Influence of slope aspect on soil physico-chemical and biological properties in the mid hills of central Nepal

This study assessed the influence of slope aspect and land use on soil physio-chemical and biological properties (soil quality indicators) on contiguous south- and north-facing slopes of the mid hills in central Nepal, having the same climate, vegetation and parent material. In each aspect, two treatments (agriculture and forest) were chosen and four replicates taken for each treatment. Soil sample collection and microarthropod extraction was done according to the standard methodology: soil core samples (10 × 10 × 5 cm) and extraction with the modified Berlese–Tullgren funnel. The investigated soil variables were temperature, moisture, faunal abundance and diversity, organic matter, organic carbon, bulk density and pH. Except in a few cases, all considered soil properties showed significant differences between aspects and land use. Soils of the north-facing slope had higher SOC content, moisture, faunal abundance and diversity, and lower temperature and pH. Variations due to topographic aspect induced varied microclimates, causing differences in faunal abundance and diversity; soil moisture, temperature and organic matter trends affected soil fertility and ultimately soil quality. Further studies are required to clarify the complex interactions between soil properties (physio-chemical and biological), vegetation and slope aspect in Nepal, as well as to develop soil biological indicators as a tool to assist in sustainable land management.     

软水中EPS对铜管/磷酸盐体系溶解性铜释放的影响

以海藻酸钠模拟水体中的细胞外高聚物(EPS)，研究软水体系中海藻酸钠对铜管／磷酸盐缓蚀行为的影响，结果表明：低浓度海藻酸钠能明显提高软水一铜管一磷酸盐体系中溶解性铜的释放，从而降低磷酸盐对铜管的缓蚀效果，而且从新管释放的溶解性铜远高于老化6个月、12个月和10年的铜管，释放溶解铜的顺序为Cnew＞C6m＞C12m＞C10y；随着海藻酸钠含量的增加，溶解性铜的释放浓度降低，但仍高于对照试验．在低pH条件下，海藻酸钠对溶解性铜的释放影响显著，从新管释放的溶解性铜浓度低于老化6个月、12个月和10年的铜管，这可能是由于不同老化时间的铜管其腐蚀表面的组成不同，水质pH值明显影响这些腐蚀副产物的溶解性铜释放；在不同停留时间内，随着水体组成的变化，溶解性铜的释放浓度不断发生变化，表明海藻酸钠与铜离子形成的络合物影响磷酸与铜的相互作用，从而影响磷酸盐对铜管的缓蚀效果．     

Synergistic effects of sodium hypochlorite disinfection and iron-oxidizing bacteria on early corrosion in cast iron pipes

• The early corrosion process in the cast iron pipes was investigated. • The increase of NaOCl (<0.75 mg/L) accelerated the cast iron corrosion. • Biocorrosion caused by IOB could be divided into three stages in the early stage. • Synergistic and antagonistic effects exist between residual chlorine and IOB. Corrosion in drinking water distribution systems (DWDSs) may lead to pipe failures and water quality deterioration; biocorrosion is the most common type. Chlorine disinfectants are widely used in DWDSs to inhibit microorganism growth, but these also promote electrochemical corrosion to a certain extent. This study explored the independent and synergistic effects of chlorine and microorganisms on pipeline corrosion. Sodium hypochlorite (NaOCl) at different concentrations (0, 0.25, 0.50, and 0.75 mg/L) and iron-oxidizing bacteria (IOB) were added to the reaction system, and a biofilm annular reactor (BAR) was employed to simulate operational water supply pipes and explain the composite effects. The degree of corrosion became severe with increasing NaOCl dosage. IOB accelerated the corrosion rate at an early stage, after which the reaction system gradually stabilized. When NaOCl and IOB existed together in the BAR, both synergistic and antagonistic effects occurred during the corrosion process. The AOC content increased due to the addition of NaOCl, which is conducive to bacterial regrowth. However, biofilm on cast iron coupons was greatly influenced by the disinfectant, leading to a decrease in microbial biomass over time. More research is needed to provide guidelines for pipeline corrosion control.     

