LINC00665 promotes the progression and immune evasion of lung cancer by facilitating the translation of TCF7 protein through dependence on IRES.

OBJECTIVE: To investigate the influence of LINC00665 on the development and immune evasion of lung cancer. METHODS: Tumor tissues and corresponding adjacent tissues were collected from 84 lung cancer patients, categorized into non-metastatic (n = 58) and metastatic (n = 26) groups. LINC00665 expression in lung cancer and metastatic lung cancer tissues was assessed via qRT-PCR. Pearson correlation analysis was conducted to examine the correlation between LINC00665 and immune-modulating cytokines (TGF-ß, IL-10, IL-1ß, IFN-γ, IL-2, TNF-α). A549 and H1299 cells, with relatively high LINC00665 expression, were used for in vitro studies. Cells were transfected with LINC00665-targeting shRNA, and changes in proliferation, apoptosis, migration, invasion, and NK cell cytotoxicity were assessed. Downstream molecular mechanisms of LINC00665 were investigated using GEO database analysis, highlighting the association with HHLA2. LINC00665's role in promoting HHLA2 expression via binding with TCF7 was explored. In low LINC00665-expressing A549/H1299 cells, overexpression of HHLA2 was performed to evaluate effects on malignant behavior and NK cell sensitivity. A xenograft model was established for in vivo validation through tumor volume and weight measurements, Ki-67 immunoreactivity analysis, and flow cytometry analysis of CD107a + NK cells. RESULTS: LINC00665, TCF7 mRNA, and HHLA2 mRNA expression levels were significantly higher in lung cancer tissues than adjacent tissues, with non-metastatic lung cancer showing higher expression than metastatic lung cancer. In metastatic lung cancer, LINC00665 positively correlated with immune-suppressive cytokines (TGF-ß, IL-10, IL-1ß) and negatively correlated with anti-tumor cytokines (IFN-γ, IL-2, TNF-α). LINC00665 knockdown significantly inhibited lung cancer cell growth and metastasis, promoting sensitivity to NK cells. Further analysis revealed that LINC00665 recruits transcription factor TCF7 to upregulate HHLA2 expression in lung cancer cells, thereby facilitating lung cancer development and immune escape. CONCLUSION: LINC00665, through recruitment of TCF7 and upregulation of HHLA2, inhibits NK cell cytotoxicity, promoting the development and immune evasion of lung cancer.

Arsenic mobilization across the sediment-water interface of the Three Gorges Reservoir as a function of water depth using DGT and HR-Peepers, a preliminary study.

The artificial regulation of the Three Gorges Reservoir (TGR) creates large water level fluctuation zones (WLFZ) that may change the behavior of metals and metalloid in sediment, particularly redox sensitive elements. Mobilization of As, Fe and Mn across the sediment-water interface (SWI) in the TGR as a function of different water depth (periodically and permanently submerged sediments, respectively) was in situ determined by diffusive gradients in thin films (DGT) and high-resolution dialysis technique (HR-Peeper), respectively. The results showed that the mobilization of As was significantly affected by Fe/Mn especially Mn, across the SWI. Duo to the oxic-anoxic transitional state in near bottom water, the reduced Fe and Mn in sediment pore water could be oxidized and precipitated again, leading to the co-precipitation of As with Fe/Mn oxides (hydroxides). Consequently, concentrations of As, Fe and Mn in labile phases and pore water were generally low across the SWI, then they sharply increased at a few centimeters below the SWI. Considering different water depth, various trends were found in labile phase, whereas concentrations of As, Fe and Mn in pore water in permanently submerged sediments were significantly higher than those in periodically submerged sediments. The dry-re-wetting alternation processes in the WLFZ may play vital roles in the resupply capacity of sediments as it was found that periodically submerged sediments with longer re-wetting time had higher Fe/Mn resupply capacity than those with shorter re-wetting times and permanently submerged sediments.

Identification of immune-related gene signature for non-small cell lung cancer patients with immune checkpoint inhibitors.

