Ting-Chien Chen

This study establishes a crucial post-operational radiological baseline for the Lungluan Wetland (LLW), a critical ecosystem near the Maanshan Nuclear Power Plant (NPP) in Taiwan, ahead of its 2025 decommissioning. Analysis of fifty sediment samples confirmed the absence of anthropogenic contamination (no detectable ¹³⁷Cs). The activities of natural radionuclides were comparable to global medians for ⁴⁰K (range: 125.7–652.3 Bq/kg) and ²³²Th (9.9–58.7 Bq/kg), while ²²⁶Ra (7.9–33.4 Bq/kg) was lower than the Asian wetland median. Although all radiological hazard indices were well below safety limits, the spatial distribution of radionuclides was highly heterogeneous. Higher concentrations were strongly correlated with fine-grained sediments (clay) and high organic matter content, predominantly in low-velocity depositional zones. These findings demonstrate that sediment characteristics and wetland hydrodynamics are the primary drivers of radionuclide distribution. This research provides an essential benchmark for assessing environmental changes during the NPP decommissioning and shows that sediment properties can serve as effective indicators for identifying potential accumulation hotspots, thereby optimizing future monitoring strategies.

The environmental fate of nickel (Ni) is dictated by its interaction with organic matter (OM), yet the specific roles of OM source and molecular size remain unclear. This study investigated the binding characteristics of Ni with size-fractionated dissolved OM (DOM) from the water column and alkaline-extractable OM (AEOM) from sediments in a tropical wetland. Using ultrafiltration and spectroscopy, we found that sedimentary AEOM was predominantly high-molecular-weight (HMW) and terrestrial compounds, whereas aquatic DOM was dominated by low-molecular-weight (LMW), microbial-derived compounds. Counterintuitively, the highest Ni binding affinity (NiBA) for both DOM and AEOM occurred in the smallest-molecular-weight fraction (<0.3 kDa). Predictive models confirmed this divergence: the model for the more chemically homogeneous AEOM was highly predictive (r = 0.89), while the model for the complex DOM was less robust (r = 0.70). Our findings demonstrate that LMW fractions are hotspots for Ni binding, challenging the common assumption that larger molecules are more reactive. We conclude that biogeochemical processing in sediments creates an OM pool that is chemically distinct and more predictable than that in the overlying water. This distinction is critical for accurately assessing Ni mobility and ecological risk in aquatic systems.

Soil samples were collected from a college campus in Taiwan to measure the levels of radionuclides, contributing to the sustainable management of campus environments. A high-resolution HPGe gamma spectrometry system was utilized to measure the activity concentrations of natural radionuclides (²²⁶Ra, ²³²Th, and ⁴⁰K) and artificial radionuclide (¹³⁷Cs). The activity concentrations of ¹³⁷Cs were not detected in the campus soils, suggesting that artificial radionuclides did not contaminate the soil, supporting sustainable soil quality. However, the average concentrations of ²³²Th and ⁴⁰K with mean values of 53.4 ± 5.1 and 504.5 ± 75.4 Bq/kg dw were higher than the global soil average of 45 and 420 Bq/kg dw, respectively. Meanwhile, the average concentration of ²²⁶Ra with a mean value of 30.1 ± 3.0 Bq/kg dw was similar to the global soil average of 32 Bq/kg. The average outdoor absorbed gamma dose rate (D_ex) and annual effective doses (AED_ex), with a mean of 67.2 nGy/h and 82.4 μSv/y, were found to be higher than the average world levels of 57 nGy/h and 70 μSv/y, respectively. Despite these findings, the radium equivalent activity Ra_eq and external hazard index H_ex, with average values of 145.2 Bq/kg and 0.39, respectively, were below the recommended limit values of 370 Bq/kg and 1.0, respectively. This study provides useful information on the background radioactivity of the study campus, which is crucial for developing sustainable strategies to ensure a safe and healthy environment, indicating that there are no radiological hazards in the soil.