Oxidation of sulphite originating from flue gas desulphurization waste in soil

The rate of catalyzed oxidation of sulphite originating from flue gas desulphurization (FGD) waste was studied under varying conditions. The pH dependence was examined in aqueous solution at the pH range of 5 to 8, the effect of soil moisture was studied in sieved soil of different moisture contents, and the oxidation of sulphite to a soil as FGD waste, was measured at different depths in a field experiment. The experiments that the half-lives of sulphite in aqueous solution were between 0.5 and 2 hours and that the oxidation rate was highest at the lowest pH. In sieved soil the half-lives of sulphite were in the range of 3 to 20 days with the oxidation rate at the highest moisture content, indication that oxygen availability was the limiting factor. The slowest decrease of the sulphite concentration was found at a soil depth of 8–10 cm which was the where the highest background concentration of sulphite was found in control plots, too.Environmental Geochemistry and Health, 1988,10(1), 26–30     

水稻秸秆沟埋还田对麦田土壤环境的影响

通过大田试验,采用秸秆沟埋还田方式,设置沟埋深度分别为20、30、40、50 cm及对照5个处理,将上季作物秸秆进行全量还田(秸秆沟埋量为2 kg.m-1),研究水稻秸秆沟埋还田对麦田土壤含水量、温度、容重和孔隙度等的影响。结果表明,降水结束后12 d内,沟埋深度20和30 cm处理土壤含水量(与埋草沟边水平距离10 cm处)显著下降(P<0.05);而沟埋深度40和50 cm处理土壤含水量(与埋草沟边水平距离10 cm处)与对照差异未达显著水平。埋草沟秸秆下层土壤温度变化较小,秸秆对下层土壤具有保温作用;除沟埋深度20 cm处理外,其他不同沟埋深度处理均能明显降低秸秆上层土壤容重,增加土壤总孔隙度,使耕层土壤疏松。     

Soil characteristics and their potential thresholds associated with <Emphasis Type="Italic">Scirpus mariqueter</Emphasis> distribution on a reclaimed wetland coast

We studied various soil characteristics associated with Scirpus mariqueter growth and spatial heterogeneity in the Shanghai Nanhui Dongtan wetlands. In September and October 2015, 12 soil characteristics (soil organic carbon, total phosphorus, total nitrogen, nitrate, nitrite, ammonia, orthophosphate, pH, moisture content, particle size, salinity, and tidal elevation) were analyzed from 101 soil samples. The key factors affecting S. mariqueter spatial distribution were determined using canonical correspondence analysis and curve-fitting analysis. Results showed that vegetation indices of height, cover, density, and biomass were positively correlated (P?<?0.05) with tidal flat elevation. S. mariqueter was mainly distributed at tidal flat elevations of 2.0–3.4 m. Plant coverage and density were positively correlated (P?<?0.05) with total nitrogen and soil salinity. Based on the curve-fitting and independent samples t-test analyses, thresholds of total nitrogen, conductivity, and tidal flat elevation of soil were 0.5475 g/kg, 0.8368 μS/cm, and 2.75 m, respectively. This study provides critical data for future coastal wetland remediation worldwide.     

Changes in desert steppe soil culturable bacteria from northwestern China and correlation with physicochemical parameters

Seasonal variations effects on desert steppe soil culturable bacteria in northwestern China and physicochemical parameters were investigated. Soil temperature ranged from 5.37 to 23.73 °C. Moisture content varied from 3.22% to 7.62%. The pH was between 7.98 and 8.72. Soil nutrients were altered in different seasons. Total potassium (K) remained the same, but available K levels ranged from 101.29 to 227.55 mg/kg. The culturable bacterial counts in January, April, July and October were 0.13 × 10⁷, 4.09 × 10⁷, 5.33 × 10⁷ and 1.8 × 10⁷ colony forming units (cfu)/g, respectively. Bacterial populations were most abundant in surface layers and declined with increase of soil depth. Seventy-two bacterial strains were isolated and classified according to 27 genera of 5 phyla groups: Firmicutes, Actinobacteria, Alphaproteobacteria, Gammaproteobacteria and Bacteroidates. The bacterial diversities varied according to seasons. In spring, only Firmicutes and Actinobacteria were isolated. In summer, Firmicutes, Actinobacteria and Bacteroidetes were detected with Firmicutes the dominant species. In autumn and winter, Firmicutes, Actinobacteria, α-Proteobacteria and γ-Proteobacteria predominated. Our results indicated that climatic variations, vegetation coverage and soil physicochemical parameters are critical factors for maintaining culturable bacterial populations and diversity in the desert steppe. Soil moisture content and temperature exerted marked influence on bacterial quantities and diversities.     