Background: The utilization of immune checkpoint inhibitors (ICIs) has become the established protocol for treating advanced non-small cell lung cancer (NSCLC). This work aimed to identify the immune-related gene signature that can predict the prognosis of NSCLC patients receiving ICI treatment. Methods: The ImmPort database was queried to obtain a list of immune-related genes (IRGs). Differentially expressed IRGs in NSCLC patients were identified using the TCGA database. RNA-seq data and clinical information from NSCLC patients receiving immunotherapy were obtained from the GEO database (GSE93157 and ////). A gene signature was generated through multivariate Cox and LASSO regression analyses. The prognostic value and function of this gene signature were thoroughly investigated using comprehensive bioinformatics analyses. Results: A total of 6 prognostic-related genes were identified from 617 differentially expressed genes, and two prognostic-related differentially expressed genes (CAMP and IL17A) were determined to construct gene signature. Our gene signature demonstrated superior performance compared to other clinicopathological parameters in predicting the prognosis of NSCLC patients receiving immunotherapy, with an area under the ROC curve (AUC) of 0.812. Furthermore, immune infiltration analysis indicated that the high-risk group was enriched with resting CD4 T cell memory, while the low-risk group showed a "hot" tumor microenvironment that promotes anti-tumor immunity in NSCLC patients. Conclusion: Gene signatures based on immune-related genes exhibited excellent indicator performance of prognosis and immune infiltration, which has the potential to be an effective biomarker for NSCLC with ICI treatment.

Programmable DNA Circuit-Facilitated Determination of Circulating Extracellular Vesicle PD-L1 for Lung Cancer Diagnosis and Immunotherapy Response Prediction.

Circulating extracellular vesicle (EV) PD-L1 is correlated with the occurrence and progression of lung cancer and has great potential as a valuable diagnostic and immunotherapy predictive biomarker. In this work, we propose a fluorescent biosensing method for the sensitive and accurate determination of circulating EV PD-L1. Specifically, after the phosphatidylserine-targeting peptide-assisted magnetic enrichment, a programmable DNA circuit is designed to translate the presence of PD-L1 to the appearance of numerous duplex DNA probes on the circulating EV surface. Upon fructose treatment, these newly formed duplex DNA probes are released from the EV surface to activate the trans-cleavage activity of CRISPR/Cas12a system, which finally produces a significant fluorescence signal. Experimental results reveal that the method not only enables sensitive determination of EV PD-L1 with a detection limit of 67 particles/mL but also demonstrates the potential use in the diagnosis and immunotherapy response prediction of lung cancer in a principle-of-proof study. Therefore, the method may provide a useful tool for EV PD-L1 determination, which may provide valuable information for the precise diagnosis and personalized treatment of lung cancer patients.

Immunotherapy resistance of lung cancer.

In recent years, immunotherapy has made remarkable breakthroughs and brought long-term survival benefits to lung cancer patients. However, a high percentage of patients do not respond to immunotherapy or their responses are transient, indicating the existence of immune resistance. Current studies show that the interactions between cancer cells and immune system are continuous and dynamic. A range of cancer cell-autonomous characteristics, tumor microenvironment factors, and host-related influences account for heterogenous responses. Furthermore, with the identification of new targets of immunotherapy and the development of immune-based combinations, we propose the response strategies to overcome resistance.

Treatment of small cell lung cancer: recent advances.

PURPOSE OF REVIEW: In this article, we aimed to summarize the recent progress being made in treatment of small cell lung cancer (SCLC). RECENT FINDINGS: SCLC is characterized by strong invasiveness, easy recurrence and early metastasis. In recent years, the emergence of immune checkpoint inhibitors (ICIs) therapy has broken the deadlock in the treatment field of SCLC. Combination strategies, such as the addition of ICIs to chemotherapy and radiotherapy, are actively underway. Some of these strategies have yielded significant survival benefits and tolerable adverse events, whereas several of them have failed with no significant improvement. In addition, the new classification of SCLC based on genomic analysis has deepened the understanding of SCLC and suggested new therapeutic directions. Similarly, the discovery of some new therapeutic targets, such as DDL3, CDK7 and PARP, also brings new hope for improving the survival of patients with SCLC. SUMMARY: In this article, we will review the recent advances of therapeutic regimen for patients with SCLC. Following the revolutionary success of adding ICIs to chemotherapy, more varieties of combination strategies have been explored in recent trials. In addition, therapeutic drug research and efficacy evaluation against for new targets are under investigation. Altogether, progress on genomic analysis, investigation of biological pathways and treatment regimen combination are providing renewed hope for patients with SCLC.

