Preliminary study on the distribution of nutrients, organic matter, trace metals in sea surface microlayer in Xiamen Bay and Jiulong Estuary

The enrichment of nutrients (Noa-, Noa-, PO43-), suspended particles, organic matter (POC, PON,DOC) , and trace metals (Cu, Ni, Cd) was determined in the sea surface microlayer of Xiamen Bay and Jiulong Estuary. The mean enrichment factors ([Xi]microlayer/[Xi ]15cm in depth) mostly ranged between 1 . 0 and 2. 0. The dissolved forms were the major forms of the components measured, the enrichment of dissolved organic matter and suspended particles could lead to the changes in the total amount and speciation of nutrients and trace metals. No correlation was observed between sample concentrations, speciation, enrichment factors and sample locations. However, some evidence shows that these parameters are correlated with sea state, indicating the complexity and dynamic nature of the sea surface microlayer.

Spatial characters of nutrients in Wujiangdu Reservoir in karst river,SW China

A preliminary assessment of the Wujiangdu Reservoir examined nutrient distribution and transport.Water samples were collected in the summer(July) of 2004, during the high-flow season. Inorganic nutrients(N,P, Si) and chlorophyll a(chl a) concentrations of the Wujiangdu Reservoir and its inflow rivers were analyzed.Other water parameters(dissolved oxygen, p H, temperature, and electrical conductivity) were measured as well.The results show gradually decreasing concentrations of NO_3^--N and dissolved silicate in the surface water moving downstream to the dam of the Wujiangdu Reservoir.Additionally, soluble reactive phosphorus concentrations measured very low, with most falling below the sensitivity threshold of the method used in surface waters. Particulate phosphorus and NO_3^--N were the predominant species of phosphorus and nitrogen in the reservoir, respectively. The concentration of nutrients in the Yeji River was the largest of all inflow rivers. The maximum concentration of chl a was found near the dam. These results reflect upstream conditions similar to that of a river, and reservoir conditions near the dam similar to that of a natural lake system.

Biomass production,nutrient cycling and distribution in age-sequence Chinese fir(Cunninghamia lanceolate)plantations in subtropical China

Biomass production and nutrient （N, P, K, Ca and Mg） accumulation, distribution and cycling were quantified in young, mature and over-mature （10-, 22-, and 34-year old） Chinese fir [Cunninghamia lanceolate （Lamb.） Hook] plantations in southern China. Total stand biomass of young, mature and over-mature stands was 38, 104 and 138 t ha-1 respectively. Biomass production increased significantly with age. Stem wood represented the highest percentage of stand biomass, accounting for 41, 55 and 63 % in the young, mature and over-mature plan- tations respectively. Nutrients concentration was highest in live needles and branches, and lowest in stem wood. The plantations accumulated more N, followed by K, Ca, Mg, and P. Nutrient return amount, nutrient utilization effi- ciency, nutrient turnover time, the ratio of nutrient return and uptake increased with stand age, which implies that young Chinese fir deplete soil nutrients to maintain growth, and efficiently utilize nutrients to decrease dependence on soil nutrients as they age. Harvesting young Chinese fir plantations would therefore lead to high nutrient loss, but prolonging the rotation length could improve soil recovery, and help sustain productivity in the long-term. Improved nutrient return through litterfall as stands get older may also be beneficial to nutrient pool recovery.

Distribution and accumulation of zinc and nitrogen in wheat grain pearling fractions in response to foliar zinc and soil nitrogen applications