Optimal sequestration of carbon dioxide and phosphorus in soils by gypsum amendment

Gypsum has been applied as a natural fertilizer and soil amendment for centuries in agriculture for providing crop nutrients such as Ca and S, and for improving soil physical properties. Recently, gypsum has been tested for sequestrating CO₂ from the air and for capturing soluble phosphates in the soil, through formation of insoluble calcium phosphates and carbonates. However, the environmental factors controlling these sequestration processes have not been systemically studied. Here, we calculate optimal conditions of sequestration using chemical equilibrium modeling. Our results show that CO₂ carbonation is effective at pH higher than 8.5 at atmospheric concentration. The removal of P is higher than 80 % for pH higher than 6.4, when Ca and P are at stoichiometric ratio. Also, placement of gypsum in subsoil is more effective for CO₂ capture than applying it on soil surface since soil pores often contain higher concentrations of CO₂ due to the soil respiration process. Overall, increases in medium pH, gypsum application rate, or CO₂ partial pressure can increase the effectiveness of the amendment.     

Medical geology of endemic goiter in Kalutara,Sri Lanka; distribution and possible causes

This study assesses the distribution of goiter in the Kalutara District, Sri Lanka in order to find causative factors for the occurrence of goiter even after the salt iodization. A questionnaire survey was conducted at the household level and at the same time iodine and selenium levels of the water sources were analyzed. Questionnaire survey results indicated the highest numbers of goiter patients in the northern part where the lowest were found in the southern sector which may be due to the presence of acid sulfate soils. Females were more susceptible and it even showed a transmittance between generations. Average iodine concentrations in subsurface water of goiter endemic regions are 28.25 ± 15.47 μg/L whereas non-goiter regions show identical values at 24.74 ± 18.29 μg/L. Surface water exhibited relatively high values at 30.87 ± 16.13 μg/L. Endemic goiter was reported in some isolated patches where iodine and selenium concentrations low, latter was <10 μg/L. The formation of acid sulfate soils in the marshy lands in Kalutara district may lead to transformation of biological available iodine oxidation into volatile iodine by humic substances, at the same time organic matter rich peaty soil may have strong held of iodine and selenium which again induced by low pH and high temperature were suggested as the instrumental factors in the endemic goiter in Kalutara district. Hence, geochemical features such as soil pH, organic matter and thick lateritic cap in the Kalutara goiter endemic area play a role in controlling the available selenium and iodine for food chain through plant uptake and in water.     

Heavy metals and soil microbes

Heavy metal pollution is a global issue due to health risks associated with metal contamination. Although many metals are essential for life, they can be harmful to man, animal, plant and microorganisms at toxic levels. Occurrence of heavy metals in soil is mainly attributed to natural weathering of metal-rich parent material and anthropogenic activities such as industrial, mining, agricultural activities. Here we review the effect of soil microbes on the biosorption and bioavailability of heavy metals; the mechanisms of heavy metals sequestration by plant and microbes; and the effects of pollution on soil microbial diversity and activities. The major points are: anthropogenic activities constitute the major source of heavy metals in the environment. Soil chemistry is the major determinant of metal solubility, movement and availability in the soil. High levels of heavy metals in living tissues cause severe organ impairment, neurological disorders and eventual death. Elevated levels of heavy metals in soils decrease microbial population, diversity and activities. Nonetheless, certain soil microbes tolerate and use heavy metals in their systems; as such they are used for bioremediation of polluted soils. Soil microbes can be used for remediation of contaminated soils either directly or by making heavy metals bioavailable in the rhizosphere of plants. Such plants can accumulate 100 mg g^?1 Cd and As; 1000 mg g^?1 Co, Cu, Cr, Ni and 10,000 mg g^?1 Pb, Mn and Ni; and translocate metals to harvestable parts. Microbial activity changes soil physical properties such as soil structure and biochemical properties such as pH, soil redox state, soil enzymes that influence the solubility and bioavailability of heavy metals. The concept of ecological dose (ED₅₀) and lethal concentration (LC₅₀) was developed in response to the need to easily quantify the influence of pollutants on microbial-mediated ecological processes in various ecosystems.     

