Characterization of Nutrients,Heavy Metals,Petroleum and Their Impact on Phytoplankton in Laizhou Bay:Implications for Environmental Management and Monitoring

The Laizhou Bay(LB)represents a substantial ecological area that is vulnerable to human activities and confronts diverse environmental challenges.This study provides a comprehensive characterization of nutrients,petroleum,heavy metals,and phytoplankton community structure across seven distinct areas in LB.The results indicate relatively high concentrations of NO_(2)-N,SiO_(4)-Si,and NO_(3)-N in the Southwest Laizhou Bay(SWLB)and Huanghe River Estuary(HRE).In contrast,the East Laizhou bay(ELB)and the North of Huanghe River Estuary(NHRE)exhibit the highest concentrations of heavy metals(As,Cr and Hg).The areas with high phytoplankton density and community diversity are mainly located in the SWLB.After adjusting for basic environmental factors,phytoplankton density and Margalef richness index D are significantly associated with nutrients(NO_(3)-N,NO_(2)-N,NH_(4)-N,SiO_(4)-Si),and heavy metal(Cr)concentrations.We highlight that,in addition to Xiaoqinghe River,nutrients brought by the Mihe River in the SWLB and heavy metal(Cr)pollution in the ELB resulting from industrial and mining activities along the coast significantly influence phytoplankton growth and community structure.Therefore,it is recommended that more monitoring and management efforts be focused on these regions in the future.

Response of soil nutrients to terracing and environmental factors in the Loess Plateau of China

Terracing is a widely adopted agricultural practice in mountainous regions around the world that aims to conserve soil and water resources.Soil nutrients play a crucial role in determining soil quality,particularly in landscapes prone to drought.They are influenced by factors such as land-use type,slope aspect,and altitude.In this study,we sought to examine the impact of terracing on soil nutrients(soil organic content(SOC),total nitrogen(TN),nitrate-nitrogen(NO_(3)^(-)-N),ammonium nitrogen(NH_(4)^(+)-N),total phosphorus(TP),available phosphorus(AP),total potassium(TK),and available potassium(AK))and how they vary with environmental factors in the Chinese Loess Plateau.During the growing season,we collected 540 soil samples from the 0 to 100 cm soil layer across five major land-use types,different slope aspects,and varying altitudes.Additionally,a meta-analysis of literature data further corroborated the effective accumulation of soil nutrients through terracing in the Loess Plateau.Our findings are as follows:(1)Terraced fields,regardless of land-use type,showed a significant improvement in SOC and TN content.(2)Soil nutrient contents within terraced fields were predominantly higher on sunny slopes.(3)Terraces at lower altitudes are characterized by elevated SOC concentrations.(4)A meta-analysis of literature data pertaining to terracing and soil nutrients in this region confirmed the effective accumulation of soil nutri-ents through terracing.The elucidated outcomes of this study offer a profound theoretical underpinning for the accurate planning and management of terraces,the scientific utilization of land resources,and the enhancement of land productivity.

The link between dietary nutrients intake and cardiovascular diseases in cold regions

Background:The cold winter weather in northern China influences the dietary habits of its residents,contributing to a heightened risk of cardiovascular disorders,such as hypertension and coronary heart disease.Key factors include low vegetable consumption and high salt and fat intakes.This study aims to investigate the relationships between northern dietary nutrient intake in northern China and cardiovascular disorders during the winter season.Methods:A food frequency questionnaire tailored to the actual eating habits in northern China was designed.Retrospective data from 955 Chinese adults were collected from November to March between 2014 to 2023.Logistic regression was employed to analyze the relationship between dietary nutrients and cardiovascular diseases,with model performance assessed using receiver operating characteristic(ROC)curves.Results:Adjusted for gender,age,and body mass index(BMI),an inverse association was observed between vitamin A(OR=0.706,95%CI:0.550,0.907),nicotinic acid(OR=0.584,95%CI:0.447,0.762),phosphorus(OR=0.777,95%CI:0.608,0.994),selenium(OR=0.719,95%CI:0.560,0.923),zinc(OR=0.683,95%CI:0.531,0.880),methionine(OR=0.730,95%CI:0.569,0.936),arginine(OR=0.753,95%CI:0.588,0.964),lysine(OR=0.706,95%CI:0.550,0.907),aspartic acid(OR=0.730,95%CI:0.569,0.936)and hypertension.Additionally,a negative association was found between niacin(OR=0.752,95%CI:0.597,0.946)and coronary heart disease.Conversely,a positive association was identified between iodine and hypertension(OR=1.305,95%CI:1.020,1.669)and coronary heart disease(OR=1.301,95%CI:1.037,1.634).Conclusion:Our study suggests that maintaining a balanced dietary intake of vitamin A,niacin,phosphorus,selenium,zinc,methionine,arginine,lysine,and aspartic acid can be beneficial in preventing hypertension.Adequate niacin intake is associated with a lower risk of coronary heart disease.However,excessive iodine intake may contribute to hypertension and coronary heart disease.

