Plastic litter colonization in a brackish water environment

Transitional waters, including coastal ponds, represent unique environments. These distinct ecosystems are often among the most severely polluted systems due to intensive human activities. Our study marks the first evaluation of aquatic invertebrates associated with plastic litter in two brackish ponds. We collected 43 items of plastic litter (including bottles and disposable plastics) during the winter and spring of 2022. Most of plastic litter (76.8 %) was colonized by aquatic invertebrates. A total of 495 individuals were observed on the plastic litter, with the number of individuals ranging from 1 to 54 (average = 13.4). The most abundant taxa were from the families Gammaridae, Serpulidae, and Sphaeromatidae. Invertebrates colonized both the external and internal surfaces of the plastic bottles. Plastic bottles trapped 25 % of the total biota. The internal entrapped taxa were mainly represented by gammarids, molluscs egg mass, and sphaeromatids. Open bottles could potentially serve as temporary or permanent traps for invertebrates colonizing their internal surfaces. We argue that the dispersal of species driven by plastics is possible but limited, just as water exchanges with the seas are limited. These brackish lakes could be transit areas, but more importantly, they could be hotspots for plastic litter.

Influence of tobacco product wastes in a protected coastal reserve adjacent to urbanization

The present study, conducted at the Kendall-Frost Mission Bay Marsh Reserve in San Diego, California, aimed to assess tobacco-related pollutants in urban waters, a topic with limited prior research. Across 26 events occurring between November 2019 and February 2022, encompassing both wet and dry seasons at two outfall sites (Noyes St. and Olney St.), water and sediment samples were subjected to analysis for nicotine and cotinine levels, with Noyes St. displaying wide variation in nicotine concentrations, reaching a peak of 50.75 ng/L in water samples, whereas Olney St. recorded a peak of 1.46 ng/L. Wet seasons consistently had higher nicotine levels in water, suggesting the possibility of tobacco litter entering the reserve through stormwater runoff. Cotinine was detected in both sites in both water and sediment samples; however, these levels were considerably lower in comparison to nicotine concentrations. Limited research assesses aquatic environmental pollution from tobacco use and disposal, especially in protected areas like urban natural reserves. This study was conducted at the Kendall-Frost Mission Bay Marsh Reserve in San Diego, California, to evaluate tobacco-related pollutants in San Diego's urban waters. Twenty-six sampling events between November 2019 and February 2022, spanning wet and dry seasons at two outfall sites, were conducted. Nicotine and cotinine, a major ingredient of tobacco and its metabolite, were analyzed in the collected water and sediment samples. Nicotine concentrations differed substantially between the outfall locations (Noyes St. and Olney St.), with Noyes St. displaying wide variations, averaging at 9.31 (±13.24) ng/L with a maximum concentration of 50.75 ng/L, and Olney St. at 0.53 (±0.41) ng/L with a maximum concentration of 1.46 ng/L in water samples. In both locations, the nicotine concentrations in water samples were higher during wet seasons than dry seasons, and this pattern was more significant at Noyes St. outfall than at Olney St. outfall, which received not only stormwater runoff but also was connected to Mission Bay. Although this pattern did not directly align with sediment nicotine levels at both sites, maximum nicotine concentration in Noyes St. sediments during wet seasons was approximately 120 times higher than in Olney St. sediments. Regarding cotinine, Noyes St. outfall water averaged 3.17 ng/L (±1.88), and Olney St. water averaged 1.09 ng/L (±1.06). Similar to nicotine, the cotinine concentrations were higher in Noyes St. water and sediment compared to Olney St., but overall, the cotinine concentrations in both water and sediment were much lower than the corresponding nicotine concentrations. The study identifies urban stormwater runoff as a potential source of nicotine and cotinine pollution in a protected reserve, implicating tobacco product litter and human tobacco use as contributing factors.

Evaluation and prediction of ecological carrying capacity in the Qilian Mountain National Park, China

With increasing human impacts on the ecosystem in natural protected areas, there is an urgent need to undertake an assessment of ecological carrying capacity taken as a benchmark for assessing regional sustainability. Based on satellite remote sensing and socio-economic statistical data from 2000 to 2019, this study distinguished the controlling factors for the spatial and temporal patterns of ecological carrying capacity in the Qilian Mountain National Park, one of the 10 pilot national parks in China. The ecological carrying capacity index (ECCI) was developed by using the Driver-Pressure-State-Impact-Response framework and a comprehensive weight method. The results showed that the multiyear averaged ECCI was low in the south and west but was high in central and eastern regions. The spatial distribution of the ECCI was constrained by soil resources, ecosystem quality, land use/cover and water environment. At the regional scale, the ECCI decreased from 2000 to 2014, especially in Tianzhu, where farmland expansion and severe droughts reduced habitat quality and ecosystem function. However, the ECCI increased significantly from 2014 to 2019, which was attributed to a warm moist climate and the implementation of eco-environmental protection policies. Forest and grassland coverage, soil and water conservation, waste water treatment amount and terrestrial water reserves accounted for 35%, 26%, 20% and 8%, respectively, of the temporal variability in the ECCI. Concurrent with national park development, the ECCI is predicted to increase in most areas from 2020 to 2029 by back-propagation artificial neural networks, except for Sunan, Shandan and Menyuan, possibly owing to increasing conflicts between humans and the environment. The findings of this study provide evidence about the effectiveness of government policies in promoting regional sustainability by altering ecosystem composition and function. In addition, the dominant drivers for the temporal variability of ecological carrying capacity varied in space according to stepwise regression analysis, calling for region-specific management strategies in mountain protected areas and their surroundings.

Occurrence and Potential Risk of Polychlorinated Biphenyls in Surface Soils from the Yellow River Delta Natural Reserve, China

A total of 28 PCB congeners were determined using gas chromatography-mass spectrometry (GC-MS) in 46 surface soils collected from the Yellow River Delta Natural Reserve (YRDNR) and its adjacent area, China. The total concentrations of PCBs in the YRDNR ranged from 0.149 to 4.32 ng/g, with a mean concentration of 0.802 ng/g. Light PCB congeners predominated in the present research area, which may be attributed to the atmospheric transportation and were also associated with the recent contamination of unintentionally produced PCBs from industrial processes. In addition, PCB 126 and PCB 169 were found to be the major toxicity contributors of dioxin-like PCBs in the YRDNR, which should require special focus.