Chromium accumulation in soil,water and forage samples in automobile emission area

Environmental contamination caused by various pollutants due to automobile emissions is an alarming issue. One important type of the pollutants are heavy metals, including chromium (Cr) added by the exhaust of toxic smoke of vehicles. These pollutants are added to forage crops cultivated near roadsides, soil and irrigation water. However, rare studies have been conducted to infer Cr accumulation near heavy automobile emission areas. This study was conducted to determine Cr concentration in irrigation water, soil and forage. Water, forage and soil samples were collected from area impacted by heavy traffic. Atomic absorption spectrophotometer was used to appraise Cr values in the collected samples. Chromium values ranged from 0.50 to 1.14 mg/kg in water samples and from 0.04 to 2.23 mg/kg in soil samples. It was highest in Zea mays grown soil, whereas minimum in Brassica campestris soil. The Cr values in forages ranged from 0.09 to 1.06 mg/kg. Z. mays observed the highest Cr accumulation, whereas the lowest Cr accrual was noted for B. campestris. The pollution load index (PLI) was the highest for Trifolium alexandrinum, while the lowest for Z. mays. Bio-concentration factor (BCF) ranged from 0.14 to 8.63. The highest BCF was noted for T. alexandrinum, while the lowest for Z. mays. The highest and the lowest daily intake of metal (DIM) was noted for Z. mays at different sites. Health risk index (HRI) was highest for Z. mays and lowest for B. campestris. The results add valuable information on heavy metal accumulation in water, soil and forage samples near to automobile emission area.     

Prevalence and control of pathogenic contamination in some sewage irrigated vegetable, forage and cereal grain crops

A total of 344 samples comprising of different vegetables, fodder and grain crops were obtained from a long-term experiment under sewage irrigation. The aerobic bacterial plate counts for vegetables, fodder and grain crops ranged between 2 x 10(6) and 3.5 x 10(7), 6 x 10(6) and 3 x 10(8), 2 x 10(5) and 3.8 x 10(10), respectively, while the corresponding Faecal coliform ranged between < 2 and 9 x 10(5), 9 x 10(2) and 2 x 10(5) and < 2, indicating that the pathogenic loads got reduced below permissible level in the produce that was harvested after sun drying in the field itself, whereas the parts coming in direct contact were the most severely contaminated. The health hazards could be markedly lowered with adoption of some of the low cost practices such as repeated washings, exposure of the produce to sunlight and raising the crops on beds. The coliform counts in vegetables were within permissible limits by two washings with water, exposing these to sunlight for about 4 h and removing the two outmost leaves of cabbage. Also, cutting above some height from ground level (0.10 m) in sorghum reduced the pollution load in fodder crops.     

Field accumulation risks of heavy metals in soil and vegetable crop irrigated with sewage water in western region of Saudi Arabia

Wastewater irrigated fields can cause potential contamination with heavy metals to soil and groundwater, thus pose a threat to human beings . The current study was designed to investigate the potential human health risks associated with the consumption of okra vegetable crop contaminated with toxic heavy metals. The crop was grown on a soil irrigated with treated wastewater in the western region of Saudi Arabia during 2010 and 2011. The monitored heavy metals included Cd, Cr, Cu, Pb and Zn for their bioaccumulation factors to provide baseline data regarding environmental safety and the suitability of sewage irrigation in the future. The pollution load index (PLI), enrichment factor (EF) and contamination factor (CF) of these metals were calculated. The pollution load index of the studied soils indicated their level of metal contamination. The concentrations of Ni, Pb, Cd and Cr in the edible portions were above the safe limit in 90%, 28%, 83% and 63% of the samples, respectively. The heavy metals in the edible portions were as follows: Cr > Zn > Ni > Cd > Mn > Pb > Cu > Fe. The Health Risk Index (HRI) was >1 indicating a potential health risk. The EF values designated an enhanced bio-contamination compared to other reports from Saudi Arabia and other countries around the world. The results indicated a potential pathway of human exposure to slow poisoning by heavy metals due to the indirect utilization of vegetables grown on heavy metal-contaminated soil that was irrigated by contaminated water sources. The okra tested was not safe for human use, especially for direct consumption by human beings. The irrigation source was identified as the source of the soil pollution in this study.     

