Effects of Different Pretreatment Methods on Determination of Microelements in Feed

[ Objective] To study the effects of different pretreatment methods on determination of microelement in feed and thus find the best pre treatment method for each microetement, t Method] The samples （concentrated feeding stuff and fodder） were pretreated through throe methods, that is, dry incineration method, HNOs HCIO, wetdecomposition method and microwave digestion method. Then the content of seven kinds of mi croelement （AI, Ca, Cu, Fe, Mn, Se and Zn） was determined by inductively coupled plasma atomic emission spectrometer （ICPAES）. I Result] These three methods were all suitable for the determination of Cu, Mn and Zn in concentrated feeding stuff and the determination of Cu and Ca in fodder. The content of Cu and Ca was higher in fodder detected by HNO3 HCIO, wetdecomposition method. The microwave digestion method was suitable for the determination of AI and Ca in concentrated feeding stuff and the determination of AI, Fe, Mn and Zn in fodder. The dry incinera tion method was fit for the determination of Fe in concentrated feeding stuff. [ Condusionl The content of different microelements should be deter mined after the feed is treated with different Ioretreatment methods.

Primary Speciation Analysis on 6 Kinds of Microelements in Glycyrrhiza uralensis Fisch.

[Objective]The aim was to analyze the primary speciation of 6 microelements in Glycyrrhiza uralensis Fisch. and provide theoretical basis for explaining pharmacodynamic principle of liquorice and discussing quality control of liquorice planting. [Method]The 6 elements Cu,Zn,Ca,Fe,Mg and Mn in roots of G.uralensis were extracted based on traditional decoction method and were separated into water-soluble state and suspension state by micro porous filtering film. The elements in water-soluble state were detected by flame atomic adsorption spectrophotometry （FAAS）. [Result]The results showed that extractive rates of the elements were in the range of 1.71%-60.06%,and immerse-residue ratio in 0.018 3-1.682 0; the results also indicated that the immerse-residue ratio of Zn was biggest （1.68）,Zn played an important medical role and might be considered as the best characteristic element in G.uralensis; the recoveries of the elements were ranged from 95.72% to 103.15% and relative standard deviations （RSD） were less than 2.38%. [Conclusion]Because of its high accuracy,FAAS method is feasible for analyzing primary speciation of microelements in G.uralensis.

Distribution of Microelements and Their Influence on the Corrosion Behavior of Aluminum Foil

The distribution of microelement Fe, Si, Cu and Mg in the surface layer of aluminum foil annealed at 300℃ and 500℃ were determined by secondary ion mass spectrometer. The corrosion structure produced by electrochemical etching was also observed. It was found that the Mg concentration at external surface was increased exponentially over the fourth degree and promoted by higher annealing temperature, which will increase the number of corrosion pits inside the large grains, and therefore the specific capacity of the foils for electrolytic capacitors. The similar effects of microelement Fe, Si and Cu were not so strong.

Preliminary Study on Spatial Variability and Distribution of Soil Available Microelements in Pinggu County, Beijing, China

The objectives of this study were to explore the spatial distribution of soil available microelements and to provide a firm foundation for scientifically formulated fertilizer. 1 076 soil samples were collected from Pinggu County of Beijing, China, and the contents of available Cu, Zn, Fe, and Mn in topsoil （0-20 cm） and subsoil （20-40 cm） were analyzed respectively. Descriptive statistics and geostatistics were used to analyze the data. The mean values of topsoil available Cu, Zn, Fe, and Mn were 1.96, 2.51, 17.32, and 10.91 mg kg^-1, respectively, which were at medium or at slightly above medium level. The topsoil content of the soil available microelements was more than that of subsoil. The result of semivariance analysis showed that the topsoil available Fe and Mn were spatially correlated at a larger distance of 21.6 and 45.3 km, and the available Cu and Zn were at a shorter distance of 3.1 and 2.9 km, respectively. The subsoil spatial correlation distances were obviously different from the topsoil, which were in the order of available Mn 〉 Cu 〉 Zn = Fe. The Kriging method was applied to calculate the unobserved points and was used to generate the contour map. The results showed that the structural factors, such as topology, soil types, and soil properties, were the main factors influencing the spatial distribution of topsoil available Fe and Mn. Topsoil available Cu and Zn contents were mainly affected by land use, and their contents in orchard and in vegetable land were greatly higher than in field. The spatial distribution of subsoil microelements was similar to that of the topsoil, which exhibited vertical distribution patterns. Fertilizer and pesticide application resulted in the higher contents of available Cu and Zn in Pinggu County. The higher content of available Zn is potentially harmful to soil environmental quality, which should be inspected.