Temporal, Spatial, and Hypsometrical Dispersion of Nutrients in the Hula Valley, Israel

Until 1957 most of the Hula Valley was occupied by swampy wetland covered by dense vegetation and old Lake Hula. Organic matter was accumulated in the bottom, decomposed under anoxic conditions creating Peat material. The wetland and the old lake were drained and the land-use was converted into agricultural development. Nutrients migrations from the Hula Valley through the headwater discharges carrying nutrients, where nitrogen enhancement is critical, significantly affecting water quality in down-stream Lake Kinneret. The fate of the Hula originated nutrients is partly known whilst fate of the others which might be probably a threat on the Kinneret water quality is unknown. The hypsometrical and spatial distribution of the Hula Valley originated nutrients within three depths level was indicated: shallowest level of surface water, intermediate level of underground water table and the deepest level of Lignite waters. The Hypsometrical and spatial distribution and regional origin of the nutrient in the Hula Valley was defined. Organic Nitrogen, Sulfate and Nitrates are mostly Hula Valley originated nutrients whilst most of the Phosphorus externally contributed to Lake Kinneret originate outside the Hula Valley. An underground north-south Hydrological gradient and nutrient migration along was indicated. It is suggested that an underground plastic barrier do not totally prevent horizontal nutrient migration. Hypsometrical downward migrated nutrients probably accumulate within the “Lignite” depth level. Management policy of increasing Peat Soil moisture, is recommended.

Effect of Saline Water on Soil Acidity, Alkalinity and Nutrients Leaching in Sandy Loamy Soil in Rwamagana Bella Flower Farm, Rwanda

The necessity to saline and sodic waters is sometimes used for irrigating agricultural activities under certain circumstances, but it is important to note that the use of these waters comes with specific considerations and limitations. One way to decrease undesirable effects of sodic waters on the physical and chemical properties of soils is to apply organic and chemical amendments within the soil. This study aimed to assess the effectiveness of saline water on soil acidity, alkalinity and nutrients leaching in sandy loamy soil at Bella flower farm, in Rwamagana District, Rwanda. The water used was from the Muhazi Lake which is classified as Class I (Saline water quality). Column leaching experiments using treated soils were then conducted under saturated conditions. The soil under experimental was first analyzed for its textural classification, soil properties and is classified as sandy loamy soil. The t-test was taken at 1%, 5% and 10% levels of statistical significance compared to control soil. The results indicated that the application of saline water to soils caused an increase in some soil nutrients like increase of Phosphorus (P), Potassium (K+), Magnesium (Mg2+), Sulphur (S), CN ratio and Sodium (Na+) and decreased soil texture, physical and chemical properties and remained soil nutrients. Consequently, the intensive addition of saline water leachates to soil in PVC pipes led to decreased of soil EC through leaching and a raiser Soluble Sodium Percentage (SSP). The rate of saline water application affected the increase accumulation of SAR and Na% in the top soil layers. The study indicated that saline water is an inefficient amendment for sandy soil with saline water irrigation. The study recommends further studies with similar topic with saline water irrigation, as it accentuated the alkalinity levels.

