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Objective: We sought to evaluate several methods of operation of a foam fractionator for fine‐solids removal (organic matter < 55 μm) in a commercial‐scale, low‐salinity (11–13‰) recirculating aquaculture system (RAS) for marine finfish production. Methods: The total suspended solids (TSS) concentrations of the RAS microscreen drum filter inflow and outflow and the foam fractionator outflow were obtained under various foam fractionator operating conditions. The outflow TSS concentration of the drum filter also served as the inflow TSS concentration for the foam fractionator. Sample collection for TSS determination was divided into two categories: particles greater than 55 μm and particles less than 55 μm. The difference between inflow and outflow TSS concentrations was used to determine the removal percentage for each particle class of each unit. Additionally, the volume of foammate produced under operating conditions by the fractionator and the amount of solids contained within the foammate were quantified. Flow through the foam fractionator was also obtained to determine the amount of solids removed per volume of influent water treated. Result: The influent TSS concentration for the seven different operating conditions evaluated ranged from 4.8 to 6.3 mg/L, with the percentage of particles less than 55 μm ranging from 69.75% to as high as 86.1%. The drum filter removed over 90% of the particles larger than 55 μm and removed 8–26% of the particles smaller than 55 μm. No difference was observed in the overall removal efficiency of the drum filter, which ranged from 19% to 44%. There was no significant difference in the foam fractionator overall removal efficiency, which ranged from 6.5% to 38.5%. Operating the foam fractionator at a high water head height (HHH) with the submersible aspirating impeller provided the greatest removal percentage of particles less than 55 μm (26.9%). However, at the HHH, only half the amount of solids was removed compared to using a Venturi injector with ozone, but energy use was roughly 26% greater. Conclusion: The foam fractionator was operated at the HHH, about 0.31 m higher than the low water head height, for production operation. Additionally, Venturi injection of ozone provided the greatest removal of solids for the volume of influent water treated over a 12‐h operational period. The submersible aspirating impeller showed potential for low‐cost use with reasonable solids removal and warrants further evaluation. Impact statementAccumulation of fine solids and the removal thereof constitute an issue for commercial recirculating aquaculture system (RAS) production of marine finfish. This study evaluates the performance of a foam fractionator under various operational conditions with a Venturi injector and submersible aspirating impeller. Information from this work adds to base data for commercial‐scale units to support development of RAS marine finfish production in the United States. [ABSTRACT FROM AUTHOR]

Lake Powell is a large water storage reservoir in the arid southwestern United States. Here, we present a 58‐yr limnology dataset that captures water quality parameters from reservoir filling to present day (temperature, salinity, major ions, total suspended solids), as well as a 38‐yr record of Secchi depth, and a ~ 30‐yr record of nutrients, phytoplankton, and zooplankton assemblages. The dataset includes 5208 unique site visits spanning 258 unique sites of which 9 have been consistently visited. It also spans the establishment of an invasive bivalve (Dreissena bugensis, i.e. Quagga mussel) which was first detected in 2012. Given the general lack of long‐term data from lakes or reservoirs in arid regions, this dataset represents a unique contribution to regional, continental, and global‐scale limnology studies. As the hot drought in the desert southwest continues, we expect this dataset will inform water management decision‐making for this largest reservoir in the Upper Colorado River Basin. [ABSTRACT FROM AUTHOR]

Excess nutrients and suspended sediment exports from agricultural watersheds are significant sources of global water quality degradation. An improved understanding of surface water and groundwater pollutant loads is needed to advance practices and policies. A study was conducted in an agricultural-forested catchment of the mid-Atlantic region of the United States. Stream water (SW) and shallow groundwater (SGW) samples were collected monthly between January 2020 and December 2021 from eight sub-catchment study sites. Samples were analyzed for nitrate (NO3-N), nitrite (NO2-N), total ammonia (NH3-N), total nitrogen (TN-N), orthophosphate (PO43-P), and total phosphate (TP-P) concentrations using spectrophotometric methods. Total suspended solids concentrations (mg/L) were quantified gravimetrically and volumetrically to estimate mean particle diameter (MZ, µm), particle surface area (CS, m2/mL), sample skewness (Ski), and particle size distributions (sand/silt/clay%). Results showed significant (p < 0.05) differences in nutrient concentrations and suspended sediment characteristics between SW and SGW between study sites. Differences were attributed to source water type and sub-watershed location. Principal components analysis indicated seasonal effects on water quality in summer months and connected land use with TSS, TN-N, and TP-P concentrations. Study results emphasize the importance of SGW water quality metrics for non-point source loading predictions to inform management decisions in agro-forested watersheds. [ABSTRACT FROM AUTHOR]

