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The drainage system is a key measure for regulating runoff nutrient losses on sloping farmlands. Confluence and diverging drainage systems are two drainage layouts representing natural water network systems and are widely distributed in sloping farmlands; however, the effects of these drainage systems on runoff nutrient losses in the sloped plots remain unclear. This study investigated the effects of different drainage systems on the characteristics of runoff nitrogen (N) losses in sloped plots using laboratory rainfall simulations. Three treatments, including bare slope (without drainage system, CK), confluence drainage system (T1), and diverging drainage system (T2), were used to compare the changes in concentrations and losses of total nitrogen (TN), dissolved nitrogen (DN), and particulate nitrogen (PN), and the DN:TN ratio in runoff under a combination of 1.8 mm min-1 rainfall intensity and three slope gradients (5°, 10°, and 15°). The results showed that the time to runoff was significantly delayed in T2 compared with that in CK and T1 across all slopes (p < 0.05). Accumulated runoff depth was considerably lower in T1 and T2 than in CK across all slopes (p < 0.05). The TN and PN concentrations in T1 were markedly lower than those in T2 on the 10° and 15° slopes (p < 0.05). The DN concentration in T1 was lowest at the 5° slope (p < 0.05). TN loss in T1 was 14.7-33.9% and 17.9-30.3% lower than those in CK and T2 across all slopes, respectively (p < 0.05). The PN loss in T1 was 56.7% and 53.3% lower than that in T2 on the 10° and 15° slopes, respectively (p < 0.05). DN loss in T1 was 39.3-72.5% lower than that in CK for all slopes (p < 0.05). DN:TN in T2 was lower than that in CK and T1 at the 10° and 15° slopes (p < 0.05). Our results confirm the effectiveness of drainage systems in reducing runoff nutrient losses in a sloped plot and demonstrate that the confluence drainage system is better at reducing N losses in runoff than diverging drainage systems.
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Fósforo , Solo , Fósforo/análise , Monitoramento Ambiental/métodos , Nitrogênio/análise , Movimentos da Água , China , ChuvaRESUMO
Soil water repellency (SWR) exists in various soil ecosystems and can interrupt water infiltration and cause soil erosion. Anthropogenic land-use change can cause shifts in SWR and soil erosion resistance (SER) in sensitive soils. However, the direction and magnitude of these shifts in SWR and SER and their interrelations remain largely unclear. This study examined the changes in SWR, soil erodibility (K), and aggregate fractions in different land uses of a karst trough valley in southwest China. Soil samples were gathered from five land uses: cropland (CL), orchard (OP), secondary forest (SF), grassland (GL), and riverbank (RB), using a 1000 m × 1000 m grid, resulting in 210 sampling sites. Results showed that the water drop penetration time was significantly higher by 86.43%, 68.85%, and 71.47% in the SF, OP, and RB than in the CL, respectively (p < 0.05). The soil organic carbon (SOC) was the greatest in the SF and the lowest in the GL and CL (p < 0.05). The 1000-250 µm aggregate fraction, mean weight diameter (MWD), and geometric mean diameter (GMD) varied markedly among the different land uses (p < 0.05). The silt content, fractal dimension (D), and K were markedly lower in the RB than in the CL, OP, SF and GL (p < 0.05). The SWR had pronouncedly positive correlations with the SOC and 1000-250 µm aggregate fraction (p < 0.05). The K displayed a negative correlation with the GMD but a positive correlation with the D (p < 0.05). The structural equation modeling analysis revealed that the SOC was affected positively by the silt content and the 1000-250 µm aggregate fraction and negatively by the K. These factors directly regulated the SWR. Our results shed light on the mechanisms of land use changes impacting the SWR, SER and other soil properties in karst environments.
