Distribution and bioaccumulation of lead in the coastal watersheds of the Northern Bohai and Yellow Seas in China

Lead alters the tolerance of dominant woody plants in subtropical coastal zones to flash drought

Under the influence of climate change and human activities, drought and heavy metal pollution are increasingly threatening the stability of coastal regions. In this study, the ecophysiological responses of three representative coastal plant species (Hibiscus tiliaceus, Barringtonia racemosa, and Terminalia neotaliala) in subtropical regions to lead addition (Pb), drought stress (D), their co-existence (Pb + D), and control (CK) were investigated. The results showed that, compared to CK, Pb treatment alone did not significantly affect plant growth during the experiment, which lasted for 8 days. In contrast, both D and Pb + D treatment caused a notable negative impact, with significant increases in abscisic acid (ABA), proline (PRO), and superoxide anion (O2-) levels and a significant decrease in net photosynthetic rates (Pn). In addition to the comparison with CK, we also observed a distinction between the effects of Pb + D treatment and those of either Pb treatment or D treatment. With Pb + D treatment, Pb accumulation in the roots and leaves of H. tiliaceus and B. racemosa and in the roots of T. neotaliala was higher than those with Pb treatment alone. Other than that, the negative impacts in growth of Pb + D treatment appeared to be delayed compared to the D treatment alone. Moreover, B. racemosa demonstrated good tolerance to Pb, drought and their co-existence treatments, indicating its potential for use in coastal vegetation restoration to enhance ecosystem resilience and stability in subtropical regions.

Large-scale distribution and ecological risk assessment of inorganic arsenic in surface sediments of Chinese marginal seas

Chinese marginal seas play a crucial role in sea-land interactions, but there is limited large-scale research on the occurrence and ecological risks of As in these areas. This study employed an extensive investigation on the spatial distribution and fractions of As in surface sediments across all four Chinese marginal seas, encompassing 111 sampling sites. The results revealed that the surface sediments exhibited elevated levels of total As content, surpassing those observed in other marginal seas worldwide. The HCl extractable fraction was found to be dominant in the Bohai Sea, Yellow Sea, and East China Sea, while the residual fraction prevailed in the South China Sea. Both environmental factors, including dissolved oxygen (DO), temperature, salinity, and manganese and iron contents in sediments, as well as biological processes such as nitrate-dependent As(III) oxidation, are likely significant contributors to variations in sedimentary As fractions. The distribution of As between reactive iron phases and reactive sulfur phases exhibited spatial variations across nearshore regions and offshore areas, indicating a shift in the relative roles of iron and sulfur in As retention. Generally, this study demonstrated that the ecological risks associated with As in surface sediments in the Chinese marginal seas ranged from low to moderate levels. The occurrence and distribution of As in these sediments were influenced by a complex interplay of environmental conditions, the geochemical cycling of iron and sulfur, and microorganism-mediated electron transfer processes.

Lead (Pb) removal and suppression of Pb-induced inflammation by Lacticaseibacillus rhamnosus A6-6

Lead (Pb) contamination poses serious environmental and health risks, necessitating effective remediation and protection strategies. This study evaluates the Pb removal efficiency of Lacticaseibacillus rhamnosus A6-6 and its protective effects against Pb-induced immunotoxicity. Pb adsorption studies demonstrated that L. rhamnosus A6-6 efficiently removed Pb, primarily through peptidoglycan-mediated biosorption, following the Langmuir model. Furthermore, the immunomodulatory effects of L. rhamnosus A6-6 were assessed using RAW 264.7 macrophage-like cells, revealing its ability to mitigate Pb-induced toxicity and inflammation by suppressing pro-inflammatory cytokine expression. These findings suggest that L. rhamnosus A6-6 is a promising candidate for Pb bioremediation and immune protection. This study enhances our understanding of metal-cell interactions and highlights practical applications in environmental remediation and potential therapeutic strategies.

Temporal trends of heavy metals in the sediments of Bohai Bay in China

The status and trend of mercury (Hg), cadmium (Cd), lead (Pb), copper (Cu), chromium (Cr), zinc (Zn), and arsenic (As) in the sediment of Bohai Bay from 1978 to 2017 were evaluated. The results indicated that the sediment status in 2017 was good. The contents of Hg, Cd, Pb, Cu, Cr, Zn, and As in all the monitoring stations were lower than category I. But, it is worth noting that the contents of Cu, Cr, and As in some stations were between threshold effects levels (TEL) and probable effects levels (PEL) guidelines, which were occasionally correlated to negative ecological effects. Since the reform and opening up of China, only the average content of Cd in 1996 was between category II and category III, but that in other years did not exceed category I. The average contents of Hg, Pb, Cu, Cr, Zn, and As were lower than category I. The Chinese Government should continue to pay high attention to the total quantity control measures of major risk factors Cd, Cu, Cr, and As.

Accumulation and ecological risk of heavy metals in soils along the coastal areas of the Bohai Sea and the Yellow Sea: A comparative study of China and South Korea

