Areas Of Southwest China Research Articles

Status on the use of anti-hypertensive drugs in the southwest areas of China

Objective: To understand the current status of anti-hypertensive drug use in patients with hypertension in the Southwest areas of China. Methods: Based on the Program of Screening and Intervention Subjects with High Risk Cardiovascular Diseases, this study presented information on adults aged 35-75 in Southwest China by convenient sampling method, from January 2016 to November 2018. Basic information and cardiovascular related data were collected. Data on hypertensive patients were recorded, including names, doses and frequency of anti-hypertensive drugs they used. Information on the use of anti-hypertensive drugs among different hypertension subgroups, potential related characteristics, types and combination patterns of drugs, etc., were analyzed. Results: A total of 394 957 subjects were included in the study, with 159 014 identified as being hypertensive [mean age (58.8±9.5) years, 40.2% male]. 29.8% of them ever received antihypertensive drugs. A total of 30 445 of the patients reported detailed information of the drugs they ever used and 22.5% of them received therapy of combined drugs. Rates of using combination therapy were consistent among subgroups with different age, gender, blood pressure level and history of cardiovascular and cerebrovascular diseases. Results from the multivariate logistic regression analysis showed that patients with previous cardiovascular and cerebrovascular events, obesity or diabetes were more likely to have received combined therapy, while patients with less education or lower income were in the opposite. Calcium antagonists (58.6%) were the main drugs being used in single drug therapy, while traditional fixed-dose combination drugs (31.4%) were the most common ones in the drug-combination therapy, followed by angiotensin converting enzyme inhibitor/angiotensin receptor blocker combined with calcium antagonists (22.4%). Angiotensin converting enzyme inhibitor/angiotensin receptor blocker combined with beta blocker was the main drug used in patients with coronary heart disease. Conclusions: Treatment programs using the antihypertensive drugs for hypertensive patients in Southwest China needs to be improved, since the irrational use of antihypertensive drugs still exists. However, we would encourage the use of combination therapy for hypertensive patients.

Selenium Uptake Characteristics of Reclaimed Soil-Crop from Mining Wasteland and Its Antagonistic Effects on Heavy Metals

To fully exploit selenium-rich land resources and ensure crop safety, the phenomenon of "double high" of Se and heavy metals in reclaimed soil of mining wasteland was studied. Soil and maize samples collected from "point-to-point" were weighted by the inverse distance weighted (IDW) method; multiple linear regression (MLR), partial least squares regression (PLSR), random forest regression (RFR), and other methods were used to predict selenium uptake by maize in a sulfur mine reclamation area in southwest China. Meanwhile, the antagonistic effects of selenium (Se) on heavy metals (Hg, As, Cd, and Cr) were analyzed. The results showed that the soil in the study area was rich in selenium resources. The average Se content in the soil reached 0.83 mg·kg-1, which was 2.87 times that of the average Se content in Chinese soil. The Se content in maize grains ranged from 0.02 mg·kg-1 to 0.16 mg·kg-1. According to correlation analysis and model prediction, the main influencing factors of selenium content in maize grains in the study area were soil selenium, pH value, organic matter, and heavy metal As. Multivariate linear regression (MLR) was the most effective method for predicting selenium content in maize grains, and the determinant coefficient R2 was 0.52. By comparing the enrichment characteristics of maize to heavy metals (Hg, As, Cd, and Cr) under different concentration gradients of Se in the soil of the study area, the results showed that Se had antagonistic effects on Hg, As, Cd, and Cr. The results can provide a basis for the development of selenium-rich agriculture in similar mining wasteland reclamation in the future.

Screening of native low mercury accumulation crops in a mercury-polluted mining region: Agricultural planning to manage mercury risk in farming communities

