Spatial Distribution, Sources, Air-Soil Exchange, and Health Risks of Parent PAHs and Derivative-Alkylated PAHs in Different Functional Areas of an Oilfield Area in the Yellow River Delta, North China

Impact of oil-extraction/port activities on distribution and exchange of PAHs/APAHs/NPAHs/OPAHs in water and sediment of the Yellow River Delta, China

The Yellow River Delta (YRD) is rich in oil, natural gas, and land resources. With the expansion of an important oil production base in North China, the increased discharge of Polycyclic aromatic hydrocarbons (PAHs) and alkylated/nitrated/oxygenated PAHs (APAHs/NPAHs/OPAHs) into the Yellow River poses a potential risk to the aquatic ecosystem and human health. A total of 42 samples were gathered from trunk streams and tributaries within the YRD region during the wet and dry seasons, and 19 PAHs, 5 APAHs, 16 NPAHs, and 7 OPAHs were measured. The concentrations of ƩPAHs, ƩAPAHs, ƩNPAHs and ƩOPAHs ranged between 29 and 620 ng/L, 6.9-81 ng/L, 0.64-9.0 ng/L, and 7.2-81 ng/L in water, respectively, and 27-420 ng/g, 5.1-130 ng/g, 0.19-1.8 ng/g and 3.9-51 ng/g in sediment, respectively. The oil extraction activities resulted in an increased presence of middle-high molecular weight PAHs and APAHs in sediment, and port activities had a notable influence on the proportion of 1-methylpyrene in both water and sediment. The fugacity fraction analysis suggested that sediment was a secondary source of OPAHs, while benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, and 5-methylchrysene migrated from water to sediment. The main contributors to PAHs, APAHs, NPAHs, and OPAHs in water and sediment were combustion and petroleum sources. Compared to water, sediment displayed a heightened ecological risk associated with PAHs, APAHs, NPAHs, and OPAHs. Adults residing in the YRD region were at higher risk of cancer than children, which deserves special attention.

PAHs in sediments and shrimps: Levels, sources, and risk estimation in a tropical coastal lagoon system near oil industry

Anthropogenic activities in the surrounding the Tehuantepec Isthmus Lagoon System (Mexican South Pacific) region are related to the emission of polycyclic aromatic hydrocarbons (PAHs), such as the Salina Cruz oil refinery, the combustion of fossil fuels, and the traditional agricultural method of "slash and burn." Therefore, PAHs have impacted shrimp fishery resources and increased human health risks of Indigenous communities such as Huaves and Zapotecos, increasing their vulnerability. PAHs were quantified in sediments and shrimp in dry, rainy, and cold front seasons; sources, ecotoxicological risk, and the bioconcentration factor in shrimp were estimated. Σ16PAHs in sediments were 166-5286.8 ng g-1 (dw) and for shrimp were 100.9-8155.8 ng g-1. Seasonal factors and Tehuano winds were essential in the PAHs distribution. Pyrogenic PAHs were dominant during the dry and the cold front seasons from industrial sources; meanwhile, petrogenic PAHs were dominant in the rainy season from river runoff and oil-fuel spill sources. PAHs levels were not correlated with organic matter in sediments (Spearman r = 0.1368, p = 0.4964). Petrogenic and pyrogenic PAHs sources were identified. The most concerning findings are the high bioaccumulation factor levels found in shrimp (553 for dibenzo[a,h]anthracene) and the identified environmental medium-high risk found in the fishery areas estimated by the Mean Maximum Permissible Concentration Quotient, which suggest a possible high health risk Indigenous communities in the region. This study could help to have better public policies in environmental management for tropical coastal ecosystems affected by the oil industry worldwide.

Characterization and risk assessment of microplastics in shoreline sediments of the Yellow River Delta

As the intersection of river, sea, and land, river deltas are hotspots for the accumulation of microplastics (MPs). This study investigated the abundance and characteristics of MPs in surface sediments from shoreline area of the Yellow River Delta in northern China, elucidated their sources, and assessed their risk. The MPs isolated from sediment samples were detected and characterized using optical microscopy and micro-Fourier transform infrared spectroscopy (μ-FTIR). The results showed that MPs were abundant (360-2160 items/kg) in the area, and occurred mainly in small sizes (<250 μm), as fibers (20.2-50.0%), filament (4.8-21.5%), and granules (8.5-20.6%), and in transparent (27.8-40.3%), blue (11.2-31.6%), or black (7.9-26.5%) color. Polyethylene terephthalate (26.08%), polyethylene (20.47%), polypropylene (13.49%), and polyvinyl chloride (10.71%) were the dominant polymer types for the MPs. The pollution load indices (1-6) indicated that all sampling sites were polluted by MPs, while the polymeric hazard indices (65.14-91.44) suggested that MPs pollution of the area was in medium range. Overall, the ecological risk indices (91.44-475.38) of the sampling sites indicated that MPs in shoreline sediments of the Yellow River Delta posed low to considerable potential ecological risk. While the dominance of polymers with medium polymeric risk scores rendered the MPs in the shoreline sediments with relatively low risk, the majority of MPs occurred in small sizes, which complicates the actual risk posed by MPs in shoreline sediments of the Yellow River Delta and deserves attention.

