Spatial variability and source analysis of soil heavy metals: A case study of the key planting area of special agricultural products in Cangxi County, China.

Heavy metal pollution in farmland soil represents a considerable risk to ecosystems and human health, constituting a global concern. Focusing on a key area for the cultivation of special agricultural products in Cangxi County, we collected 228 surface soil samples. We analyzed the concentration, spatial distribution, and pollution levels of six heavy metals (Cr, Cu, Pb, Ni, Zn, and Hg) in the soil. Moreover, we investigated the sources and contribution rates of these heavy metals using Principal Component Analysis/Absolute Principal Component Scores (PCA/APCS) and Positive Matrix Factorization (PMF) models. Our findings indicate that none of the six metals exceeded the pollution thresholds for farmland soils. However, the mean concentrations of Cr and Ni surpassed the background levels of Sichuan Province. A moderate spatial correlation existed between Pb and Ni, attributable to both natural and anthropogenic factors, whereas Zn, Cu, Hg, and Cr displayed a strong spatial correlation, mainly due to natural factors. The spatial patterns of Cr, Cu, Zn, Pb, and Ni were similar, with higher concentrations in the northern and eastern regions and lower concentrations centrally. Hg's spatial distribution differed, exhibiting a broader range of lower values. The single pollution index evaluation showed that Cr and Ni were low pollution, and the other elements were no pollution. The average value of comprehensive pollution index is 0.994, and the degree of pollution is close to light pollution. Predominantly, higher pollution levels in the northern and eastern regions, lower around reservoirs. The PCA/APCS model identified two main pollution sources: agricultural traffic mixed source (65.2%) and natural parent source (17.2%). The PMF model delineated three sources: agricultural activities (32.59%), transportation (30.64%), and natural parent sources (36.77%). Comparatively, the PMF model proved more accurate and reliable, yielding findings more aligned with the study area's actual conditions.

On boat: A magnificent panorama of River Basin in Tang Dynasty.

Based on the framework of historical geography, this paper studies the panorama of Chinese river basin in Tang Dynasty, and attempts to reveal the connection between boat and panorama of river basin. Research uses logistic regression as method, takes 13,100 five-characters and eight-lines poems in Tang Dynasty as samples to study the influencing factors of boat. Results show that a total of 218 Chinese characters have a statistically significant effect on the factor of boat (P ≤ 0.05), including 141 risk factors and 77 protective factors. This research deepens the historical geography understanding of following nine aspects related to the "boat" in Tang Dynasty: ① waterfront regions, ② natural water systems, ③ aquatic animals & plants, ④ official travel, ⑤ fishery & commerce, ⑥ boat driving, ⑦ wonderful time, ⑧ emotion of boat trip, ⑨ daily life on boat.

Adaptability evaluation of human settlements in Chengdu based on 3S technology.

This study aims to showcase the adaptability evaluation of human settlements in Chengdu with the use of 3S technology. Chengdu was selected as the research object; natural eco-environmental factors such as terrain fluctuations, temperature and humidity, vegetation type, land use, and vegetation cover were analyzed, together with human disturbance factors such as traffic and gross domestic product (GDP); and the index weights were calculated by analytic hierarchy process (AHP). The evaluation model of Chengdu's residential environment adaptability was constructed based on the analysis carried out by the 3S technology: projection transformation, remote sensing interpretation, information extraction, and analysis. The results of the analysis reflected the zoning and spatial distribution characteristics of Chengdu's residential environment adaptability, and show that (1) the adaptability index of Chengdu's human settlement environment is between 15.98 and 76.75, and the suitability of human settlement environment is seen gradually decreasing from the middle, where it is the highest, when moving to the west and to the east of Chengdu; (2) according to the present situation, the suitability index can be divided into high-grade suitable areas, relatively high-grade suitable areas, moderately suitable areas, and low suitable areas; (3) the correlation between the spatial distribution of Chengdu population and each index factor is as follows: per capita GDP > topographic relief > temperature and humidity > vegetation coverage > traffic network density > land use > hydrological factors; (4) there is a good correlation between Chengdu's human settlements suitability index and the present population density grid layer, and its correlation coefficient is 0.7326; and (5) the leading impact indicators of human settlements are different in different regions. The results show that the natural environmental conditions in Chengdu are superior and that the ecological environmental quality is relatively stable, but the human settlement suitability index is relatively low in the southeast and Longmenshan areas of Chengdu.

The prognostic role of RASSF1A promoter methylation in breast cancer: a meta-analysis of published data.

PURPOSE: Epigenetic alterations have been investigated as prognostic indicators in breast cancer but their translation into clinical practice has been impeded by a lack of appropriate validation. We present the results of a meta-analysis of the associations between RASSF1A promoter methylation status and both disease free survival (DFS) and overall survival (OS) in female breast cancer. METHODS: Eligible studies were identified through searching the PubMed, Web of Science and Embase databases. Studies were pooled and summary hazard ratios (HR) with corresponding confidence intervals (CIs) were calculated. Funnel plots were also carried out to evaluate publication bias. RESULTS: A total of 1795 patients from eight studies were included in the meta-analysis. There are eight studies which investigated DFS in 1795 cases. The relative hazard estimates ranged from 1.77-5.64 with a combined HR of 2.75 (95%CI 1.96-3.84). The HR of RASSF1A promoter methylation on DFS adjusted for other potential prognostic factors was 2.54 (95%CI 1.77-3.66). There has been five trials which analyzed the associations of RASSF1A promoter methylation status with OS in 1439 patients. The hazard estimates ranged from 1.21-6.90 with a combined random-effects estimates of 3.47 (95%CI 1.44-8.34). OS reported in multivariate analysis was evaluated in four series comprising 1346 cases and the summarized random-effects HR estimate was 3.35 (95%CI 1.14-9.85). Additionally, no publication bias was detected for both OS and DFS. CONCLUSION: The results of this meta-analysis suggest that RASSF1A promoter hypermethylation confers a higher risk of relapse and a worse survival in patients with breast cancer. Large prospective studies are now needed to establish the clinical utility of RASSF1A promoter methylation.

[Decomposition of Triploid populus tomentosa fine root and Lolium multiflorum grass root in a composite ecosystem and their nutrient dynamics].

This paper studied the root decomposition and its nutrient dynamics of Triploid populus tomentosa and Lolium multiflorum in a plantation converted from farmland at Tianquan County of Sichuan Province. The results showed that the weight loss rate of fine root and grass root showed an exponential relationship with time, with an annual loss of 76.17%, 69.80%, 73.44% and 79.53% for fine roots of 0 approximately 1, 1 approximately 2 and 0 approximately 2 mm in diameter and grass root, respectively. During the decomposition of fine roots, their N and Ca contents increased, while P, K and Mg contents were in adverse. The nutrient contents of grass root during its decomposition had an irregular variation. The remaining percentage of fine root P, K and Mg had the same trend as root weight loss during its decomposition, while that of N and Ca had a slight decrease. For grass root, its N, P, K, Ca and Mg contents declined rapidly at the initial stage of decomposition, and then decreased slowly with irregular deposition rate.