China's public health initiatives for climate change adaptation.

China's health gains over the past decades face potential reversals if climate change adaptation is not prioritized. China's temperature rise surpasses the global average due to urban heat islands and ecological changes, and demands urgent actions to safeguard public health. Effective adaptation need to consider China's urbanization trends, underlying non-communicable diseases, an aging population, and future pandemic threats. Climate change adaptation initiatives and strategies include urban green space, healthy indoor environments, spatial planning for cities, advance location-specific early warning systems for extreme weather events, and a holistic approach for linking carbon neutrality to health co-benefits. Innovation and technology uptake is a crucial opportunity. China's successful climate adaptation can foster international collaboration regionally and beyond.

Synergistic impact of co-exposures to whole blood metals on chronic kidney disease in general US adults: a cross­sectional study of the National Health and Nutrition Examination Survey 2011-2020.

The impact of exposure to metals on chronic kidney disease (CKD) has only been investigated in two-way or single metal interactions in previous studies. We investigated the associations between five single metals in blood and their mixed exposure and CKD by using the machine learning approach. Relevant data were extracted from the National Health and Nutrition Examination Survey (NHANES 2011-2020), and the level of five metals in blood detected by inductively coupled plasma mass spectrometry was considered as exposures, namely, cadmium (Cd), lead (Pb), total mercury (Hg), manganese (Mn), and selenium (Se). The correlations between individual metal and metal mixtures and CKD were then evaluated by survey-multivariable logistic regression (SMLR), generalized weighted quantile sum (WQS), and Bayesian kernel machine regression (BKMR). Altogether, our study included 12,412 participants representing 572.6 million non-institutionalized US adults. Several single metals with the high quartile of exposure showed a positive association with the CKD ratio including Cd [(AOR = 1.873, 95% CI: 1.537, 2.284), Q4], Pb [(AOR = 1.559, 95% CI: 1.295, 1.880), Q4], and total Hg [(AOR = 1.169, 95% CI: 1.018, 1.343), Q2], while Mn [(AOR = 0.796, 95% CI: 0.684, 0.927), Q2] and Se [(AOR = 0.805, 95% CI: 0.664, 0.976), Q4] were negatively associated with the CKD ratio. In light of the positive fit of the WQS regression model, a significantly positive correlation was found between mixed metals and CKD (AOR = 1.373, 95% CI: 1.224, 1.539) after full covariate adjustment, and a similar finding was also detected in the BKMR model. Our study revealed that each single metal including Cd, Pb, and total Hg might have a positive association with CKD while this association was negative for both Mn and Se. The five metals might have a positive joint effect on CKD.

Joint effect of whole blood metals exposure with dyslipidemia in representative US adults in NHANES 2011-2020.

With little knowledge on the joint effects of metal exposure on dyslipidemia, we aimed to investigate the relationship between exposure to metal and dyslipidemia among US adults based on the National Health and Nutrition Examination Survey (NHANES). Based on the five NHANES waves (2011-2020), we selected five metals in blood as exposure, namely, cadmium (Cd), lead (Pb), total mercury (Hg), manganese (Mn), and selenium (Se), which were detected by inductively coupled plasma mass spectrometry. Survey-multivariable logistic regression, generalized weighted quantile sum (WQS), and Bayesian kernel machine regression (BKMR) were performed to determine whether dyslipidemia was associated with single metals or mixed metals. Our study included 12,526 participants aged from 20 to 80, representing 577.1 million non-institutionalized US adults. We found a positive association between several metals including Pb [adjusted odds ratio (AOR) = 1.332, 95%CI: 1.165, 1.522], total Hg (AOR = 1.264, 95%CI: 1.120, 1.427), Mn (AOR = 1.181, 95%CI: 1.046, 1.334), and Se (AOR = 1.771, 95%CI: 1.576, 1.992) and dyslipidemia. According to the WQS approach, metal mixtures were positively associated with dyslipidemia (AOR: 1.310, 95%CI: 1.216, 1.411) after a full-model adjustment. As is shown in the BKMR model, mixed metals tended to be positively associated with dyslipidemia ratios in a significant manner. Females, non-Hispanic White populations, people aged over 60, and those who did a little physical activity had a greater risk for dyslipidemia. Our findings suggest metals including Cd, Pb, Hg, Mn, and Se and their combinations may adversely affect dyslipidemia among US adults. Due to the cross-sectional nature of the study, it is possible that reverse causation may exist.

Association of ambient PM1 exposure with maternal blood pressure and hypertensive disorders of pregnancy in China.