Historical mercury (Hg) mining in the Wanshan Hg mining area in southwest China and other regions worldwide has contaminated soils and left a legacy of health risks for communities consuming crop products harvested from these soils. Agricultural planning strategy is urgently needed in these regions for reducing human exposure to Hg pollution through selecting native low-Hg-accumulating crops for future planting in contaminated farmlands. For this purpose, 43 existing crops grown on the farmlands across the Wanshan Hg mining areas (with a total of 4566 ha farmlands) were screened for identifying their Hg concentrations and accumulation capacities. A total of 679 sets of samples were collected, and Hg concentrations were in the range of 2.4–1075 μg kg−1 in the edible sections of the studied crops, and 0.6–789.6 mg kg−1 in the corresponding soils. Four types of the investigated crops had Hg concentrations in their edible sections, which were lower than the Chinese governmental reference values (10–20 μg kg−1 in fresh weight). These four crops include radish (2.03–10.71 μg kg−1, n = 13), strawberry (2.80–10.43 μg kg−1, n = 15), corn (1.23–21.32 μg kg−1, n = 28) and potato (0.84–13.39 μg kg−1, n = 41). The four crops were planted again in the second year at two contaminated farmlands with soil Hg concentrations of 105 ± 5.2 mg kg−1 in Aozhai village and 23 ± 3.3 mg kg−1 in Wawu village, and consistent results with those from the field survey were obtained, i.e., the four crops had the Hg concentrations lower than the Chinese governmental reference values. Based on these findings, a land-use strategy was proposed for the farmlands with different soil Hg concentrations in the Wanshan Hg mining area for properly planting the four screened low-Hg-accumulating crops. Implementing this strategy would reduce Hg accumulation in the edible sections of agricultural products by up to 92% while increasing the economic output by 3.6 times as compared to the current cropping practice in the region. Thus, the agricultural planning strategy developed in the present study has large potential in reducing human dietary Hg exposure while preserving local horticulture.

Effects of Nano-Copper Poisoning on Immune and Antioxidant Function in the Wumeng Semi-Fine Wool Sheep.

The Wumeng semi-fine wool sheep is vital to the production system of the Wumeng mountainous area in Southwest China. To study the effect of nano-copper poisoning in the Wumeng semi-fine wool sheep, nano-copper poisoning model was established in sheep. We determined blood physiological and biochemical parameters, immune indexes, and antioxidant indicators. The results showed that Hb, RBC, and PCV levels in blood from the nano-copper group were markedly lower (P < 0.01) than those in the control group. Serum LDH, AST, ALT, CPK, and Cp from the nano-copper group were significantly higher (P < 0.01) than those in control animals. Serum SOD, GSH-Px, CAT, and T-AOC from the nano-copper group were significantly lower (P < 0.01) than those in control sheep, and MDA content in serum from the nano-copper group were markedly higher (P < 0.01) than those in control sheep. The levels of IL-2, IL-6, IL-1β, IgA, IgM, and IgG from the nano-copper group were significantly lower (P < 0.01) than those in the control group. It was concluded that nano-copper poisoning could not only affect the immune function of Wumeng semi-fine wool sheep but also reduce the antioxidant capacity.

Tillage induces rapid loss of organic carbon in large macroaggregates of calcareous soils

Soil organic carbon (SOC) sequestration and protection not only mitigate CO2 emission but also promote soil fertility. Naturally, calcareous soils in the karst area contain significantly higher SOC concentration than the red soils in non-karst area of the same region. After cultivation, calcareous soils are susceptible to SOC loss, with substantial SOC loss occurring within two years. However, the underlying mechanisms are not well understood. To expand our understanding of the process of rapid SOC loss and the role played by soil aggregate disruption, we conducted a 1-year in situ study in a karst area in Southwest China. We tilled the soil at different intervals—every 6 (T1), 4 (T2), 2 (T3), and 1 (T4) months—causing aggregate disruption of different intensities. No-tillage soil (T0) was treated as a control. After 1 year, the SOC concentration in the soil under the tillage treatments (T1, T2, T3, and T4) was significantly reduced; however, in the no-tillage soil, no significant change was observed. The SOC loss within the first 3 months accounted for approximately 70 %–84 % of the total SOC loss, indicating that SOC loss was most pronounced during the initial tillage period. SOC was mainly stored in the 2–8 mm soil aggregates. Tillage-induced disruption of the 5–8 mm aggregates resulted in a decline of the physical protection of SOC, leading to substantial SOC loss from these aggregates. Besides, the SOC loss was positively correlated to the amount of Ca2+ leaching, indicating that enhanced carbonate dissolution might contribute to the decline in aggregate stability and associated SOC loss. Our results emphasize the importance of zero-tillage management and maintenance of large soil macroaggregates for sustainable land use of calcareous soils in karst regions.