Effects of inorganic nutrients and environmental factors on the removal of n-propylbenzene and isopropylbenzene in seawater by cryptophytes Rhinomonas reticulata S6A

To effectively remove n-propylbenzene(n-PBZ)and isopropylbenzene(i-PBZ)leaked into seawater using Rhinomonas reticulata S6A(a newly isolated marine microalga),the effects of three inorganic nutrients and four environmental factors on their degradation were determined after 7 d of inoculation.Results show that NaNO_(3) at 300 mg/L caused a higher removal efficiency of both n-PBZ and i-PBZ(44.79%and 39.26%),while for NaH_(2) PO_(4)·H_(2) O,greater removal rates of two PBZs(47.30%and 42.23%)were achieved at 30 and 20 mg/L,respectively.NaHCO_(3) supplementation(500-750 mg/L)resulted in a large reduction(43.67%-45.04%)in i-PBZ concentration.The change in seawater pH(from 6 to 9)did not affect the elimination of n-PBZ and i-PBZ.The most suitable salinity and temperature were 30 and 25-30℃,respectively,leading to the PBZs removal of~40%.Light intensity exhibited significant influence on elimination of PBZs,and the maximum removal efficiencies of 56.07%(n-PBZ)and 55.00%(i-PBZ)were recorded under 200 and 600μmol/(m^(2)·s),respectively.In addition,the microalga could still remove PBZs when it failed to grow well due to darkness,strong light,low temperature,or low salinity,which might mean that good growth of alga is not always a necessary condition for PBZs removal.Therefore,attention should be paid to the suitability of nutrient levels and environmental conditions(excluding pH)in seawater when using microalgae for bioremediating PBZs-contaminated seawater.

Tracing the sources of nutrients through the Tsushima/Korea Strait

The nutrients from the East China Sea(ECS) through the Tsushima/Korea Strait(TS) strongly impact the eco system of the Japan Sea(JS).The complex origins of the Tsushima Warm Current and the various nutrient sources in the ECS result in complex spatial-temporal variations in nutrients in the TS.Using a physical-biological model with a tracking technique,we studied the effects of nutrient sources from the ECS on the TS.Among all the nutrient sources,the Kuroshio has the highest nutrient concentrations in the TS.Its maximum concentration occurs at the bottom,while those of rivers and atmospheric depo sition occur at the surface,and that of the Taiwan Strait occurs in the middle layer.The nutrient transport through the TS exhibits similar seasonal variations,as does the volume transport.The transport of nutrients from the Kuroshio accounts for more than 85% of the total.The transport of nutrients from the Taiwan Strait is greater during autumn and winter.The transport of dissolved inorganic nitrogen(DIN) from both rivers and atmospheric deposition through the TS peak in August.Nutrient transport cannot be equated with volume transport.The DIN in the less saline zone originates not only from rivers but also from atmospheric deposition and the Kuroshio.The transport of nutrients from the Taiwan Strait is not as significant as its volume transport in the TS.

Influence of methyl donor nutrients as epigenetic regulators in colorectal cancer:A systematic review of observational studies

BACKGROUND Dietary methyl donors might influence DNA methylation during carcinogenesis of colorectal cancer(CRC).However,whether the influence of methyl donor intake is modified by polymorphisms in such epigenetic regulators is still unclear.AIM To improve the current understanding of the molecular basis of CRC.METHODS A literature search in the Medline database,Reference Citation Analysis(https://www.referencecitationanalysis.com/),and manual reference screening were performed to identify observational studies published from inception to May 2022.RESULTS A total of fourteen case-control studies and five cohort studies were identified.These studies included information on dietary methyl donors,dietary components that potentially modulate the bioavailability of methyl groups,genetic variants of methyl metabolizing enzymes,and/or markers of CpG island methylator phenotype and/or microsatellite instability,and their possible interactions on CRC risk.CONCLUSION Several studies have suggested interactions between methylenetetrahydrofolate reductase polymorphisms,methyl donor nutrients(such as folate)and alcohol on CRC risk.Moreover,vitamin B6,niacin,and alcohol may affect CRC risk through not only genetic but also epigenetic regulation.Identification of specific mechanisms in these interactions associated with CRC may assist in developing targeted prevention strategies for individuals at the highest risk of developing CRC.