Evidence concerning PM1 exposure, maternal blood pressure (BP), and hypertensive disorders of pregnancy (HDP) is sparse. We evaluated the associations using 105,063 participants from a nationwide cohort. PM1 concentrations were evaluated using generalized additive model. BP was measured according to the American Heart Association recommendations. Generalized linear mixed models were used to assess the PM1-BP/HDP associations. Each 10 µg/m3 higher first-trimester PM1 was significantly associated with 1.696 mmHg and 1.056 mmHg higher first-trimester SBP and DBP, and with 11.4% higher odds for HDP, respectively. The above associations were stronger among older participants (> 35 years) or those educated longer than 17 years or those with higher household annual income (> 400,000 CNY). To conclude, first-trimester PM1 were positively associated with BP/HDP, which may be modified by maternal age, education level, and household annual income. Further research is warranted to provide more information for both health management of HDP and environmental policies enactment.

Association of urinary exposure to multiple metal(loid)s with kidney function from a national cross-sectional study.

BACKGROUND: Arsenic (As), cadmium (Cd) and copper (Cu) are hazardous for kidney function, while the effects of selenium (Se) and zinc (Zn) were unexplored for the narrow safe range of intake. Interactions exists between these multiple metal/metalloid exposures, but few studies have investigated the effects. METHODS: A cross-sectional survey was performed among 2210 adults across twelve provinces in China between 2020 and 2021. Urinary As, Cd, Cu, Se and Zn were measured using inductively coupled plasma-mass spectrometry (ICP-MS). Serum creatinine (Scr) and N-acetyl-beta-D glucosaminidases (urine NAG) were quantified in serum and urine, respectively. Kidney function was evaluated by the estimated glomerular filtration rate (eGFR). We employed logistic regression and Bayesian kernel machine regression (BKMR) models to explore the individual and joint effects of urinary metals/metalloids on the risk of impaired renal function (IRF) or chronic kidney disease (CKD), respectively. RESULTS: Association was found between As (OR = 1.24, 95 % CI: 1.03, 1.48), Cd (OR = 1.65, 95 % CI: 1.35, 2.02), Cu (OR = 1.90, 95 % CI: 1.59, 2.29), Se (OR = 1.51, 95 % CI: 1.24, 1.85) and Zn (OR = 1.33, 95 % CI: 1.09, 1.64) and the risk of CKD. Moreover, we observed association between As (OR = 1.18, 95 % CI: 1.07, 1.29), Cu (OR = 1.14, 95 % CI: 1.04, 1.25), Se (OR = 1.15, 95 % CI: 1.06, 1.26) and Zn (OR = 1.12, 95 % CI: 1.02, 1.22) and the risk of IRF. Additionally, it was found that Se exposure may strength the association of urinary As, Cd and Cu with IRF. Furthermore, it is worth noting that Se and Cu contributed greatest to the inverse association in IRF and CKD, respectively. CONCLUSION: Our findings suggested that metal/metalloid mixtures were associated with kidney dysfunction, Se and Cu were inverse factors. Additionally, interactions between them may affect the association. Further studies are needed to assess the potential risks for metal/metalloid exposures.

How Parental Predictors Jointly Affect the Risk of Offspring Congenital Heart Disease: A Nationwide Multicenter Study Based on the China Birth Cohort.

