Response of nutrient loss to natural erosive rainfall events under typical tillage practices of contour ridge system in the rocky mountain areas of Northern China.

Changes in natural rainfall characterized by heavy precipitation and high rainfall intensity would increase the risks and uncertainty of nutrients losses. Losses of nitrogen (N) and phosphorus (P) with water erosion from agriculture-related activities has become the principal nutrients resulting the eutrophication of water bodies. However, a little attention has been paid to the loss characteristic of N and P responding to natural rainfall in widely used contour ridge systems. To explore the loss mechanism of N and P in contour ridge system, nutrient loss associated with runoff and sediment yield was observed in in situ runoff plots of sweet potato (SP) and peanut (PT) contour ridges under natural rainfall. Rainfall events were divided into light rain, moderate rain, heavy rain, rainstorm, large rainstorm, and extreme rainstorm level, and rainfall characteristics for each rainfall level were recorded. Results showed that rainstorm, accounting for 46.27% of the total precipitation, played a destructive role in inducing runoff, sediment yield, and nutrient loss. The average contribution of rainstorm to sediment yield (52.30%) was higher than that to runoff production (38.06%). Rainstorm respectively generated 43.65-44.05% of N loss and 40.71-52.42% of P loss, although light rain induced the greatest enrichment value for total nitrogen (TN, 2.44-4.08) and PO4-P (5.40). N and P losses were dominated by sediment, and up to 95.70% of the total phosphorus and 66.08% of TN occurred in sediment. Nutrient loss exhibited the highest sensitivity to sediment yield compared to runoff and rainfall variables, and a significant positive linear relationship was observed between nutrient loss and sediment yield. SP contour ridge presented higher nutrient loss than that in PT contour ridge, especially for P loss. Findings gained in this study provide references for the response strategies of nutrient loss control to natural rainfall change in contour ridge system.

Influence of Potamogeton crispus harvesting on phosphorus composition of Lake Yimeng.

Harvesting is an important method used to control the overproduction of Potamogeton crispus in lakes. A three-year comparative field study was performed in a eutrophic lake (harvested area) and its connected lake (non-harvested area) to determine the effects of harvesting on the phosphorus (P) composition and environmental factors in the water and sediment. Results revealed that harvesting significantly reduced the dissolved total P and dissolved organic P (DOP) and increased the alkaline phosphatase activity and particulate P (PP) in the water. No significant differences were detected in the water total P (TP), soluble reactive P, chlorophyll-a, pH, and dissolved oxygen between the harvested and non-harvested areas. Sediment TP and organic P (OP) were significantly reduced in the harvested area. Harvesting changed the P composition in the water. In the non-harvested area, P was mainly formed by DOP (40%) in the water body, while in the harvested area, PP was the main water component (47%). Harvesting increased the proportion of inorganic P (IP) in the sediment and decreased the proportion of OP. In the water, the IP to TP ratio in the non-harvested and harvested areas were 58.26% and 63.51%, respectively. Our results showed that harvesting changed the P composition in the water and sediment. In the harvesting of submerged vegetation, our results can serve as a reference for the management of vegetation-rich lakes.

Relationship between the coprecipitation of phosphorus-on-calcite by submerged macrophytes and the phosphorus cycle in water.

To assess potential phosphorus removal, we utilized Potamogeton crispus to determine the effects of calcium addition on phosphorus removal. Plastic film was used to block material exchange between the overlying water and the sediment, and we compared the experimental results with long-term monitoring results of Yimeng Lake, which contained a dense population of P. crispus. The results revealed that the first 10-40 days constituted a period of rapid P decrease, as P. crispus could effectively remove the phosphorus in the water through coprecipitation of CaCO3-P. The treatment groups indicated that P. crispus released calcium into the overlying water, and after the addition of calcium ions, P. crispus showed increased phosphorus removal efficiency in the water. Total phosphorus (TP) and P/Ca content increased with increasing pH in the treatment groups, and the TP and pH declined as the calcium content increased in the treatment groups. Long-term field observations showed that the calcium-to-phosphorus ratio in the coprecipitates was dependent on the pH during the crystallization process. Thus, water calcium driven by P. crispus plays an important role in the phosphorus cycle of water, due to P. crispus assisted precipitation. This study revealed the effect of P. crispus on the water purification, the migration and transformation of Ca and P in sediment and overlying water under the condition of sediment calcium addition, so as to provide a theoretical basis for the ecological restoration of shallow lakes eutrophication.

Nutrients and Environmental Factors Cross Wavelet Analysis of River Yi in East China: A Multi-Scale Approach.

