WITHDRAWN: Development of EMC-based empirical model for estimating spatial distribution of pollutant loads and its application in rural areas of Korea

Assessing spatiotemporal risks of nonpoint source pollution via soil erosion: a coastal case in the Yellow River Delta, China

Nonpoint source pollution (NPSP) has always been the dominant threat to regional waters. Based on empirical models of the revised universal soil loss equation and the phosphorus index, an NPSP risk assessment model denoted as SL-NPSRI was developed. The surface soil pollutant loss was estimated by simulating the rain-runoff topographic process, and the influence of path attenuation was quantified. A case study in the Yellow River Delta and corresponding field surveys of soil pollutants and water quality showed that the established model can be applied to evaluate the spatial heterogeneity of NPSP. NPSP usually occurs during high-intensity rainfall periods and in larger estuaries. Summer rainfall increased pollutant transport into the sea from late July to mid-August and caused estuarine dilution. Higher NPSP risks often correspond to coastal areas with lower vegetation coverage, higher soil erodibility, and higher soil pollutant concentrations. Agricultural NPSP originating from cropland significantly increase the pollutant fluxes. Therefore, area-specific land use management and vegetation coverage improvement, and temporal-specific strategies can be explored for NPSP control during source-transport hydrological processes. This research provides a novel insight for coastal NPSP simulations by comprehensively analyzing the soil erosion process and its associated pollutant loss effects, which can be useful for targeted spatiotemporal solutions.

Exploring the Extent of Phosphorus and Heavy Metal Uptake by Single Cells of Saccharomyces cerevisiae and Their Effects on Intrinsic Elements by SC-ICP-TOF-MS

The effect of six heavy metals, namely, silver (Ag), lead (Pb), palladium (Pd), copper (Cu), nickel (Ni), and chromium (Cr), on phosphorus (P) uptake by yeast was investigated by single-cell analysis using inductively coupled plasma time-of-flight mass spectrometry (SC-ICP-TOF-MS). It was found that the P content in cells with 1.55 g L^–1 P feeding after P starvation was increased by ∼70% compared to control cells. Heavy metals at 10 ppm, except Cu, had a negative impact on P accumulation by cells. Pd reduced the P content by 26% in single cells compared to control cells. Metal uptake was strongest for Ag and Pd (0.7 × 10^–12 L cell^–1) and weakest for Cr (0.05 × 10^–12 L cell^–1). Exposure to Cr markedly reduced (−50%) Mg in cells and had the greatest impact on the intrinsic element composition. The SC-ICP-TOF-MS shows the diversity of elemental content in single cells: for example, the P content under standard conditions varied between 12.4 and 890 fg cell^–1. This technique allows studying both the uptake of elements and sublethal effects on physiology at a single-cell level.

Quantifying the Contribution of Agricultural and Urban Non-Point Source Pollutant Loads in Watershed with Urban Agglomeration

Urban agglomeration is a new characteristic of the Chinese urbanization process, and most of the urban agglomeration is located in the same watershed. Thus, urban non-point source (NPS) pollution, especially the characteristic pollutants in urban areas, aggravates NPS pollution at the watershed scale. Many agricultural studies have been performed at the watershed scale; however, few studies have provided a study framework for estimating the urban NPS pollution in an urban catchment. In this study, an integrated approach for estimating agricultural and urban NPS pollution in an urban agglomeration watershed was proposed by coupling the Soil and Water Assessment Tool (SWAT), the event mean concentration (EMC) method and the Storm Water Management Model (SWMM). The Hun-Taizi River watershed, which contains a typical urban agglomeration and is located in northeastern China, was chosen as the study case. The results indicated that the per unit areas of total nitrogen (TN) and total phosphorus (TP) in the built-up area simulated by the EMC method were 11.9% and 23 times higher than the values simulated by the SWAT. The SWAT greatly underestimated the nutrient yield in the built-up area. This integrated method could provide guidance for water environment management plans considering agricultural and urban NPS pollution in an urban catchment.

Residual organics removal from manganese electrochemical solution using combined Fenton oxidation process with adsorption over activated carbon

The removal of residual organics from manganese (Mn) electrochemical solution using combined Fenton oxidation process with adsorption over activated carbon (AC) was investigated. The effect of operating conditions such as dosage of H₂O₂, H₂O₂/Fe²⁺ ratio, initial pH value, reaction temperature, and reaction time on Fenton oxidation was studied. Experimental results indicated that a maximum chemical oxygen demand (COD) of 83.2% was obtained under the optimized set of conditions: H₂O₂ concentration of 0.15 mol/L, H₂O₂/Fe²⁺ molar ratio of 3, initial pH value of 3, reaction temperature of 50 °C, and reaction time of 90 min. The leaching solution was furthered treated over AC and COD removal rate increased to 93.1% under 3.75 g/L dosage of AC, adsorption temperature of 70 °C, and adsorption time of 120 min. The adsorption mechanism of Mn over AC was detailly investigated, while the porous texture of AC was studied by nitrogen adsorption isotherm.

Water quality characterization of storm and irrigation runoff from a container nursery

Commercial nurseries grow specialty crops for resale using a variety of methods, including containerized production, utilizing soilless substrates, on a semipervious production surface. These "container" nurseries require daily water application and continuous availability of mineral nutrients. These factors can generate significant nutrients [total nitrogen (TN), and total phosphorus (TP)] and sediment [total suspended solids (TSS)] in runoff, potentially contributing to eutrophication of downstream water bodies. Runoff is collected in large ponds known as tailwater recovery basins for treatment and reuse or discharge to receiving streams. We characterized TSS, TN, and TP, electrical conductivity (EC), and pH in runoff from a 5.2 ha production portion of a 200-ha commercial container nursery during storm and irrigation events. Results showed a direct correlation between TN and TP, runoff and TSS, TN and EC, and between flow and pH. The Storm Water Management Model (SWMM) was used to characterize runoff quantity and quality of the site. We found during irrigation events that simulated event mean concentrations (EMCs) of TSS, TN, and TP were 30, 3.1 and 0.35 mg·L^-1, respectively. During storm events, TSS, TN and TP EMCs were 880, 3.7, and 0.46 mg·L^-1, respectively. EMCs of TN and TP were similar to that of urban runoff; however, the TSS EMC from nursery runoff was 2-4 times greater. The average loading of TSS, TN and TP during storm events was approximately 900, 35 and 50 times higher than those of irrigation events, respectively. Based on a 10-year SWMM simulation (2008-2018) of runoff from the same nursery, annual TSS, TN and TP load per ha during storm events ranged from 9230 to 13,300, 65.8 to 94.0 and 9.00 to 12.9 kg·ha^-1·yr^-1, respectively. SWMM was able to characterize runoff quality and quantity reasonably well. Thus, it is suitable for characterizing runoff loadings from container nurseries.