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Fertilization and cultivation managements exert significant effects on crop growth and soil-associated nutrients in croplands. However, there is a lack of knowledge regarding how these practices affect soil phosphorus-cycling enzymes and functional genes involved in regulating global P-cycling, especially under intense agricultural management practices in sloping croplands. A long-term field (15-year) trial was conducted in a 15° sloping field based on five treatments: no fertilizer amendments + downslope cultivation (CK); mixed treatment of mineral fertilizer and organic manure + downslope cultivation (T1); mineral fertilizer alone + downslope cultivation (T2); 1.5-fold mineral fertilizer + downslope cultivation (T3); and mineral fertilizer + contour cultivation (T4). Bulk and rhizosphere soil samples were collected after the maize crop was harvested to determine the P fraction, P-cycling enzymes, and phosphatase-encoding genes. Results indicated that fertilization management significantly increased the inorganic (Pi) and organic soil (Po) P fractions compared to CK, except for NaOH-extractable Po in T1 and T3 in bulk and rhizosphere soils, respectively. For the cultivation treatments, the content of Pi pools in the downslope cultivation of T1 and T3 was significantly larger than that in the contour cultivation of T4 in bulk and rhizosphere soils. However, the content of NaOH-extractable Po in T1 and T3 was lower compared to T4 in bulk soil and vice versa for the NaHCO3-P and HCl-Po fractions in the rhizosphere. We also found that fertilization and cultivation managements significantly increased the activity of acid phosphatase (ACP), alkaline phosphatase (ALP), phytase, phosphodiesterases (PDE), and phoC and phoD gene abundance in bulk and rhizosphere soils, with a larger effect on the activity of ALP and the phosphatase encoding phoD gene, especially in T1 and T3 in the rhizosphere. Soil organic carbon (SOC) and microbial biomass C and P (MBC and MBP) were the main predictors for regulating P-cycling enzymes and phoC- and phoD gene abundance. A strong association of P-cycling enzymes, especially ALP and phytase, and the abundance of phoD genes with the P fraction indicated that the soil P cycle was mainly mediated by microbial-related processes. Together, our results demonstrated that an adequate amount of mineral fertilizer alone or combined with organic fertilizer plus downslope cultivation is more effective in promoting soil P availability by enhancing the activity of ALP, phytase, and phoD genes. This provides valuable information for sustaining soil microbial-regulated P management practices in similar agricultural lands worldwide.
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6-Fitase , Monoéster Fosfórico Hidrolases , Monoéster Fosfórico Hidrolases/genética , Zea mays/genética , Fósforo , Solo , Carbono , Rizosfera , Hidróxido de Sódio , Fosfatase Alcalina , Corantes , Fertilizantes , Fertilização , Produtos Agrícolas/genéticaRESUMO
Periodically hydrologic alterations driven by seasonal change and water storage capacity management strongly modify physicochemical properties and chlorophyll-a (Chl-a) and their interactions in dam-induced lakes. However, the extent and magnitude of these changes still remain unclear. This study aimed to determine the effects of periodically hydrologic alterations on physicochemical variables and Chl-a in the dam-induced urban Hanfeng Lake, upstream of Three Gorges Reservoir. Shifts in Chl-a and 13 physicochemical variables were recorded monthly in the lake from January 2013 to December 2014. Chl-a was neither seasonal nor inter-annual differences while a few physical variables such as flow velocity (V) exhibited significantly seasonal variabilities, and chemical variables like total nitrogen (TN), nitrate-nitrogen (NO3-N), total phosphorus (TP), dissolved silica (DSi) were markedly inter-annual differences. Higher TN:TP (40:1) and lower NO3-N:DSi (0.8:1) relative to balanced stoichiometric ratios suggested changes in composition of phytoplankton communities and potentially increased proportion of diatom in Hanfeng Lake. Chl-a was predicable by combination of dissolved oxygen (DO), TN and DSi in dry season, and by V alone in wet season. During the whole study period, Chl-a was solely negatively correlated with TN:TP, indicating decline in N concentration and increase in P could therefore increase Chl-a. Our results highlight pronounced decoupling of linkages between Chl-a and physicochemical variables affected by periodically hydrologic alterations in dam-induced aquatic systems.
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Eutrofização , Lagos , China , Clorofila/análise , Clorofila A , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análiseRESUMO
Plastic pollution is a global concern given its prevalence in aquatic and terrestrial ecosystems. Studies have been conducted on the distribution and impact of plastic pollution in marine ecosystems, but little is known on terrestrial ecosystems. Plastic mulch has been widely used to increase crop yields worldwide, yet the impact of plastic residues in cropland soils to soil health and crop production in the long term remained unclear. In this paper, using a global meta-analysis, we found that the use of plastic mulch can indeed increase crop yields on average by 25%-42% in the immediate season due to the increase of soil temperature (+8%) and moisture (+17%). However, the unabated accumulation of film residues in the field negatively impacts its physicochemical properties linked to healthy soil and threatens food production in the long term. It has multiple negative impacts on plant growth including crop yield (at the mean rate of -3% for every additional 100 kg/ha of film residue), plant height (-2%) and root weight (-5%), and soil properties including soil water evaporation capacity (-2%), soil water infiltration rate (-8%), soil organic matter (-0.8%) and soil available phosphorus (-5%) based on meta-regression. Using a nationwide field survey of China, the largest user of plastic mulch worldwide, we found that plastic residue accumulation in cropland soils has reached 550,800 tonnes, with an estimated 6%-10% reduction in cotton yield in some polluted sites based on current level of plastic residue content. Immediate actions should be taken to ensure the recovery of plastic film mulch and limit further increase in film residue loading to maintain the sustainability of these croplands.