Presence of polycyclic aromatic compounds in river sediment and surrounding soil: Possible impact from shale gas wastewater

Shale gas has been extensively extracted in the Sichuan Basin in China in recent years. To gain insight into the potential impact of shale gas wastewater (SGW) discharge, sediment in a small river receiving treated SGW, as well as cultivated soil and paddy soil irrigated by the river water were collected. The occurrence and distribution of polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and their alkylated/oxygenated derivatives (APAHs/OPAHs), and thiophenes were investigated, the resultant potential ecological risks were assessed subsequently. The total concentration of PACs varied in the range of 1299.9-9286.4, 2069.4-11,512.3, and 475.7-2927.9 ng/g in sediment, cultivated soil and paddy soil, respectively, with thiophenes followed by APAHs being the abundant components in all the studied samples, demonstrating the potential impact of SGW discharge on sediment and surrounding soil environment. Based on the measured concentrations, potential ecological risks posed by PAHs and APAHs were calculated, and moderate to high ecological risks were observed in partial sampling sites, which mainly caused by 3-4 rings PAHs and APAHs.

Distribution and source analysis of soil toxic organic compounds of coal-electricity production base in arid and semi-arid region of China

The presence and distribution of toxic organic compounds in soil pose significant challenges. Whether their distributional characteristics are more complex, especially in arid and semi-arid regions with harsh climatic conditions? This study analyzed the composition, classification, spatial distribution, and sources of 123 toxic organic compounds in 56 soil samples of coal-electricity production base. Those compounds were classified into 11 categories, mainly pesticides (41 compounds), organic synthesis intermediates (31 compounds), and drugs (23 compounds). Seventeen of those compounds were detected over the rate of 30 %, with 13 of them being under the Toxic Substances Control Act (TSCA) inventory. The primary sources of toxic organic compounds were determined using Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF), including the degradation of pesticide residues (22.03 %), emissions of plastic pellets (16.64 %), industrial waste emissions (12.80 %), emissions from livestock (12.74 %), plastic films (11.22 %) and coal-to-liquid projects (10.78 %). This research underscores the widespread presence of toxic organic compounds in soil, highlighting their origins and distribution patterns, which are essential for developing targeted environmental management strategies in arid and semi-arid regions.

Influence of oil extraction on concentration distributions, migration, secondary formation and carcinogenic risk of NPAHs and OPAHs in air and soil in an oilfield development area in China

Oil extraction leads to environmental pollution from the oilfields and dweller activities, however, knowledge of the concentration distributions, migration, secondary formation and toxicity of nitrated/oxygenated polycyclic aromatic hydrocarbons (N/OPAHs) in oilfield regions is limited. In this research, atmospheric and soil samples in 7 different location types in an important oil industrial base in China were gathered. The ΣNPAHs and ΣOPAHs in the air ranged from 0.05 to 2.47 ng/m3 and 0.14-22.72 ng/m3, respectively, and in soil ranged from 0.22 to 17.81 ng/g and 9.69-66.86 ng/g, respectively. Both NPAHs and OPAHs in the atmosphere exhibited higher concentrations during winter. The atmospheric NPAH concentrations decreased exponentially with distance from urban area especially in the summer, revealing the impact of vehicles on the air in the Yellow River Delta area. High NPAH and OPAH concentrations were found only in soil near oil extraction facilities, indicating that the impact of oil extraction is limited to the soil near the extraction facilities. The air-soil exchanges of N/OPAHs were assessed through fugacity fraction analysis, and NPAHs were in the equilibrium-deposition state and OPAHs were in the net-deposition state in the winter. Higher incremental lifetime cancer risk (ILCR) occurred at the urban, industrial, and oilfield sites in the atmospheric samples, and the soil samples had the largest ILCR values in the oilfield sites. However, ILCR values for both air and soil did not exceed the threshold of 10-6.

Occurrence and distribution of microplastics in the adjacent environment of Yellow River Delta, China

In the precent study, the microplastics (MPs) pollution level was evaluated in diverse environmental samples from the Yellow River Delta. The results indicated that the abundance of MPs in water, sediment and soil samples ranged from 0.50 to 7.83 items·L-1, 200 to 4200 items·kg-1, and 100 to 1400 items·kg-1, respectively. Film form of MPs was dominant in water, while fiber MPs were dominant in both sediment and soil samples. In all samples, most MPs were < 1 mm in size. White was the main color in water, black was the main color in sediment and soil samples. The most common MPs type was polyethylene (33 %) in water, while rayon accounted for the majority of MPs in sediment (42 %) and soil (70 %) samples. The redundancy analysis results showed that MPs in water and sediment were more affected by water quality, while soil MPs were easily affected by landscape pattern.