Treatment efficacy of HER2-mutant lung adenocarcinoma by immune checkpoint inhibitors: a multicenter retrospective study.

BACKGROUND: Despite the remarkable clinical advance of immune checkpoint inhibitors (ICIs) in the treatment of lung cancer, there are limited studies focused on evaluating efficacy of ICIs for patients with human epidermal growth factor receptor 2 (HER2)-mutant lung adenocarcinoma. METHODS: We conducted a multicenter retrospective study of patients with HER2-mutant lung adenocarcinoma who received ICIs therapy at Shanghai Pulmonary Hospital, Shanghai Chest Hospital and the First Affiliated Hospital of Wenzhou Medical University between 2016 and 2021. Response was defined with reference to the Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1. RESULTS: Among the 26 patients enrolled in our study, the overall objective response rate (ORR) was 38.5%, disease control rate (DCR) was 84.6% and median progression-free survival (PFS) was 7.4 months. Majority of patients were treated with immunochemotherapy combination regimens (16/26, 61.5%), with a median PFS of 8.4 months. Among the 9 patients receiving ICIs-based therapy as first-line treatment, 5 patients had partial response (PR) and 4 patients had stable disease (SD), with a median PFS of 9.1 months. Of the entire cohort, 5 patients who received ICIs before epidermal growth factor receptor (EGFR)/HER2-targeting drugs achieved a median PFS of 8.4 months. CONCLUSION: Our retrospective study provides clinical evidence that front line of ICIs-based therapy is also worth considering for the treatment to improve survival outcomes of patients with HER2-mutant lung adenocarcinoma.

Differences in Carbon and Nitrogen Migration and Transformation Driven by Cyanobacteria and Macrophyte Activities in Taihu Lake.

The metabolic activities of primary producers play an important role in the migration and transformation of carbon (C) and nitrogen (N) in aquatic environments. This study selected two typical areas in Taihu Lake, a cyanobacteria-dominant area (Meiliang Bay) and a macrophyte-dominant area (in the east area of the lake), to study the effects of cyanobacteria and macrophyte activities on C and N migration and transformation in aquatic environments. The results showed that total N and total particulate N concentrations in the water of the cyanobacteria-dominant area were much higher than those in the macrophyte-dominant area, which was mainly due to the assimilated intracellular N in cyanobacteria. Macrophyte activity drove a significantly higher release of dissolved organic C (DOC) in the water than that driven by cyanobacteria activity, and the DOC contents in the water of the macrophyte-dominant area were 2.4~4.6 times the DOC contents in the cyanobacteria-dominant area. In terms of the sediments, organic matter (OM), sediment total N and N species had positive correlations and their contents were higher in the macrophyte-dominant area than in the cyanobacteria-dominant area. Sediment OM contents in the macrophyte-dominant area increased from 4.19% to 9.33% as the sediment deepened (0~10 cm), while the opposite trend was presented in the sediments of the cyanobacteria-dominant area. Sediment OM in the macrophyte-dominant area may contain a relatively high proportion of recalcitrant OC species, while sediment OM in the cyanobacteria-dominant area may contain a relatively high proportion of labile OC species. Compared with the macrophyte-dominant area, there was a relatively high richness and diversity observed in the bacterial community in the sediments in the cyanobacteria-dominant area, which may be related to the high proportion of labile OC in the OM composition in its sediments. The relative abundances of most OC-decomposing bacteria, denitrifying bacteria, Nitrosomonas and Nitrospira were higher in the sediments of the cyanobacteria-dominant area than in the macrophyte-dominant area. These bacteria in the sediments of the cyanobacteria-dominant area potentially accelerated the migration and transformation of C and N, which may supply nutrients to overlying water for the demands of cyanobacteria growth. This study enhances the understanding of the migration and transformation of C and N and the potential effects of bacterial community structures under the different primary producer habitats.