Decomposition in estuarine salt marshes: the effect of soil salinity and soil water content

The relation between decomposition rates and soil salinity and moisture conditions in tidal marshes of the Westerschelde estuary was investigated. In the first part of the study, these soil factors were experimentally manipulated in field plots which were either screened from rainwater or which received an additional weekly supply of freshwater from April to September 1989. These treatments had no clear effect on soil salinities and moisture conditions in a low marsh site. Decomposition rates of Spartina anglica leaves (kept in litterbags in the plots) also did not differ between treatments. In screened plots of a middle marsh site, decomposition rate of Elymus pycnanthus leaves decreased significantly. The effect of the experimental treatments on soil moisture content was variable, but comparatively high soil salinity values (up to 61.3) were consistently found in these plots. It is suggested that the elevated salinity levels induced the decrease in decomposition rate.In the second part of the study, cellulolytic decomposition, measured by loss of tensile strength of strips of cotton test cloth, was investigated in relation to a non-manipulated range of soil salinities (3.8–24.2), by exposing the strips in a series of tidal marshes along the salt gradient of the Westerschelde estuary. No correlation between decomposition rate and soil salinity was found. In addition, no relation was found between decomposition rate and soil water content. The results of both parts of this study lead us to the hypothesis that rate limitation of decomposition in estuarine tidal marsh soils is found at high soil salinities only.     

Effect of soil salinity and soil water availability on growth and chemical composition ofSorghum halepense L.

Summary Effects of soil salinity and soil water regime on growth and chemical composition ofSorghum halepense L. was studied with a view to evaluating its potential as a forage crop in saline soils. The experiment was conducted under controlled conditions using pot-culture with three levels of soil salinity (EC_e 0.5, 5.0, 10.0 ds/m) and three soil water regimes (60%, 40% and 20% of water holding capacity of the soil). High soil salinity and low soil water combiningly had an adverse effect on plant growth but the biomass production was appreciably high (57 to 75% of control) even under high soil salinity (EC_e 10 ds/m) when sufficient water was available. Belowground plant parts were relatively more salt-tolerant than shoots. There occurred an increase in the concentration of certain nutrients (N, Ca, Mg, TNC) in the plants in response to salinity, which along with increased root: shoot ratios was inferred as an adaptive feature of the plant for persistence under saline conditions.     

辽西水土保持林土壤改良效应的研究

通过分析比较油松纯林和油松-固N树种混交杯土壤的理化性质和油松生长量,结果表明,油松-固N树种混交杯土壤有机质含量、全N、全P、速效P和水解N含量都比油松纯林显著提高,土壤容重减小,硬度降低,初渗速度增大．油松胸径和树高生长量也有较明显提高,对土壤的改良作用比油松纯林效果更加显著．通过土壤酶活性和固N树种固N活性的测定,对不同水土保持林的土壤肥力状况作出了综合评价。     

水土保持林土壤抗蚀性能评价研究

运用土壤有机质含量、水稳性团聚体含量、水稳性团粒平均重量直径、团聚度和分散系数等各项指标,对不同树种组成、不同林龄水土保持林的土壤抗蚀性能进行分析、评价.结果表明,水土保持林对于提高土壤抗蚀性能具有重要作用,这种作用主要针对表层土壤而言;与油松纯林相比,油松阔叶树混交林土壤有机质含量较高,水稳性团聚体含量增加了1.71%～38.53%;且随着林龄的增长,水土保持林土壤抗蚀性能不断增强.     