Ecosystem Health: Assessment Framework, Spatial Evolution, and Regional Optimization in Southwest China

Regional ecological health, the core of comprehensive ecosystem assessments, is an important foundation for regional exploration, environmental conservation, and sustainable development. The mountainous areas in southwest China are backward in economy, but industrialization and urbanization have been rapid in recent years. This study assessed the ecosystem health of the Sichuan and Yunnan provinces in China using a pressure-state-response (PSR) model. Spatiotemporal patterns of regional ecosystem health were analyzed from 2000 to 2016, including overall characteristics as well as local characteristics. Ecosystem health in most regions was improved over time (Y = 0.0058X − 11.0132, R2 = 0.95, P 0.05). Overall, the regional ecosystems to the east of the Hu line—an imaginary line dividing east and west China into roughly equivalent parts—were healthier than those to the west. The pressure and state scores of ecosystems were determined by physiographic condition, and the response scores by government policies and social concern. The spatiotemporal patterns of ecosystem health were dominated to a greater extent by natural than anthropogenic factors, which explains why the shift in the patterns aligned with the direction of the Hu line. Dividing regions into key management areas based on natural geographical conditions and socioeconomic development could contribute to the formulation of a reasonable ecological and environmental protection policy, guaranteeing ecosystem services in the long run.

Effects of shading and herb/liana eradication on the assembly and growth of woody species during soil translocation in Southwest China

Due to the intensification of human activities and global climate change, large areas of forest have been degraded and converted to other land uses. Soil translocation, which transfers the topsoil of donor forest to the receiving site to allow for the germination and reestablishment of soil seed bank and seedling, is a promising method for restoring vegetation that is similar to the donor forest. However, the lower similarity between the germinated community and donor forest has diminished its application against the ecological restoration and biodiversity compensation. We hypothesized that the exposure of donor forest soil to strong sunlight and early herb/liana competition may block germination and establishment of woody species (trees and shrubs) following soil translocation. To test this, here we investigated the effect of shading and weeding treatment on woody species assembly and seedlings growth at a karst rocky desertification area in southwest China. The results showed that soil translocation in blank control significantly increased the richness and similarity of woody species compared with receiving site. Moreover, soil translocation with shade treatment not only increased the richness and density of species during the germination period, but it also improved the survival and growth of most species—especially Osteomeles anthyllidifolia, Fraxinus malacophylla, Quercus baronii, and Rhamnus parvifolia—when compared with soil translocation in blank control after 18 months. Additionally, although soil translocation with blank control and weeding, and soil translocation with shade and weeding increased neither the number of woody species nor the density of shrubs species, they improved the density and similarity of tree species as well as the similarity of shrub species. We concluded that soil translocation with shade and weeding is likely more effective and helpful to restore the vegetation that is more similar to the donor forest in semi-humid regions of southwest China and comparable regions worldwide. But in practice, only soil translocation with moderate shade is deemed the optimal restoration method because it maintain the “recovery effect” while decrease the labor cost. Nevertheless, we should further assess the longer-term development and stabilization of established vegetation.

Accumulation and transport of antimony and arsenic in terrestrial and aquatic plants in an antimony ore concentration area (south-west China)

Environmental contextPhytoremediation requires an understanding of bioconcentration and translocation processes that determine behaviour and fate of potentially toxic elements. We studied the distribution of antimony and arsenic in terrestrial and aquatic soil-plant systems in an antimony ore zone. We found that the common climbing plant Kudzu (Pueraria lobata) is suitable for phyto-stabilisation of antimony-bearing tailings, while tiger grass (Thysanolaena maxima) was able to extract antimony and arsenic from contaminated soils. AbstractAntimony (Sb) pollution is a major environmental issue in China. Many historical abandoned tailings have released high concentrations of Sb and its associated element arsenic (As) to surrounding environments. This has prompted the need to understand accumulation and translocation processes that determine the behaviour and fate of Sb and As in contaminated soil–plant systems and to identify suitable plant species for phytoremediation. Here we investigate distribution of Sb and As in terrestrial and aquatic dominant plant species and associated soils, all of which are naturally found in an Sb ore concentration area in south-west China. Total Sb and As concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS). The percentage of soluble Sb and As in the total concentrations were determined; the results showed that the basic soil environment facilitates the release of Sb and As from contaminated soils, and that Sb has higher mobility than As. Bioconcentration factor (BCF) and translocation factor (TF) were used for evaluating the ability of plants to accumulate and transport Sb and As, respectively. The results indicated that all selected plant species have the potential to tolerate high concentrations of Sb and As. Consequently, this study suggested that Pueraria lobata (PL) can be used as the preferred species for phytostabilisation of abandoned Sb-bearing tailings, given that PL has well-developed roots and lush leaf tissues and the ability to translocate Sb from roots to aboveground parts. Thysanolaena maxima (TM) is suitable for phyto-extraction of Sb and As in contaminated soils.