Real-world outcomes of chemo-antiangiogenesis versus chemo-immunotherapy combinations in EGFR-mutant advanced non-small cell lung cancer patients after failure of EGFR-TKI therapy.

BACKGROUND: Despite the potent efficacy of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) in the treatment of EGFR-mutant non-small cell lung cancer (NSCLC) patients, drug resistance inevitably ensues, and there remains a paucity of treatment options in clinical practice. METHODS: We identified patients with EGFR-mutant advanced NSCLC presenting to Shanghai Pulmonary Hospital and Shanghai Chest Hospital between January 2015 and December 2020 treated with chemo-antiangiogenesis or chemo-immunotherapy combinations after EGFR-TKI resistance. Patient information was collected, and the objective response rate (ORR), disease control rate (DCR), and progression-free survival (PFS) were assessed. RESULTS: A total of 144 patients who met our inclusion criteria were enrolled. Chemo-immunotherapy combinations achieved a higher objective response rate (ORR) compared with chemo-antiangiogenesis combinations (29.5% vs. 13.0%, P=0.018). The DCR was similar between the two groups (93.0% vs. 88.6%, P=0.585), as was the median PFS (7.59 vs. 6.90 months, P=0.552). In the subgroup analyses, patients who developed secondary T790M mutations after EGFR-TKI treatment were less likely to benefit from chemo-immunotherapy combinations than their T790M-negative counterparts (3.42 vs. 7.63 months, P=0.028). For patients who received chemo-antiangiogenesis combinations after TKI resistance, no significant difference was observed in the median PFS between T790M-positive and T790M-negative patients (median PFS: 5.33 vs. 7.46 months, P=0.202). Additionally, multivariate analysis showed that an elevated platelet count was independently associated with a worse PFS for both groups. CONCLUSIONS: The efficacy of chemo-immunotherapy combinations was comparable to chemo-antiangiogenesis combinations after failure of EGFR-TKI therapy. For patients harboring EGFR T790M mutations, chemo-antiangiogenesis combinations may be the preferred therapeutic option. In addition, platelet count could be a potential prognostic factor for patients after failure of EGFR-TKI therapy. Further research should be conducted on larger populations and in a prospective setting.

Favorable clinical outcomes of checkpoint inhibitor-based combinations after progression with immunotherapy in advanced non-small cell lung cancer.

Aim: Immune checkpoint inhibitors (ICIs) have dramatically changed the treatment paradigm in patients with non-small-cell lung cancer (NSCLC). However, progression patterns with immunotherapy are currently unclear and therapeutic options beyond resistance remain challenging. Methods: We reviewed advanced NSCLC patients between January 2016 and December 2019 who were treated with anti-PD-1/PD-L1 inhibitors in our center and identified those who developed disease progression. Later-line treatment strategies were collected and objective response rate, progression-free survival (PFS), and overall survival (OS) were assessed. Results: Of the 118 patients, 46 (39.0%) showed oligoprogression and 72 (61.0%) showed systemic progression. No difference in progression patterns was observed between monotherapy and combination therapy. Systemic progression was strongly associated with never-smokers (51.4% vs. 21.7%, P = 0.001) and ECOG PS = 2 (13.9% vs. 2.2%, P = 0.048) at baseline. The distribution of progression sites was roughly similar between oligoprogression and systemic progression, and the most commonly affected anatomic site was lung (66.9%), followed by bone (12.7%) and lymph nodes (11.0%). For patients beyond first disease progression, checkpoint inhibitor-based combinations could lead to a significantly longer PFS2 compared with ICIs monotherapy (9.63 months vs. 4.23 months, P = 0.004, HR = 0.394, 95%CI: 0.174-0.893) and other therapy (9.63 months vs. 4.07 months, P = 0.046, HR = 0.565, 95%CI: 0.326-0.980). Median OS of the ICIs combination group was not reached but was significantly longer than other therapy group (NR vs. 14.37 months, P = 0.010, HR = 0.332, 95%CI: 0.167-0.661). Conclusion: Systemic progression occurs more frequently among NSCLC patients receiving ICIs. Checkpoint inhibitor-based combinations show favorable outcomes as subsequent treatment strategies after the failure of previous ICIs treatment.