广东白盆珠水库水源林土壤水源涵养能力研究

通过对广东省白盆珠水库水源林土壤类型调查及土壤水分物理性质的测定,结果表明:库区水源林水平地带性土壤属赤红壤,山地土壤垂直带谱明显,分布有赤红壤、山地红壤、山地黄壤和山顶灌丛草甸土4个类型。土壤容重约为1.338g·cm^-3,随海拔升高土壤砂粒含量增加。土壤总孔隙度在45%～50%,非毛管孔隙度在5%～9%之间,毛管孔隙度35%～50%。不同森林类型土壤的最大持水量在30%～50%,即50～60mm,变化不大;蓄水容量有较大区别,范围在500～850t·hm^-2,灌丛草甸土最大,针阔混交林次之,沟谷阔叶林最小;排水能力约在130～180t·hm^-2,并以灌丛草甸土为最大,次生阔叶林为最小。该库区水源林土壤的排水和蓄水容量分别为62.69万t、316.29万t,消洪补枯能力明显。但水源林土壤非毛管孔隙度较小,蓄水量小于广东各种有林地森林类型平均蓄水量,所以该库区的水源林还需加强保育,以提升土壤的水源涵养能力。     

Research on the cooling island effects of water body: A case study of Shanghai,China

The water cooling island (WCI) is important to the mitigation of urban heat island (UHI) effects. In this study, the three aspects: WCI range (L_max), amplitude of temperature drop (ΔT_max) and temperature gradient (G_temp) are used to investigate the WCI effects of the water bodies in Shanghai, China based on the high resolution Google Earth and Landsat-8 satellite image data of the eighteen lakes and three rivers within the outer ring road of the city. The results show that the water bodies have mean L_max of 0.74 km, ΔT_max of 3.32 °C and G_temp of 5.15 °C/km. The WCI effects of the lakes are significantly stronger than that of rivers. In addition, geometry, proportion of vegetation and impervious surfaces are important impact factors on the WCI effects of water bodies. In particular, L_max and ΔT_max of water bodies are negatively correlated to their geometry and the proportion of impervious surfaces, but positively correlated to the proportion of vegetation around them. The results suggest that with a fixed area of water body, the geometry of the water body should be relatively simple, the proportion of vegetation should be increased and the proportion of impervious surfaces should be reduced to realize good WCI effects. This provides useful implications for urban planners and designers to mitigate UHI effects.     

Effect of excess water in an oxisol on ammonium,nitrate, iron and manganese availability and nutrient uptake of two tropical forage species

Summary A glasshouse experiment was conducted to determine how reduction conditions would affect plant nutrient availability and uptake in a red-yellow latosol (Acrustox). Soil analysis showed that the most important changes were a marked increase in extractable iron and an inhibition of nitrification. The grass andropogon (Andropogon gayanus Kunth var.bisquamulatus (Hoechst) Hack) and the legume stylo (Stylosanthes capitata (Vog)) responded differently to reducing conditions.Andropogon showed low P, Ca, Mg, Fe and Mn content in the shoots but an intense coating of oxidized iron was observed on the surface of roots. Stylo plants, on the other hand, showed no iron deposition on the root surfaces but a high iron content in the shoots. No decreased P, Ca or Mg content was observed in this case. It was concluded that in water saturated soil, reduction took place and plant performance was affected not only by restricted root development but by preventing P, Ca and Mg uptake in andropogon and increasing Fe uptake in stylo plants. It is suggested that restricted P, Ca and Mg uptake by andropogen would be the result of iron deposition on root surfaces.     

Consecutive seasonal effect on yield and water productivity of drip deficit irrigated sorghum in saline soils

Drought stress destructively affects the growth and productivity of sorghum crop, especially under saline soils. Therefore, Field trials were performed to determine the influence of water stress on water productivity (water productivity for grain, (G-WP) and water productivity for forage, (F-WP), yield of sorghum and soil properties in salt-affected soil (8.20 dS m^?1) under different sowing dates and irrigation regimes. The summer sowing (SS) was performed on 1 April while fall sowing (FS) was established on 2 August. The irrigation regimes were; 100, 90, 80, and 70% of crop evapotranspiration (ETc). The findings displayed that the fodder and grain yields were increased by 23% and 26% under SS compared to FS over the two seasons 2017 and 2018, respectively. Among irrigation levels, the maximum values of grain and fodder yield were given by 100% of ETc, while a non-significant difference was observed between 100% and 90% of ETc. Moreover, the maximum values of G-WP (1.31%) and F-WP (9.00%) were recorded for 90% of ETc. Interestingly, the soil salinity was decreased in 0–0.6 m depth, and more decline was noted in 0–0.2 m depth using 90% of ETc. The highest salt accumulation withinside the soil profile was recorded under 70% of ETc in comparison to 100% of ETc. Thereupon, under water scarcity, application of 90% of ETc is recommended with SS to save 10% of the applied irrigation water without a significant decrease in grain yield (GY).     