Objective: Congenital heart disease (CHD) is complex in its etiology. Its genetic causes have been investigated, whereas the non-genetic factor related studies are still limited. We aimed to identify dominant parental predictors and develop a predictive model and nomogram for the risk of offspring CHD. Methods: This was a retrospective study from November 2017 to December 2021 covering 44,578 participants, of which those from 4 hospitals in eastern China were assigned to the development cohort and those from 5 hospitals in central and western China were used as the external validation cohort. Univariable and multivariable analyses were used to select the dominant predictors of CHD among demographic characteristics, lifestyle behaviors, environmental pollution, maternal disease history, and the current pregnancy information. Multivariable logistic regression analysis was used to construct the model and nomogram using the selected predictors. The predictive model and the nomogram were both validated internally and externally. A web-based nomogram was developed to predict patient-specific probability for CHD. Results: Dominant risk factors for offspring CHD included increased maternal age [odds ratio (OR): 1.14, 95% CI: 1.10-1.19], increased paternal age (1.05, 95% CI: 1.02-1.09), maternal secondhand smoke exposure (2.89, 95% CI: 2.22-3.76), paternal drinking (1.41, 95% CI: 1.08-1.84), maternal pre-pregnancy diabetes (3.39, 95% CI: 1.95-5.87), maternal fever (3.35, 95% CI: 2.49-4.50), assisted reproductive technology (2.89, 95% CI: 2.13-3.94), and environmental pollution (1.61, 95% CI: 1.18-2.20). A higher household annual income (100,000-400,000 CNY: 0.47, 95% CI: 0.34-0.63; > 400,000 CNY: 0.23, 95% CI: 0.15-0.36), higher maternal education level (13-16 years: 0.68, 95% CI: 0.50-0.93; ≥ 17 years: 0.87, 95% CI: 0.55-1.37), maternal folic acid (0.21, 95% CI: 0.16-0.27), and multivitamin supplementation (0.33, 95% CI: 0.26-0.42) were protective factors. The nomogram showed good discrimination in both internal [area under the receiver-operating-characteristic curve (AUC): 0.843] and external validations (development cohort AUC: 0.849, external validation cohort AUC: 0.837). The calibration curves showed good agreement between the nomogram-predicted probability and actual presence of CHD. Conclusion: We revealed dominant parental predictors and presented a web-based nomogram for the risk of offspring CHD, which could be utilized as an effective tool for quantifying the individual risk of CHD and promptly identifying high-risk population.

Association Between Exposure to Outdoor Artificial Light at Night and Sleep Disorders Among Children in China.

Importance: Healthy sleep has an important role in the physical and mental health of children. However, few studies have investigated the association between outdoor artificial light at night (ALAN) and sleep disorders in children. Objective: To explore the associations between outdoor ALAN exposure and sleep disorders in children. Design, Setting, and Participants: This population-based cross-sectional study, part of the National Chinese Children Health Study, was conducted from April 1, 2012, to June 30, 2013, in the first stage and from May 1, 2016, to May 31, 2018, in the second stage in 55 districts of 14 cities in China. This analysis included 201 994 children and adolescents aged 2 to 18 years. Data were analyzed from February 20 to March 21, 2022. Exposures: Outdoor ALAN exposure (in nanowatts per centimeters squared per steradian) within 500 m of each participant's residential address obtained from the satellite imagery data, with a resolution of approximately 500 m. Main Outcomes and Measures: Sleep disorders were measured by the Chinese version of the Sleep Disturbance Scale for Children. Generalized linear mixed models were used to estimate the associations of outdoor ALAN with sleep scores and sleep disorders. Results: The study included 201 994 children and adolescents (mean [SD] age, 11.3 [3.2] years; 106 378 boys [52.7%]), 7166 (3.5%) of whom had sleep disorder symptoms. Outdoor ALAN exposure of study participants ranged from 0.02 to 113.48 nW/cm2/sr. Compared with the lowest quintile (Q1) of outdoor ALAN exposure, higher quintiles of exposure (Q2-Q5) were associated with an increase in total sleep scores of 0.81 (95% CI, 0.66-0.96) in Q2, 0.83 (95% CI, 0.68-0.97) in Q3, 0.62 (95% CI, 0.46-0.77) in Q4, and 0.53 (95% CI, 0.36-0.70) in Q5. Higher quintiles of exposure were also associated with odds ratios for sleep disorder of 1.34 (95% CI, 1.23-1.45) in Q2, 1.43 (95% CI, 1.32-1.55) in Q3, 1.31 (95% CI, 1.21-1.43) in Q4, and 1.25 (95% CI, 1.14-1.38) in Q5. Similar associations were observed for sleep disorder subtypes. In addition, greater effect estimates were found among children younger than 12 years. Conclusions and Relevance: The findings of this cross-sectional study suggest that sleep disorders are more prevalent among children residing in areas with high levels of outdoor ALAN and the associations are generally stronger in children younger than 12 years. These findings further suggest that effective control of outdoor ALAN may be an important measure for improving the quality of children's sleep.

The genomic origins of the Bronze Age Tarim Basin mummies.