灌淤土施氮后土壤硝态氮的动态变化

通过室内模拟试验,探讨不同水分条件下灌淤土施用不同氮肥后硝态氮随时间的变化规律,并在田间条件下,测定不同氮肥形态和数量对土壤硝态氮含量的影响。灌淤土施氮后土壤硝态氮含量变化与土壤含水量及氮肥种类有关。施肥9d后,土壤中的硝态氮迅速增加;土壤水分低于田间持水量的50%或水分过饱和都明显影响灌淤土的硝化作用;施用大颗粒尿素产生的硝态氮最少,淋失或流失的几率小。灌淤土土体中硝态氮的残留与施氮种类及数量有直接关系。施肥使土壤表层硝态氮显著增加,施用大颗粒尿素尤为突出,但施大颗粒尿素后,60cm土体中残留的硝态氮总量最少。随着施氮量增加,表层土体中硝态氮含量增加。合理的施肥水平一般不会造成硝态氮的大量累积,而过量施氮则导致硝态氮明显积累,对通气透水性好的灌淤土,容易造成硝态氮淋失。     

Impact of natural and calcined starfish (<Emphasis Type="Italic">Asterina pectinifera</Emphasis>) on the stabilization of Pb,Zn and As in contaminated agricultural soil

Metal stabilization using soil amendments is an extensively applied, economically viable and environmentally friendly remediation technique. The stabilization of Pb, Zn and As in contaminated soils was evaluated using natural starfish (NSF) and calcined starfish (CSF) wastes at different application rates (0, 2.5, 5.0 and 10.0 wt%). An incubation study was conducted over 14 months, and the efficiency of stabilization for Pb, Zn and As in soil was evaluated by the toxicity characteristic leaching procedure (TCLP) test. The TCLP-extractable Pb was reduced by 76.3–100 and 91.2–100 % in soil treated with NSF and CSF, respectively. The TCLP-extractable Zn was also reduced by 89.8–100 and 93.2–100 % in soil treated with NSF and CSF, respectively. These reductions could be associated with the increased metal adsorption and the formation of insoluble metal precipitates due to increased soil pH following application of the amendments. However, the TCLP-extractable As was increased in the soil treated with NSF, possibly due to the competitive adsorption of phosphorous. In contrast, the TCLP-extractable As in the 10 % CSF treatment was not detectable because insoluble Ca–As compounds might be formed at high pH values. Thermodynamic modeling by visual MINTEQ predicted the formation of ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O) and portlandite (Ca(OH)₂) in the 10 % CSF-treated soil, while SEM–EDS analysis confirmed the needle-like structure of ettringite in which Pb was incorporated and stabilized in the 10 % CSF treatment.     

贺兰山东坡典型植物群落土壤微生物量碳、氮沿海拔梯度的变化特征

土壤微生物量是陆地生态系统碳循环的重要组成部分,在生态系统物质循环和能量转化中占有特别重要的地位。开展土壤微生物量与海拔高度的关系的研究,能促使人们对土壤微生物空间分布格局及其形成机制的认识,预测全球变化对生态系统功能的影响。本文对贺兰山不同海拔梯度具有代表性的荒漠化草原（HM）、蒙古扁桃灌丛（BT）、油松林（YS）、青海云杉林（QH）和高山草甸（CD）等5种植物群落土壤微生物生物量及其微生物商进行了研究。结果表明：表层土壤（0～20 cm）微生物生物量碳（MBC）、氮（MBN）大小次序为：CD〉QH〉YS〉BT〉HM,MBC、MBN随海拔梯度的升高显著增加,与土壤有机碳、氮含量有着一致的变化规律,但是微生物商（qMB）表现出沿海拔梯度先增加后减小的变化趋势,最大值出现在蒙古扁桃灌丛土壤,MBC/MBN则没有明显的变化规律。相关分析表明,不同海拔高度的土壤微生物量碳氮不仅与年均降水量、土壤含水量,而且与土壤有机碳、全氮呈显著线性正相关关系（P〈0.01）,但是与年均气温、土壤容重呈显著线性负相关关系（P〈0.01）。贺兰山土壤微生物量碳、氮随海拔高度升高而增加,降水量、气温、土壤湿度、土壤有机碳和全氮可能是影响土壤微生物量沿海拔梯度变化的关键因子。     

Phytoremediation of bauxite-derived red mud by giant reed

In 2010 the pond dam of an aluminium manufacturing plant in Hungary broke and flooded many towns with toxic red mud. At least 10 people were dead and over 150 hospitalized. Bauxite residue is often referred as red mud due to the colour of the bauxite ore and iron oxides. Red mud is separated during the refining process. The production of 1 t of alumina generally results in the creation of 1–1.5 t of red mud. Red mud is toxic for the environment due to high alkalinity, salinity and trace metals. Here, we used the plant Arundo donax L. (giant reed) to uptake trace metals and decrease salinity and pH of red mud. We measured plant toxicity, trace metal availability and biomass production. Results show a 25 % decrease in electrical conductivity of red mud and a 6 % decrease in electrical conductivity of mud-polluted soil. Giant reed cultivation decreases available Cd, Pb, Co, Ni and Fe. Biomass of giant reed seedlings in red mud and mud/control soil mixture was increased by 40.4 and 47.2 %, respectively, comparing with control soil. Our findings show that giant reed is promising to decontaminate soils contaminated by red mud.     