Coral reef ecological pump for gathering and retaining nutrients and exporting carbon:a review and perspectives

How coral reefs with high productivity and biodiversity can flourish in oligotrophic tropical oceans has inspired substantial research on coral reef ecosystems.Increasing evidence shows that similar to water in an oasis in the desert,there are stable nutrient supplies to coral reefs in oligotrophic oceans.Here,with emphasis on the fluxes of organic matter,we summarize at the ecosystem level(1)the multiple input pathways of external nutrients,(2)the storage of nutrients in reef organisms,(3)the efficient retaining and recycling of dissolved and particulate organic matter within coral reef ecosystems,(4)the distinctly high phytoplankton productivity and biomass inside and near oceanic coral reefs,and(5)the export of reef-related organic carbon to adjacent open oceans.These properties enable coral reefs to function as ecological“pumps”for gathering nutrients across ecosystems and space,retaining and recycling nutrients within the ecosystem,supporting high phytoplankton productivity,and exporting organic carbon to adjacent open oceans.Particularly,the high phytoplankton productivity and biomass make waters around coral reefs potential hotspots of carbon export to ocean depths via the biological pump.We demonstrate that organic carbon influx is vital for coral reef ecosystems’carbon budget and carbon export.The concept of the coral reef ecological pump provides a framework to improve the understanding of the functioning of the coral reef ecosystem and its responses to disturbance.Prospects of the coral reef ecological pump in coral reef studies are discussed in changing oceans driven by human activities and global change in the Anthropocene.

Spatial distribution and export of nutrients and metal elements in the subterranean estuary of Daya Bay

Subterranean estuaries(STE)are important seawater-groundwater mixing zones with complex biogeochemical processes,which play a vital role in the migration and transformation of dissolved materials.In this study,we first investigated the spatial distributions of dissolved inorganic nitrogen(DIN),dissolved inorganic phosphorous(DIP),dissolved inorganic silicon(DSi)and metal elements(As,Ba,Cr,Cu,Fe,Mn,Ni,Pb,and Zn)in STE including upper intertidal,seepage face and subtidal zones.We then estimated submarine groundwater discharge(SGD)and associated nutrient and metal element fluxes.From the generalized Darcy’s law method,SGD was estimated to be 30.13 cm/d,which was about 7 times larger than the inflow(4.16 cm/d).The nutrient and metal fluxes from SGD were estimated to be(5.33±4.99)mmol/(m^(2)·d)for DIN,(0.22±0.03)mmol/(m^(2)·d)for DIP,(16.20±2.05)mmol/(m^(2)·d)for DSi,(1325.06±99.10)μmol/(m^(2)·d)for Fe,(143.41±25.13)μmol/(m^(2)·d)for Mn,(304.06±81.07)μmol/(m^(2)·d)for Zn,(140.21±13.33)μmol/(m^(2)·d)for Cu,(84.49±2.94)μmol/(m^(2)·d)for Pb,(37.38±5.51)μmol/(m^(2)·d)for Ba,(27.88±3.89)μmol/(m^(2)·d)for Cr,(10.10±6.33)μmol/(m^(2)·d)for Ni,and(6.25±3.45)μmol/(m^(2)·d)for As.The nutrient and metal fluxes from SGD were relatively higher than those from the inflow,suggesting that nearshore groundwater acted as the sources of nutrients and metal elements discharging into the sea.The environmental potential pollution of coastal seawater was evaluated by pollution factor index(Pi),comprehensive water quality index(CWQI),and ecological risk index(ERI).Pb mainly caused potential danger of nearshore environment with considerable contamination(Pi=5.78±0.19),heavy pollution(CWQI=4.09)and high ecological risk(ERI=18.00).This study contributed to better understanding the behavior of nutrients and metal elements and improving the sustainable management of STE under the pressure of anthropogenic activities and climate change.

Association of nutrients intake during pregnancy with the risk of allergic disease in offspring:a meta-analysis of prospective cohort studies

To investigate the role of nutrients intake during pregnancy with longitudinal development of rhinitis,asthma,eczema,wheeze,and food allergy in offspring.The PubMed,Embase,and Cochrane library were searched for articles published throughout May 2022.The pooled effect estimate were presented using relative risk and calculated by the random-effects model.Twenty-three prospective cohort studies enrolling 210817 individuals were included.The risk of wheeze in offspring were lowered when high vitamin D,vitamin E,zinc,and milk intakes during pregnancy,whereas high meat intake during pregnancy could induce additional risk of wheeze in offspring.Moreover,highβ-carotene and magnesium intakes during pregnancy were related to lower eczema risk in offspring,whereas eczema risk in offspring was increased for pregnant women with high intake of butter and margarine.Finally,the asthma risk in offspring could protect against for pregnant women with high intake of vitamin D and apple,whereas high folic acid during pregnancy could produce excess asthma risk in offspring.This study provides the summary evidences regarding the role of nutrients intake during pregnancy and subsequent risk of rhinitis,asthma,eczema,wheeze,and food allergy,and further effective intervention strategies should be employed to improve childhood allergic diseases.