MIGRATION CHARACTERISTICS OF MICROELEMENTS IN PROCESS OF LANDSCAPE GEOCHEMISTRY IN MT.NAMJAGBARWA AREA

To provide scientific basis for appraising natural resources in Mt. Namjagbarwa area, the migration characteristics of geochemical microelements, such as Zn, V, Ti, Pb, Ni, Cu, Cr, Co, Be and Ba, in the landscape zones of alpine scrub and meadow, the mountainous dark coniferous forest, the mountainous mixed broadleaf and coniferous forest, the mountainous quasi-subtropical semi-evergreen broadleaf forest, the mountainous subtropical evergreen broadleaf forest, and the valley quasi-tropical monsoon rainforest have been described in the paper.

Clinical Effect of Fuzheng Jiedu Granule (扶正解毒颗粒) on Serum NO, NOS and Microelements in Patients with Coronary Heart Disease in Long-term Contact with Nickel

Objective: To study the clinical effect of Fuzheng Jiedu granule (扶正解毒颗粒,FJG) and its influence on serum nitric oxide (NO), nitric oxide synthase (NOS) and microelements in patients with coronary heart disease who are in long-term contact with nickel. Methods: Sixty patients were randomly divided into two groups, the treated group and the control group, 30 in each group. Conventional Western medicinal treatment was applied to both groups, but to the treated group, FJG was given additionally by oral intake, and the therapeutic course for both groups was 4 weeks. Besides, a health control group was set up with 15 healthy subjects selected from the same area, who had no history of contact with nickel. Clinical symptoms of the patients and changes in their electrocardiogram (ECG) and serum levels of NO, NOS and microelements were observed before and after treatment. Results: The total effective rate on clinical symptoms in the treated group was 93. 3% and that in the control group 63. 3% , comparison between the two showing significant difference (P<0.05); the total effective rate on ECG in the two groups was 90.0% and 56.7% respectively, which also showed significant difference (P<0.05). After treatment, levels of serum NO, NOS, Mg, Zn and Ca increased and those of Ni, Mn and Fe decreased significantly (P<0.05 or P<0.01) in the treated group, while in the control group, changes in these laboratory indexes were insignificant. Conclusion: FJG could lower the blood nickel level and regulate the unbalance of microelements, help restore serum NO and NOS in persons exposed to nickel and improve the clinical symptoms of patients with coronary heart disease and in long-term contact with nickel.

Microelements Distribution in Sulfides from Black Smokers of Hydrothermal Vent Field Broken Spur(MAR)

Numerous investigations on submarine hydrothermal ore-forming occurrence have been actively carried out in the last two decades with significant results.The Ag and Au enrichments in the sulfides from black smokers ofhydrothermal vent field Broken Spur(MAR) aroused our interest to study their mineral hosting forms.Samples were collected from seven hydrothermal chimneys within Broken Spur in the British-Russian BRAVEX(1994) and

Investigation on mechanism of reducing diffusible hydrogen in weld using microelements

In this paper,the influence of microelements yttrium(Y)and tellurium(Te)on the diffusible hydrogen in weld bead has been investigated in a systemic way by means of alloying addition in the molten pool(AAMP).The results indicate that AAMP can notably reduce the diffusible hydrogen,economize the precious microelements microelements and improve the technological properties.Thus the microelements will play an important role in further developing the welding materials.This paper lays emphasis on the discussion of the mechanism of reducing hydrogen by microelements Y and Te.It is considered from the results that both Y and Te belong to surface active elements and can reduce the diffusible hydrogen in weld bead because they can change the surface properlies of molten pool metal and reduce the absorption of hydrogen atom in arc space of liquid metal surface.This research has a great significance in the development and utilization of microelements in welding.

