Changsuo Li

The relocation and closure of electroplating industries have generated numerous contaminated brownfields, many of which are located in areas with potential for residential and commercial redevelopment. However, information regarding the distribution characteristics, migration, and health risks of heavy metals at decommissioned electroplating sites remain limited. In this study, 160 soil samples were collected from a decommissioned electroplating factory in Dezhou, Shandong Province, China, to characterize the spatial distribution and migration behavior of Ni, Zn, and Cr(VI), identify contamination hotspots and potential pollution sources, and evaluate associated carcinogenic and non-carcinogenic risks under the planned future land-use scenario. Human health risks were quantitatively evaluated using the United States Environmental Protection Agency (USEPA) risk assessment model with exposure parameters adapted to the local Chinese population. Results showed that the site was severely contaminated by heavy metals, with 27.5% [Cr(VI)], 6.9% (Ni), and 1.9% (Zn) of the samples exceeding the applicable screening values. The maximum concentrations reached 10,600 mg·kg⁻¹ for Ni, 17,300 mg·kg⁻¹ for Zn, and 390 mg·kg⁻¹ for Cr(VI). Contamination hotspots were concentrated in former production workshops and the wastewater treatment area. The depth profiles suggested contaminant-specific migration patterns, with Cr(VI) detected at a depth of 6.5 m, indicating its strong mobility in subsurface soils. Health risk assessment revealed that oral exposure was the dominant exposure pathway for both adults and children, while inhalation contributed negligibly to overall exposure. Estimated non-carcinogenic risks were higher for children than for adults, with the HI for Ni reaching 2.70. Furthermore, the maximum total carcinogenic risk estimated for Ni exposure in children was 7.50 × 10⁻³, exceeding the acceptable risk threshold. These findings demonstrate the importance of integrating contaminant distribution, source identification, and human health risk assessment when managing decommissioned electroplating brownfields and provide a scientific basis for risk-based remediation and sustainable redevelopment.

Nitrate is a key indicator for assessing groundwater quality, and nitrate pollution in groundwater poses a threat to water security and ecological health in the Yellow River Basin. Taking the Changxiao hydrogeological unit as an example, this paper studies the characteristics, influencing factors and health risks of nitrate pollution in groundwater by using nitrate pollution index, hierarchical cluster analysis, factor analysis, Monte Carlo simulation and human health risk assessment. The results show that the average concentration of NO ₃ ^- -N is 19.48 mg/L, with pore water exhibiting the highest levels, followed by karst water and then fissure water in terms of average concentration. The average nitrate pollution index is 3.31, and 50% of the samples are severely polluted with nitrate. The pollution is mainly distributed in densely populated areas, especially near Xiaoli Town, Guide Town and Ancheng Town. Both anthropogenic and natural factors affect the groundwater chemical field in the study area. In areas with serious nitrate pollution, the impact of human activities is particularly serious. Probabilistic health risk assessment shows that the probabilities of potential risks posed by nitrate in pore water to children and adults are 24.37% and 6.67%, respectively; and in karst water, the probabilities to children and adults are 24.83% and 3.64%, respectively. The potential risk of nitrate to adults is far less than that to children who requires special attention. According to sensitivity analysis, the concentration of nitrate is the main variable affecting health risk assessment, which should be paid attention to reduce health risks. These results provide a scientific basis for groundwater pollution control and rational water resource management in both the study area and the lower Yellow River reaches.