A long‐term exposure outdoor microcosm study was conducted to evaluate the effects of zinc (Zn) on zooplankton, phytoplankton, and periphyton in a freshwater system. Five Zn treatment concentrations (nominal: 8, 20, 40, 80, and 160 μg/L Zn) and an untreated control with 3 replicates each were used. Various physical and chemical characteristics of the microcosms and biological assessment endpoints (e.g., total abundance, group abundance, species richness, chlorophyll a, etc.) were measured to determine the effects of Zn over time. In general, physical and chemical characteristics (e.g., total dissolved solids, total suspended solids, dissolved oxygen, pH, dissolved organic carbon) of water fluctuated over time, but they were not significantly different within treatments and controls during the study. Zinc significantly affected the population dynamics and community structure of plankton. The effects occurred 7 d after initial treatment exposures began and continued to the end of the treatment phase, especially at the high treatment concentrations. Total and group abundance, species richness, the Shannon index, and chlorophyll a concentrations for high Zn treatment concentrations were significantly lower than the controls during the treatment phase. The no‐observed‐effect, lowest‐observed‐effect, and median effect concentrations were generally lower than the literature‐reported results from single‐species toxicity tests for fish and invertebrates, suggesting that plankton are more sensitive to Zn than planktivores. Although primary producers play an important role in the ecosystem, they have not been consistently incorporated into numerical environmental quality criteria for freshwater organisms, at least in the United States. The results of the present study are useful for development of environmental quality guidelines for freshwater ecosystems and ecological risk assessment. Environ Toxicol Chem 2021;40:2053–2072. © 2021 SETAC [ABSTRACT FROM AUTHOR]

Combustion residuals and the resulting leachate from storage sites represent a large volume of wastewater in the United States (U.S.) that has not been quantified. This work estimates the constituents present, volume of wastewater, and costs of treatment for both combustion residual landfill leachate and the leachate from surface impoundment closures. Combustion residual landfill leachate produced from contact with bituminous coal combustion byproducts is generally predicted to be higher in lithium and manganese, whereas landfill leachate produced from contact with subbituminous coal combustion byproducts is generally predicted to be higher in mercury and vanadium. The annual volume of a single landfill with combustion residual leachate can reach more than 800,000 cubic meters. This leachate represents an annual volume of 26.8–42.8 million cubic meters nationally. Closing surface impoundments can yield between 830 and 1040 cubic meters of leachate nationally for a three-year closure period. Costs as low as $1.5/m3 or as high as $95/m3 are observed. Treatment trains will need to remove 72% of total suspended solids (TSS), 87% of arsenic, and 64% of mercury from landfill leachate. When applied to impoundments, these treatment trains would need to remove 97% of arsenic. [Display omitted] • Combustion residual leachate from coal has been difficult to historically quantify. • High-level estimates suggest 27–43 million cubic meters nationally from landfills. • For impoundments a 3-year closure yields 830–1040 million cubic meters nationally. • Both impoundment and landfill leachate have arsenic, requiring treatment. • Treatment costs range from $1.50 to $95 per cubic meter. [ABSTRACT FROM AUTHOR]