This study analyzed the activity concentrations of various radionuclides in irrigation water, rice components, and corresponding soil samples from eleven paddy fields, revealing significant findings with potential environmental and health implications. The soil exhibited high levels of activity concentrations ranging from 350 to 829, 12.4 to 41.2, and 18.5 to 60.3 Bq/kg, with mean values of 609, 31.1, and 45.0 Bq/kg for ⁴⁰K, ²²⁶Ra, and ²³²Th respectively. Additionally, 12 soil samples from two paddy fields showed ¹³⁷Cs activity concentrations of 5.6 ± 1.3 Bq/kg. The rice plant roots accumulated the highest percentages of total activity concentrations for ²²⁶Ra, ²³²Th, and ¹³⁷Cs, ranging from 76–86%, while only 1.1–10.0% were found in the un-hulled grain. For ⁴⁰K, activity concentrations were distributed among the root (23%), stem (32%), leaf (35%), and un-hulled grain (10%). The mean activity concentrations were 99 ± 12, 0.49 ± 0.09, 0.43 ± 0.12, and 0.10–0.31 Bq/kg for ⁴⁰K, ²²⁶Ra, ²³²Th, and ¹³⁷Cs for un-hulled rice grain, respectively. Transfer factors (TFs) from soil to un-hulled rice grain were calculated as (1.21–2.86) × 10⁻¹ for ⁴⁰K, (0.07–0.11) × 10⁻¹ for ²³²Th, (0.11–0.29) × 10⁻¹ for ²²⁶Ra, and (0.16–0.61) × 10⁻¹ for ¹³⁷Cs. Notably, significant negative correlations were observed between TFs and soil concentrations for ⁴⁰K (r = 0.92, p < 0.001, n = 11) and ²²⁶Ra (r = 0.98, p = 0.026, n = 4), suggesting that macronutrients in soil solutions may inhibit the linear transfer of natural nuclides from the soil solution to rice plants.

This study analyzes the concentration of radioactive material in the soil near the Maanshan nuclear power plant (NPP). Out of the thirty samples, only one sample was found to have ¹³⁷Cs radioactivity measuring 2.58 Bq/kg. The activity concentrations were 77.2–517.7 Bq/kg, 3.9–31.6 Bq/Kg, and 5.3–39.1 Bq/kg, respectively, with mean values of 344.4 Bq/kg, 18.6 Bq/kg, and 26.5 Bq/kg for ⁴⁰K, ²²⁶Ra, and ²³²Th, respectively. These levels are lower than the global average of soil activity concentrations. The activity concentrations varied, with the highest levels being 7–8 times greater than the lowest levels. Clay content had a positive correlation and sand content had a negative correlation with ⁴⁰K, ²²⁶Ra, and ²³²Th activity concentrations. The activity concentrations followed a normal distribution for ⁴⁰K, ²²⁶Ra, and ²³²Th. The activity ratios for ²³²Th/²²⁶Ra, ⁴⁰K/²³²Th, and ⁴⁰K/²²⁶Ra were 1.43 ± 0.22, 13.1 ± 1.9, and 18.8 ± 4.1, respectively, and ratios show light minerals in the soils. The average values for external hazard indices (H_ex) and radium equivalent activity (Ra_eq) were 0.22 Bq/kg and 83.0 Bq/kg, respectively, both of which are below the recommended limit values of 1.0 Bq/kg and 370 Bq/kg, respectively. The outdoor absorbed dose rate (D_Rex) and annual effective dose equivalent (AED_ex) were 39.0 nGy/h and 47.8 μSv/y, respectively, both of which are lower than the global soil average of 59 nGy/h and 70 μSv/y, respectively. These results indicate that local residents and tourists are not at significant risk of radiological hazards from the soil. The soil activity concentrations can serve as a baseline for continuous monitoring, even after the Maanshan NPP is decommissioned in 2025.

Estrogens in river systems can significantly impact aquatic ecosystems. This study aimed to investigate the multiphase partitioning of estrogens in Wulo Creek, Taiwan, which receives animal feedlot wastewater, to understand their distribution and potential environmental implications. Water samples were separated into suspended particulate matter (SPM), colloidal, and soluble phases using centrifugation and cross-flow ultrafiltration. Concentrations of estrone (E1), 17β-estradiol (E2), and estriol (E3) in each phase were analyzed using LC/MS/MS. Partition coefficients were calculated to assess estrogen distribution among phases. Estrogens were predominantly found in the soluble phase (85.8–87.3%). The risk assessment of estrogen equivalent (EEQ) values suggests that estrogen concentration in water poses a higher risk compared to SPM, with a majority of the samples indicating a high risk to aquatic organisms. The colloidal phase contained 12.7–14.2% of estrogens. The log K_COC values (4.72–4.77 L/kg-C) were significantly higher than the log K_OC and log K_POC values (2.02–3.40 L/kg-C) for all estrogens. Colloids play a critical role in estrogen distribution in river systems, potentially influencing their fate, transport, and biotoxicity. This finding highlights the importance of considering colloidal interactions in assessing estrogen behavior in aquatic environments.