Research Progress on Nutrients of Artemisia argyi

Artemisia argyi is a traditional Chinese herb,which is widely distributed in various areas in China.In recent years,due to the development of A.argyi related industries and the continuous improvement of people’s health awareness,experts and scholars are concerned about the nutrients and effects of A.argyi.A.argyi is rich in carbohydrates,proteins,essential amino acids,fatty acids,minerals,vitamins,dietary fibers,flavonoids and other nutrients.It has the effects of antioxidant,anti-tumor,antibacterial,antiinflammatory,neuroprotection and immune regulations,and has been widely applied in the fields of COVID-19 prevention,food health care,food preservation and feed breeding,and has good development potential.This review summarized the research and application of A.argyi nutrients,in order to provide reference and application for further study.

Effects of Tillage Depth on Nutrients and Microbial Communities in Tobacco-Planting Soil

The implementation of appropriate tillage practices is of great significance for agricultural production. However, the effects of different tillage depths on soil nutrients content and microbial communities in tobacco-planting soils are still lacking systematic research. In this study, three different tillage depths of 15 cm (T1), 20 cm (T2), and 30 cm (T3) were set up for field experiments in Liupanshui, Guizhou Province, to explore the effects of tillage depth on tobacco-planting soil nutrients and bacterial and fungal communities based on 16S rRNA and ITS sequencing and figure out the key factors affecting soil microbial communities. The results showed that T2 and T3 increased the contents of organic matter, total nitrogen, total phosphorus, available phosphorus, and available potassium in tobacco-planting soil, and increased the diversity of bacterial communities compared with T1. There was no significant difference in the structure of bacterial and fungal communities in different tillage depth treatments, but some dominant genera were significantly enriched in T2 and T3. Desulfobacter, Setophoma, Humicola, and Acremonium were significantly enriched in T2. Chthonomonas and Fusarium were significantly enriched in T3. These genera favor the decomposition of organic matter and the cycling of nutrients, and control soil pests and diseases. Redundancy analysis indicated that TP and AK were the key factors influencing the dominant genera of bacteria and fungi. This study provides a scientific basis for the selection of soil tillage depth for tobacco production in this region.

Latest advances in epigenetic mechanisms of nutrients in breast cancer and the relation of homocysteine mechanism

The incidence rate of breast cancer is the second highest of all cancers.Alterations to one's epigenome are among the most critical factors in breast cancer control.In breast cancer,nutrients can influence epigenetic pathways and homocysteine(Hcy)levels.Hcy has been related to cognitive decline,Alzheimer's disease,and cancer.Similar to how altered Hcy metabolism is strongly influenced by genetic,epigenetic,and environmental factors,it is significantly linked to cancer.This review aims to discuss the relationship between the levels of Hcy in breast cancer and the effects of nutrients on epigenetic processes.Dietary interventions have the ability to control epigenetic processes,and the Hcy levels are associated with both epigenetic mechanisms and nutritional supplements in breast cancer.Certain nutrients have been discovered to have an impact on these processes.Altered Hcy metabolism is influenced by genetic,epigenetic,and environmental factors and has a substantial link to the emergence of cancer.Nutrients,such as folic acid,vitamin B12 and many phytonutrients that have been found to affect the epigenetic processes in breast cancer may alter DNA methylation and histone modification,which in turn may affect how cancer cells behave.The review emphasizes the need for additional studies to fully comprehend nutrition's potential for the epigenetic mechanism and the relation between Hcy metabolism in breast cancer.

