Polish Soil Quality Standards Versus Risk-Based Soil Screening Levels for Metals and Arsenic

The main objective of the study was derivation of risk-based soil screening levels (RBSSLs) under two basic exposure scenarios—industrial and residential, and their comparison with the relevant soil quality standards (SQSs), applied in Poland as remedial targets. The RBSSLs were derived from standardized sets of equations that are based on the recently updated U.S. Environmental Protection Agency's human health risk assessment methods. The article presents the results concerning 12 contaminants listed in the SQS ordinance: arsenic, barium, cadmium, cobalt, chromium, copper, mercury, molybdenum, nickel, lead, tin, and zinc. Taking only the human health protection criterion into account, most of SQSs for non-carcinogenic metals under both industrial and residential scenarios seem to be too stringent if used as the remedial levels, which may lead to unnecessary remediation. On the other hand, the SQSs for carcinogenic contaminants (As, Cr^VI) correspond to cancer risk levels significantly higher than the acceptable level of 1E-06. The findings of the study may constitute the first step to justify the amendment of the Polish SQS ordinance aimed at establishing the new soil quality values based on clearly defined criteria.     

丘岗稻田地下水位动态及对土壤氮磷有效性的影响

对红壤丘岗区渍潜田地下水位动态变化规律及对土壤氮磷有效性的影响进行了研究。结果表明,渍潜田地下水位的月变化具有十分明显的规律性,一般以秋冬季节（1－3月份和9－12月份）地下水位最低,而以春夏季节（4－8月份）地下水位最高,故以早稻受渍害最为严重,其原因主要是受降雨和灌溉的共同影响。根据渍潜田地下水位的变化特点不同,可将其分为地下水位和相对稳定型和非稳定型两种类型,并提出了相应的水分管理模式,地下水位的变化能明显影响土壤养分的有效性,随着地下水位的升高,土壤有效氮和磷含量下降。渍潜田土Fe-P和O－P含量也有随地下水位的升高而呈下降的趋势,其含量亦显著低于非渍潜田土壤,因而导致了土壤磷素有效性的下降。     

Synergistic Effects of Organic Contaminants and Soil Organic Matter on the Soil-Water Partitioning and Effectiveness of a Nonionic Surfactant (Triton X-100)

Napthalene- and decane-contaminated soils were treated with Triton X-100 (a nonionic surfactant) to characterize the soil-water partitioning behavior of the surfactant in soils with different organic content. Soil samples with different organic content were prepared by mixing sand-mulch mixtures at different proportions. The experimental results indicated that the amount of surfactant sorbed onto soil increased with increasing soil organic content and increasing surfactant concentration. The effective critical micelle concentration (CMC) also increased with increasing organic content in soil. The CMC of Triton X-100 in aqueous systems without soil was about 0.3 mM and the effective CMC values measured for soil-water-surfactant systems (approximately 1:19 soil/water ratio) with 25%, 50%, and 75% mulch content were 0.9, 1.0, and 1.7 mM, respectively. Sub-CMC surfactant sorption was modeled accurately with both the Freundlich and the linear isotherm. The maximum surfactant sorption onto soil varied from 66% to 82% of added surfactant in the absence of contaminant. The effective CMC values for Triton X-100 increased to some extent in the presence of contaminants, as did the maximum surfactant sorption. The maximum surfactant sorbed onto the soil with 75% mulch content increased from 82% for clean soils, to 95% and 96% for soils samples contaminated with naphthalene and decane, respectively.     

EN CORE® Sampler Performance: Storing Soil for VOC Analysis

The En Core® sampler is designed to collect and store soil samples in a manner that minimizes loss of contaminants due to volatilization and/or biodegradation. Use of this device is described in American Society for Testing and Materials (ASTM) Practice D 6418, Standard Practice for Using the Disposable En Core Sampler for Sampling and Storing Soil for Volatile Organic Analysis. Two studies were performed to evaluate the performance of the En Core sampler to store VOC-contaminated soil for analysis. One study involved spiking soil samples with low concentrations of VOCs (less than 200?µg/kg) and storing them under various conditions prior to analysis. Results from this study show that the En Core sampler gives 80% or greater recoveries of low concentrations of VOCs from soil samples stored under a number of conditions. The second study was performed to generate data on the performance of the 25-g En Core sampler to store soil samples spiked with EPA Method 1311, Toxicity Characteristic Leaching Procedure (TCLP), volatile organic analytes. Results show that the En Core device gives 80% or greater recoveries of most of the Method 1311 volatile organic analytes from soil stored under various conditions for 14 days.     