Placental Mesenchymal Stromal Cells (PMSCs) and PMSC-Derived Extracellular Vesicles (PMSC-EVs) Attenuated Renal Fibrosis in Rats with Unilateral Ureteral Obstruction (UUO) by Regulating CD4+ T Cell Polarization.

PURPOSE: Recent evidence has shown that CD4+ T helper (Th) cells are involved in renal inflammation and fibrosis. However, whether renal fibrosis can be alleviated by intervening in the polarization of CD4+ T cells remains unknown. Our research investigated the effects of intravenously administered placenta mesenchymal stromal cells (PMSCs) or treatment with extracellular EVs (EVs) derived from PMSCs (PMSC-EVs) on the polarization of CD4+ T cells in rats with unilateral ureteral obstruction (UUO). We further verified how PMSCs affect inflammatory factor secretion and the levels of regulatory T (Treg) and Th17 CD4+ T cells in vitro. MATERIALS AND METHODS: We evaluated renal interstitial inflammation and fibrosis by pathological section staining, tested the polarization of CD4+ T cells (Th17 and Treg phenotypes) by flow cytometry (FCM) and immunohistochemistry, and detected the cytokines secreted by CD4+ T cells by enzyme-linked immunosorbent assay (ELISA). RESULTS: Compared with that of control rats, the renal tissue of PMSC-treated rats exhibited lower renal Masson scores and more Foxp3+ cell infiltration, with a significantly decreased IL17A+CD4+ T cell/CD4+ T cell ratio and a significantly elevated anti-inflammatory cytokine (IL-10) level. When CD4+ T cells were cocultured with PMSCs, CD4+IL17A+ cell percentages were decreased in a UUO model after 7 days of coculture with PMSCs. The secretion of TGF-ß and IL-10 was significantly increased (P < 0.05), while the secretion of IFN-γ, IL-17, and IL-6 was significantly decreased (P < 0.05) in the PMSC coculture group. Moreover, after treatment with PMSC-EVs, tubulointerstitial fibrosis was alleviated, and Foxp3+/IL-17+ cell infiltration was increased in the kidneys of UUO model animals on day 7. CONCLUSIONS: PMSCs can convert the inflammatory environment into an anti-inflammatory environment by affecting the polarization of CD4+ T cells and macrophages, inhibiting the inflammatory factors IFN-γ and IL-17, and upregulating the expression of the anti-inflammatory factors TGF-ß and IL-10, ultimately leading to renal protection. Such functions may be mediated by the paracrine activity of PMSC-EVs.

Geochemistry of phosphorus release along transect of sediments from a tributary backwater zone in the Three Gorges Reservoir.

As an important phosphorus (P) source in water, sediment P release can influence water quality in the tributary backwater zone of "river-type" reservoir. Chemical sequential extraction and diffusive gradients in thin films technique (DGT) were applied to study sediment P mobility in the Daning River backwater zone (DNB) in the Three Gorges Reservoir (TGR). Influenced by the TGR backwater intrusion, both of water P forms and sediment P forms in the DNB zone exhibited increased spatial distributions from upper reach to lower reach. Sediment particles in the upper, middle, lower reaches were mainly derived from the settled particles (with high Ca contents) carried by the Daning River outflow, the former and sedimentary dead algal, the settled particles carried by the TGR backwater, respectively. According to P adsorption/desorption experiment results and concentration gradients of DGT-labile P at the sediment-overlying interface (SWI), sediments in the DNB zone acted as P source for overlying water during the sampling period. In the lower reach of the DNB zone and the adjacent TGR mainstream, iron oxides reduction in the anoxic or anaerobic sediments drove the synchronous release of labile P and Fe(II). Whereas, algal decomposition directly produced labile P and S(-II) in the top 0 to -10 mm sediment layer in the middle reach, and then the downward increases of labile P and Fe(II) in the depth of -30 to -80 mm were caused by iron oxides reduction. In the upper reach, the released labile P in sediments might be re-trapped by precipitating with Ca(II) or being adsorbed onto the newly formed iron oxides near the SWI. Sediment P release in DNB zone had a limited influence on water quality, but the influence would be significant in the future time after the external P source is reduced efficiently.

