Yellow Sea in summer. The existence of the bottom cold water mass enhanced the thermocline and pycnocline in the North Yellow Sea shelf area. The pycnocline obstructed the vertical diffusion of nutrients in the NYSCWM, resulting in a subsurface maximum chlorophyll a (chl a) layer, which further contributed to the maximum subsurface volume concentration of SPM. Flocculation was ubiquitous in the study area and was the main reason for the asynchronous variability in the mass concentration, turbidity and volume concentration of SPM. Three different kinds of flocculation mechanisms were identified, including the effects of biological activities in water masses above the NYSCWM, physicochemical effects in the near-benthic nepheloid layer within the NYSCWM, and their combined effects in shallow coastal areas. The flocculation of SPM enhanced the transport of particles from the surface to the bottom of the water column and made an important contribution to the formation of the North Yellow Sea mud deposit.