Bioaccumulation of Inorganic Chemicals from Soil by Plants: Spiked Soils vs. Field Contamination or Background

Risk assessors are often cautioned against the use of tests of highly bioavailable salt solutions added to soil to estimate the bioaccumulation of chemicals from waste site soils by plants. In this investigation, a large number of laboratory and field studies that measured the bioaccumulation of inorganic chemicals in plants were reviewed. The objective was to discern whether or not the relationship between the concentration of the element in aboveground vegetation and that in soil was different if the contamination was aged in the field rather than freshly added to soil in salt solution. For two of the eight elements, selenium and cadmium, salt solution experiments were associated with greater soil-plant uptake ratios than field measurements. Thus, these are not reliable data for use in the derivation of plant uptake regressions for screening-level ecological risk assessments at field sites. In contrast, the plant uptake of arsenic, copper, lead, mercury, nickel, and zinc, when added in salt solutions, was generally within the 95% prediction limit of regressions derived from field data. Chemical form, plant taxon, soil type, experimental methodology, and aging may be as important as the source of the chemical in predicting plant uptake of inorganic chemicals from soil.     

Adsorption of RDX to Soil with Low Organic Carbon: Laboratory Results,Field Observations,Remedial Implications

The purpose of this article is to review both laboratory and field observations of RDX adsorption to soils and to use those results to estimate the effects of a planned remedial action. Adsorption isotherms for RDX are generally observed to be linear and reversible. Statistical tests were performed to determine the relationship between K_d and various soil characteristics. A linear relationship between Kd and soil organic carbon was observed, as expected, but regression of K_d to organic carbon content indicated a non-zero intercept, suggesting that other sorbents may also be significant at low OC (e.g., > 0.5 %). No other soil properties were significantly related to Kd so the mechanism of adsorption at low organic carbon was not determined. These results were used to interpret observations of RDX in the vadose zone at Milan Army Ammunition Plant (MAAP), TN. MAAP exhibits widespread soil contamination by RDX. Depth to groundwater ranges from 40 to 80?ft. Unsaturated soils are fine grained near the surface, and sandy near the water table. RDX is concentrated in the upper 2?ft, where concentrations in some places exceed 1 %. Subsurface concentrations are generally less than 50?mg/kg. The distribution of RDX in soil, soil moisture and groundwater, and soil physical testing data were interpreted using simple models. The distribution of RDX is consistent with the following conceptual model: ??Water containing RDX was dis charged to the land surface (prior to 1983); ??Crystalline RDX remains in surface soil (remedial activities are ongo ing); ??Infiltrating rainwater leaches RDX from surface soils; ??This leachate carries RDX through the deeper vadose zone, resulting in significant soil contamination through out the full thickness of the vadose zone; these soils can generate leachate and adversely affect ground- water quality for many years to come. Field results were consistent with the adsorption studies. Simple models consistent with the field and laboratory observations indicate that deeper soils that are not planned to be remediated may continue to leach unacceptable concentrations to groundwater for approximately 180 years. The Army intends to evaluate whether it will be most cost-effective to address this continuing source by treating soils or groundwater.     