The identity of the earliest inhabitants of Xinjiang, in the heart of Inner Asia, and the languages that they spoke have long been debated and remain contentious1. Here we present genomic data from 5 individuals dating to around 3000-2800 BC from the Dzungarian Basin and 13 individuals dating to around 2100-1700 BC from the Tarim Basin, representing the earliest yet discovered human remains from North and South Xinjiang, respectively. We find that the Early Bronze Age Dzungarian individuals exhibit a predominantly Afanasievo ancestry with an additional local contribution, and the Early-Middle Bronze Age Tarim individuals contain only a local ancestry. The Tarim individuals from the site of Xiaohe further exhibit strong evidence of milk proteins in their dental calculus, indicating a reliance on dairy pastoralism at the site since its founding. Our results do not support previous hypotheses for the origin of the Tarim mummies, who were argued to be Proto-Tocharian-speaking pastoralists descended from the Afanasievo1,2 or to have originated among the Bactria-Margiana Archaeological Complex3 or Inner Asian Mountain Corridor cultures4. Instead, although Tocharian may have been plausibly introduced to the Dzungarian Basin by Afanasievo migrants during the Early Bronze Age, we find that the earliest Tarim Basin cultures appear to have arisen from a genetically isolated local population that adopted neighbouring pastoralist and agriculturalist practices, which allowed them to settle and thrive along the shifting riverine oases of the Taklamakan Desert.

Ancient genomes reveal tropical bovid species in the Tibetan Plateau contributed to the prevalence of hunting game until the late Neolithic.

Local wild bovids have been determined to be important prey on the northeastern Tibetan Plateau (NETP), where hunting game was a major subsistence strategy until the late Neolithic, when farming lifestyles dominated in the neighboring Loess Plateau. However, the species affiliation and population ecology of these prehistoric wild bovids in the prehistoric NETP remain unknown. Ancient DNA (aDNA) analysis is highly informative in decoding this puzzle. Here, we applied aDNA analysis to fragmented bovid and rhinoceros specimens dating ∼5,200 y B.P. from the Neolithic site of Shannashuzha located in the marginal area of the NETP. Utilizing both whole genomes and mitochondrial DNA, our results demonstrate that the range of the present-day tropical gaur (Bos gaurus) extended as far north as the margins of the NETP during the late Neolithic from ∼29°N to ∼34°N. Furthermore, comparative analysis with zooarchaeological and paleoclimatic evidence indicated that a high summer temperature in the late Neolithic might have facilitated the northward expansion of tropical animals (at least gaur and Sumatran-like rhinoceros) to the NETP. This enriched the diversity of wildlife, thus providing abundant hunting resources for humans and facilitating the exploration of the Tibetan Plateau as one of the last habitats for hunting game in East Asia.

Human paleodiet and animal utilization strategies during the Bronze Age in northwest Yunnan Province, southwest China.

Reconstructing ancient diets and the use of animals and plants augment our understanding of how humans adapted to different environments. Yunnan Province in southwest China is ecologically and environmentally diverse. During the Neolithic and Bronze Age periods, this region was occupied by a variety of local culture groups with diverse subsistence systems and material culture. In this paper, we obtained carbon (δ13C) and nitrogen (δ15N) isotopic ratios from human and faunal remains in order to reconstruct human paleodiets and strategies for animal exploitation at the Bronze Age site of Shilinggang (ca. 2500 Cal BP) in northwest Yunnan Province. The δ13C results for human samples from Shilinggang demonstrate that people's diets were mainly dominated by C3-based foodstuffs, probably due to both direct consumption of C3 food and as a result of C3 foddering of consumed animals. Auxiliary C4 food signals can also be detected. High δ15N values indicate that meat was an important component of the diet. Analysis of faunal samples indicates that people primarily fed pigs and dogs with human food waste, while sheep/goats and cattle were foddered with other food sources. We compare stable isotope and archaeobotanical data from Shilinggang with data from other Bronze Age sites in Yunnan to explore potential regional variation in subsistence strategies. Our work suggests that people adopted different animal utilization and subsistence strategies in different parts of Yunnan during the Bronze Age period, probably as local adaptations to the highly diversified and isolated environments in the region.

[Epidemiologic survey on the prevalence and distribution of childhood functional constipation in the northern areas of China: a population-based study].