Level of Macronutrients and Microelements of Blood Plasma in Different Forms of Pulmonary Tuberculosis

By the method of atomic emission spectrometry with inductively coupled plasma, the content of macro and microelements in the blood plasma of 35 practically healthy people living in the Northern region of Azerbaijan and in the Nizhny Novgorod region of the Russian Federation was studied as well as of 23 patients with pulmonary tuberculosis with different phases of the disease. The elemental homeostasis of the blood plasma did not significantly differ depending on the region of residence, except for the potassium level (by 1.3 times greater for Russians) and strontium (by 10 times higher among the inhabitants of the Northern region of Azerbaijan). In patients with focal pulmonary tuberculosis, there were no significant differences in the content of elements in the blood plasma. With pulmonary tuberculosis, accompanied by decomposition processes, the content of calcium, copper, zinc and iron in blood plasma significantly increases in comparison with healthy people. Analysis of the level of these macro- and microelements can be used to determine the transition of the early form of pulmonary tuberculosis to infiltrative and/or cavernous forms, in which the patient becomes epidemiologically dangerous to others.

Influence of Physical Activity on Concentration of Macro-and Microelements in Physically Active Students＇ Hair

The aim of the work is to evaluate the influence of physical activity character on concentration of macro-and microelements in hair of physically active students. 127 students of I-IV year of Physical Education program at Lithuanian University of Educational Sciences participated in the research, aged from 20 to 24. They were split into three groups. The first （I） group （n = 48） consisted of endurance sport athletes （skiers, biathlon athletes, middle and long distance runners, rowers and cyclists）. The second group （II） （n = 61） was made up of the basketball, football, handball and volleyball players. The third group （III） consisted of combat sports （wrestling and boxing） athletes （n = 18）. For establishing the concentration of macro- and microelements in hair, x-ray fluorescence method was applied, using CEP-1 ELVAX （MP.MN 3730-2011） device. The results showed that the hair of the students of Physical Education program, practicing endurance sports possessed more calcium, copper, manganese in comparison to the athletes practicing other sports. Concentration of the main elements--zinc, iron, selenium and chromium in the hair of combat sports representatives was statistically significant. Concentration of potassium was also the greatest in this group of the investigated. However, this group of athletes also possessed the greatest values of toxic elements （plumbum, arsenic） in their hair, comparing to the athletes of endurance sport and players. In their hair, hydrargyrum concentration was significantly greater comparing to the values of this element in players＇ hair. The greatest mean values of cadmium were established in players＇ hair.

Identified Analytical Profile for Microelements, Trace Metals, Amino Acids and Screening of Anti-Diabetic Activity from Flower and Leaf Extracts of Moringa oleifera in Streptozotocin (STZ)-Induced Diabetic Rats

Background: Moringa oleifera plant is popularly known for its rich phytoconstituents and nutritional value and important medicinal values in both traditional and modern systems of medicine. We explored the present study for measurements of microelements, amino acid, phenolic content in hydro-al-coholic flower and leaf extracts of Moringa oleifera along with anti-diabetic activity in Streptozotocin (STZ)-induced diabetic male Wistar rats. Methodology: The micronutrients were determined by using atomic absorption spectrophotometer at 285 nm and 422 nm for Calcium (Ca), phosphorus (P), Iron (Fe), and Zinc (Zn), etc. The trace elements were also measured by spectrophotometer. The essential amino acid was determined by using Amino acid analyser. The total phenolic content in hydro-alcoholic extracts (flower and leaf) M. oleifera measured the absorbance at 760 nm by UV spectrophotometer. The screening of anti-diabetic activity HAFE and HALE of Moringa oleifera at two different dose of 100 and 200 mg/kg b.w. for 21 days were performed by determining the changes in biochemical parameters. Result and Discussion: The results revels that the presence of micronutrients, trace elements and amino acids in both flower and leaf of M. oleifera. The hydrolaocholic extracts of HAFE and HALE at 200 mg/kg b.w. showed significant antidiabetic activity compared with standard Glibenclamide. Whereas dose at 100 mg/kg b.w. showed moderate activity. Conclusion: In conclusion, the M. oleifera exhibits more effectiveness against STZ-induced diabetes. The HAFE and HALF extracts exhibited significant anti-diabetic property and active components may be isolated and clinical studies is required for further evaluation. Because of the rich source of phytoconstients, nutritional elements will be helpful in processed food products as dietary supplements especially for malnutrition in children in the current era.