土壤盐分及水分含量对落羽杉幼苗生长的影响

One year old Taxodium distichum seedlings were grown in pots with varied soil water and salt (NaC1) levels (alone and in combination) under greenhouse conditions to determine their effects on the growth and biomass allocation of the seedlings. The results showed that there were significant effects of soft salt and water contents on the relative height growth, relative stem diameter growth, biaomass increment and allocation, shoot/root ratio, seedling survival, ratio of branch to stem area, ratio of leaf mass to stem area, and ratio of leaf mass to branch area. According to the biomass increment, relative height growth and relative stem diameter growth, 20 treatments were classified into 3 groups by means of systematic cluster analysis. The first one was the treatments waterlogging, flooding, waterlogging 0.15% NaC1, flooding 0.15% NaC1, and waterlogging 0.3% NaC1, which had a high growth, the second one was the treatments flooding 0.45% NaC1, flooding 0.3% NaCl, 75% of field capacity, and 75% of field capacity 0.15% NaCl, which had a medium growth, and the last onewas the treatments 50% of field capacity, 50% of field capacity 0.15% Nat1, waterlogging 0.45% Nat1,25% of field capacity, 25% of field capacity 0.15% NaC1, 75% of field capacity 0.3% NaC1, 75% of field capacity 0.45% NaC1, 25% of field capacity 0.3% NaC1, 50% of field capacity 0.3% NaC1, 50% of field capacity 0.45% NaC1, and 25% of field capacity 0.45% NaC1, which had a poor growth.     

供水及间甲酚对小麦间作蚕豆土壤微生物多样性和酶活性的影响

通过盆栽试验,探讨供水(田间持水量的45%、60%和75%)和化感物质间甲酚对小麦、蚕豆不同种植模式生长盛期土壤微生物多样性和酶活性的影响.结果表明,随灌水水平的降低,不同处理的土壤细菌、真菌和放线菌数量随之减少,间甲酚可加剧灌水减少引起的微生物数量的减少;间甲酚对不同处理土壤微生物多样性指数均具有降低作用,提高灌水水平可缓解间甲酚对间作群体土壤微生物多样性的负效应,但间甲酚在75%灌水水平下对单作微生物多样性的负效应最大,45%的供水水平和间甲酚作用下间作可维持更高的土壤微生物多样性.间甲酚对土壤过氧化氢酶的化感作用不显著,对脲酶和酸性磷酸酶活性的化感作用显著;3种土壤酶活性随供水水平的降低均显著下降,但供水与间甲酚、种植模式的互作效应对酶活性的影响不显著;间作对土壤过氧化氢酶和酸性磷酸酶活性具有极显著影响.     

Soil and plant water relations in a crested wheatgrass pasture: response to spring grazing by cattle

Summary Few field studies have attempted to relate effects of actual livestock grazing on soil and plant water status. The present study was initiated to determine the effects of periodic defoliations by cattle during spring on soil moisture and plant water status in a crested wheatgrass (Agropyron cristatum (L.) Gaertn. and A. desertorum (Fisch. ex Link) Schult.) pasture in central Utah. Soil moisture in the top 130 cm of the soil profile was depleted more rapidly in ungrazed plots than in grazed plots during spring and early summer. Soil moisture depletion was more rapid in grazed plots in one paddock after 1 July due to differential regrowth, but there was no difference in soil water depletion between plots in another paddock during the same period. This difference in soil water depletion between paddocks was related to a difference in date of grazing. Although more water had been extracted from the 60 cm to 130 cm depths in ungrazed plots by late September, cumulative soil moisture depletion over the entire 193 cm profile was similar in grazed and ungrazed plots. Prior to 1 July, grazing had no effect on predawn leaf water potentials as estimated by a pressure chamber technique; however, after 1 July, predawn leaf water potentials were lower for ungrazed plants. Midday leaf water potentials were lower for grazed plants before 1 July, but did not differ between grazed and ungrazed plants after 1 July. A 4- to 8-day difference in date of defoliation did not affect either predawn or midday leaf water potentials. The observed differences in water use patterns during spring and early-summer may be important in influencing growth and competitive interactions in crested wheatgrass communities that are subject to grazing by domestic livestock.     