Immunohistochemistry and clinical value of sirtuin 2 in non-metastasized non-small cell lung cancer.

BACKGROUND: This study aimed to define whether sirtuin 2 (SIRT2) expression levels are related to the prognosis of non-small cell lung cancer (NSCLC) patients. METHODS: A survival analysis was carried out using the Kaplan-Meier (KM) plotter database. Immunohistochemical staining was performed and KM's method was used to estimate the survival rates for SIRT2 expression in 72 clinical samples. RESULTS: A survival analysis of 1,926 NSCLC patients showed that patients with low SIRT2 expression levels had significantly longer overall survival (OS) than those with high SIRT2 expression levels (P=0.0077; HR =1.19). In 72 non-metastasized NSCLC tissues, the positive rate of SIRT2 expression was 90.3% (65/72), among which, the positive expression rates of squamous cell carcinoma (SCC) and adenocarcinoma (ADC) were 96.4% (27/28) and 85.4% (35/41), respectively. Survival analysis showed that patients with low SIRT2 expression levels had significantly longer median survival time (MST) than those with high SIRT2 expression levels (15.0 versus 14.0 months, P=0.029). Furthermore, the results of subgroup analysis demonstrated patients with low SIRT2 expression levels had significantly longer survival time in ADC group (15.0 versus 12.0 months, P=0.022), but there wasn't significant difference in SCC group (15.0 versus 14.0 months, P=0.932). A multivariate Cox proportional hazards model, which included gender, age, TNM stage, differentiation and SIRT2 expression, showed that SIRT2 expression was an independent factor related to prognosis [HR =1.903, 95% confidence interval (95% CI): 1.085-3.339, P=0.025]. CONCLUSIONS: SIRT2 expression levels were significantly related to the survival time of patients with lung ADC but not SCC. Our study indicated SIRT2 was perhaps a specific prognostic biomarker for non-metastasized lung ADC.

[Analysis of Transport and Transformation Characteristics Between Dissolved Phosphorus and Particulate Phosphorus in Water of the Three Gorges Reservoir].

To understand the difference between transport coefficients of water runoff, sand discharge, and phosphorus flux in each subsection of a river, a judgement method for analyzing the characteristics of phosphorus transport and transformation in water of rivers was established in this study. Based on the measured data of water runoff, sand discharge, and phosphorus fraction concentrations in the water of the Three Gorges Reservoir (TGR) in January and July 2015, characteristics of phosphorus transport and transformation in the water were analyzed by using the conceptual method. The results showed that the predominant phosphorus fraction in water of the TGR was total dissolved phosphorus (TDP), which accounted for 51%-96% of total phosphorus in water. The TDP flux relative to runoff in the TGR decreased in January 2015 That was caused by the adsorption of TDP by suspended particles in the dry season. In contrast, TDP flux showed additive effect relative to water runoff in July 2015 due to exogenous water inputs with high TDP concentrations in the wet season. Both sand and total particulate phosphorus (TPP) presence in the water showed obvious sediment and retention characteristics during the two periods. The TPP flux presented an additive effect relative to sand discharge, meaning that the major transformation direction of phosphorus fractions was from TDP to TPP. The subsection between Qingxichang and Wanzhou was the main retention area of water, sand, and phosphorus in the TGR, which can be associated with the enhancement of phosphorus adsorption capacity caused by particle size reduction of suspended particles in the subsection.

SPOP promotes FADD degradation and inhibits NF-κB activity in non-small cell lung cancer.

FAS-associated protein with death domain (FADD) is the pivotal adaptor protein, which transmits apoptotic signals mediated by the death receptors. Here we report that high FADD protein level predicts poor prognosis of non-small cell lung cancer (NSCLC) patients and its protein level is mainly regulated by the 26S proteasome. We also found that ubiquitin ligase SPOP (speckle-type POZ protein) binds to FADD and mediates its degradation, which can be blocked by MG132 treatment. Notably, SPOP inhibits NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activity and its target genes expression via FADD. These results reveal the function of SPOP-FADDNFκB axis in NSCLC cells, which is associated with prognosis of NSCLC patients.