Available Contents and Spatial Distribution of Soil Microelements of Tobacco Fields in Liupanshui City

The contents of soil microelements can affect the growth, yield and quality of tobacco, but it is not clear of the status quo of soil microelements in tobacco fields in Liupanshui city. In this study, soil samples of the plough layers (0 - 20 cm) were collected from January to March in 2021 from 500 typical tobacco fields in Liupanshui City (100, 180 and 220 fields in Zhongshan, Shuicheng and Panzhou, respectively), the particle size composition, pH, the contents of organic matter (OM), available boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) were measured and discussed. the results show that the mean contents of B, Cu, Fe, Mn, Mo and Zn are 0.92, 2.55, 66.47, 47.26, 0.39 and 3.96 mg/kg, respectively, and among which, B, Cu and Zn are at the high grades while Fe, Mn and Mo are at the very-high grades. There are significant differences in B, Fe and Zn among the three regions, while Cu is significantly different between Zhongshan and Shuicheng, Mn is significantly different between Panzhou with Zhongshan and Shuicheng, and Mo is significantly different between Zhongshan and Panzhou. The proportions of fields deficient in microelements are relatively low, no field is Fe-deficient, and the fields deficient in Mo, B, Cu, Zn and Mn are only account for 10.40%, 9.40%, 7.40%, 2.80% and 2.00% of the total fields respectively. B-deficient fields (green and light green colors, the same below) are mainly scattered in the northwest of Zhongshan and in the north and south of Panzhou, Cu-deficient fields mainly in the middle of Shuicheng and Panzhou, Mn-deficient fields mainly in northern Zhongshan, central Shuicheng and north of Panzhou. Mo-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou, while Zn-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou. Altitude is negatively correlated with Mn (P < 0.05), pH is negatively correlated with B (P < 0.05), Fe and Mn (P < 0.01), and OM is positively correlated with Fe and Zn (P < 0.01). Sand is negatively correlated with B (P < 0.05), Mn and Mo (P < 0.01), but positively correlated with Zn (P < 0.01). Silt is positively correlated with Mo (P < 0.05);clay is positively correlated with B (P < 0.05) and Mn (P < 0.01), but negatively correlated with Zn (P < 0.01). In conclusion, most of the fields do not need to apply micro-fertilizers in Liupanshui, but the fields deficient in microelements should be considered to use the corresponding fertilizers.

Ecological and geochemical aspects of interlayer water use for potable water supply of urban population:a case study in the Dnieper–Donetsk aquifer system,Ukraine

The article is devoted to the study of ecological and geochemical features of interlayer waters of the Dnieper–Donetsk aquifer system in Ukraine,used for the potable water supply of Kyiv.A wide range of methods was used,including Microsoft Excel,Statistica,and Attestat software packages,MapInfo Professional 6.5 and ArcGIS-ArcMap 9.3 programs;the method of mass spectrometry with inductively coupled plasma(ICP-MS)and GEMS software were performed.Monitoring study results(during 2007–2023)were analyzed for two interlayer aquifers—Cenomanian-Callovian groundwater complex and Bajocian aquifer.It was determined that the normalized value of mineralization increased with a decrease in water intake during 1980–2010,which indicates a relative increase in the content of mineral substances during longterm exploitation.A high negative correlation(Kcor.=-0.54 to-0.86)is also typical for normalized values of oxidizability,total hardness,pH,Ca,Mg,and Cl content.Comparative analysis of two different aquifers revealed that the macrocomponent composition of Bajocian aquifer remains stable,once for Cenomanian-Callovian groundwater complex,there is a tendency to decrease hydrogen carbonates and increase chlorides and sulfates,whereas the cation composition remains relatively stable.A significant increase(by 55%)of the total mineralization in the representative well located on the right bank of the Dnieper River was found.There is also a significant increase(by more than 5 times)in the iron content,which the authors associate with the unsatisfactory technical condition of the well casing pipes.Physico-chemical modeling of trace elements,performed for investigated aquifers,shows that both aquifers are characterized by the predominant migration of the following metals in the cationic form(aqua-ions):Ca,Mg,Na,Ba,Co,Cu,Mn,Ni,Sr,Zn.It was found that the predominant migration forms of metals in the studied interlayer waters are free uncomplexed ions,carbonate,and hydroxo complexes.