The accumulation of nutrients in rivers is a major cause of eutrophication, and the change in nutrient content is affected by a variety of factors. Taking the River Yi as an example, this study used wavelet analysis tools to examine the periodic changes in nutrients and environmental factors, as well as the relationship between nutrients and environmental factors. The results revealed that total phosphorus (TP), total nitrogen (TN), and ammonia nitrogen (NH4+-N) exhibit multiscale oscillation features, with the dominating periods of 16-17, 26, and 57-60 months. The continuous wavelet transform revealed periodic fluctuation laws on multiple scales between nutrients and several environmental factors. Wavelet transform coherence (WTC) was performed on nutrients and environmental factors, and the results showed that temperature and dissolved oxygen (DO) have a strong influence on nutrient concentration fluctuation. The WTC revealed a weak correlation between pH and TP. On a longer period, however, pH was positively correlated with TN. The flow was found to be positively correct with N and P, while N and P were found to be negatively correct with DO and electrical conductance (EC) at different scales. In most cases, TP was negatively correlated with 5-day biochemical oxygen demand (BOD5) and permanganate index (CODMn). The correlation between TN and CODMn and BOD5 was limited, and no clear dominant phase emerged. In a nutshell, wavelet analysis revealed that water temperature, pH, DO, flow, EC, CODMn, and BOD5 had a pronounced influence on nutrient concentration in the River Yi at different time scales. In the case of the combination of environmental factors, pH and DO play the largest role in determining nutrient concentration.

Effect of Ridge Height, Row Grade, and Field Slope on Nutrient Losses in Runoff in Contour Ridge Systems under Seepage with Rainfall Condition.

Seepage plays a key role in nutrient loss and easily occurs in widely-used contour ridge systems due to the ponding process. However, the characteristics of nutrient loss and its influential factors under seepage with rainfall condition in contour ridge systems are still unclear. In this study, 23 seepage and rainfall simulation experiments are arranged in an orthogonal rotatable central composite design to investigate the role of ridge height, row grade, and field slope on Nitrate (NO3--N) and Orthophosphate (PO4+3-P) losses resulting from seepage in contour ridge systems. In total, three types of NO3--N and PO4+3-P loss were observed according to erosion processes of inter-rill-headward, inter-rill-headward-contour failure, and inter-rill-headward-contour failure-rill. Our results demonstrated that second-order polynomial regression models were obtained to predict NO3--N and PO4+3-P loss with the independent variables of ridge height, row grade, and field slope. Ridge height was the most important factor for nutrient loss, with a significantly positive effect and the greatest contribution (52.35-53.47%). The secondary factor of row grade exerted a significant and negative effect, and was with a contribution of 19.86-24.11% to nutrient loss. The interaction between ridge height and row grade revealed a significantly negative effect on NO3--N loss, whereas interactions among the three factors did not significantly affect PO4+3-P loss. Field slope only significantly affected NO3--N loss. The optimal design of a contour ridge system to control nutrient loss was obtained at ridge height of 8 cm, row grade of 2°, and field slope of 6.5°. This study provides a method to assess and model nutrient loss, and improves guidance to implement contour ridge systems in terms of nutrient loss control.

Cancer Survivors Could Get Survival Benefits from Postdiagnosis Physical Activity: A Meta-Analysis.

BACKGROUND: Physical activity presents significant protection against death from cancer in the general population, so the global recommendations on physical activity for health are recommended by the WHO. While the recommendation is a guideline for general population, whether all cancer patients could get benefits from physical activity and whether the cancer patients who did not meet the requirement of the recommendation could get benefits from the physical activity, compared with the cancer patients with no physical activity, are unclear. Accordingly, we conducted a meta-analysis to identify whether the physical activity, even if low level of physical activity, could reduce the mortality of various cancer patients. METHOD: We conducted a systematic search of PubMed, Embase, and Cochrane Library for published cohorts and case-control studies of cancer survivors with physical activity comparing with no physical activity and reported outcomes of mortality through October 15, 2018. Two investigators independently reviewed the included studies and extracted relevant data. The effect estimate of interest was the hazard ratios (HRs). RESULTS: There are 21811 participants in total in the nine studies, and 2386 cancer deaths in this meta-analysis. Among them, 1 was a case-control study and 8 were cohort studies. The meta-analysis results showed that physical activity was associated with a significantly reduced risk of mortality in cancer survivors, with a pooled HR and 95% CI of 0.66 (0.58∼0.73), reducing mortality by 34% and also suggested that low level of physical activity could reduce the mortality with an HR and 95% CI of 0.60 (0.50∼0.69). CONCLUSION: The results of this meta-analysis demonstrated that postdiagnosis physical activity, no matter the level of physical activity, could significantly reduce the mortality by 34%, compared with the no physical activity. At the same time, the results also suggested that cancer survivors undergoing low level of physical activity had a 40% reduction in mortality, which means that the cancer patients with poor ECOG need to do physical activity as much as they can, even if the amount of physical activity was low.