• Decades old data used in stormwater modeling may not represent current conditions. • Investigated temporal and step trends in four decades of stormwater quality data. • Significant, decreasing monotonic trends observed for nutrients, sediments, metals. • Step trend declines aligned with environmental regulations unrelated to stormwater. • Reductions were most substantial in metals followed by sediments then nutrients. Identifying sources of pollutants in watersheds is critical to accurately predicting stormwater quality. Many existing software used to model stormwater quality rely on decades-old data sets which may not represent current runoff quality in the United States. Because of environmental regulations promulgated at the federal level over previous decades, there is a need to understand long-term trends (and potential shifts) in runoff quality to better parameterize models. Pollutant event mean concentrations (EMCs) from the National Stormwater Quality Database (NSQD) were combined with those from recent sources to understand if untreated stormwater quality has changed over the past 40 years. A significant decreasing monotonic trend (i.e., continually decreasing in a nonuniform fashion) was observed for total suspended solids (TSS), total phosphorus (TP), total Kjeldahl nitrogen (TKN), total copper (Cu), total lead (Pb), and total zinc (Zn) in the resultant database, suggesting that runoff quality has become less polluted with time. Median EMCs decreased from 99.2 to 42 mg/L, 0.34 to 0.26 mg/L, 1.27 to 1.03 mg/L, 40 to 6.8 µg/L, 110 to 3.7 µg/L, and 375 to 53.3 µg/L for TSS, TP, TN, Cu, Pb, and Zn, respectively, from the 1980s to the 2010s. These significant reductions often aligned temporally with advancements in clean manufacturing, amendments of the Clean Air Act, and other source control efforts which impact pollutant bioavailability and atmospheric deposition. Results suggest environmental regulations not specifically targeting stormwater management have had a positive impact on stormwater quality and that temporal fluctuations should be considered in modeling. [Display omitted] [ABSTRACT FROM AUTHOR]

Wildfire is an integral part of a healthy environment, but it can have significant consequences for water utilities because of drastic effects on source water quality and associated treatment needs. [ABSTRACT FROM AUTHOR]

Surface water quality impairment in agricultural watersheds is a major environ-mental concern in the United States. To assess seasonal and spatial variability of surface water quality and identify factors associated with surface water quality variability, we monitored sur-face water quality at seven locations in Bayou Plaquemine Brule Watershed in Louisiana twice monthly from March of 2002 to February of 2008 and performed multivariate analyses of the dataset. Using the Soil and Water Assessment Tool (SWAT) model, we identified critical areas of nonpoint source pollution in the watershed. While temperature, turbidity, dissolved oxygen (DO), conductivity and pH were determined in the field using YSI Sonde (YSI Incorporated, Yellow Springs, Ohio), surface water samples were analyzed for total nitrogen (TN), total phosphorus (TP), nitrate/nitrite-N (N03/N02-N), soluble reactive phosphate (SRP), total suspended solids (TSS), and five-day biological oxygen demand (BOD.) in laboratory. The monthly water quality sampling included a regular sampling and an after-rain-event sampling. Average DO for the summer months, March through November, was 4.91 ± 0.08 mg L"1 (4.91 ± 0.08 ppm), while average DO for the winter months, December through February, was 8.32 ± 0.12 nig L 1 (8.32 ±0.12 ppm). Dissolved oxygen was negatively correlated with TN (r = -0.22, p < 0.001), SRP (r = -0.17, p < 0.001), TP (r = -0.17, p < 0.001), BOD. (r = -0.25, p < 0.001), and surface water temperature (r = -0.70, p < 0.001). Turbidity was strongly correlated with TSS (r = 0.59, p < 0.001), suggesting that most turbidity in the water body conies from suspended solids. Similarly BOD. was significantly positively correlated with TN (r = 0.43, p < 0.001), NO,/NO,-N (r = 0.26, p < 0.001),TP (r = 0.25, p < 0.001), and SRP (r = 0.18, p < 0.001). Results of factor analyses showed sediment, phosphorus (P), nitrogen (N), surface water temperature, dissolved solids, and acidity/alkalinity as the most important factors associated with surface water quality variability in this watershed. Although relatively higher concentrations of sediments, TP, and TN were observed in the upper reaches of the watershed based on water quality monitoring, the SWAT simulation results showed the critical nonpoint source pollution areas of sediment, P, and N in the lower reaches of the watershed. Lower reaches of the watershed have mainly rice and crawfish production, while the upper reaches include primarily sugarcane, pasturelands, and soybean production. Information on seasonal variability of surface water quality, factors associated with surface water quality variability, and the critical areas for nonpoint source pollution will be valuable inputs for developing a watershed management plan for effective nonpoint source pollution control in an agricultural watershed. [ABSTRACT FROM AUTHOR]