This study investigated the distribution and binding affinity of dissolved copper (Cu) and organic carbon (OC) in size-fractioned dissolved organic matter (DOM) in a constructed wetland (CW). Two sites were studied: one at the inflow (P-1) and one within the wetland (P-2). The DOMs (DOM) was 74.9 ± 24.0 μmol/g-C at site P-1 and 17.3 ± 2.6 μmol/g-C at site P-2. The CuBA_DOM ratios were decreased in wetlands of bulk and size-fractioned DOM (p < 0.001 to p = 0.073). The SUVA₂₅₄ values for bulk DOM solution were 2.54 ± 0.15 and 1.68 ± 0.18 L/mg-C/m, and humidification index (HIX) values were 1.74 ± 0.16 and 2.09 ± 0.19 for sites P-1 and P-2, respectively. Optical indicators suggested that the wetland process decreased aromaticity but increased the humification degree of DOM. Furthermore, the CuBA_DOM ratios positively correlated with SUVA₂₅₄ and HIX within the constructed wetland DOM but not in the influent DOM. Understanding the Cu distribution and binding affinity to size-fractioned DOM makes it possible to develop strategies to mitigate the potential effects of copper pollution in wetlands.

This study investigated the distribution of copper in sediment dissolved and particulate organic matter (DOM and POM) based on their size. The DOM and alkaline extracted POM (AEOM) were separated into five size fractions using a cross-flow ultrafiltration (CFUF) system. The results showed that Cu mass was mainly distributed in the low molecular weight (AEOM) ranged from 17.0 to 149.6 μmol/g-C in site-1 and from 20.6 to 143.7 μmol/g-C in site-2. The HMW CuBA_AEOM ratios were significantly higher than the LMW ratios. The Cu and DOM binding affinity ratios (CuBA_DOM) ranged from 5.6 to 358.6 μmol/g-C and 17.2 to 126.6 μmol/g-C in site-1 and site-2, respectively. However, the LMW CuBA_DOM ratios were significantly higher than the HMW ratios. Optical indices suggested that the AEOM had more aromaticity and terrestrial and allochthonous contributions than the DOM. The optical indices were significantly correlated with the CuBA_AEOM ratios but weakly correlated with the CuBA_DOM ratios. Sediment exchange between POM and DOM may affect copper distribution. DOM has a low-molecular-weight composition, while POM retains high-molecular-weight organic matter.

Uncertainty remains over composting time and maturity degree for compost production. The objectives of this study were to establish maturity indicators for composting based on spectral and chemical components and to provide a reference for future composting management. Several indicators of composting were assessed for three commercial composts at 0, 7, 15, 30, 45, and 60 days during the germination of Chinese cabbage, including (1) central temperature, (2) moisture content, (3) pH, (4) electrical conductivity, (5) C/N ratio, (6) E4/E6 ratio, (7) fluorescence humification index (HIX), and (8) germination index (GI). We evaluated the optimal composting time using these indicators, reflecting the changes in hog manure, chicken manure, and agricultural by-product composts throughout their composting process to provide a basis for maturity time. The results showed that the E4/E6 ratio, C/N ratio, humic acid (HA), fulvic acid (FA), and germination rate, which reached a stable status after 30 days of composting, could be the indicators of “early-stage” maturity. In contrast, central temperature, electrical conductivity, HIX, and GI reached stable values after 45 days of composting and thus could be more suitable indicators of full maturity. Based on our results, we recommend a minimum composting time of 30 days to achieve primary maturity, while fully matured compost may be obtained after 45 days.

This study investigated natural gamma emitting radionuclides ⁴⁰K and ²²⁶Ra in rice consumed in Taiwan. Thirty rice samples, collected from local markets, included 24 local rice and 6 imported rice samples. Radionuclide activities were 24.05 ± 10.21 and 0.62 ± 0.61 Bq/kg for ⁴⁰Kand ²²⁶Ra for all rice samples. The activity of each radionuclide was insignificantly different for local and imported samples (p = 0.33 and 0.52 for ⁴⁰K and ²²⁶Ra, respectively). The annual effective doses from rice consumption were estimated to be 6.80 ± 2.89 and 7.86 ± 7.81 μSv/y for ⁴⁰K and ²²⁶Ra, respectively, and the sum ingestion dose of ²²⁶Ra and ⁴⁰K was 14.66 ± 8.57 μSv/y. These values were one order of magnitude less than the 290 μSv/y world average of the ingestion exposure from natural sources. The results suggest that rice consumption in Taiwan is radiologically safe for the investigated radionuclides.