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Agricultura , Plásticos , China , Produtos Agrícolas , Ecossistema , Abastecimento de Alimentos , SoloRESUMO
BACKGROUND: The objectives of this study were to build a normal tissue complication probability (NTCP) model of radiation-induced hypothyroidism (RHT) for nasopharyngeal carcinoma (NPC) patients and to compare it with other four published NTCP models to evaluate its efficacy. METHODS: Medical notes of 174 NPC patients after radiotherapy were reviewed. Biochemical hypothyroidism was defined as an elevated level of serum thyroid-stimulating hormone (TSH) value with a normal or decreased level of serum free thyroxine (fT4) after radiotherapy. Logistic regression with leave-one-out cross-validation was performed to establish the NTCP model. Model performance was evaluated and compared by the area under the receiver operating characteristic curve (AUC) in our NPC cohort. RESULTS: With a median follow-up of 24 months, 39 (22.4%) patients developed biochemical hypothyroidism. Gender, chemotherapy, the percentage thyroid volume receiving more than 50 Gy (V50), and the maximum dose of the pituitary (Pmax) were identified as the most predictive factors for RHT. A NTCP model based on these four parameters were developed. The model comparison was made in our NPC cohort and our NTCP model performed better in RHT prediction than the other four models. CONCLUSIONS: This study developed a four-variable NTCP model for biochemical hypothyroidism in NPC patients post-radiotherapy. Our NTCP model for RHT presents a high prediction capability. TRIAL REGISTRATION: This is a retrospective study without registration.
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Hipotireoidismo/epidemiologia , Modelos Biológicos , Carcinoma Nasofaríngeo/radioterapia , Neoplasias Nasofaríngeas/radioterapia , Lesões por Radiação/epidemiologia , Adolescente , Adulto , Idoso , Feminino , Humanos , Hipotireoidismo/sangue , Hipotireoidismo/etiologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Curva ROC , Lesões por Radiação/sangue , Lesões por Radiação/etiologia , Dosagem Radioterapêutica , Estudos Retrospectivos , Fatores de Risco , Tireotropina/sangue , Tiroxina/sangue , Adulto JovemRESUMO
Escalating climate extreme events disrupt hydrological processes by affecting both water availability and sediment dynamics. However, the interconnection between hydrological variability and climatic extremes remains underexplored, particularly in cold regions under a changing climate. Here, we develop a yield-based dichotomy framework to examine the impact of shifted climatic extreme patterns on hydrological regimes in the Ishikari River Basin (IRB), Hokkaido, Japan, which is a crucial area for local agriculture and urban development. Utilizing a modified Soil and Water Assessment Tool (SWAT) integrated with downscaled CMIP6-GCM climate projections under Shared Socioeconomic Pathways (SSPs) scenarios, we identified significant annual variability in water and sediment yields associated with extreme climate events. Hot-dry conditions correlate with lower water and sediment yields, whereas increased cold extremes may result in higher sediment yields across the IRB. Our findings also indicate that hotter and drier patterns interact with hydrological processes, potentially establishing new hydrologic regimes and shifting climatic extremes-induced thresholds for yield classification within the IRB. Notably, under SSP585, both water availability and sediment transport are projected to intensify, increasing flood risks and exacerbating sedimentation challenges. Our study highlights the urgent need for adaptive water management strategies to address these anticipated changes in hydrological regimes in response to global climate change.