Increasing zinc(Zn)concentration in wheat grain is important to minimize human dietary Zn deficiency.This study aimed to investigate the effect of foliar Zn and soil nitrogen(N)applications on the accumulation and distribution of N and Zn in grain pearling fractions,N remobilization,and the relationships between nutrient concentration in the vegetative tissues and grain or its fractions in two cropping years in the North China Plain.The results showed a progressive decrease in N and Zn concentrations from the outer to the inner parts of grain,with most of the accumulation in the core endosperm.Foliar Zn application significantly increased N concentration in the pericarp,and soil N application increased N concentration in each grain fraction.Both treatments significantly increased core endosperm Zn concentration.Foliar Zn had no effect on grain N and Zn distribution.Soil N application made N concentrated in the aleurone,promoted Zn translocation to the core endosperm and also increased N remobilization and its efficiency from the shoot to the grain,but no improved contribution to grain was found.N concentration in grain and its fractions were positively correlated with N in vegetative organs at anthesis and maturity,while positive correlations were obtained between N concentration in the pericarp and progressive central area of the endosperm and Zn concentration in the core endosperm.Thus,foliar Zn and soil N applications effectively increased yield and N and Zn concentrations in the wheat grain,particularly in the endosperm,and could be promising strategies to address Zn deficiency.

Effect of Land Reclamation on Nutrient Distribution in Reclaimed Farmlands Overlying Xuzhou Underground Coal Mines *1

This research was carried out to evaluate the effect of the reclamation procedure with respect to soil fertility and nutrient distribution pattern in the reprecipitated reclaimed soil. Although there was an obvious indication of low levels of essential nutrients in the reclaimed farmlands (organic matter=0.32 g kg -1 ,total N=380.8 mg kg -1 , available P=4.7 mg kg -1 ), compared to the undisturbed farmlands (organic matter=2.5 g kg -1 , total N=1 220 g kg -1 , available P=20.8 mg kg -1 ), the uneven pattern of nutrient distribution was also shown to have been the major limitation to successful reclamation. Further improvement can be achieved through the integration of intensive eco farming systems using proper fertilizer field correction (PFFC) and organic manure for successful reestablishment and management of newly reclaimed farmlands overlying the Xuzhou coal mine subsidence.

Nutrient Accumulation and Distribution in Cotton Promoted by Removal of Mulch Film

Plastic film mulching affects changes in nutrient contents in soil and absorption and utilization of nutrients in plants were by changing hydrothermal condition of soil.The temporal and spatial variation of the total soil salt and nutrient contents with mulch film removed at three different times during the early cotton growth stage and its effects on nutrient absorption and accumulation in cotton plants were studied over 2015-2017.The film removal treatments reduced salt accumulation in normal rainfall year(2017).Film removal increased contents of soil organic matter,the total phosphorus and available potassium at the end of growth stage,increased contents of soil hydrolyzable nitrogen and the total nitrogen in the surface soil layer(0-10 cm),and increased the total nitrogen contents in the deep soil layer(40-50 cm).Film removal increased accumulation of nitrogen and phosphorus nutrients in cotton plants in 2017 and accumulation of nitrogen,phosphorus and potassium nutrients in cotton plants in heavy rainfall year(2016).These experimental results indicated that removal of mulch film at an appropriate and targeted time in the bud stage of cotton promoted nutrient absorption.

Plastic-film-covered Rice Cultivation with Drip Irrigation and Development of Sowing Planter

This study aimed to gain more high-quality rice with less water and im- prove the level of national food security. Based on the optimized planting density of rice with drip irrigation, direct sowing technology for plastic-film-covered rice cultiva- tion with drip irrigation was proposed. Furthermore, sowing planter for plastic-film- covered drip-irrigation rice cultivation was developed in accordance with the require- ments for the combination of agricultural technique and agricultural machinery. Ac- cording to the large-scale field production evaluation, the film-punching direct-sowing technology for dry cultivation of rice can greatly reduce the labor consumption and results in neat emergence of seedlings. Productive practice shows that using the developed sowing planter for plastic-film-covered rice cultivation with drip irrigation leads to vacancy rate ≤3%, pass rate of grain number ≥85%, soil-covering rate ≥ 95%, and hole number per acre of 31 000-33 000. In addition, the sowing planter can adapt to the agronomic technical requirements for high-density cultivation of rice and provide technical support for the rice production in arid regions of China. Key words Fargesia murielae; Nutrition mechanism; Age grade; Nutrient distribution