Effect of light and nutrients on interspecific interactions between submerged macrophytes:implications for restoration of multispecies aquatic vegetation in eutrophic lakes

Constructing multispecies submerged vegetation systems and maintaining stable seasonal succession is crucial for restoring shallow eutrophic lakes.However,little is known about the interactions between successional and existing species of different growth forms,particularly under the low light and high nutrient conditions of eutrophic lakes.We measured the functional traits of mature Vallisneria natans(Lour.)Hara plants and Potamogeton crispus L.shoots in monoculture and mosaic patterns under different light and nutrient conditions.The effect of light on functional traits of the submerged macrophyte species was more significant than that of nutrients,but the reverse was true for P.crispus biomass allocation.Moreover,interspecific interactions affected only the submerged macrophytes under the low light condition and varied with species.Specifically,the interaction of P.crispus to V.natans was biased towards competition,while the interaction of V.natans to P.crispus was converted from facilitation to competition by eutrophication,particularly in the homogenous mosaic growth pattern.This study demonstrates that sufficient light is a prerequisite and patch planting is an effective means to form a multispecies submerged vegetation system.In addition,we emphasize that the coexistence of eutrophication and low light will likely result in a competition between submerged macrophytes thus simplifying the vegetation,even if their growth forms and growing seasons are different.These findings help explain the collapse of multispecies submerged vegetation and guide the restoration of aquatic plants in eutrophic lakes.

Distribution patterns of vegetation biomass and nutrients bio-cycle in alpine tundra ecosystem on Changbai Mountains,Northeast China

A study was conducted to test the correlation between biomass and elevation and the differences in concentration and storks of nutrients among five vegetation types （Felsenmeer alpine tundra vegetation-FA, Lithic alpine tundra vegetation-LA, Typical alpine tundra vegetation-TA, Meadow alpine tundra vegetation-MA, and Swamp alpine tundra vegetation-SA） on alpine tundra of Changbai Mountains, Jilin Province, China in growing seasons of 2003, 2004 and 2005. The biomass of 43 mono-species and soil nutrients in alpine tundra ecosystem were also investigated. Dominant species from Ericaceae （such as Rhododendron chrysanthum and Vaccinium jliginosum var. alpinum） were taken to analyze organ biomass distribution. Result showed that the biomass and elevation had a significant correlation （Biomass-237.3 in（Elevation） ＋494.36; R^2=0.8092; P〈0.05）. No significant differences were found in phosphorus and sulphur concentrations of roots, stems and leaves among the five vegetation types. There were significant differences in nitrogen and phosphorus stocks of roots, stems and leaves and in sulphur stock of stems and leaves among TA, MA, and SA vegetation types （p〈0.05）. The nutrient stock of five vegetations was averagely 72.46 kg.hm^-2, of which N, P, S were 48.55, 10.33 and 13.61 kg·hm^-2, respectively. Soil N and S concentrations in meadow alpine tundra soil type was significantly higher than those in other four soil types （Cold desert alpine tundra soil, Lithic alpine tundra soil, Peat alpine tundra soil, and Gray alpine tundra soil）. Phosphorous concentration in SA type was higher （p〈0.05） than in other types. Soil nutrient stock （0-20cm） was averagely 39.59 t.hm^-2, of which N, P, S were 23.74, 5.86, 9.99 t·hm^-2, respectively.

Concentrations of foliar and surface soil in nutrients Pinus spp. plantations in relation to species and stand age in Zhanggutai sandy land, northeast China

The concentrations of the foliar and surface soil nutrients and the variation with species and stand age were studied inPinus spp. plantations in Zhanggutai area, northeast China. The results showed that the total N, total P and C: N ratio of the soil inP. sylvestris var.mongolica stands were significantly higher in comparison with those inP. tabulaeformis andP. densiflora stands. ForP. sylvestris var.mongolica, the foliar P concentration appeared to decrease with age, and the foliar N and K concentrations did not show a consistent change with age. As for the different tree species of the similar age, the foliar N and P concentrations were significantly different (p<0.05), being withP. sylvestris var.mongolica>P. densiflora>P. tabulaeformis. The foliar N: P ratio ofP. densiflora significantly was higher thanP. sylvestris var.mongolica andP. tabulaeformis, while the foliar K was no obvious difference between the three tree species. There were significant correlation (p<0.05) between soil total N and P, soil organic matter and total P, foliar N and P, but it did not show significant correlations between soil and foliar nutrient concentrations, which might attribute to the excessive litter raking, overgrazing and low soil moisture in this area. Based on the foliar N: P ratio, we introduced a combination threshold index of N: P ratio with their absolute foliar nutrient concentrations to determine the possible limiting nutrient. According to the critical N: P ratio and their absolute foliar N, P concentrations, theP. sylvestris var.mongolica stands showed a decreased N limitation degree with age, theP. densiflora stands showed unlimited by N and P in the whole, and theP. tabulaeformis stands showed co-limited by N and P. No significant difference in soil nutrient concentrations of the surface soils was found between 45, 29, 20-yr-oldPinus sylvestris var.mongolica plantation stands. Keywords coniferous trees - foliar nutrient concentration - limiting nutrients - N - P ratio - Zhanggutai sandy land CLC number S718.55 Document code A Article ID 1007-662X(2004)01-0011-08 Foundation item: This research was supported by Key Knowledge Innovation Project (KZCX3-SW-418) of Chinese Academy of Sciences.Biography: CHEN Guang-sheng (1978-), male, master candidate in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. ChinaResponsible editor: Song Funan