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To explore the effects of long-term balanced fertilization and straw mulching on soil nutrients and stoichiometric ratios in purple soil sloping cropland, nine plots (length 7 m×width 3 m) were established in Dianjiang County as the research sample area of long-term farmland nitrogen and phosphorus loss monitoring. The following three treatments were set up:conventional mode (CK), balanced fertilization mode (M1), and balanced fertilization+straw mulching mode (M2), with three replications for each treatment to compare the contents of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) and their stoichiometric changes under different treatments from 2018 to 2020. The results showed:K contents showed significant differences among the three treatments in 2018, in the order of CK>M2>M1. NO3--N and NH4+-N contents showed significant differences among the three treatments in 2019, both in the order of M1>M2>CK. Other nutrient contents showed no significant difference among different treatments each year. Soil C and N contents showed non-significant differences among different years. The total K contents of CK, M1, and M2 in 2018 were significantly higher than that in other years and were 78.26% and 98.79%, 19.13% and 35.4%, and 54.49% and 41.76% higher than that in 2019 and 2020, respectively. The total P content in the CK and M2 treatments decreased with years, and that of CK and M2 in 2018 was 20.29% and 10.67% and 39.68% and 17.33% higher than that in 2019 and 2020, respectively. The available potassium (AK) content of the three treatments showed non-significant differences among different years, whereas the contents of nitrate nitrogen (NO3--N), ammonium nitrogen (NH4+-N), and available phosphorus (AP) showed significant differences among the different treatments, with all being the highest in 2020. Soil C:P, C:K, N:P, N:K, and P:K ratios of each treatment showed significant differences among different years (P<0.05). Soil C:K, N:K, and AN:AP ratios all showed significant differences among different fertilization modes in 2018 and 2019, respectively (P<0.05). There was a significantly linearly positive relationship between soil C and N concentration and soil P and K concentration. There were very significant linear positive correlations between soil C:K and C:P, N:K, N:P, and P:K; N:K with C:P, P:K, and N:P; and N:P with C:P, N:P, and C:P. Soil P concentration was highly significantly linearly negatively correlated with C:K and N:K ratios. There were significant positive correlations between soil NO3--N, NH4+-N, AN:AP, and AN:AK; NH4+-N, AN:AP, and AN:AK; and AN:AP and AN:AK. The results suggested that balanced fertilization and straw mulching was a more suitable management mode for purple soil sloping cropland.
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Nitrogênio , Nutrientes , Fósforo , Potássio , Solo , FertilizaçãoRESUMO
Fertilization management and crop growth can affect soil water repellency (SWR) through altering other soil properties such as micro-aggregate, soil organic carbon (SOC) and total nitrogen (TN). However, the extents and magnitudes of these effects remain unclear. This study aimed to determine the effects of different crop growth periods and long-term fertilization managements on SWR and selected soil physicochemical properties and their linkages. Soil samples were collected from agricultural plots experiencing different maize growth periods (ES, elongation stage; TS, tasseling stages; FS, filling stage; and MS, maturity stage) and fertilization managements (CK, no fertilizer with downslope cultivation; T1, combined manure and chemical fertilizers with downslope cultivation; T2, chemical fertilizer with downslope cultivation; T3, 1.5-fold chemical fertilizer with downslope cultivation; T4, chemical fertilizer with contour cultivation) in a representative sloping cropland with Entisols, southwest China. SWR, micro-aggregate fractions, and other physiochemical properties like soil organic carbon (SOC) and total nitrogen (TN) were determined. Results showed that SWR increased by 64.93% in T1 than in CK, and fertilization managements (i.e., T1, T2, T3, and T4) markedly increased soil 1000-250 µm fraction by 34.50-50.74% and reduced 250-50 µm fraction by 22.95-48.87% than CK did. SWR was 27.35%-78.74% higher in ES than that in other growth periods. The highest soil 250-50 fractions (30.80%) and the lowest <50 µm fractions (43.95%) both appeared in TS. SOC was both differed by fertilization management and growth period, while TN was only affected by the former. SWR was predicted well by TN alone. Our results indicate that long-term fertilizer application enhances SWR and have great significance for optimizing sustainable agricultural management in the similar sloping croplands.