Abiotic control on the dissipation of chlorpyrifos spiked in an Udic Ferrisol at a lower dosage

The dissipation routes of chlorpyrifos spiked in an Udic Ferrisol at the dosage of 400 ng g^?1, which represents a residual level after an agricultural application, were studied in a laboratory, using the natural soil under three moisture regimes, sterilised, and organic matter-free soils in the dark at 20°C. The obtained results showed that higher soil moisture caused faster dissipation, and the abiotic and biotic contributions to the total dissipated amount of the applied chlorpyrifos in the soil accounted for 77.3–85.2% and 14.7–22.7%, respectively. In the sterilised soil, the contribution of organic matter to chlorpyrifos dissipation was noticed to account for 95% in the earlier two weeks, and was nearly equal to that of soil minerals two weeks after the incubation.     

碳酸盐岩山地土壤施用有机肥的溶蚀作用探讨

选择碳酸盐岩山地常见耕植、未耕植土层,通过概化制作为系列模拟柱试验土层,按当地正常施肥方法,向土层定量施入有机肥并浇灌及控制其它相关条件变化,再定期观测预埋土层不同深度碳酸岩石片的溶蚀量和土层其它指标的变化,作了施用有机肥的土中碳酸岩石溶蚀变化研究。结果揭示,在未耕植红黏土表层施用有机肥,大大减弱了土中碳酸岩石的溶蚀作用,且减弱程度随土深加大而降低。但对其下伏碱性岩粉层而言,施肥又引起了溶蚀量的微小增加变化;另在耕植土表层施用有机肥,对其土中碳酸岩石的溶蚀作用改变不大,且无论施肥与否溶蚀作用随土深加大又略显增大变化。而其下部红黏土中碳酸岩石的溶蚀量要远大于耕植土中的溶蚀量,并受施肥的影响较小。表明,农业施肥对未耕植土土中包被、包裹的碳酸岩石溶蚀影响较大,对下伏碱性岩粉层的层中、层下碳酸岩石的溶蚀影响较小。同时,施肥对耕植土土中、土下碳酸岩石的溶蚀影响不大。人类可采取禁令开垦较薄土层措施,来有效规避耕作施肥对土中碳酸岩石溶蚀作用的抑制,减少反石漠化的不利因素。此将为丰富碳酸盐岩山地成土演化理论和石漠化灾害的防治提供依据。     

Gypsum addition to soils contaminated by red mud: implications for aluminium, arsenic, molybdenum and vanadium solubility

Red mud is highly alkaline (pH 13), saline and can contain elevated concentrations of several potentially toxic elements (e.g. Al, As, Mo and V). Release of up to 1 million m³ of bauxite residue (red mud) suspension from the Ajka repository, western Hungary, caused large-scale contamination of downstream rivers and floodplains. There is now concern about the potential leaching of toxic metal(loid)s from the red mud as some have enhanced solubility at high pH. This study investigated the impact of red mud addition to three different Hungarian soils with respect to trace element solubility and soil geochemistry. The effectiveness of gypsum amendment for the rehabilitation of red mud-contaminated soils was also examined. Red mud addition to soils caused a pH increase, proportional to red mud addition, of up to 4 pH units (e.g. pH 7 → 11). Increasing red mud addition also led to significant increases in salinity, dissolved organic carbon and aqueous trace element concentrations. However, the response was highly soil specific and one of the soils tested buffered pH to around pH 8.5 even with the highest red mud loading tested (33 % w/w); experiments using this soil also had much lower aqueous Al, As and V concentrations. Gypsum addition to soil/red mud mixtures, even at relatively low concentrations (1 % w/w), was sufficient to buffer experimental pH to 7.5–8.5. This effect was attributed to the reaction of Ca²⁺ supplied by the gypsum with OH^? and carbonate from the red mud to precipitate calcite. The lowered pH enhanced trace element sorption and largely inhibited the release of Al, As and V. Mo concentrations, however, were largely unaffected by gypsum induced pH buffering due to the greater solubility of Mo (as molybdate) at circumneutral pH. Gypsum addition also leads to significantly higher porewater salinities, and column experiments demonstrated that this increase in total dissolved solids persisted even after 25 pore volume replacements. Gypsum addition could therefore provide a cheaper alternative to recovery (dig and dump) for the treatment of red mud-affected soils. The observed inhibition of trace metal release within red mud-affected soils was relatively insensitive to either the percentage of red mud or gypsum present, making the treatment easy to apply. However, there is risk that over-application of gypsum could lead to detrimental long-term increases in soil salinity.     