Groundwater, a vital source of water supply, is currently experiencing a pollution crisis that poses a significant risk to human health. To understand the hydrochemical formation mechanisms, quality and risk to human health of groundwater in the upper reaches of the Wulong River basin, 63 sets of groundwater samples were collected and analyzed. A combination of mathematical statistics, correlation analysis, Gibbs diagram, ion ratio, and cation exchange were comprehensively employed for hydrochemical analysis, and further water quality index (WQI) and human health risk assessment were conducted. The results indicate that groundwater is generally neutral to weakly alkaline. The dominant cations in the groundwater are Ca²⁺ and Mg²⁺, while the main anions are HCO₃⁻ and SO₄²⁻. The hydrochemical types of groundwater mainly include HCO₃·SO₄-Ca, HCO₃-Ca and HCO₃-Na. The diverse hydrochemical types are mainly due to the fractured and discontinuous nature of the aquifers. The hydrochemical characteristics are influenced by the dissolution of silicate and carbonate minerals, cation exchange processes, and anthropogenic pollution. The presence of NO₃⁻ in groundwater is primarily attributed to agricultural activities. The groundwater is mainly categorized as "Good" (36.6%) and "Poor" (60.8%). "Very poor" and "Excellent" categories are rare, accounting for only 1.2% and 1.4%, respectively, and no samples are classified as "Non-drinkable". The Ew_i for NO₃⁻ is the highest, indicating severe contamination by anthropogenic NO₃⁻ pollution. Human health risk assessment reveals that water samples posing exposure risks account for 82.54% for children and 79.37% for adults. This study highlighted that anthropogenic nitrate pollution has deteriorated groundwater quality, posing risks to human health. It also suggests an urgent need to enhance research and protective measures for groundwater in similar regions, such as the Shandong Peninsula.

Dehalogenating bacteria are still deficient when targeted to deal with chlorinated hydrocarbons (CHCs) contamination: e.g., slow metabolic rates, limited substrate range, formation of toxic intermediates. To enhance its dechlorination capacity, biochar and its composites with appropriate surface activity and biocompatibility are selected for coupled dechlorination. Because of its special surface physical and chemical properties, it promotes biofilm formation by dehalogenating bacteria on its surface and improves the living environment for dehalogenating bacteria. Next, biochar and its composites provide active sites for the removal of CHCs through adsorption, activation and catalysis. These sites can be specific metal centers, functional groups or structural defects. Under microbial mediation, these sites can undergo activation and catalytic cycles, thereby increasing dechlorination efficiency. However, there is a lack of systematic understanding of the mechanisms of dechlorination in biogenic and abiogenic systems based on biochar. Therefore, this article comprehensively summarizes the recent research progress of biochar and its composites as a “Taiwan balm” for the degradation of CHCs in terms of adsorption, catalysis, improvement of microbial community structure and promotion of degradation and metabolism of CHCs. The removal efficiency, influencing factors and reaction mechanism of the degraded CHCs were also discussed. The following conclusions were drawn, in the pure biochar system, the CHCs are fixed to its surface by adsorption through chemical bonds on its surface; the biochar composite material relies on persistent free radicals and electron shuttle mechanisms to react with CHCs, disrupting their molecular structure and reducing them; biochar-coupled microorganisms reduce CHCs primarily by forming an “electron shuttle bridge” between biological and non-biological organisms. Finally, the experimental directions to be carried out in the future are suggested to explore the optimal solution to improve the treatment efficiency of CHCs in water.

Karst groundwater is a crucial water source, but it has faced significant environmental risks in recent years. The complexity of the groundwater system necessitates innovative approaches to studying karst groundwater. This paper focuses on the karst groundwater of the Baotu Spring area in Jinan. Using the nanoparticle tracking analysis instrument, it is observed that the collected groundwater contains many natural nanoparticles, with particle sizes mainly ranging from 76.3 to 621.8 nm and concentrations primarily between 0.31 and 5.0 × 10⁵ Particles/L. The transmission electron microscope (TEM) is used to study the characteristics of naturally occurring nanoparticles in the karst groundwater. The results show that the karst groundwater mainly contains particles of Ca, Na, Fe, Al, Si, and other elements, which exist in granular and irregular forms. The size of individual particles varies from 40 to 600 nm, and they are mostly amorphous and monocrystalline. The characteristics of the particles suggest that the direct recharge area mainly receives infiltration from atmospheric precipitation, with minimal influence from human activities and agriculture. In contrast, the indirect recharge and discharge areas are more significantly affected by external environments, including domestic sewage, industrial wastewater discharge, and agricultural fertilizers. These findings also suggest that elements can be transported in particle form during water-rock interactions, potentially playing a significant role in the cycling of elements between water and rocks. The particles in the study area are situated in a relatively oxidized environment, suggesting that fracture and oxidation are the main processes for particle formation. Particles can effectively transport metallic elements in groundwater, offering fresh perspectives on the migration of these elements and acting as carriers for inorganic substances, thereby increasing their mobility in aquatic environments. Given the widespread presence of natural nanoparticles in the water cycle system, some stable nanoparticles can serve as new types of groundwater tracing agents during the groundwater migration process.