Strengthen Karst Surface Systematic Processes Research, Support Ecological Restoration and Social Improvement in Karst Rocky Desertification Areas in Southwest China

Strengthen Karst Surface Systematic Processes Research, Support Ecological Restoration and Social Improvement in Karst Rocky Desertification Areas in Southwest China

Influence of Heterogeneous Karst Microhabitats on the Root Foraging Ability of Chinese Windmill Palm (Trachycarpus fortunei) Seedlings

Chinese windmill palms (Trachycarpus fortunei) are widely planted in karst bedrock outcrop areas in southwest China because of their high economic and ecological values. The aims of this study were to investigate the foraging ability of Chinese windmill palm seedlings planted in six different types of karst microhabitat and to identify the main environmental factors that influence root foraging ability. We planted three-year-old Chinese windmill palm seedlings in six typical karst microhabitats (i.e., rocky trough, rocky surface, rocky gully, rocky soil surface, rocky pit, and soil surface microhabitats). One year after transplanting, the seedlings were excavated to determine the morphological parameters values of new roots and the nutrient concentrations of new roots and leaves. The root foraging ability of Chinese windmill palm seedlings, defined as new root length and new root surface area, was significantly greater in the rocky trough, rocky soil surface, and soil surface microhabitats than in the rocky gully, rocky surface, and rocky pit microhabitats (p < 0.05). Redundancy analysis revealed that the main positive factor affecting the rooting ability of Chinese windmill palm seedlings was soil thickness. Chinese windmill palm seedlings improved their root absorption efficiency by increasing their root length and root surface area under soil nutrient deficiency conditions. The organic carbon, total nitrogen, and available potassium in soil positively influenced the concentration of N and K in roots. Total potassium in soil negatively influenced the biomass of new annual leaves and concentrations of N, P and K in new annual roots and leaves. Chinese windmill palm seedlings can be grown in the different karst microhabitats, especially in the rocky trough, rocky soil surface, and soil surface microhabitats, and, therefore, it is suitable for use in the regeneration of karst forests.

Negative effects of farmland expansion on multi-species landscape connectivity in a tropical region in Southwest China

The expansion of farmland has negative effects on the natural landscape patterns supporting ecological processes, which in turn can be reflected in changes in the landscape connectivity for animal movements. There is an urgent need to address the issue of the changes to landscape connectivity caused by farmland expansion, especially in tropical areas in Southwest China that have high biodiversity levels and intense human cultivation. Using Menghai County in Xishuangbanna as the study area, six landscape pattern indexes were used to evaluate the landscape patterns and fragmentation based on land use data, and a multi-species circuit theory method was used to quantitatively analyze the changes and spatial variability in landscape connectivity. The results showed that the encroachment of farmland greatly increased the degree of landscape fragmentation. Current density maps of circuit connectivity based on multi-species showed that the spatial differences in the landscape ecological networks were obvious. The key corridors identified by the Zonation model showed that the landscape connectivity in the western area of Menghai County was higher than that in the central area. Comparing the changes between different periods, the maximum current declined the most, with a loss of nearly 25%, from 1995 to 2000. By 2000, the key corridors in the central region had almost completely disappeared. The above information indicated that the farmland expansion led to fragmentation, influenced the movement processes of the regional wild species and reduced the degree of landscape connectivity. This study on the evaluation of the impact of farmland expansion will improve the understanding of the effects of human activities on regional landscape connectivity and provide an operational approach to conservation planning.