Responses of Contrasting Rice (Oryza sativa L.) Genotypes to Salt Stress as Affected by Nutrient Concentrations

The study was conducted to investigate the effects of applying different concentrations of the macronutrients K＋,Ca2＋,and Mg2＋ on the responses of contrasting rice（Oryza sativa L.） genotypes under salt stress.A solution culture experiment was conducted in a phytotron at the International Rice Research Institute（IRRI）,under controlled temperature and humidity and natural sunlight.When subjected to salt stress of 100 mmol L-1 using NaCl,the salt tolerant genotypes FL478 and IR651,accumulated less Na＋ and maintained lower ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ than the sensitive genotypes IR29 and Azucena.These tolerant genotypes also had higher concentrations of K＋ in their shoots and greater root and shoot biomass and green leaf area.Tolerant genotypes also maintained much lower concentration of Na＋ and lower and more favorable ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in their active and developing tissues.Salt tolerance and shoot and root growth of both tolerant and sensitive genotypes were enhanced considerably when higher concentrations of Ca2＋ and Mg2＋ were applied in culture solution.The concentration of Na＋ and the ratios of Na＋/K＋,Na＋/Ca2＋,and Na＋/Mg2＋ in shoots also declined significantly.The beneficial effects of higher calcium were greater than that of magnesium and application of higher concentration of K＋ seems to have minor effects.Responses to salinity in rice can therefore be considerably enhanced through proper nutrient management,by increasing the concentrations of nutrient elements that have favorable effects such as Ca2＋ and Mg2＋.Calcium is particularly more effective than both magnesium and potassium,and can be applied at relatively larger quantities in salt affected soils.

Chemical characteristics and estimation on the vertical flux of N，P，Si in upwelling area of Taiwan Strait

Based on the data obtained from oceanographic surveys at the central and northern parts of the TaiwanStrait during the period from 1983 to 1988, it is showed that the nutrient content in the coastal and bottom waters isrelatively high with an upward and offward decrease, and that the upwelling in the Fujian coastal area controls the distribution of nutrients in summer.The upwelling water is characterized by 2. 29 μmol/dm￣3 of nitrate; 2. 83 μmol/dm￣3of silicate; 0. 20 μmol/dm￣3 of dissolved inorganic phosphate,respectively. Significant correlation between nutrientsand dissolved oxygen content and its degree of saturation, temperature, and salinity, respectively are found in the upweiling area. Average of N/P ratio in the area(15. 9) approaches to Redfield ratio. Their vertical flux is estimated tobe 23. 6 mg/(m￣2·d) for - P, 223 mg/(m￣2·d) for NO-N, 302 mg/(m￣2·d) for SiO-Si, respectively,which is the main source Of nutients in the areas in summer. The mean of the flux of P and NO-N is about86 % and 73% necessary for phytoplankton in the euphotic zone.

A discussion on vertical profiles of dissolved Cu, Cd and Ni in the northwestern Pacific, south of Japan

Some of the results about vertical profile of heavy metals of seawater to the south of Japan in Oct. 1990 are presented and discussed in relation to the concentration of dissolved Cu, Cd and Ni to biogeochemical environments. It points out that the distribution of dissolved Cu is higher in surface water than that in/upper 500 m layer, and maxima value attains the 8. 2 n mol/dm3 in depth of 4 000 m. The concentrations of dissolved Ni ranges from 3. 4 n mol/dm3 in surface seawater to 8. 5 n mol/dm3 in the deep to the south of Japan. The highest values are observed in the colder waters. This paper shows also that the vertical profile of dissolved Cd is perfect nutrient-type distribution. And dissolved Cd and Phosphate are linearly correlated by the regression equation. The ·Cd : ·N : ·P atomic ratio is 3. 5 × 10-4 : 14 : 1.

