Salt Pollution Research Articles

Removal of Hazardous Cationic Salt Pollutants During Electrochemical Treatment from Contaminated Mixed Heterogeneous Saline Soil

Salt-affected soils are found mainly in arid and semiarid regions. In these areas, weak precipitation rate causes salt accumulation at high level on the soil surfaces, leading to drastic modifications in soil properties, affecting hence the environment, human health and civil engineering infrastructure and facilities. This research aimed to study the performance of the electrochemical treatment on removal of hazardous cationic salt including sodium, potassium and magnesium cations. The novelty of this work lies in the investigation of the potential of electroosmosis phenomenon as a driving vector in the removal of cationic hazardous salt during its regularized path toward the cathodic area. Therefore, a controlled-permanent analysis of contaminated catholyte water over processing time was achieved, in order to understand the evolution of contaminant removal during treatment time via the electroosmosis process. For this purpose, five relevant indices were evaluated, including electric current, electroosmotic flow, pH, electrical conductivity and cationic hazardous salt removal efficiency. Experimental tests were conducted in laboratory-designed cell using different electric potential difference for a total period of 8 days. Owing to the electroosmosis phenomenon, salt contaminants migrated and accumulated in the catholyte chamber, facilitating thereby their removal. Among these contaminants, sodium and potassium exhibit the highest decontamination efficiency with a rate of 88 and 85%, respectively. Magnesium ions show moderate removal with a percentage of 53%, due to the pH gradient, degree of hydration, ionic valence and mobility. The results demonstrate that the electrochemical treatment may be an efficient method for remediation of saline low-permeable heterogeneous soils.

An innovative procedure for testing RTV and composite insulators sampled from service in search of diagnostic quantities

The proven reliability of ceramic cap-and-pin insulators for high voltage (HV) and extra-high voltage (EHV) overhead lines suffers in the presence of harsh industrial or strong salt pollution [1]. In these cases, apart from the countermeasures such as increasing creepage distance, washing, and applying greases, insulators with a silicone rubber surface have demonstrated better performance [2]. The two alternatives for having insulators with a polymeric surface are (1) composite insulators, which consist of an inner fiberglass rod and an outer silicone rubber housing, and (2) precoated toughened glass cap-and-pin insulators with room temperature vulcanized (RTV) silicone rubber coating, hereafter referred to as RTV insulators.

Quaternary Landforms and Basin Morphology Control the Natural Eutrophy of Boreal Lakes and Their Sensitivity to Anthropogenic Forcing

Both natural and anthropogenic changes in boreal lakes have been studied utilizing paleolimnological methods, but the spatial variation in the natural conditions of lakes and its connection to geological factors has drawn less attention. Our aims were to examine the spatial distribution of naturally eutrophic lakes on the previously glaciated terrain of central-eastern Finland and the relationship between pre-human disturbance water quality and geological factors related to the basins and their catchments. Furthermore, we studied the pre- to post-human disturbance changes in the diatom assemblages and water quality of 48 lakes (51 sampling sites) across the pre-disturbance phosphorus gradient by using the top-bottom sampling approach and multivariate statistics. According to our results, naturally eutrophic boreal lakes are more common than previously thought, occurring on fine-grained and organic Quaternary landforms, including fine-grained till. Our study emphasizes the importance of the previously overlooked matter of till grain-size variation as a driver behind the spatial variation in the natural trophic states of boreal lakes. The location of a lake in the hydrologic landscape and basin morphology appear to be important factors as well. Shallow, naturally eutrophic lakes with short water residence times and high catchment area to lake area and volume ratios have been particularly sensitive to anthropogenic forcing. Our results indicate that cultural eutrophication is not the only water protection challenge for the relatively remote and dilute boreal lakes, but salinization and alkalinization are also serious threats that should be taken into account. Therefore, it is crucial to consider the notable variation in the natural conditions of boreal lakes in addition to mitigating the effects of anthropogenic forcing, such as nutrient loading, catchment erosion, salt pollution, and climate change, in order to achieve efficient water protection.