Long-term effect of superphosphate on accumulation of soil phosphorus and exchangeable cations on a grazed,irrigated pasture site

The annual herbage dry matter yield, herbage P concentrations and quantities of P, K, Mg and Ca cycled by grazing sheep were calculated for a 37 year-old grazed pasture supplied with superphosphate at rates of 0, 188 and 376 kg ha^-1 annually. The amount and distribution of inorganic and organic P and exchangeable K, Mg and Ca in the soil below the three grazed treatments was also measured and compared with that below a wilderness area which had not been used for agriculture. Increasing rates of superphosphate increased herbage dry matter yield, herbage P concentrations and thus the amounts of P ingested and, in turn, excreted by the grazing sheep. Annual quantities of K, Mg and Ca cycled back to the pasture in the form of excreta were also increased. The increased cycling of K by animals induced by increasing superphosphate applications resulted in greater losses of K and consequently concentrations of exchangeable and non-exchangeable ‘fixed’ K in soil decreased in the order wilderness > control > 188 > 376. Differences were evident to a depth of 20 cm. Some losses of Mg during cycling also occurred and concentrations of exchangeable Mg followed the order: wilderness > control >188=376. Concentrations of exchangeable Ca increased with pasture development due to additions of Ca in lime and superphosphate. Concentrations of total soil organic P (0–4 cm) increased in the order: wilderness < control <188<376 but for inorganic P and total P the control had a lower content than wilderness indicating losses of P during cycling in the grazed control treatment. Phosphorus fractionation suggested that with increasing superphosphate rates inorganic P primarily accumulated in a form adsorbed to Al hydrous oxides and as calcium phosphate compounds whilst organic P accumulated in both labile forms and forms associated with humic compounds. In the fertilised sites both inorganic and organic P accumulated in the soil profile to a depth of 20 cm.     

Variation and distribution of total mercury in water, sediment and soil from northern Lake Victoria, East Africa

Lake Victoria, the world's largest tropical freshwater lake, is an important resource, ecologically and economically. THg distribution in the northern parts of the lake are not well known, so to answer this gap, patterns in total mercury (THg) in water, soil and two dated sediment cores from northern Lake Victoria were determined. Water THg concentrations ranged from 0.7 to 5.8 ng/L, and there were no apparent differences observed between Napoleon and Winam Gulfs. Two precipitation samples had Hg concentrations of 7 and 31 ng/L. Surface soil samples collected from various agricultural sites around Jinja, Napoleon Gulf, have THg concentrations between 12.7 and 48.4 ng/g dry weight; they were correlated with organic carbon, total phosphorus and % clay. A near-shore core taken in Itome Bay in Napoleon Gulf, and an offshore core collected from the deepest part of the lake had similar THg concentrations and profiles (78 to 458 ng/g dry weight). The increase in THg concentration in the profiles of both cores began around 1960 and peaked around 1980. The similar sedimentary THg profiles and fluxes in the cores suggest that the THg sources to L. Victoria are primarily atmospheric, with some erosion inputs, and that equatorial African ecosystems are not exempt from the global increase in baseline THg concentrations.     

主要管理措施对人工林土壤碳的影响

人工林碳汇在全球碳循环及温室气体减排中发挥着重要作用。人工林是处于人为调控下的生态系统类型,经营管理措施是影响人工林土壤碳平衡的重要因素。通过科学合理的生态系统管理,增强人工林的土壤碳汇,对减缓气候变化具有十分重要的意义。本文综述了主要经营管理措施(造林树种、轮伐期、采伐、灌溉和施肥)对人工林土壤碳储量与碳通量影响的研究进展,结果表明:人工林经营管理措施可通过改变林地的温度、水分、养分和土壤结构,来影响土壤有机碳储量和土壤呼吸等碳循环过程。但目前人工林管理对土壤碳影响的研究还很不足,一些营林措施还未展开相关研究。未来应针对人工林管理措施对土壤碳的影响做更全面的定量研究。     