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Fertilizantes , Solo , Agricultura/métodos , Carbono/análise , China , Produtos Agrícolas , Fertilização , Fertilizantes/análise , Esterco/análise , Nitrogênio/análise , Solo/química , ÁguaRESUMO
Interpreting leaf nitrogen (N) allocation is essential to understanding leaf N cycling and the economy of plant adaptation to environmental fluctuations, yet the way these mechanisms shift in various varieties under high temperatures remains unclear. Here, eight varieties of pecan (Carya illinoinensis [Wangenh.] K. Koch), Mahan, YLC10, YLC12, YLC13, YLC29, YLC35, YLJ042, and YLJ5, were compared to investigate the effects of high temperatures on leaf N, photosynthesis, N allocation, osmolytes, and lipid peroxidation and their interrelations. Results showed that YLC35 had a higher maximum net photosynthetic rate (Pmax) and photosynthetic N-use efficiency (PNUE), while YLC29 had higher N content per area (Na) and lower PNUE. YLC35, with lower malondialdehyde (MDA), had the highest proportions of N allocation in rubisco (Pr), bioenergetics (Pb), and photosynthetic apparatus (Pp), while YLC29, with the highest MDA, had the lowest Pr, Pb, and Pp, implying more leaf N allocated to the photosynthetic apparatus for boosting PNUE or to non-photosynthetic apparatus for alleviating damage. Structural equation modeling (SEM) demonstrated that N allocation was affected negatively by leaf N and positively by photosynthesis, and their combination indirectly affected lipid peroxidation through the reverse regulation of N allocation. Our results indicate that different varieties of pecan employ different resource-utilization strategies and growth-defense tradeoffs for homeostatic balance under high temperatures.
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To elucidate the effects of long-term fertilization and cultivation on runoff rates and runoff-related nitrogen (N) and phosphorus (P) losses, the following five treatments were established on sloping purple soil cropland:â no fertilizer with downslope tillage (CK), â¡ combined application of manure and fertilizer with downslope tillage (T1), ⢠chemical fertilizers with downslope tillage (T2), ⣠chemical fertilizer with increasing fertilization with downslope tillage (T3), and ⤠chemical fertilizer with contour tillage (T4). The runoff rate, runoff-related total N (TN), and total P (TP) concentrations and their loss rates from 104 erosive rainfall events were determined for the period 2008-2019. Results showed that although runoff rates were not significantly different among the fertilization treatments (P>0.05), runoff was markedly lower in fertilization treatments than in the CK treatment (P<0.05). Runoff-related TN concentrations were significantly higher in the CK compared to the fertilization treatments (P<0.05), while there were no significant differences among the T2, T3, and T4 treatments, which had higher concentrations than the T1 treatment. Runoff-related TP concentrations were significantly higher from the T1, T2, and T3 treatments than the CK treatment (P<0.05), and were significantly lower in the T4 than the CK treatment (P<0.05). TN loss rates were not significantly different among the fertilization treatments (P>0.05), but were all lower than the CK treatment (P<0.05). Furthermore, TP loss rates were not significantly different among the downslope treatments (P>0.05), but were all higher than the contour treatment (P<0.05). Runoff rates showed no significant relationships with TN and TP concentrations in the CK, T1, and T2 treatments but were significantly negatively linearly correlated in T3 (P<0.05) and significantly positively linearly correlated in T4 (P<0.05). These results potentially provide scientific guidance for the prevention and control of agricultural non-point source pollution on sloping croplands in the purple soil area.
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Clarification of the effects of long-term fertilization and cultivation on soil organic carbon (C), nitrogen (N), phosphorus (P), and potassium (K) contents and their stoichiometric ratios can contribute to existing research on the C and nutrient biogeochemical cycles and their interacting mechanisms. Such information is also of great significance to fertilization management and for the control of non-point pollution. Fifteen plots (8 m long, 4 m wide) were set up on a representative purple hillslope (15°). Five treatments (three replications) were used on the plots:i) no fertilizer with downslope cultivation (CK), ii) combined application of manure and fertilizer with downslope cultivation (T1), iii) chemical fertilizers with downslope cultivation (T2), iv) chemical fertilizer with increasing fertilization with downslope cultivation (T3), and v) chemical fertilizer with contour cultivation (T4). The C, N, P and K contents and their ratios in the five treatments corresponding to 0-10 cm and 10-20 cm soil depths were compared. The results showed that C, N and P contents for the different treatments were differed significant and could be ranked:T1 > T3 > T4 > T2 > CK (P<0.05). K content was not significantly different among the four fertilizations (P>0.05) but was significantly higher than the CK treatment (P<0.05), and could be ranked:T4 > T3 > T2 > T1 > CK. The C:N ratios in the five treatments were significantly different (P<0.05) at a soil depth of 10-20 cm (T4 > T3 > T1 > CK > T2). The C:P ratios in the five treatments were significantly different (P<0.05) at a soil depth of 0-10 cm (T1 > T3 > CK > T4 > T2). The C:K, N:P, N:K, and P:K ratios for the five treatments at both of the soil depths showed significant differences (P<0.05), and the C:K, N:K, and P:K were ranked as T1 > T3 > T4 > T2 > CK, whereas the N:P ratio was ranked as T1 > CK > T4 > T3 > T2. The C, N, P, and K contents and their stoichiometric ratios decreased with increasing soil depth. Soil C, N and P in the study site showed moderate variations based on their coefficient of variation (CV):37.50%, 38.91%, and 25.35%, respectively. Soil K on the other hand showed a weak variation (CV 5.03%). Soil C:N and C:P also showed a weak variation with a CV of 7.52% and 14.38%, respectively. Soil C:K, N:P, N:K, and P:K showed moderate variations, with a CV of 35.62%, 17.01%, 37.24% and 44.78%, respectively. There were significant positive interrelations among soil C, N, P, and K contents and their stoichiometric ratios (P<0.05). The average N:P ratio was 2.09, which was much lower than the average value for various soil types in China. Our results indicate that soil N is the key limiting nutrient in purple hillslope land, and that the combination of organic and inorganic fertilizers can effectively alleviate the N deficiency in the study area.