[Effects of Sediment Burial and Exogenous Cd Input on Biomass Allocation and Antioxidative Enzyme Activities of Suaeda salsa in the Coastal Wetland of the Yellow River Delta].

The Yellow River Delta has been facing the threat of functional degradation during the recent years. The Water-Sediment Regulation Project not only supplements abundant freshwater, but also alters the sediment burial and heavy metal levels, which affects vegetation growth. Thus, we selected the pioneer species Suaeda salsa, to study the effects of different sediment burial depths (0, 3, 6, 12 cm) and exogenous Cd inputs (0, 0.5, 1.0, 1.5 mg·kg-1) on biomass allocation and activities of antioxidative enzymes in the coastal wetlands of the Yellow River delta. The results showed that a shallow or moderate burial depth had a stimulatory effect on chlorophyll content, while an excessive burial depth inhibited the growth of Suaeda salsa and chlorophyll content. With increasing Cd input, chlorophyll content and dry mass decreased. At a lower Cd input and moderate burial depth, activities of CAT and SOD increased, and at high levels, SOD activities decreased, while activities of CAT at a 12 cm burial depth and 1.0 mg·kg-1, 1.5 mg·kg-1 Cd input were higher than those for the control (62.66% and 58.56%). CAT activities reached high values (15.76 U·mg-1) at a high Cd input (1.5 mg·kg-1) and burial depth (12 cm). Analysis of variance showed that Cd input had a significant effect on protein content, and CAT and SOD activities, and sediment burial depth had a significant effect on the protein content and SOD activities. Interaction between Cd input and sediment burial depth had a significant effect on CAT and SOD activities (P<0.05). These results demonstrated that sediment burial depth and Cd input had a great influence on the growth of Suaeda salsa, and to some extent, Suaeda salsa could change its biomass allocation and antioxidative enzyme activities to adapt to severe environments.

Attenuation of early liver fibrosis by herbal compound "Diwu Yanggan" through modulating the balance between epithelial-to-mesenchymal transition and mesenchymal-to-epithelial transition.

BACKGROUND: Diwu Yanggan (DWYG) is a Chinese compound herbal preparation which consists of five Chinese herbs. This study investigates the preventative effects of DWYG on liver fibrosis induced by carbon tetrachloride (CCl4) and explores its possible mechanisms of action. METHODS: Liver fibrosis was induced in male Wistar rats by injecting a 50% CCl4/soybean oil solution subcutaneously twice a week for six weeks. After six weeks of treatment, serum aspartate transaminase (AST) and alanine transaminase (ALT) assay, liver tissue histological assessment and hepatic hydroxyproline assay were respectively carried out to examine the effects of DWYG on liver function and fibrosis degree. The impacts of DWYG on the expression levels of epithelial marker E-cadherin, mesenchymal marker Vimentin, transforming growth factor ß1 (TGF-ß1) and bone morphogenetic protein-7 (BMP-7) were further examined by quantitative real-time RT-PCR and Western blot analysis. In addition, the differences of Hedgehog (Hh) signaling pathway activity between DWYG-treated and DWYG-untreated fibrotic liver tissues were also evaluated by quantitative real-time RT-PCR and Western blot analysis. RESULTS: Upon DWYG treatment, the serum levels of ALT and AST, hepatic hydroxyproline content and the degree of fibrosis in CCl4-induced fibrotic model rats were dramatically declined. In accompany with the alleviation of the degree of fibrosis, DWYG treatment provoked the reversal of epithelial-to-mesenchymal transition (EMT) to mesenchymal-to-epithelial transition (MET) in the fibrotic liver tissues, which was characterized with the up-regulation expression of E-cadherin and down-regulation expression of Vimentin. Furthermore, we observed that the expression level of TGF-ß1 was reduced whereas the expression level of BMP-7 was enhanced in liver tissues of DWYG-treated rats, therefore the expression ratio of TGF-ß1/BMP-7 was dramatically decreased compared to CCl4-induced fibrosis model rats. In addition, quantitative real-time RT-PCR and Western blot analysis demonstrated that after DWYG treatment the expressions of Hh ligand Shh, receptor Smo and Ptc, and transcription factor Gli1 in CCl4-induced fibrotic liver tissues were dramatically repressed. CONCLUSIONS: DWYG demonstrates therapeutic potential to prevent liver fibrosis by modulating the balance between EMT and MET through reducing the expression ratio of TGF-ß1/BMP-7 and inhibiting the excessive activation of Hh signaling pathway.