Abstract: There is increasing interest in decentralization of wastewater collection and treatment systems. However, there have been no systematic studies of the performance of small treatment facilities compared with larger plants. A statistical analysis of 4 years of discharge monthly report (DMR) data from 210 operating wastewater treatment facilities was conducted to determine the effect of average flow rate and capacity utilization on effluent biochemical oxygen demand (BOD), total suspended solids (TSS), ammonia, and fecal coliforms relative to permitted values. Relationships were quantified using generalized linear models (GLMs). Small facilities (40 m3/d) had violation rates greater than 10 times that of the largest facilities (400,000 m3/d) for BOD, TSS, and ammonia. For facilities with average flows less than 40,000 m3/d, increasing capacity utilization was correlated with increased effluent levels of BOD and TSS. Larger facilities tended to operate at flows closer to their design capacity while maintaining treatment suggesting greater efficiency. [Copyright &y& Elsevier]

Polycyclic aromatic hydrocarbons (PAHs) are semivolatile organic compounds consisting of two or more fused aromatic rings. These compounds are produced in the atmosphere as by-products of the incomplete combustion of almost any fuel. After emitting the atmosphere, this pollutants fallout to the ground as dry or wet deposition depends on its form and many factors. The concentration of PAH in the atmosphere is in the order of ng/m3. Atmospheric PAHs are partitioned between the particulate and the gaseous phases. PAHs have received increased attention in recent years in air pollution studies because some of these compounds are highly carcinogenic or mutagenic. Some PAHs were classified as probable or possible carcinogens to humans. For this reason, especially after 1980’s years, concentrations of these pollutants have been monitored continuously, especially in water mass and atmosphere. In many metropolitans, concentrations and potential toxicity of PAHs to city ecosystem have been determined in monitoring network or individual studies. In the base of these monitoring programs, sources of PAHs identified and quantified at receptor locations with different techniques. This study is the first about atmospheric concentration of PAHs in Istanbul. In this study, 16 EPA`s PAHs and TSP (Total Suspended Solids) concentration were performed in three sampling stations for four seasons in the period of September 2006-December 2007 in Istanbul. Spatial and temporal profiles were determined and diagnostic ratios were applied for source apportiontment of the pollutants. Airborne samples were collected using PS-1 samplers with GFF filter to collect airborne particlebound PAH and TSP. The filter was followed by a glass cartridge containing polyurethane foam plug and XAD-2 resin. All sampled filters and glass cartridges were extracted by soxhlet method with nhexane: diethylether mixture for 20 h. The extract was then concentrated and cleaned up with silica gelcolumn using procedures by EPA. Analysis of all extracts were performed by means of reversed-phase HPLC using UV-visible and fluorescence detectors in series. A total of 326 airborne samples were collected and analyzed for 16 PAHs and TSP in the period at three monitoring stations; Yildiz (135 samples- urban site), DMO (129 samples-urban site) and Kilyos (62 samples-rural site). Total average PAH concentrations were 100.66±61.26, 84.63±46.66 and 25.12±13.34 ng m-3 and TSP concentrations were 101.16±53.22, 152.31±99.12, 49.84±18.58 μg m-3 for Yildiz, DMO and Kilyos stations respectively. When comparing average concentration, maximum PAH values were observed for Yildiz station but maximum TSP values were observed for DMO station. At all the sites, the lighter compounds (MW<200) were the most abundant species. Nevertheless some reduction was observed in percentage of the low molecular weight PAHs during the warm season for all stations. Because PAHs with high molecular weight are found mainly adsorbed in particulate matter, a good correlation between TSP and heavier PAH concentration is expected. In general, correlation values between TSP and total heavier PAH values were good for Yildiz and DMO stations. Averagecorrelation values were 0.60 and 0.56 for Yildiz and DMO stations respectively. The pattern of PAH and TSP concentrations showed spatial and temporal variations. Strong seasonality was observed especially for urban stations. The highest level was observed in winter in urban areas while the lowest in summer in rural area. When comparing seasonal values, Winter 2006 had the highest PAH levels for all stations and the lowest levels were observed in Spring and Summer 2007. Comparing yearly variations, year 2006 had bigger PAH values than year 2007. PAH concentration values were compared literature studies. The comparison of the results with the examples given in the literature was in a good agreement. The concentrations or ratios of specific PAH compounds have been used to indicate towards the corresponding emission sources, especially for vehicle emissions In the study, PAH concentration values were analyzed with diagnostic ratios. The ratios of PAHs were compared with individual concentration values in order to determine sources of PAHs. Yildiz and DMO sites was affected by traffic-related sources, and diesel emission sources had higher contribution than gasoline ones. On the other hand, low level traffic emission was obtained for Kilyos station as expected. [ABSTRACT FROM AUTHOR]