Impact of vegetation restoration on soil organic carbon stocks and aggregates in a karst rocky desertification area in Southwest China

The objectives of the study were as follows: (a) to determine the response of soil organic carbon (SOC) fractions to vegetation restoration; (b) to examine the contributions of aggregate-associated OC to total soil OC accumulation along vegetation restoration, (c) to identify the factors that affect SOC accumulation along natural vegetation restoration in a karst region in Southwest China. Four vegetation restoration stages, namely, grassland, shrubland, shrub-arbor mixed forestland, and arbor forestland, were compared with cropland (CL). Soil samples were collected at depths of 0–10 cm and separated into five aggregate size fractions. SOC, light fraction OC (LFOC), easily oxidizable OC (EOC), and aggregate-associated OCs were determined for different aggregate sizes and total soil. Natural vegetation restoration increased macroaggregate amount but decreased the fractions of meso- and microaggregates. Vegetation restoration significantly increased total SOC, EOC, and LFOC concentrations and stocks and soil aggregate-associated OC concentrations. The responses of EOC and LFOC in total soil and soil aggregates were more sensitive than those of SOC along with vegetation restoration. Aggregate-associated OC concentrations generally increased with a decrease in aggregate size. Macro- and microaggregate-associated OC stocks increased, but mesoaggregate-associated OC stocks decreased following the conversion of CL to a natural vegetation ecosystem. The increase in SOC stocks was primarily attributed to the macroaggregate-associated OC stocks and their changes. OC concentrations and stocks in total soil and the soil aggregates were significantly positively related to exchangeable calcium content. Vegetation restoration considerably affects the amount of soil aggregates, OC concentrations, and stocks in total soil and soil aggregates. Changes in OC concentrations and stocks can be more pronounced in the liable carbon fraction than in total SOC. The increase in SOC was mostly attributed to OC accumulation in macroaggregates. Exchangeable calcium also affected soil OC accumulation in total soil and soil aggregates.

Evaluation of CORDEX Regional Climate Models in Simulating Extreme Dry Spells in Southwest China

In recent decades, Southwest China (SWC) has experienced a series of severe and extensive droughts resulting in tremendous socioeconomic losses. The annual maximum dry spell length (AMDSL), which refers to the number of consecutive days without rainfall, or days with rainfall below a threshold, plays an important role in triggering drought. The main objective of this study is to provide a comparison of the capabilities of current regional climate models (RCMs) in simulating extreme dry spell characteristics in mountainous SWC. Five available RCM simulations utilized in the Coordinated Regional Climate Downscaling Experiment (CORDEX)-East Asia project over 1981 to 2005 were employed in this study; the RCMs being NIMR-HadGEM3, SNU-MM5, SNU-WRF, KNU-RegCM4 and YSU-RSM. Firstly, it was found that all RCMs reasonably simulate the main seasonality features of rainfall and dry days in SWC. Furthermore, besides YSU-RSM, the other four RCMs can accurately capture the spatial pattern of dry-day occurrence based on Taylor diagram diagnosis. Secondly, we assessed the performance of five RCMs to detect and reproduce the climatology and variability of the AMDSL. In general, RCMs simulate the spatial pattern of long-term mean and interannual variability of the AMDSL in SWC well. Based on Taylor diagram evaluation, NIMR-HadGEM3 was the best among 5 RCMs in simulating the AMDSL characteristics. Thirdly, the generalized extreme value (GEV) distribution is considered the most suitable model fitting the AMDSL in both observation and RCM experimental data in comparison to other three-parameter probabilistic models. Higher value centers of the scale parameter and the location parameter indicate a wider and amplified distribution of the AMDSL over the low-latitude highlands (LLH) region against other areas in Southwest China, which is consistent with spatial patterns of climatological AMDSL. In addition, sensitivity analysis of different thresholds for dry days show that the 1 mm threshold is suitable for this study and different threshold choices have little effect on simulation ability.

Incentivizing household forest management in China's forest reform: Limitations to rights-based approaches in Southwest China

On the basis that property rights provide effective incentives to their users, rights-based approaches have become well-received for purposes of improved resource management, production, and conservation. Recent reform in China's collective-owned forest sector has also been guided by a rights-based approach in generating new incentives and economic benefits for households. Forest property rights have been reconfigured into formal, private, and transferable form, and households are financially compensated for rights' attenuation. In this paper, we draw on a household survey (N = 331) and a series of interviews (N = 29) to empirically examine how three types of forest rights are exercised and perceived by rural households in the Wuling Mountain Area, a relatively poor and mountainous area in Southwest China. Our findings show that although the new rights arrangements are largely perceived as credible by households, the rights are rarely exercised, without tangible contributions to the intended benefits. In explaining this, we find that current economic values of household forests are low. This may suggest that rights-based approaches are unlikely to realize their intended effects if the natural resources themselves are of too little value, an oversight in conventional discussions on resource rights.