Characteristics of soil micro-and macro-arthropods and soil properties in Songnen Grassland of China during different periods of freeze–thaw season

ABSTRACT

Soil properties have an important influence on soil fauna in the grassland ecosystem. However, the relationship between the structural characteristics of soil fauna and properties in the grassland ecosystem in freeze–thaw season remains unclear. Hence, the feature of soil arthropods and properties in Songnen Grassland of China were investigated in fall–winter alternating (T1), completely frozen (T2) and winter–spring alternating periods (T3) during freeze–thaw season in three years. Results showed slight differences in the community composition of soil animals with Oribatida, Prostigmata and Mesostigmata as co-dominant groups in all sampling periods. The total number of individuals of soil arthropod at low temperature was low. The pH value, electrical conductivity (EC), and moisture content had the same order of T3?>?T2?>?T1. The activities of invertase and urease increased with increasing soil temperature, whereas protease activity had no relationship with soil temperature, soil moisture, EC and soil organic matter (SOM), activities of protease and urease were principal factors affecting individual abundance of soil animals. The sequence of their effect degrees was moisture content > EC > SOM > protease activity > urease activity. The changes in the quantitative characteristics of soil animals were related to soil properties. Therefore, soil properties can affect the structural characteristics of soil arthropod in the Songnen Grassland of China in the freeze–thaw season.     

Vegetation competition model for water and light limitation. I: Model description, one-dimensional competition and the influence of groundwater

Vegetation growth models often concentrate on the interaction of vegetation with soil moisture but usually omit the influence of groundwater. However the proximity of groundwater can have a profound effect on vegetation growth, because it strongly influences the spatial and temporal distribution of soil moisture and therefore water and oxygen stress of vegetation. In two papers we describe the behavior of a coupled vegetation-groundwater-soil water model including the competition for water and light. In this first paper we describe the vegetation model, compare the model to measured flux data and show the influence of water and light competition in one dimension. In the second paper we focus on the influence of lateral groundwater flow and spatial patterns along a hillslope. The vegetation model is based on a biophysical representation of the soil-plant-atmosphere continuum. Transpiration and stomatal conductance depend both on atmospheric forcing and soil moisture content. Carbon assimilation depends on environmental conditions, stomatal conductance and biochemical processes. Light competition is driven by tree height and water competition is driven by root water uptake and its water and oxygen stress reaction. The modeled and measured H₂O and CO₂ fluxes compare well to observations on both a diurnal and a yearly timescale. Using an upscaling procedure long simulation runs were performed. These show the importance of light competition in temperate forests: once a tree is established under slightly unfavorable soil moisture conditions it can not be outcompeted by smaller trees with better soil moisture uptake capabilities, both in dry as in wet conditions. Performing the long simulation runs with a background mortality rate reproduces realistic densities of wet and dry adapted tree species along a wet to dry gradient. These simulations show that the influence of groundwater is apparent for a large range of groundwater depths, by both capillary rise and water logging. They also show that species composition and biomass have a larger influence on the water balance in eco-hydrological systems than soil and groundwater alone.     

土壤锌自然消减的研究进展

从影响土壤锌自然消减的因素方面，阐述了锌自然消减的研究进展。土壤锌自然消减受温度、水分、pH值、有机质、改良剂、化学肥料、栽培植物等因素的影响。温度降低、pH升高和淹水均使土壤中锌的有效性降低。种植超积累植物如遏蓝菜、紫花苕子、印度芥菜等，可以超量吸收土壤中的锌，加速锌的消减。土壤中的某些动物和微生物有吸收利用锌的特性，蚯蚓对锌有良好的富集作用。采取农业措施如施用有机肥、化肥、加入改良剂，栽培植物等，都能降低污染土壤中锌的有效性。文章还提出了该方面今后的研究重点。