Assessment of Bioavailability of Some Heavy Metals to Wheat and Faba Bean in Sahl El-Tina, Egypt

Accumulation of heavy metals viz., Mn, Zn, Cu, Ni, Pb, Co, Cd and Cr in soils and commonly grown crop plants (wheat and faba bean) was studied in the fields in Sahl El-Tina, located in the Northwestern Sinai Peninsula, Egypt. Irrigation water at different sites was slight to moderately saline with no sodium hazard. About 50% of irrigation water samples revealed salt combinations consisting of NaCl, MgCl2, MgSO4, CaSO4 and Ca(HCO3)2, thereby indicating marine salt pollution. The results also revealed that heavy metals in irrigation and drainage water were within the recommended levels. The total contents of Ni, Pb, Co and Cd in subsoil samples were higher than the levels in topsoil samples, suggesting strong evidence of indigenous supply. However, total contents of Mn, Zn, Cu and Cr in topsoil samples were higher than the levels in subsoil samples, implying anthropogenic source of contamination. The highest single-element pollution index value in soil was found for Cd, which ranged from 0.289 to 3.763, indicating low to high contamination levels. Except for Zn and Pb which showed low contamination level, other elements showed low to moderate contamination levels in soil. The combined pollution index ranged from 0.238 to 1.688, indicating low to moderate multi-element contamination levels in soil. Except for Zn and Cd, the levels of heavy metals in wheat and faba bean were greater than the permissible limits. The highest transfer coefficients of metals from soil to plant were found for Zn and Cd in wheat. On the other hand, the highest coefficients in faba bean were found for Pb, Cd, Zn and Cu. Faba bean showed the ability to accumulate heavy metals in higher amounts than wheat. It was evident that there is a multi-element pollution source for the growing crops in Sahl El-Tina that could be due to the anthropogenic activities in respect of some elements but inherently for others.

Seasonal pattern of anthropogenic salinization in temperate forested headwater streams

Salinization of freshwaters by human activities is of growing concern globally. Consequences of salt pollution include adverse effects to aquatic biodiversity, ecosystem function, human health, and ecosystem services. In headwater streams of the temperate forests of eastern USA, elevated specific conductance (SC), a surrogate measurement for the major dissolved ions composing salinity, has been linked to decreased diversity of aquatic insects. However, such linkages have typically been based on limited numbers of SC measurements that do not quantify intra-annual variation. Effective management of salinization requires tools to accurately monitor and predict salinity while accounting for temporal variability. Toward that end, high-frequency SC data were collected within the central Appalachian coalfield over 4 years at 25 forested headwater streams spanning a gradient of salinity. A sinusoidal periodic function was used to model the annual cycle of SC, averaged across years and streams. The resultant model revealed that, on average, salinity deviated approximately ±20% from annual mean levels across all years and streams, with minimum SC occurring in late winter and peak SC occurring in late summer. The pattern was evident in headwater streams influenced by surface coal mining, unmined headwater reference streams with low salinity, and larger-order salinized rivers draining the study area. The pattern was strongly responsive to varying seasonal dilution as driven by catchment evapotranspiration, an effect that was amplified slightly in unmined catchments with greater relative forest cover. Evaluation of alternative sampling intervals indicated that discrete sampling can approximate the model performance afforded by high-frequency data but model error increases rapidly as discrete sampling intervals exceed 30 days. This study demonstrates that intra-annual variation of salinity in temperate forested headwater streams of Appalachia USA follows a natural seasonal pattern, driven by interactive influences on water quantity and quality of climate, geology, and terrestrial vegetation. Because climatic and vegetation dynamics vary annually in a seasonal, cyclic manner, a periodic function can be used to fit a sinusoidal model to the salinity pattern. The model framework used here is broadly applicable in systems with streamflow-dependent chronic salinity stress.