Effect of Paclobutrazol plus Ethephon Treatment on Endogenous Hormones and Carbon and Nitrogen Nutrients in Litchi Variety ‘Feizixiao'

[Objective] This study aimed to investigate the effect of spraying the mixture of paclobutrazol and ethephon on the endogenous hormones and carbon and nitrogen nutrients in litchi variety ＇Feizixiao＇.[Method] [Result] The results showed that foliar spraying of the mixture of paclobutrazol and ethephon could effectively inhibit litchi variety ＇Feizixiao＇ to produce winter shoots,promote the flower bud differentiation and improve flower formation rate; meanwhile,this treatment could also increase the contents of ABA and ZR,and the ratios of ABA/IAA,ABA/GA3,ZR/IAA,ZR/GA3,and decrease the contents of IAA and GA3; additionally,it could increase the contents of soluble sugar,starch and total nitrogen,and raise C/N ratio,thus improving the flower formation rate.[Conclusion] Foliar spraying of the mixture of paclobutrazol and ethephon is an effective pathway for solving warmth damage to litchi.

Security Risk Analysis on the Nutrients and Heavy Metals of Biogas Slurry in Agricultural Application

[Objective] This study was to provide scientific basis for the security application of biogas slurry in agriculture through the analysis on the security risk of nu- trients and heavy metals of biogas slurry in agricultural application. [Method] The components of the slurry produced by the anaerobic digestion of straws and manures were systematically analyzed. Different types of biogas slurry with different concentrations were used to conduct the germination test. [Result] The types and proportions of raw materials, and alkali pretreatment affected the compositions and nature of the biogas slurry. Alkali pretreatment could reduce the contents of heavy metals and improved the contents of nitrogen, phosphorous, organic matter and available components. The contents of heavy metals in the biogas slurry were as follows： Cd of 8.76 μg/kg, Cr of 52μg/kg, Pb of 210 μg/kg, Hg of 0.512 μg/kg, As of 140μg/kg, and the contents of Cu and Zn were the highest among the heavy metals, respectively, 279 and 680 μg/kg. All the contents were under the limit standards of the urban wastes for agricultural use. The germination tests of the seeds verified that the slurry with the concentration of lower than 5% could accelerate the germination, while the salt stress could inhibit the growth of seedlings in the slurry. [Conclusion] When the dung are uses as the raw materials for fermentation, appropriate control should be conducted on the feeding proportion or the heavy metals should be pre-removed; when the slurry is used as the liquid fertilizer to apply in the farmland, the dilution or desalting treatment should be conducted at first.

Distribution of Nutrients in Arable Land Soil of Western Hainan

[Objective] This study aimed to reveal distribution characteristics of soil nutrients in tropical farmland, thereby providing a reference for cropland management and balanced fertilization in the tropical area. [Method] Combining field survey and laboratory analysis, distribution status of nutrients in arable land of Baisha Li Autonomous County of Hainan Province was investigated. [Result] The soil in Baisha Li Autonomous County was acidic in overall with average pH value of 5.0. it had medium organic matter level （average of 19.3 g/kg） and rich alkali-hydrolyzable nitrogen content, but was lack of available phosphorus and available potassium. The spatial distribution of available nitrogen, available phosphorus and available potassi- um in the soil was uneven. The spatial distribution of soil nutrients was mainly related to soil parent materials of the investigated area and pH value of the investigated soil. [Conclusion] According to the distribution characteristics of nutrients in the soil, awareness of land use and land maintenance should be strengthened, application amount of organic fertilizers should be increased, chemical fertilizers should be applied rationally, and fertilization structure should be optimized in the future.