Characteristics of Copper Sorption by Various Agricultural Soils in China and the Effect of Exogenic Dissolved Organic Matter on the Sorption

To explore the effect of exogenic dissolved organic matter (DOM) on Cu(II) sorption in agricultural soils, 26 agricultural soils were collected across China. Exogenic dissolved organic matter, extracting from wheat straw (DOM_W) and swine manure (DOM_S), respectively, were added to the soils to conduct a series of batch sorption and characterization experiments. The solid-liquid partition coefficient (K_d) ranged from 0.02 to 76.46 L g^?1, suggesting different Cu(II) sorption on various soils. PCA analysis indicated that pH, free Fe/Al oxides, carbon, and total Cu content had a significant positive relationship with the Cu(II) sorption, respectively. And the contribution rate of pH was the highest (38.15%). Moreover, DOM markedly inhibited the Cu(II) sorption in alkaline soils while promoted the Cu(II) sorption in acidic soils, which were interacted by the soil properties and DOM characteristics. The effect of DOM_S on Cu(II) sorption were more obvious than DOM_W, which were further confirmed by Fourier transform infrared (FTIR) spectroscopy. FTIR also showed Cu(II) was primarily adsorbed on the specific functional groups, such as CO, OH, and CO, providing direct evidences for the binding of Cu(II) with DOM. This study can guide the rational use of organic fertilizers, and also provide baseline knowledge for the prevention and control of soil pollution.     

Impacts of ISCO Persulfate,Peroxide and Permanganate Oxidants on Soils: Soil Oxidant Demand and Soil Properties

The consumption of in-situ chemical oxidation (ISCO) oxidant by soil oxidizable matter (OM), termed the soil oxidant demand (SOD), is an essential factor when designing treatments for successful remediation at an ISCO site. This study aims to assess the impact of different oxidants on SOD and the soil itself, using the Taguchi experimental design. Five oxidation systems, including persulfate (PS), hydrogen peroxide (HP), permanganate (PM), Fe²⁺ activated PS and Fe²⁺ activated HP, and four factors including oxidant concentration, activator concentration, reaction time, and pH were investigated. The results of the Taguchi analysis in this study show that oxidant concentration had the greatest effect on the SOD. Other factors also affected the SOD and the optimum conditions for achieving a lower SOD were determined using the Taguchi design method. Additionally, original and oxidized soils were analyzed using a scanning electron microscope equipped with an X-ray energy dispersive spectrometer to determine the surface morphology and chemical composition of the samples. Variations in soil organic carbon levels and total soil bacterial counts were recorded and the speciation of soil minerals (Fe, Mn, Cu, and Zn) was analyzed.     

Heterogeneous Catalytic Oxidation of Phenanthrene by Hydrogen Peroxide in Soil Slurry: Kinetics,Mechanism, and Implication

The degradation of phenanthrene sorbed on soil has been carried out using a H₂O₂/goethite heterogeneous catalytic oxidation process. The effect of operating variables, such as the goethite concentration, pH, H₂O₂ concentration, soil organic matter, and bicarbonate ions has been investigated. The reaction followed pseudo-first order kinetics. The rate constants were evaluated and varied between 2.0×10^?4 and 1.1×10^?3?min^?1 depending on the H₂O₂ concentration. The highest rate of degradation of phenanthrene was observed at a H₂O₂ concentration of 5?M and 134.0?g/kg goethite. The intermediate product formed during the degradation of phenanthrene was identified to be salicylic acid that finally degraded to CO₂ and H₂O. H₂O₂ consumption continued as the OH radical attacked the salicylic acid. More than 80% consumption of the 5?M H₂O₂ took place within 30?min, and the degradation was almost complete after 3?h of reaction. Neutral pH was found to be effective in the removal of phenanthrene. Both soil organic matter (SOM) and bicarbonate ions in the soil inhibited the oxidation rate of phenanthrene.     

Influence of Temperature and Oil Content on the Soil/Air Partition Coefficient for Hexachlorobenzene in Oil-Contaminated Rice Paddy Field Soil

The soil/air partition coefficients (K _SA ) for hexachlorobenzene (HCB) in oil-contaminated (crude oil and diesel) rice paddy field soils were measured in a solid fugacity meter at different oil concentrations over the temperature range of 5 to 30°C at 100% relative humidity. The results showed that values of K _SA increased with a decrease of temperature. As for oil content, there is a critical separate phase concentration (CSPC) above which K _SA increased with increasing of oil content. When oil content is above CSPC, oil plays a role as a separate phase that enhances the sorption capacity of the soil. At a given temperature (20°C) values of CSPC depended on the natural organic matter (NOM) contents of the soil, while for a given oil concentration they depended on the temperature. The normalized oil/air partition coefficients ) for HCB deduced from K _SA for oils and experimentally determined with crude oil/quartz sand system were similar and 0.7–7 times higher than the normalized organic/air partition coefficient ), which implied that oil was a super sorbent. The enthalpies (ΔH_SA) for crude oil and diesel were 64.9 and 55.7 kJ mol^?1, respectively.     