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The specific nitrate reduction pathway in Pseudomonas putida Y-9 under aerobic conditions was studied. Strain Y-9 removed 82% of the nitrate accompanied by an accumulation of ammonium and a decrease of total nitrogen. Ammonium inhibited nitrate transformation (removal efficiency was 22.65%), illustrating that nitrate assimilation exists in strain Y-9. The detectable ammonium in the supernatant during the nitrate reduction process came from intracellular locations in strain Y-9. The nirBD that encodes nitrite reductase had an important role in strain growth and ammonium production. A 15N isotope experiment demonstrated that strain Y-9 can conduct dissimilatory nitrate reduction to ammonium (DNRA) and nirBD controls this process. This further indicated that the loss of total nitrogen is due to denitrification. All results highlighted that strain Y-9 performs simultaneous nitrate assimilation, DNRA, and denitrification under aerobic conditions, and nirBD controls the assimilation and DNRA process. Thereinto, nitrate assimilation dominates the removal of nitrate.
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Compostos de Amônio , Pseudomonas putida , Desnitrificação , Nitratos , Nitrogênio , Óxidos de NitrogênioRESUMO
Based on the seasonal changes in the nitrogen and phosphorus concentrations in Hanfeng Lake from March 2017 to February 2018, the nutrient limitation status was evaluated by the stoichiometric molar ratio of nitrogen and phosphorus. The results showed that the average concentrations of TN, DN, and NO3--N were 1.60, 1.25, and 0.91 mg·L-1 in Hanfeng Lake, respectively. The seasonal changes of those indicators were similar, showing the highest concentration in winter and lowest in summer. NO3--N accounted for TN significantly in the water body, and the concentrations of NH4+-N and NO2--N remained at low levels and changed steadily. The average concentrations of TP, DP, and PO43--P were 0.13, 0.09, and 0.06 mg·L-1, respectively. The changes in the concentrations of TP and DP were similar, showing a trend of increasing in spring and summer, and then decreasing in autumn and winter, while the PO43--P concentration showed the trend of fluctuated decrease. TN/TP varied from 11.07 to 56.02, with an average value of 29.23. TN/TP changed seasonally, with the highest value occurring in winter and the lowest value in summer. The conditions of the water body were conducive to growth and reproduction of algae for most of the time during sampling months. The water body was occasionally nitrogen limited and rarely phosphorus limited. The seasonal variation in TN/TP ratio was affected by several factors such as rainfall runoff, fertilizer use, sewage discharge, and aquatic biological activities. Further, protection strategies were proposed for the improvement of the water body in terms of present water quality characteristics in Hanfeng Lake.