Spatial variations of macrozoobenthos and sediment nutrients in Lake Yangcheng: Emphasis on effect of pen culture of Chinese mitten crab

We determined the effect of Chinese mitten crab（CMC） pen culture on the quantified spatial distribution of the macrozoobenthic community and sediment nutrients in Lake Yangcheng.Redundancy analysis indicated that water temperature, macrophyte occurrence, sediment type, and crab culture were the main environmental factors that influence the spatiotemporal macrozoobenthic distribution. Macrozoobenthic assemblages in the lake were characterized by eutrophic indicator species. In the most polluted estuaries, the abundance and diversity indices of the whole community and abundance of chironomids and oligochaetes were significantly depressed, and sediment carbon（C） and phosphorus（P） were significantly enhanced compared with those in the western, middle（MB）, and eastern basin（EB）. Crab culture in this lake had significant effects on the species composition of the macrozoobenthic community in one of three CMC culture pens（CP）, and generally depressed the abundance of most chironomid and oligochaete species. Significantly increased diversity, evenness, sediment carbon and nitrogen content, and sediment C：P ratio in the CP were found compared with those in the three basins.However, no conspicuous difference in sediment P content between the CP and the two basins of MB and EB was detected. Our results showed that the enhanced diversity and evenness of macrozoobenthos might be associated with the joint effect of macrophyte planting and crab predation, and macrophyte planting may modify the effects of CMC culture by leading to disproportional accumulation of C and N in the sediment relative to P in the CP of the lake.

Oxygen and Glucose Transportation and Distribution on 3D Osteochondral Scaffold in Silico Model

Nutrients supply especially like nutrients and oxygen play vital role in tissue engineering process.It is found that tissue could not grow very well in the middle of the scaffold because few nutrients could transport to the middle.Nutrient limitations would reduce cell proliferation and differentiation.In that case,there is urgent need to understand the nutrient distribution for both in vitro and in vivo study,as no technology is able for researchers to observe the nutrients transport during those process.In this paper,a numerical model coupling with VOF(volume of fluid)model and species transport model together for predicting the distribution of oxygen and glucose in the scaffold after implantation in to the site is developed.Comparing with our previous in vivo tests,the regenerated tissue distribution has a similar trend as oxygen distribution rather than glucose.The reported scaffold manufactured by additive manufacturing provided a good interconnected structure which facilitated the nutrient transportation in the scaffold.Considering nutrient transportation,this numerical model could be used in better understanding the nutrients transportation in the scaffold,and leading to a better understanding of tissue formation in the scaffold.

Effects of plant species richness on stand structure and productivity

Aims Aboveground biomass production commonly increases with species richness in plant biodiversity experiments.Little is known about the direct mechanisms that cause this result.We tested if by occupying different heights and depths above and below ground,and by optimizing the vertical distribution of leaf nitrogen,species in mixtures can contribute to increased resource uptake and,thus,increased productivity of the community in comparison with monocultures.Methods We grew 24 grassland plant species,grouped into four nonoverlapping species pools,in monoculture and 3-and 6-species mixture in spatially heterogeneous and uniform soil nutrient conditions.Layered harvests of above-and belowground biomass,as well as leaf nitrogen and light measurements,were taken to assess vertical canopy and root space structure.Important Findings The distribution of leaf mass was shifted toward greater heights and light absorption was correspondingly enhanced in mixtures.How ever,only some mixtures had leaf nitrogen concentration profiles predicted to optimize whole-community carbon gain,whereas in other mixtures species seemed to behave more‘selfish’.Nevertheless,even in these communities,biomass production increased with species richness.The distribution of root biomass below ground did not change from monocultures to three-and six-species mixtures and there was also no indication that mixtures were better than monocultures at extracting heterogeneously as compared to homogeneously distributed soil resources.We conclude that positive biodiversity effect on aboveground biomass production cannot easily be explained by a single or few common mechanisms of differential space use.Rather,it seems that mechanisms vary with the particular set of species combined in a community.