稻田不同水分管理方式对土壤线虫群落的影响

在下辽河平原地区就稻田不同水分管理方式对土壤线虫多度、营养类群、群落组成的影响进行了研究．结果表明,0～10cm土层不同水分管理处理的线虫总数在耙耕前和黄熟期显著低于对照,10～20cm土层各时期处理间线虫总数的差异不显著,20～30cm土层线虫总数在耙耕前和黄熟期差异极显著．北方单季稻水田试验共观察到土壤线虫16科22属．绕线属(Plectus)、垫刃属(Tylenchus)、单宫属(Monhystera)是优势属,绕线属和垫刃属对不同的水分管理比较敏感．在耙耕前和黄熟期不同水分管理方式对0～10cm土壤食细菌线虫能够产生显著影响．稻田土壤中食细菌线虫和植物寄生线虫是优势营养类群,而捕食／杂食性线虫的相对多度最低．     

A case study of energy,water and soil flow chains in an arid ecosystem

Little attention has been directed to the study of soil flow and the complex relationships among energy water and soil flow in terrestrial ecosystems. Soil plays an important role in arid ecosystems. After water soil is the second key factor in the development of an arid ecosystem since soil is the only part of the system capable of absorbing and storing water and nutrients during the hot and long summer period. The present work presents a case study of an ecological soil flow chain in an arid environment and analyses the relationship between this chain and the energy and water flow chains. The study was conducted at the Sde Boqer experiment site located in the northern Negev of Israel where average annual rainfall is 92 mn. Data collected during five consecutive years show that the soil movement process within the ecosystem studied cannot be considered as a purely physical phenomenon, but rather as a part of a complex system in which the burrowing and digging activity of Isopods and Porcupines plays an important role by providing disaggregated soil particles easy to remove by shallow flows. Although controlled by the spatial distribution of soil moisture the biological activity acts as a regulator of soil depth and thus of soil moisture. If this regulating role is deleted from the system a new ecosystem, more arid, can be expected to develop. It is therefore concluded that the study of state and flow variables of an arid ecosystem should consider altogether the water, soil, energy and mineral chains.     

Zinc,iron, and sodium in hair of deer from areas of contrasting soil productivity

The contribution of soils to animal biology through the soil’s effect on the ecosystem is an important concept in ecology. Zinc, Fe, and Na contents were determined in autumnal collections of hair of fawn white-tailed doe deer (Virginianus odocoileus) from two areas of contrasting soil productivity. The area-weighted soil productivity of one area was 40 compared with 79 for the other area. Hair collections were made in each of 8 consecutive years. The mean difference in dressed weight of fawn does collected from these areas in late autumn over 4 yr amounted to 7.2 kg. Some of this weight difference was presumed to be accounted for by a difference in the level of mineral nutrition because the amount of forage was not limiting in either area. Considering the total sample of 8 yr, the mean contents of Zn were 96 and 98, of Fe were 42 and 45, and of Na were 38 and 36 mg/kg for the respective areas. None of the elements was significantly different each year over the observation period. In 3 yr, at least one of the elements differed, and in 1 yr all three differed. The contents of the elements were not related to April through August precipitation, which was considered a measure of plant-available water thought to be important in mineral absorption by forage vegetation. Zinc was significantly different in 29 of the 56 between-year comparisons within areas; Fe differed in 2 and Na in 14 comparisons. The site of collection of the doe was known within a 2.6-km² area for about 80% of the samples for one of the areas and 90% for the other; therefore, either a soil series or soil association could be identified with the deer. Soils were grouped into two categories in each sampling area; the groupings reflected the intensity of weathering and leaching in one area, and in the other case where soil weathering was not as well developed, substantial soil taxonomic contrast related to grass or deciduous tree vegetation associated with soil development. Only Fe in hair from does collected in the more intensively weathered soil area was significantly different, perhaps reflecting higher levels of plant-available Fe made available to plants because of breakdown of Fe-bearing minerals.