[Distribution of Phosphorus Fractions in Surface Sediments of Minjiang Mainstreams].

In recent years, the total phosphorus pollution in Minjiang River was serious, and the surface sediments of the Minjiang River also threatened water quality. To study the spatial distributions of phosphorus in the surface sediments of the Minjiang River, samples of surface sediments were collected upstream (Aba District) and downstream (Yibin District) of the Minjiang River in December, 2016. The sediments were analyzed with the modified sequential extraction method (SEDEX) to obtain six forms of phosphorus, including exchangeable phosphorus (Ex-P), exchangeable organic phosphorus (Org-P), iron-bound phosphorus (Fe-P), authigenic phosphorus (Ca-P), detrital phosphorus (De-P), and refractory phosphorus (Res-P). The results indicated that the contents of total phosphorus (TP) in surface sediments ranged from 522.17 µg ·g-1 to 979.22 µg ·g-1, which were far more than the soil phosphorus background values (700 µg ·g-1). The spatial distribution characteristics of the TP of surface sediments indicated that the TP concentrations in sediments at the Meishan sections (the middle reach of the Minjiang River) were higher than those in the other sections. This was related to the smaller particle size and higher OM contents in sediments in the Meishan sections. The main phosphorus forms in the sediments in the Minjiang River were Ca-P and De-P, with their concentrations accounting for 75% of TP in the sediments. The bio-available phosphorus, which included Ex-P, Org-P, and Fe-P, accounted for 0.31%-29.62% of TP in the sediments of the Minjiang River. The concentrations of bio-available phosphorus in sediments at the Meishan sections and Leshan sections (the middle reach) were highest, indicating that bio-available phosphorus in the surface sediments was high, and its potential environmental impact risks were higher.

Impact of upstream river inputs and reservoir operation on phosphorus fractions in water-particulate phases in the Three Gorges Reservoir.

The impoundment of the Three Gorges Reservoir (TGR) has changed water-sand transport regime, with inevitable effects on phosphorus transport behavior in the TGR. In this study, we measured phosphorus fractions in water and suspended particles transported from upstream rivers of the TGR (the Yangtze River, the Jialing River and the Wu River) to reservoir inner region over the full operation schedule of the TGR. The aim was to determine how phosphorus fractions in water and particulate phases varied in response to natural hydrological processes and reservoir operations. The results showed that total phosphorus concentration (TP) in water in the TGR inner region was 0.17±0.05mg/L, which was lower than that in the Yangtze River (0.21±0.04mg/L) and the Wu River (0.23±0.03mg/L), but higher than that in the Jialing River (0.12±0.07mg/L). In the TGR inner region, there was no clear trend of total dissolved phosphorus (TDP), but total particulate phosphorus (TPP) showed a decreasing trend from tail area to head area because of particle deposition along the TGR mainstream. In addition, the concentrations of TPP in water and particulate phosphorus in a unit mass of suspended particles (PP) in the TGR inner region were higher in October 2014 and January 2015 (the impounding period and high water level period) than that in July 2015 (the low water level period). The temporal variations of PP and TPP concentrations in the TGR may be linked to the change of particle size distribution of suspended particles in the TGR. The particle size tended to be finer due to large-size particle deposition under stable hydrodynamic conditions in the process of TGR impoundment, resulting in high adsorption capacities of phosphorus in suspended particles. The results implied that phosphorus temporal variations in the TGR could exert different impacts on water quality in the TGR tributaries.

Distribution, sources, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface water in industrial affected areas of the Three Gorges Reservoir, China.