Prospects and Problems of Implementation of Recreation Works in Degradated Areas

This article is devoted to work aimed at normalizing the condition of degraded soils in open-pit mines as a result of anthropogenic influences through phytomass. By creating a biological cover from plants, it has been achieved to improve the composition of the soil. Plants such as Datura starmonium, Portuluca oleracea, Caspella bursa-pastoris, Chenopodium vulvaria, Chenopodium album, Plantago lanceolata, Vaccaria hispanica, Vicia angustifolia were used for the research. The effect of micronutrients on plants was studied.

Effects of Microelement Fertilizers on Main Economic Characters and Yield of Peanut

The main purpose of this study was to explore and master the optimal types and application methods of microelement fertilizers suitable for peanut cultivation in Linyi City.The results showed that the application of zinc,magnesium,sulfur,calcium and other microelement fertilizers to peanut plants had a certain yield-increasing effect,and zinc had the most significant yield-increasing effect.Compared with the control check(CK),the yield per unit area increased by 1431 kg/hm^(2),equivalent to an increase of 38.4%.Meanwhile,according to field investigation and observation,the treatment of increasing zinc fertilizer had a certain promotion effect on peanut emergence rate,seedling growth potential,and yield components.

Effects of Reducing Mn^(2+),Cu^(2+) and Zn^(2+) Concentrations in Nutrient Solution on SOD Activity in Grafted Cucumber Seedling Leaves Under Cold Stress

[Objective] The research aimed to study the effects of reducing the concentrations of Mn2＋, Cu2＋ or Zn2＋ in nutrient solution on the contents of Mn, Cu and Zn of grafted cucumber leaves as well as on the SOD and isozymes activities and the rate of electrolytic leakage under cold stress. [Method] Nutrient solution containing low concentrations of Mn2＋, Cu2＋ or Zn2＋ were used for cultivating the grafted cucumber seedlings for the cold treatment. [Result] The results indicated that reducing the concentrations of Mn2＋, Cu2＋ or Zn2＋ in nutrient solution had declined the SOD activities in grafted cucumber leaves and increased the rates of electrolytic leakage. Mn2＋ had shown the maximum influences, followed by Cu2＋, and Zn2＋ had shown the minimum influences. [Conclusion] Cold resistance of cucumber can be improved by changing the contents of Mn2＋, Cu2＋ or Zn2＋ in nutrient solution.

Effects of Different Nitrogen Fertilizer Levels on Fe,Mn,Cu and Zn Concentrations in Shoot and Grain Quality in Rice (Oryza sativa)

In a pot experiment, effects of N fertilizer application on the concentrations of Fe, Mn, Cu and Zn in shoot of rice and the quality of brown rice were studied. In the treatments with N fertilizer application, the concentrations of Fe, Mn, Cu and Zn in most parts of rice shoot increased compared with control （no N fertilizer application）. This indicated that the transportation ability of microelements from root to shoot in rice was improved with N fertilizer application. Effect of N fertilizer on IR68144 was similar to that of on IR64, but the concentrations of the microelements in plant differed, suggesting that the characteristic expression of the two rice genotypes was not controlled by the amount of N fertilizer supplied. The concentrations of those microelements in brown rice increased at first and then decreased with increasing N fertilizer application, reaching the highest at 160 kg/ha, at which the Fe, Mn, Cu and Zn concentrations in brown rice increased by 28.96%, 41.34%, 58.31% and 16.0% for IR64, and by 22.16%, 13.75%, 8.75% and 20.21% for IR68144 compared with control, respectively. Moreover, N fertilizer promoted the accumulation of protein, decreased the accumulation of amylose in grain, and enhanced gel consistency of brown rice. These results indicate that appropriate N fertilizer management could increase micronutrient contents in grain and improve nutrition quality of rice.