Abstract: Boston Harbor, a bay–estuary in the north-east USA, has recently been the site of one of the largest wastewater infrastructure projects conducted in the USA, the Boston Harbor Project (BHP). The BHP, which was conducted from 1991 to 2000, ended over a century of direct wastewater treatment facility discharges to the harbor. The BHP caused the loadings of total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS) and particulate organic carbon (POC) to the harbor, to decrease by between 80% and 90%. Approximately one-third of the decreases in TSS and POC loadings occurred between 1991 and 1992; the remaining two-thirds, between 1995 and 2000. For TN and TP, the bulk of the decreases occurred between 1997 or 1998, and 2000. [Copyright &y& Elsevier]

Abstract: This paper examines and compares the management practices and regulatory approaches used by the Mid-Atlantic States of Delaware, Maryland, New Jersey, and Pennsylvania for improving the quality of storm-water runoff. Such practices range from simple extended detention criteria in Pennsylvania through the BMP credit system used by Maryland, to the latest “green technology” methods promoted in Delaware and the recharge, quality and peak reduction approaches of New Jersey. All practices are designed to meet EPA requirements for total suspended solids (TSS) removal, but verification of performance is not required. More sophisticated methods of evaluating TSS removal that can be used for engineering design purposes are needed. [Copyright &y& Elsevier]

The article discusses the mercury (Hg) transport in response to storm from the Adirondck region of New York, USA. It is said that the fluxes of Hg in surface waters are affected by hydrological events, in which Hg transport may influence the bioavailability of the chemical to aquatic biota. It is cited that Hg concentrations were not correlated with dissolved organic carbon (DOC) or total suspended solids (TSS). It is mentioned that the attributes of watershed and storm have a role in Hg transport and bioavailability.

The deposition of suspended sediment is an important process that helps wetlands accrete surface material and maintain elevation in the face of sea level rise. Optical remote sensing is often employed to map total suspended solids (TSS), though algorithms typically have limited transferability in space and time due to variability in water constituent compositions, mixtures, and inherent optical properties. This study used in situ spectral reflectances and their first derivatives to compare empirical algorithms for estimating TSS using hyperspectral and multispectral data. These algorithms were applied to imagery collected by NASA's Airborne Visible/Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) over coastal Louisiana, USA, and validated with a multiyear in situ dataset. The best performing models were then applied to independent spectroscopic data collected in the Peace–Athabasca Delta, Canada, and the San Francisco Bay–Delta Estuary, USA, to assess their robustness and transferability. A derivative-based partial least squares regression (PLSR) model applied to simulated AVIRIS-NG data showed the most accurate TSS retrievals (R2 = 0.83) in these contrasting deltaic environments. These results highlight the potential for a more broadly applicable generalized algorithm employing imaging spectroscopy for estimating suspended solids. [ABSTRACT FROM AUTHOR]