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The hydrograph of Hanfeng Lake, which is the largest pre-dam of theThree Gorges Reservoir, varied between the fluvial stage and lake stage after the lake was officially operated, resulting in large shifts in the aquatic biogeochemical processes. To explore the spatial-temporal distribution of nitrogen and phosphorus concentrations and identify their influencing factors in Hanfeng Lake, seven sampling sites were set up to monitor the changes of nutrients and other water indicators at different water depths monthly from January to December 2018. The results showed that completely vertical mixing across water profiles was observed. The nutrient concentrations were not significantly different between the top, middle, and bottom water depths (P>0.05). Total nitrogen concentration decreased from January to September but gradually increased from October to December, with a monthly average concentration of 1.52 mg·L-1. NO2--N concentration decreased in the first four months, increased sharply from May to June, and decreased from July to December with a monthly average concentration of 0.05 mg·L-1. NO3--N concentration gradually decreased from January to June, and gradually increased from July to December. NH4+-N concentration was the highest in July, with a concentration of 0.44 mg·L-1, and the change in other months was not notable, with a monthly average concentration of 0.09 mg·L-1. The concentrations of total phosphorus (TP), dissolved phosphorus, and soluble reactive phosphorus showed insignificant changes in trends throughout the year, with monthly average concentrations of 0.17 mg·L-1, 0.11 mg·L-1, and 0.05 mg·L-1, respectively. The phosphate concentration was mainly sourced from the upstream Nan River and Taoxi River, and gradually decreased from upper Zhendong to the downstream regulating dam. Of these nutrients, TP was the key factor in the growth of algae in Hanfeng Lake.
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Interspecific mycelial interactions between white rot fungi are always accompanied by an increased production of laccase. In this study, the potential of the white rot fungus Dichomitus squalens to enhance laccase production during interactions with two other white rot fungi, Trametes versicolor or Pleurotus ostreatus, was assessed. To probe the mechanism of laccase induction and the role that laccase plays during combative interaction, we analyzed the differential gene expression profile of the laccase induction response to stressful conditions during fungal interaction. We further confirmed the expression patterns of 16 selected genes by qRT-PCR analysis. We noted that many differentially expressed genes (DEGs) encoded proteins that were involved in xenobiotic detoxification and reactive oxygen species (ROS) generation or reduction, including aldo/keto reductase, glutathione S-transferases, cytochrome P450 enzymes, alcohol oxidases and dehydrogenase, manganese peroxidase and laccase. Furthermore, many DEG-encoded proteins were involved in antagonistic mechanisms of nutrient acquisition and antifungal properties, including glycoside hydrolase, glucanase, chitinase and terpenoid synthases. DEG analyses effectively revealed that laccase induction was likely caused by protective responses to oxidative stress and nutrient competition during interspecific fungal interactions.
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Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Lacase/biossíntese , Lacase/genética , Interações Microbianas/fisiologia , Polyporaceae/enzimologia , Polyporaceae/genética , Técnicas de Cocultura , Genes Fúngicos/genética , Micélio/enzimologia , Micélio/genética , Micélio/fisiologia , Nutrientes , Estresse Oxidativo , Pleurotus/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Análise de Sequência de RNA , Trametes/fisiologia , TranscriptomaRESUMO
To understand the status of agricultural non-point source pollution and to find out the primary pollution sources and the key control areas in the Hanfeng Lake Basin, the discharges of total nitrogen (TN) and total phosphorus (TP) from farming, livestock and poultry breeding, and rural living in thirty-two counties in 2015 were estimated using the pollutant discharge coefficient method. The spatial distribution characteristics of the quality and intensity of the TN and TP emissions from these sources were investigated using the GIS spatial analysis method. Pollution evaluation and source analysis were also carried out using the equivalent pollution load method. The results show that the total loads of TN and TP in the Hanfeng Lake Basin are 2721.42 t and 492.04 t, respectively. The discharge of pollutants is the largest in the Nanhe Basin and the smallest in the area around Hanfeng Lake. The total pollutant loads from the agricultural non-point sources varied greatly, with fertilizer application and livestock and poultry breeding being the main sources. The contribution from fertilizer application is 76.92%, which represents the primary source of TN and TP pollution in the Hanfeng Lake Basin. Among the townships, the equivalent pollution loads of Dunhao, Tieqiao, and Baiqiao are higher than 350 m3·a-1; thus, these are the key control towns. According to the results of the equivalent pollution method and cluster analysis, the 32 counties were divided into four types of pollution areas. These areas are planting-livestock breeding dominant area, fertilizer-livestock breeding dominant area, fertilizer dominant area, and heavily polluted planting dominant area.