Effects of Different Lead Compounds on Growth and Heavy Metal Uptake of Wetland Rice

Effects of different lead compounds, PbCl2, Pb(NO3)2 and Pb(OAc)2, on the rice growth and uptake of lead and some microelements by wetland rice were studied. The results showed that the seed germination, rice seedling growth, chlorophyl content, grain yield and uptake of Pb, Cu, Zn, Fe and Mn by rice plant were affected by the chemical forms of Pb compounds added in soil to a certain degree. The germination rate and the amount of chlorophyl decreased remarkably with increasing Pb concentration, the root extension was restrained obviously by the presence of Pb, and the effect of PbCl2 was more evident than that of Pb(NO3)2 or Pb(OAc)2. The pot incubation test with yellow brown soil and red soil showed that there was no significant regularity in effect of Pb on grain yield, but the difference in the influence of various Pb compounds on yield was clearer. The effect on the amount of Pb in straw and brown rice was in the sequence of Pb(NO3)2> Pb(OAc)2> PbCl2. In case the content of Pb in brown rice was 0.5 mg/ kg, the relative loading capacities of yellow brown soil for Pb added as PbCl2, Pb(OAc)2 and Pb(NO3)2 were 100, 90 and 60 respectively. Pb uptake by wetland rice was closely related to the chemical species of Pb in soil, but there was no comparability among chemical forms of different Pb compounds in the same soil. The uptake of Cu, Zn, Fe and Mn by wetland rice was markedly affected by the addition of Pb, and different Pb compounds varied in their impacts on the uptake of other metals by different organs of wetland rice, e.g. the concentration of Fe in root increased significantly (r = 0.92), while opposite was true for Fe in brown rice (r =-0.92) due to the application of Pb(OAc), in soil. These results demonstrate that the effect of accompanying anions of Pb on the physiological and biochemical processes of wetland rice was rather complex.

Decomposition patterns of leaf litter of seven common canopy species in a subtropical forest： dynamics of mineral nutrients

Dynamical patterns of mineral elements during decomposition processes were investigated for seven common canopy species in a subtropical evergreen broad-leaved forest by means of litterbag technique over 2 years. The species studied are representative for the vegetation in the study area and differed significantly in chemical qualities of their litter. No significant relationships were found between decomposition rate （percentage dry mass remaining and decomposition constant k） and initial element cuncentrations.However, there were significant correlations betweeu the percentage of dry mass remaining and the mineral element concentrations in the remaining litter for most cases. The rank of the element mobility in decomposition process was as follows： Na = K 〉 Mg ≥ Ca 〉 N ≥ Mn ≥ Zn ≥ P 〉 Cu 〉〉 Al 〉〉 Fe. Concentrations of K and Na decreased in all species as decomposition proceeded. Calcium and Mg also decreased in concentrntion but with a temporal increase in the initial phase of decomposition, while the concentrations of other elements （Zn, Cu, AL and Fei increased for all species with exception of Mn which revealed a different pattern in different species. In most species, microelements （Cu, Al, and Fe） significantly increased in absolute amounts at the end of the litterbag incubation, which could be ascribed to a lange extent to the mechanism of abiotic fixation to humic substances rather than biological immobilization.

Photosynthetic capability and Fe, Mn, Cu, and Zn contents in two Moraceae species under different phosphorus levels

The strong adaptability of Broussonetia papyrifera （L.） Vent. to low phosphorus （P） conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. pa- pyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate （PN）; chlorophyll a fluorescence （ChlF） characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P defi- ciency （0.125, 0.063, and 0.031 mmol/L P treatments）, whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency （0.016 and 0 mmol/L P treatments）. Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a consid- erable decrease of photosynthetic capability in B. pa- pyrifera and M. alba was associated with low Cu and Zn contents. The PN of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structureand electron transport efficiency by influencing the con- tents of Cu or Zn, thereby affecting photosynthesis.