不同稻作制对红壤性水稻土中锰剖面分布的影响

为了探讨红壤性水稻土锰的迁移和转化行为,通过长达16a的定位试验研究了不同稻作制、有机肥以及地下水位对土壤剖面中全锰、活性锰和交换态锰分布的影响。试验结果表明,长期淹水种稻引起0-20cm土壤层次全锰、活性锰和交换态锰含量的显著下降,而在20－40cm和40－75cm土层相对累积。不同稻作制比较,0－20cm土层中全锰、活性锰和交换态锰含量以稻稻泡显著高于稻稻绿和稻稻油处理,而20－40cm和40－75cm土层3种锰形态的含量各稻作制之间无显著差异,表明实行水旱轮作的稻稻绿与稻稻油两种稻作制耕层土壤锰的淋溶损失比持续淹水的稻稻泡制更为严重。相对而言,不同有机肥施用水平和地下水位对土壤剖面中锰分布的影响要小于稻作制,总的趋势为：土壤剖面中锰的空间分异程度以高量有机肥＞常量有机肥＞单施化肥;低水位＞高水位。从土壤中锰的空间分布规律可以看出,水旱轮作（尤其是在低水位和有机无机配合的条件下）比长期淹水更有利于土壤锰氧化还原引起的深层淋溶与淀积,加速了典型水稻土剖面的形成。     

The Nature and Longevity of Agricultural Impacts on Soil Carbon and Nutrients: A Review

Since the domestication of plant and animal species around 10,000 years ago, cultivation and animal husbandry have been major components of global change. Agricultural activities such as tillage, fertilization, and biomass alteration lead to fundamental changes in the pools and fluxes of carbon (C), nitrogen (N), and phosphorus (P) that originally existed in native ecosystems. Land is often taken out of agricultural production for economic, social, or biological reasons, and the ability to predict the biogeochemical trajectory of this land is important to our understanding of ecosystem development and our projections of food security for the future. Tillage generally decreases soil organic matter (SOM) due to erosion and disruption of the physical, biochemical, and chemical mechanisms of SOM stabilization, but SOM can generally reaccumulate after the cessation of cultivation. The use of organic amendments causes increases in SOM on agricultural fields that can last for centuries to millennia after the termination of applications, although the locations that provide the organic amendments are concurrently depleted. The legacy of agriculture is therefore highly variable on decadal to millennial time scales and depends on the specific management practices that are followed during the agricultural period. State factors such as climate and parent material (particularly clay content and mineralogy) modify ecosystem processes such that they may be useful predictors of rates of postagricultural biogeochemical change. In addition to accurate biogeochemical budgets of postagricultural systems, ecosystem models that more explicitly incorporate mechanisms of SOM loss and formation with agricultural practices will be helpful. Developing this predictive capacity will aid in ecological restoration efforts and improve the management of modern agroecosystems as demands on agriculture become more pressing.     

The Influence of Soil Properties on the Mobility of Metals Following a Single Application of Polluted Sewage Sludge to Seventy Agricultural Topsoils: A Laboratory Column Study

The main aim of this study was to examine the influence of soil properties on the leaching of Cd, Cr, Cu, Ni, Pb, and Zn following the application of polluted sewage sludge to contrasting topsoils. Seventy agricultural soil samples from different parts of Spain were amended with a single dose of sewage sludge (equivalent to 50 t dry weight ha^?1) and a column study was performed under controlled conditions. After two, four, and six months of incubation, 283 ml of distilled water (equivalent to a rainfall event of 25 l m^?2) was applied. The leachates were then collected and analyzed for metals. For all of the soils considered, the pH was the most important parameter for the control of mobility metals (except for Cu, determined by the sand and soil organic carbon and only to a lesser extent by the soil pH r² = 0.604, p < 0.001) and was negatively related to all of the studied metals. For Pb and Zn, soil pH was the single soil property explaining their mobility (r² = 0.411, p < 0.001 for Pb; r² = 0.713, p < 0.001 for Zn) while for Cd, Cr and Ni, EC, sand and silt also appeared in the statistical models (r² = 0.753, p < 0.001 for Cd; r² = 0.366, p < 0.001 for Cr; r² = 0.784, p < 0.001 for Ni). In the basic soils, soil texture was the most important soil property controlling the mobility of metals (except for that of Pb, which it only weakly predicted). For the acidic-neutral soils, the soil pH was the most important soil property controlling metal mobility (except for that of Cr, which was mainly determined by the pseudo-total Cr content).     