Karst areas are widespread in China and can be divided into southern karst and northern karst based on the geographical boundary of Qinling Mountains and Huaihe River. In northern karst regions, karst springs are the predominant landform. Previous studies on karst springs have predominantly focused on macroscopic perspectives, such as water chemistry characteristics, with less attention given to the microscopic characteristics of springs. Therefore, this study focused on the Jinan Baotu Spring area, representative of a typical northern karst region, and investigated the natural nanoparticles present in different aquifers at various depths from a microscopic point of view. Through the observation of nanoparticle tracking analyzer (NTA), numerous nanoparticles were identified in the groundwater samples. The particle size range of the particles contained in groundwater is mainly concentrated in the range of 150–500 nm, and the particle concentration is mainly concentrated in the range of 1.5–5.0 × 10⁵ Particles/L. The microstructure, chemical composition, and element distribution of these nanoparticles were analyzed using TEM-EDS techniques. The results unveiled the presence of Ti-bearing nanoparticles in various groundwater layers, including both crystalline and amorphous states, as well as nanoparticles exhibiting the coexistence of crystal and amorphous structures. By comparing the measured lattice spacing with PDF cards, the crystalline Ti-bearing nanoparticles were identified as rutile, brookite, anatase, ilmenite, pseudorutile, and ulvospinel. Furthermore, the main components of the amorphous Ti-bearing nanoparticles predominantly consisted of Ti or a mixture of Ti and Fe. EDS analysis further indicated that the Ti-bearing nanoparticles carried additional metal elements, such as Zn, Ca, Mn, Mo, Cr, and Ni, suggesting their potential role as carriers of metal elements during groundwater transportation. This discovery provided new insights into the migration of metal elements in groundwater and underscores the capacity of nanoparticles to enhance the mobility of inorganic substances within the water environment. Notably, brookite was detected in three different areas, including the direct discharge area, indirect recharge area, and discharge area, which may indicate that some special natural nanoparticles could serve as natural mineral tracer particles in the process of groundwater migration.

Clay minerals are effective adsorbents for the remediation of pesticides in wastewater due to their large superficial areas and excellent cation-exchange capabilities. However, this adsorption effect can be reduced by the accumulation of adsorbents on clay minerals, amongst other problems. Therefore, in this study, montmorillonite (Mnt) modified by layered double hydroxide (LDH) with different loading amounts was successfully prepared using an in situ method. The results from X-ray diffraction, Fourier-transform infrared spectrometry, Brunauer–Emmet–Teller (BET) and scanning electron microscopy analyses revealed that LDH structures were successfully combined with the Mnt layer and formed a porous structure. However, excess LDH still caused the aggregation and accumulation of layers. The adsorption performance of LDH@Mnt for atrazine (ATZ) and paraquat (PQ) was investigated, and the removal efficiency of the LDH@Mnt composite was higher than those of Mnt and LDH alone. The kinetic study revealed that the adsorption process fitted the pseudo-second-order model and internal diffusion model, and 3-LDH@Mnt had the greatest absorbability efficiency for both ATZ and PQ, indicating the adsorption process was controlled by the number of active sites of the adsorbent. The generalized Langmuir model accurately characterized the adsorption process of ATZ and PQ elimination in the adsorption isotherm investigation, indicating that the adsorption energies of the active sites on the adsorbents were different. 3-LDH@Mnt had better absorbability performance for ATZ/PQ, and the sorption capacities were 7.03 and 91.9 mg g^–1, respectively. According to site energy distribution theory, the amount of sorption sites of the composite adsorbent was large and the average adsorption energy was high, both of which being beneficial for the adsorption of ATZ and PQ. The effects of pH, coexisting anions and reuse experiments were also tested, indicating that the LDH@Mnt composite possessed high adsorption stability. This excellent removal performance represents a promising strategy for the remediation and elimination of pesticide contaminations from the environment.