Soils in coastal areas of the land-sea interface are vulnerable to heavy metal (HM) accumulation and subsequently to human health risk. However, few studies have investigated the HM pollution and risk in soils along the coastal areas of the Yellow Sea Large Marine Ecosystem (YSLME), in an international perspective. This study is the first comprehensive work in the YSLME encompassing 122 coastal locations along the Bohai Sea (BS), Yellow Sea of China (YSC), and Yellow Sea of South Korea (YSK). Soil HM pollution showed great spatial variations cross the regions and countries. Accumulations of As, Cu, Pb, and Zn in the YSK were significantly higher than those in the BS and YSC (p < 0.05). Whilst the elevated Cd, Hg, and Ni in soils were found in the BS and YSC compared to those in the YSK (p < 0.05). Meantime, the assessment of ecological risk posed by HMs indicated higher potential risk in the BS than other coastal areas. In specific, Cd and Hg posed a higher risk in the BS and YSC, while As showed relatively high risk in the YSK, indicating site-dependent accumulation of HMs in soils. Soil pH and organic matter were found to be important factors affecting the HM accumulation in the study areas. Industrial activities are the major driving factors influencing spatial distributions of HMs, and such activities exhibited different degrees of influence across the sampling sites. Altogether, the results of present study first identified the bilateral characteristics of soil HM pollution along the entire coasts of the YSLME in a comprehensive manner in several aspects: (1) sources, (2) hot spots, (3) priority chemicals of concern, and (4) site-specific potential risk of the soil HMs. Overall, this study provides references and backgrounds for future environmental management strategies and aids in developing a bilateral government policy towards coastal pollution management of HMs from an international scale and perspective.

Ecological risk assessment of heavy metals in sediments and water from the coastal areas of the Bohai Sea and the Yellow Sea

The Yellow Sea Large Marine Ecosystem (YSLME) is an important socioeconomic zone in Asia, but has been deteriorated by various environmental pollutants over the last half century. However, comprehensive coastal pollution assessments, particularly for heavy metals (HMs), have been limited from an international perspective. Here, we first evaluate coastal HM pollution in sediment and water from 119 riverine, estuarine, and marine locations along the BS and Yellow Sea to perform a comparative assessment between the two countries of China and South Korea. The occurrence, distribution, sources, multimedia fate, interactions, associated environmental factors, and potential ecological risks relating to the HM pollution are widely addressed. Eight typical HMs (As, Hg, Zn, Cu, Pb, Cd, Cr, and Ni) were targeted in both sediments and water, and in situ water properties (pH, dissolved oxygen, salinity, and temperature) and sediment properties (pH and organic matter (OM) content) were analyzed. The results indicated that As, Cd, Cr, Cu, Ni, and Pb concentrations in water were higher in the estuarine area than those in riverine and marine areas and that particularly severe HM pollution was evidenced in the BS. The dominant elements in pollution hot spots varied greatly among the countries and regions. According to the geo-accumulation index (I_geo) and pollution load index (PLI) values, the sediments exhibited high Hg and Pb pollution in the BS; high As, Hg, and Pb pollution in the Yellow Sea of China; and high Cd and Hg pollution in the Yellow Sea of South Korea. In general, the sediments were moderately contaminated by HMs based on the high PLI (>1.0) and risk index (RI) values (>160). Ni and Cr in the sediment mainly originated from geogenic sources, while the other elements (Zn, As, Cd, Cu, Hg, and Pb) were primarily linked to anthropogenic sources. Based on the partial redundancy analysis, we found that environmental factors, especially OM, contributed significantly to the concentrations of HMs in both the sediments and water. The sediment HMs significantly contributed to the waterborne HMs due to their release from the sediments to the water column. An overall assessment of the contamination status, spatial distribution, and potential sources of HMs suggested that the water-sediment interaction of HMs and the influence by environmental factors should be subsequently considered for a better understanding of the multimedia fate of HMs in the given dynamic YSLME system or similar environments elsewhere.

Alleviation of lead-induced oxidative stress and immune damage by selenium in chicken bursa of Fabricius

We investigated lead (Pb)-induced oxidative stress and immune damage in the chicken bursa of Fabricius (BF) and the ameliorative effect of selenium (Se). Seven-day-old male chickens were randomly divided into four groups and were provided standard diet and drinking water, Na₂SeO₃ added to the standard diet and drinking water, standard diet and (CH₃COO)₂Pb added to drinking water, and Na₂SeO₃ added to the standard diet and (CH₃COO)₂Pb added to drinking water for 30, 60, and 90 days. The presence of Pb inhibited total antioxidant capacity (T-AOC), glutathione peroxidase (GPx), glutathione S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activities; decreased glutathione (GSH) content; increased malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents; inhibited interleukin (IL)-2 and interferon-γ (IFN-γ) messenger RNA (mRNA) expression; and increased IL-4, IL-6, IL-10, IL-12β, and IL-17 mRNA expression. The presence of Se relieved all of the above Pb-induced changes. There were close correlations among GSH, CAT, T-AOC, SOD, GPx, MDA, and H₂O₂ and among IL-2, IL-4, IL-6, IL-12β, IL-17, and IFN-γ. Our data showed that Pb caused oxidative stress and immune damage in the chicken BF. Se alleviated Pb-induced oxidative stress and immune damage in the chicken BF.

The effect of bioturbation by Lumbriculus variegatus on transport and distribution of lead in a freshwater microcosm

The present study investigated the effect of bioturbation by the oligochaete worm Lumbriculus variegatus on the transport and environmental distribution of lead (Pb). Experiments used L. variegatus at densities of 0 ind./m(2), 2093 ind./m(2), and 8372 ind./m(2), in freshwater microcosms with Pb-spiked sediment. At the end of the 14-d experiment, Pb levels in the water column, tissues of L. variegatus, and sediment were determined, and bioturbation was quantified using luminophores. The bioturbation by L. variegatus increased Pb transport from the sediment to the water column. However, it did not significantly affect Pb bioaccumulation by L. variegatus or Pb levels in the sediment. The biodiffusion coefficient (Db) was positively related to worm density, but did not differ between Pb-spiked sediment and uncontaminated sediment. The latter finding suggests that Pb at the 100 μg/g concentration used in the present study did not affect L. variegatus bioturbation. The present study shows that bioturbation can enhance Pb transfer across the sediment-water interface and thus enhance Pb availability to organisms in the water column.