Arctic Soil Respiration: Effects of Climate and Vegetation Depend on Season

Arctic ecosystems are important in the context of global climate change because the most rapid rises in air temperature are expected at high northern latitudes during winter. The presence of extensive soil carbon reserves in the Arctic suggests that substantial feedbacks to CO₂-induced climate change could occur if warming alters carbon cycling belowground. Characterization of the controls on regional patterns of belowground CO₂ release through the annual cycle is an important step towards evaluating potential feedbacks from arctic ecosystems to climate change. In this study, we assess seasonal control over the influences by climate and vegetation-type on CO₂ efflux from belowground in the Alaskan tundra. Our results indicate that climate had strong effects on belowground CO₂ release in both seasons. By contrast, vegetation-type had little impact on CO₂ efflux from belowground in winter but was the principal control in summer. Together, these results demonstrate that seasonality is a critical factor regulating climate and vegetation-type effects on belowground CO₂ release, which should be included in regional models of net carbon balance in arctic ecosystems. Received 8 December 1998; accepted 2 April 1999.     

Decreasing the Abundance of Juncus effusus on Former Agricultural Lands with Noncalcareous Sandy Soils: Possible Effects of Liming and Soil Removal

More and more agricultural land in the Netherlands is becoming available for ecological restoration projects. However, nutrient levels in the top layer of the soils are high because the agricultural lands have been heavily fertilized for decades. As drainage ditches are no longer maintained when agricultural use ends, the agricultural lands usually become much wetter. As a result, former agricultural soils tend to develop extensive monotonous stands of Juncus effusus , which have little value from an ecological point of view. In this article, we present the results of field measurements/observations and experiments to examine the relationship between nutrient availability and J. effusus growth. In addition, we present and discuss results of experiments to study the potential beneficial effects of liming. Our findings show that the growth of J. effusus on moist or wet soils seems to be strongly determined by the Olsen-P concentration in the soil. The restoration of diverse, species-rich vegetation types on former agricultural lands with a noncalcareous sandy soil will in most cases not be possible within a reasonable time span without topsoil removal. Liming might be a valuable additional measure to enhance the quality of the soil after topsoil removal, and to prevent mobilization of P to groundwater or surface water. If removal of the topsoil is considered to create P limitation, it is important to study P concentrations at various depths to establish the amount of soil that has to be removed.     

Steinernema feltiae (DD-136) and S. glaseri: Persistence in Soil and Bark Compost and Their Influence on Native Nematodes

Infective juveniles (J3) of the entomogenous nematodes Steinernema feltiae DD-136 (ca. 10,000 J3/100 ml) and S. glaseri (ca. 2,500 J3/100 ml) were incubated in steam-sterilized and nonsterilized sandy soil and bark compost for 8 weeks at 25 C. The nematodes were recovered by a two-step extraction procedure at 1-week intervals, and their infectivity to lepidopterous larvae (Spodoptera litura and Galleria mellonella) and their effect on the population and community of native nematodes in soil were determined. Survival of inoculated nematodes and mortality of insects were enhanced in sterilized media. Nonsterilized bark compost proved to be equally as suitable a medium as sterilized compost. In nonsterilized soil, the survival curve of S.feltiae declined more rapidly than that or S. glaseri which was less infective to insects despite its greater persistence even in nonsterilized soil. Soon after the addition of steinernematids to soil, the population of native nematodes showed a fluctuation with an increase in rhabditids and a decrease in other kinds of nematodes.