What is the relationship between ecosystem services and urbanization? A case study of the mountainous areas in Southwest China

China is undergoing a rapid urbanization process, and urbanization will have a direct impact on regional ecosystems and affect regional ecosystem services. Considering the mountainous counties in Southwestern China as the research object, this study reveals the spatial clustering characteristics of four typical ecosystem services (food production, soil conservation, water yield and carbon sequestration) as well as the trade-offs and synergies among ecosystem services in different urbanized areas. At the same time, piecewise linear regression is used to determine the threshold of the influence of urbanization on ecosystem services. The results indicate that: 1) There are spatial autocorrelations among the four typical ecosystem services; with strong clustering characteristics, the positive correlation types are “clustered” locally; and with significant spatial heterogeneity, the negative correlation types are scattered and mainly appear in the highly urbanized area. 2) There are also remarkable differences in the relationship among various ecosystem services in different urbanized areas, and in particular, there are marked trade-offs between food production and carbon sequestration in the moderately urbanized area and the highly urbanized area. However, there are synergies between them in the lowly urbanized area. 3) With an increase in the compounded night light index (CNLI), water yield, carbon sequestration, food production and overall ecosystem services values present an increasing-decreasing trend, the soil conservation function value shows a decreasing-increasing trend. The response of water yield, carbon sequestration, food production, and overall ecosystem services to the compounded night light index (CNLI) has a threshold of 1.2642, 1.4833, 1.3388, 1.5146 and 1.2237, respectively. Based on the detected relationships between urbanization and ecosystem services, this study provides a theoretical reference for the selection of urbanization development models in key ecological functional areas.

Survey of Pretreatment HIV Drug Resistance and Genetic Transmission Network Analysis Among HIV Patients in a High Drug-Use Area of Southwest China.

Background: Pretreatment drug resistance (PDR) poses an increasing threat to the success of antiretroviral treatment (ART) programs in China. We aimed to conduct a survey of PDR among HIV patients in an area in Southwest China with extensive drug trafficking.Methods: Consecutive cross-sectional surveys were conducted in Liangshan Prefecture of Sichuan Province from 2009 to 2018 based on the WHO-recommended method. PDR was identified by testing pol region sequences with the Stanford HIVdb algorithm (version 7.0). PDR prevalence and related factors were assessed by multivariable logistic regression. The transmission of HIV drug resistance was analyzed using a genetic transmission network.Results: HIV-1 pol genes from 1889 patients were successfully amplified. The distribution of HIV-1 genotypes was as follows: CRF07_BC (94.0%), CRF08_BC (2.3%), CRF01_AE (2.0%) and others (1.4%). Of the participants, 6.9% (95% CI: 4.1-8.1%) had pretreatment resistance to 12 antiretroviral drugs recommended by the WHO, and nucleoside reverse transcriptase inhibitor (NRTI), non-nucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitors (PI) resistance were identified among 1.4% (95% CI: 0.7-3.4%), 5.8% (95% CI: 1.2-8.7%) and 0.4% (95% CI: 0.1-3.0%) of the patients, respectively. In the multivariate logistic model, the prevalence of PDR was 1.52-fold higher among intravenous drug users (IDUs) than among patients infected by heterosexual transmission (95% CI: 1.07-2.38; P=0.049), and the prevalence of PDR among patients diagnosed from 2017-2018 was 2.03-fold higher than that among patients diagnosed from 2009-2016 (95% CI: 1.18-5.76; P=0.018). A total of 26 clusters containing PDR and a rapidly growing drug resistance-related cluster containing the E138Q and V179D mutations were identified by genetic transmission network analysis.Conclusion: The results show a moderate overall level of PDR prevalence and rapidly growing drug resistance over time. Preventive intervention should be focused on controlling the HIV epidemic among drug users, and surveillance is urgently needed to monitor the trend of PDR.