Karst groundwater is an important water supply, especially in northern China. With the rapid development of China’s economy, anthropogenic activities have had a significant impact on karst groundwater formation, circulation and other processes. In this paper, the Baotu spring basin, which is closely related to anthropogenic activities, was selected as the research object to carry out a study of water chemical characteristics and evolutionary processes. And, mathematical statistics, Piper trilinear diagram, Gibbs diagram, and ion ratio methods were used to analyze the characteristics and evolution processes of groundwater. The results of this study show that the hydrogeochemical components of karst groundwater are mainly controlled by the weathering of rocks, mainly by the dissolution of carbonate rocks and silicates with the dominant cation of Ca²⁺ and the dominant anion of HCO₃⁻. Considering the role of anthropogenic activities, including agricultural and industrial activities, the evolution process of karst groundwater is mainly controlled by hydrogeochemical effects such as mineral dissolution and filtration, the mixing of multiple water bodies, anthropogenic activities (domestic sewage, industrial and agricultural wastes), oxidation–reduction and cation alternating adsorption. Moreover, the influence of anthropogenic activities on the formation and evolution of karst groundwater gradually increases, leading to the rise in nitrate content in karst groundwater and accelerating carbonate rock dissolution. The research results of this paper can provide a favorable reference for environmental protection and research on karst groundwater in areas of intensive anthropogenic activity.

Environmental nanoparticles are known to be present in various aquatic environments, exerting significant influences on water quality, particularly in water distribution systems. However, there has been a notable dearth of research on the presence and impact of environmental nanoparticles in mineral water, a unique water resource. In this study, we employed Nanoparticle Tracking Analysis (NTA) and conducted High-Resolution Transmission Electron Microscopy (HRTEM) to address this research gap. This groundbreaking study represents the first comprehensive exploration of environmental nanoparticles within natural mineral water from Zibo City, Shandong Province, China. The results of the NTA showed that the concentration of the particles was 5.5 × 10⁵ particles/mL and the peak diameter of the size distribution was 180 nm. The HRTEM showed that the nanoparticles were granular, pinniform, rodlike, and flakey in shape, and some of the nanoparticles existed in aggregation. The energy-dispersive spectrometry results showed that most of the nanoparticles contained O, Mg, Ca, Si, Fe, Ti, and P, and some of them also contained F, V, S, and Mn. When combined with the characteristics of the selected area electron diffraction pattern, the nanoparticles were confirmed to be Ca-bearing nanoparticles, attapulgite nanorods, MnO₂ nanosheets, and TiO₂ nanoparticles. These findings shed light on a novel manifestation of elemental compositions in mineral water. Furthermore, considering the chemical and physical attributes of both the nanoparticles and mineral water, it is highly plausible that these environmental nanoparticles result from the weathering of minerals. The presence of these nanoparticles within mineral water offers a unique opportunity to advance our comprehension of nanoparticle behavior across diverse systems. Significantly, the realm of environmental nanoparticle science holds paramount importance for ongoing endeavors in ensuring water safety, enhancing treatment processes, and facilitating effective remediation procedures.