Water samples were collected from wastewater treatment plant (WWTP), drain water (DW), major tributaries (MT), and main course of the Yangtze River (MY) in areas of three industrial parks (IPs) in Chongqing city in the Three Gorges Reservoir (TGR). Sixteen EPA priority polycyclic aromatic hydrocarbon (PAH) pollutants were quantified to identify the effects of industrial activities on water quality of the TGR. The results showed that 11 individual PAHs were quantified and 5 PAHs (naphthalene (Nap), acenaphthylene (Acy), benzo[k]fluoranthene (BkF), indeno[1,2,3-cd]pyrene (InP), and benzo[g,h,i]perylene (BgP)) were under detection limits in all of the water samples. Three-ring and four-ring PAHs were the most detected PAHs. Concentrations of individual PAHs were in the range of not detected (nd) to 24.3 ng/L. Total PAH concentrations for each site ranged from nd to 42.9 ng/L and were lower compared to those in other studies. The mean PAH concentrations for sites WWTP, DW, MT, and MY showed as follows: DW (25.9 ng/L) > MY (15.5 ng/L) > MT (14.0 ng/L) > WWTP (9.3 ng/L), and DW contains the highest PAH concentrations. Source identification ratios showed that petroleum and combustion of biomass coal and petroleum were the main sources of PAHs. The results of potential ecosystem risk assessment indicated that, although PAH concentrations in MT and MY are likely harmless to ecosystem, contaminations of PAHs in DW were listed as middle levels and some management strategies and remediation actions, like strengthen clean production processes and banning illegal sewage discharging activities, etc., should be taken to lighten the ecosystem risk caused by PAHs especially risks caused by water discharging drains.

[Distribution of Nitrogen and Phosphorus in the Tidal Reach and Estuary of the Daliao River and Analysis of Potential Eutrophication].

Based on the monitoring data in the tidal reach and estuary of the Daliao river in August and November, 2013, the seasonal and spatial distribution of the nitrogen and phosphorus forms were studied, and the degree of eutrophication was evaluated. The results showed that nitrate nitrogen was the main chemical species and occupied about fifty-five percent of inorganic nitrogen, and the particulate phosphorus was the main chemical species and occupied about fifty percent of total phosphorus in the tidal reach and estuary of the Daliao river in wet and dry seasons, 2013. The concentrations of nitrogen and phosphorus nutrients decreased in the direction from tidal reach to estuary of the Daliao river. Correlation analysis showed that there was a significant negative correlation between the nitrogen and phosphorus forms and salinity in most of the water body, which illustrated that physical dilution of seawater played a major role in the spatial distribution of nitrogen and phosphorus forms. The concentrations of nitrogen and phosphorus nutrients in the dry season were higher than those in the wet season, this was mainly related to the seasonal terrestrial input of the tidal reach. The concentration of the dissolved inorganic nitrogen was higher than 0.30 mg · L⁻¹, and the value of N/P was higher than 60, which indicated that PO4³â»-P was the nutrient limiting phytoplankton growth in the tidal reach and estuary of the Daliao river in August and November, 2013.

Spatial-temporal variations of phosphorus fractions in surface water and suspended particles in the Daliao River Estuary, Northeast China.

The transport and storage of phosphorus in estuary is a complex biogeochemical process as the result of the convergence of fresh and saline water. The objective of the current study is to investigate the spatial-temporal variations of phosphorus fractions in surface water and suspended particles of Daliao River Estuary, China. Samples were collected in August (wet season) and November (dry season), 2013. The results showed that total particulate phosphorus (TPP) in water accounted for more than 50 % of the total phosphorus (TP). Meanwhile, in suspended particles, more than 62 % of particulate phosphorus was in the form of bioavailable phosphorus, including exchangeable phosphorus (Exc-P), extractable organic phosphorus (Exo-P), and iron-bound phosphorus (Fe-P), which meant that the potential impacts of bioavailable phosphorus in suspended particles on estuarine water environment cannot be ignored. There were significantly seasonal variations of phosphorus fractions in the Daliao River Estuary. The concentrations of phosphorus fractions in water in wet season were much lower than that in dry season because of the dilution effect of larger rainfall in wet season. In addition, spatial distribution characteristics of phosphorus fractions were also obvious. Due to terrigenous phosphorus input from the upstream of tidal reach and seawater dilution effect in coastal estuary, total dissolved phosphorus (TDP) concentrations in water gradually decreased from tidal reach to coastal estuary. However, the concentrations of TPP and TP in water and Exo-P in suspended particles presented spatial fluctuation, and these were greatly attributed to sediment re-suspension in coastal estuary.