Determination of polyhalogenated carbazoles in soil using gas chromatography-triple quadrupole tandem mass spectrometry

Polyhalogenated carbazoles (PHCZs) are emerging environmental contaminants that have caused wide concerns due to their dioxin-like toxicity and environmental persistence. It would be desirable to determine all of these chemicals using a simple analytical method. Within this study, a simple and sensitive method combining accelerated solvent extraction (ASE) with gas chromatography-triple quadrupole tandem mass spectrometry (GC–MS/MS) was established to simultaneously analyze eleven frequently detected PHCZs in soil, including CCZ-3, CCZ-36, CCZ-1368, CCZ-2367, BCZ-3, BCZ-27, BCZ-36, BCZ-136, BCZ-1368, 1-B-36-CCZ, 18-B-36-CCZ. The calibration curves of the target analytes showed good linearity (R2 > 0.99, level = 6), and method detection limits (MDLs) ranging from 1.5 to 14.6 pg g−1. The average recoveries of the analytes in soil samples ranged from 64% to 126% with the RSD ranging from 2.0% to 10%. The developed method was successfully used for determination of these eleven PHCZs in soil samples from a tie-dye area in southwest China. Total concentrations of these eleven PHCZs ranging up to 46.3 ng g−1 dw. CCZ-36, BCZ-3, CCZ-3, 1-B-36-CCZ, 18-B-36-CCZ, and BCZ-1368 were the most abundant compounds in soil.

Livelihood Strategies of Rural Households in Ning’er Earthquake-Stricken Areas, Yunnan Province, China

Natural hazards not only cause direct losses of household income and assets but also affect the choice and outcome of livelihood strategies. Based on the questionnaire survey from 2007 on Mw 6.1 Ning’er earthquake-hit areas in Southwest China, we analyzed the relationship between livelihood assets (or capitals) and livelihood strategies of local rural households and identified the main factors influencing the choice of livelihood strategy. The results indicate that statistically significant differences exist in livelihood assets among livelihood strategies. The choice of livelihood strategies is affected significantly by the status of livelihood assets. High financial capitals enable households to engage in higher-returns or capital-intensive livelihood activities. Improving vocational education and skills training for rural residents, especially for the youth, is also important in developing new livelihood strategies beyond their traditional lifestyle. Higher social capitals provide households the opportunity to select a higher return and income livelihood strategy. In addition, as part of efforts to enhance physical capitals, housing construction planning and technical guidance are of critical importance to improve the anti-seismic performance of rural buildings and decrease their livelihood risk in earthquake-prone areas. It is important for farmers to improve and diversify their livelihood strategies according to regional geographical environment and the comparative advantages of their own livelihood assets.

Cause Analysis of Abutment Toppling Deformation of a Hydropower Station in Southwest China

Toppling deformation and failure is a typical form of instability of rock mass deformation and failure on anti-inclined slope in alpine gorge area. Based on the analysis of the distribution characteristics of the toppling deformation body in a hydropower station reservoir area in southwest China, this paper simulated the relationship between the distribution of river terraces and the toppling deformation body by using the discrete element method, and the conclusion that the influence of river downcutting on the toppling deformation is obtained.

Metabolic fractures: How household livelihood practices differentiate agricultural input use in southwest China

As smallholders in the global South engage in new ways with agricultural markets, they change their farming strategies and use of agricultural inputs. In many locales, heavy use of synthetic fertilizers and pesticides gives state authorities figurative headaches and farmers actual health hazards and soil degradation. It has been argued that agricultural commercialization and urbanization generate metabolic rifts—gaps in nutrient cycling that impoverish soils and accumulate wastes. Replacement of organic with synthetic inputs is central to this dynamic. We join metabolic rift theory with livelihood analysis to examine how varying livelihood strategies differentiate input use in an area of southwest China where farming is partially commercialized. We draw on household survey data to identify five household clusters with distinct on-farm activity patterns. Regression analyses show that these farming strategies mediate effects of household and community attributes on use of synthetic fertilizers, synthetic pesticides, and organic manure fertilizer. Strategies associated with diverse on-farm crop rotations are associated with greater use of manure. Emergent tree-borne crops are associated with greater pesticide use, but new high-elevation cash crops are linked to less use of both synthetic and organic inputs. These variations have gendered impacts: women's work around compost fertilizer gives way to male-dominated synthetic input management. Our theoretical synthesis and empirical results enrich both livelihoods and metabolic rift scholarship by showing how livelihood strategies mediate political economic forces, generating heterogeneous input use. This study demonstrates the uneven processes through which metabolic rifts tear open and the necessity for soil enhancement efforts to address farmers' variegated practices.