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The objective of this study was to build models to predict complete pathologic response (pCR) after neoadjuvant chemoradiotherapy (nCRT) in esophageal squamous cell carcinoma (ESCC) patients using radiomic features. A total of 55 consecutive patients pathologically diagnosed as having ESCC were included in this study. Patients were divided into a training cohort (44 patients) and a testing cohort (11 patients). The logistic regression analysis using likelihood ratio forward selection was performed to select the predictive clinical parameters for pCR, and the least absolute shrinkage and selection operator (LASSO) with logistic regression to select radiomic predictors in the training cohort. Model performance in the training and testing groups was evaluated using the area under the receiver operating characteristic curves (AUC). The multivariate logistic regression analysis identified no clinical predictors for pCR. Thus, only radiomic features selected by LASSO were used to build prediction models. Three logistic regression models for pCR prediction were developed in the training cohort, and they were able to predict pCR well in both the training (AUC, 0.84-0.86) and the testing cohorts (AUC, 0.71-0.79). There were no differences between these AUCs. We developed three predictive models for pCR after nCRT using radiomic parameters and they demonstrated good model performance.
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Quimiorradioterapia Adjuvante , Neoplasias Esofágicas/tratamento farmacológico , Neoplasias Esofágicas/radioterapia , Carcinoma de Células Escamosas do Esôfago/tratamento farmacológico , Carcinoma de Células Escamosas do Esôfago/radioterapia , Adulto , Idoso , Neoplasias Esofágicas/diagnóstico por imagem , Carcinoma de Células Escamosas do Esôfago/diagnóstico por imagem , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Curva ROC , Análise de Regressão , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Resultado do TratamentoRESUMO
A large number of landslides were triggered by the Mw7.9 Wenchuan earthquake which occurred on 12th May 2008. Landslides impacted extensive areas along the Mingjiang River and its tributaries. In the landslide deposits, soil and gravel fragments generally co-exist and their proportions may influence the hydrological and erosion processes on the steep slopes of the deposit surface. Understanding the effects of the mixtures of soil and gravels in landslide deposits on erosion processes is relevant for ecological reconstruction and water and soil conservation in Wenchuan earthquake area. Based on field surveys, indoor artificial rainfall simulation experiments with three rainfall intensities (1.0, 1.5 and 2.0 mm·min-1) and three proportions of gravel (50%, 66.7% and 80%) were conducted to measure how the proportion of gravel affected soil erosion and sediment yield in landslide sediments and deposits. Where the proportion of gravel was 80%, no surface runoff was produced during the 90 minute experiment under all rainfall intensities. For the 66.7% proportion, no runoff was generated at the lowest rainfall intensity (1.0 mm·min-1). As a result of these interactions, the average sediment yield ranked as 50> 66.6> 80% with different proportions of gravel. In addition, there was a positive correlation between runoff generation and sediment yield, and the sediment yield lagging the runoff generation. Together, the results demonstrate an important role of gravel in moderating the mobilization of landslide sediment produced by large earthquakes, and could lay the foundation for erosion models which provide scientific guidance for the control of landslide sediment in the Wenchuan earthquake zone, China.
Assuntos
Sedimentos Geológicos , Deslizamentos de Terra , Modelos Estruturais , Chuva , Solo , Água , China , Terremotos , Desenho de Equipamento , Tamanho da Partícula , Movimentos da ÁguaRESUMO
The laccase production by mycelial antagonistic interaction among white-rot fungi is a very important pathway for lignin degradation research. To gain a better understanding of competitive mechanisms under mycelial antagonistic interaction among three lignin-degrading white-rot basidiomycetes of Trametesversicolor (Tv), Pleurotusostreatus (Po) and Dichomitussqualens (Ds), mycelial morphology and proteins in three co-culture combinations TvPo (Tv cocultivated with Po), PoDs (Po cocultivated with Ds), TvDs (Tv cocultivated with Ds) were compared with corresponding each two mono-cultures. In this study, scanning electron microscopy detection of co-cultures indicated a highly close attachment of fungal hyphae with each other and conidiation could be inhibited under fungal interaction. In addition, a label-free proteomic analysis revealed changes on fungal proteomes existed in their counterpart competitors of co-culture. The maximum number of 1020 differentially expressed proteins (DEPs) were identified in PoDs relative to Po while the minimum number of 367 DEPs were identified in PoDs relative to Ds. Notably, we also found a large number of overexpressed proteins were oxidative stress-related proteins, followed by carbohydrate metabolism-related proteins and energy production-related proteins in all three co-culture combinations compared with control. These results were important for the future exploration of molecular mechanisms underlying lignin-degrading fungal interaction.