OBJECTIVE: Functional constipation (FC) is a common complaint in childhood but the prevalence still remains unclear, the aim of this study was to explore the prevalence of FC in childhood in the northern parts of China. METHODS: A screening program on FC in childhood was carried out in 5 northern cities (Beijing, Tianjin, Shenyang, Changchun, Harbin) of China according to symptoms under the Rome III criteria. Random clustered sampling of the inhabitants was carried out under stratification of cities, geographic zones, schools or nurseries. Sample size of each area was in proportion to the population of the area. The range of age was 4-14. All subjects under study were requested to fill in a questionnaire distributed by the teachers. The screening program was carried out immediately after a section survey was completed. All together, 20 000 questionnaires were distributed with 19 638 retrievals. According to the result of the screening, a small number of patients who met the criteria were further selected to undergo a detailed clinical examination in the hospital including laboratory examination, colonic transit time, defecography or/and barium enema, electromyologram and anorectal manometry to exclude organic disease of the colon. Simultaneously, a detailed questionnaire was requested to fill under the assistance of trained doctors or medical students. Prevalence of FC of the population was adjusted by the rate of correct diagnosis from the detailed study. RESULTS: The adjusted point prevalence of FC in 5 northern cities of China according to Rome III criteria was 4.73% with higher prevalence rate of FC seen in the Beijing area (5.02%) than in other cities (4.82%, 4.76%, 4.27%, 4.40%, with P < 0.001). Male to female ratio was 1.26:1 with majority of the FC fell in the 4 - 6 year olds (5.76%). CONCLUSION: FC appeared a common disorder in childhood in the northern parts of China which called for greater attention. Higher prevalence was noted in the age groups of 4-6.

[Preliminary study on diagnostic standard of functional constipation in children from five cities in North China].

OBJECTIVE: To explore the symptomatic criteria for diagnosis in children with functional constipation(FC) in North China. METHODS: A screening program for FC in children was carried out in 5 northern cities (Beijing, Tianjin, Shenyang, Changchun, Harbin) of China according to symptoms using Rome III( criteria. Random clustered sampling of the inhabitants was carried out under stratification of city, region and school or kindergarten. Sample size of each area was in proportion to the population of the area. The range of age was 4-14. All the subjects were requested to fill in a questionnaire distributed by the teacher. The screening program was carried out immediately after a plot survey. A total of 20,000 questionnaires were distributed and 19,638 retrieved. According to the result of the screening, a small number of patients who fulfilled the criteria were further selected to undergo detail clinical examinations in the hospital including laboratory examination, colonic transit time, defecography or/and barium enema, electromyogram and anorectal manometry to exclude organic disease of the colon. A detailed questionnaire was filled in with the assistance from a trained doctor or a medical student. Potential risk factors and the relative symptoms were explored by comparing frequencies between FC group and non-FC group using χ2 and Logistic analysis. RESULTS: Eighteen symptoms (defecation less than 3 times per week, dry hard sausage-shape stool, difficulty in defecation, abdominal pain, nausea and vomiting, etc) could exist in control group, but FC group had a higher frequency. The difference was statistically significant. Multivariable stepwise logistic regression analysis showed that defecation less than 3 times per week, hard sausage-shape feces, difficulty in defecation, and the need for laxative were associated with FC. The absence of other symptoms had no influence on diagnosis of FC. The sensitivity, specificity and diagnostic accuracy of symptomatic standard diagnostic test based on Rome III( criteria in FC children showed that ≥2 items had the best diagnostic accuracy but moderate sensitivity and specificity. CONCLUSION: The symptomatic criteria for FC diagnosis in children are suggested as follows: (1) defecation frequency less than 3 times per week; (2) dry, hard, sausage-shape stool in most defecation; (3) difficulty in most defecation; (4) use of medication or digital evacuation. FC can be considered when 2 of the above 4 criteria are met and the symptoms last at least 2 months.

A split-face study of intense pulsed light on photoaging skin in Chinese population.

BACKGROUND AND OBJECTIVES: Intense pulsed light (IPL) is regarded as the gold standard of nonablative photo-rejuvenation. Yet there is still a need to observe its efficacy and safety on dark skin using a split-face module. STUDY DESIGN/MATERIALS AND METHODS: Twenty-four Chinese women with photoaging were enrolled in this study. Patients were randomized to receive four IPL treatments at 3- to 4-week intervals on one side of face, with the other side spared as control. Changes of photoaging were evaluated using a global evaluation, an overall self-assessment, a Mexameter and a Corneometer. Skin biopsies were taken after four sessions of treatment on one side of face. The melanocyte density and the contents of melanin, collagen fibers, and elastic fibers were stained and used to evaluate the improvement on dyschromia and other signs of photoaging. RESULTS: The global scores of photoaging on treated side decreased significantly from 3.02 to 1.22, while it remained unchanged on the untreated side. Twenty-one of 24 patients (87.5%) rated their improvement as excellent or good. The difference on the values of melanin index and erythema index on treated side were significantly larger than those on untreated side after the 1st session, the 4th session and at 3-month follow-up (P<0.05). The melanin contents were significantly decreased and the collagen fibers were obviously increased only on treated side (P<0.05). Adverse effects of treated side were limited to mild pain and transient erythema. CONCLUSION: Using this split-face module, IPL treatment is proved both clinically and histologically to be effective in treating photoaging skin in Chinese population. Adverse effects were minimal and acceptable.

Protective effects of green tea extracts on photoaging and photommunosuppression.

OBJECTIVES: This study aimed to investigate whether the sunscreen-containing 2-5% green tea extracts (GTEs) protect ultraviolet irradiation (UVR)-induced photoaging and photoimmunosuppression. MATERIALS AND METHODS: Twenty volunteers were exposed to repetitive solar-simulated UVR (ssUVR) on the upper back at a dosage of 1.5 minimal erythema doses (MED) per day for four consecutive days. Thirty minutes before each UVR and 6, 24, and 48 h after the last UV exposure, the products containing vehicle, and 2-5% GTEs were applied onto five sites on the dorsal skin, respectively. The skin biopsies were obtained 72 h after the last UVR. The thickness of the stratum corneum and epidermis was measured under the microscope and the expression of cytokeratins (CK)-5/6, CK16, metalloproteinases (MMP)-2, MMP-9, and the CD1a(+) Langerhans cells (LCs) were determined using immunohistochemistry. RESULTS: Our results showed that UVR substantially induced cutaneous erythema, thickening of the epidermis, overexpression of CK5/6, CK16, MMP-2, MMP-9, and depletion of CD1a(+) LCs. The sunscreens containing different concentrations of GTEs conferred significant protection against the photoaging and photoimmunology-related biological events. Interestingly, the protective effects were not parallel to the concentrations of GTEs, with 2% and 3% GTEs showing the most efficacious photoprotection. CONCLUSIONS: GTEs-containing sunscreens have potential photoprotective effects on UVR-induced photoaging and photoimmunosuppression.

Efficacy and safety of intense pulsed light in treatment of melasma in Chinese patients.

BACKGROUND: Melasma is commonly seen in the Asian population. Traditional therapies are less effective and may cause adverse effects. OBJECTIVE: The objective was to study the efficacy and safety of a new intense pulsed light (IPL) device in the treatment of melasma in Chinese patients. METHODS: Eighty-nine women with melasma were enrolled in this open-labeled study. Subjects received a total of four IPL treatments at 3-week intervals. Changes in facial hyperpigmentation and telangiectasis were evaluated using an objective, skin colorimeter (Mexameter, Courage & Khazaka), the melasma area and severity index (MASI), and a global evaluation by the patients and blind investigators. RESULTS: Sixty-nine of 89 patients (77.5%) obtained 51% to 100% improvement, according to the overall evaluation by dermatologists. Self-assessment by the patients indicated that 63 of 89 patients (70.8) considered more than 50% or more improvement. Mean MASI scores decreased substantially from 15.2 to 4.5. Mexameter results demonstrated a significant decrease in the degree of pigmentation and erythema beneath the melasma lesions. Patients with the epidermal-type melasma responded better to treatment than the mixed type. Adverse actions were minimal. CONCLUSION: IPL treatment is a good option for patients with melasma. Adverse actions of IPL were minimal and acceptable.

[Effect of exogenous selenium on soybean yield and its total N and P contents and on soil enzyme activities].

Based on pot experiment with black soil, the effects of various concentrations and various valence of exogenous selenium on soybean yield and its N and P contents and on soil enzyme activities were studied. The results showed that applying 0.25 microgram.g-1 soil and 0.5 microgram.g-1 soil of both Se4+ and Se6+ could increase soybean yield and its N content and promote soil urease activity, but decrease the P content of soybean and soil phosphatase activity. When the concentration of Se6+ was 0.5 microgram.g-1 soil, there was a significantly parabola relationship between the N content of soybean and soil urease activity; and when the concentration of Se6+ was 0.25 microgram.g-1 soil, there was a significantly parabola relationship between the P content of soybean and soil phosphatase activity. There were no significant relationships between the N and P contents of soybean and the activities of test soil enzymes when Se4+ was applied.

[Research advances in plant selenium nutrition and its mechanism].

The amount of selenium in soil environment significantly influences the selenium nutrition of plants. In this paper, the absorption, accumulation and translocation of Se in plants was discussed, and the toxicity of selenium and its effect on crop yield and quality was summarized. The advances in related researches were also introduced. On the basis of these, a new approach on the effect of selenium on soil enzyme activities to elaborate the essentiality of selenium for plants was proposed.