Linking water quality with amphibian breeding and development: a case study comparing natural ponds and Sustainable Drainage Systems (SuDS) in East Kilbride, Scotland

Amphibians have declined due to habitat loss and alteration. Sustainable Drainage Systems (SuDS) provide potential habitat for amphibians in urban landscapes. However, the contaminants they accumulate may cause increased pollutant exposure, and limited research has addressed whether differences in water quality between SuDS and natural ponds might restrict their use by amphibians. This study aimed to explore the effects of water quality on amphibian breeding and development in SuDS and natural ponds in East Kilbride, Scotland. A generalised linear modelling approach was employed to determine sources of variation in common frog (Rana temporaria) breeding and development in relation to pond size, pH, electrical conductivity (EC), chlorophyll and heavy metal concentrations. Key findings included that EC indicative of salt pollution was higher in SuDS than natural ponds, amphibians bred in both site types, but frog spawn clump densities were lower in SuDS, and tadpole development rates were higher in SuDS sites but decreased when aluminium concentrations exceeded concentrations those of surface water standards. However, pond desiccation was a significant element in the 2018 study year. It was concluded that natural ponds and SuDS varied in water quality but were important in supporting amphibian populations. However, water quality might influence amphibian development more than breeding attempts; implications and management recommendations are highlighted based on these observations.

Study on Evolution Process of Chemical Characteristics of Groundwater in Pearl River Basin

This paper studies the degree of chemical pollution of groundwater in the Pearl River Basin and the chemical evolution mechanism of water body. Then it analyzes the change trend of discharge, balance, total dissolved solids (TDS), water ion concentration and other parameters of groundwater in the basin in the past 20 years, as well as discusses the impact of chemical evolution process of groundwater on water cycle. According to the study, the groundwater storage volume in the Pearl River Basin has begun to decrease year by year because of the excessive exploitation of groundwater caused by increased human activities, industrial and agricultural water consumption. When the cover depth of groundwater is great, the external replenishment of groundwater gradually reduces with salt, minerals and chemical pollutants continuously accumulating, which will lead to the gradual increase of TDS of groundwater. Seasonal changes have a little impact on the chemical evolution of groundwater. Groundwater recharge area mainly contains Ca2+-Na+-HCO3- that will be converted to Na+-K+- HCO3--Cl- in discharge area. The chemicals contained in groundwater are mainly related to geotechnical types, environmental conditions and various chemical reactions. The study on the chemical characteristics and evolution rule of groundwater can provide theoretical reference for the rational and effective use of water resources.

Salt Contamination Calculation in Insulators During Monsoon Using Artificial Neural Network

Control framework consistent quality depends mostly on the natural and climate conditions which cause flashover on contaminated protectors. Such flashover prompts framework blackouts. Close to the beach front zones the salt pollution can be quickly based on the surface of the shields and frame a directing layer by retaining wet from the fog. This layer at times prompts flashover. Investigation of defilement of separator under marine contamination is the point of this examination, and the impacts of different meteorological elements on the disease seriousness have been researched altogether. In the present paper, an endeavour has been made to gauge the contamination severity under different climate conditions amid the stormy season utilising Artificial Neural Organize. The anomaly determination issue has been considered in this work to take out few exceedingly scattered exploratory information. The connection between ESDD with temperature T, stickiness H, weight P, precipitation R and wind speed WV has been created utilising ANN as a function estimator.

Salt Contamination Calculation in Insulators During Monsoon Using Artificial Neural Network

Control framework consistent quality depends mostly on the natural and climate conditions which cause flashover on contaminated protectors. Such flashover prompts framework blackouts. Close to the beach front zones the salt pollution can be quickly based on the surface of the shields and frame a directing layer by retaining wet from the fog. This layer at times prompts flashover. Investigation of defilement of separator under marine contamination is the point of this examination, and the impacts of different meteorological elements on the disease seriousness have been researched altogether. In the present paper, an endeavour has been made to gauge the contamination severity under different climate conditions amid the stormy season utilising Artificial Neural Organize. The anomaly determination issue has been considered in this work to take out few exceedingly scattered exploratory information. The connection between ESDD with temperature T, stickiness H, weight P, precipitation R and wind speed WV has been created utilising ANN as a function estimator.

Effects of potash mining on river ecosystems: An experimental study

In spite of being a widespread activity causing the salinization of rivers worldwide, the impact of potash mining on river ecosystems is poorly understood. Here we used a mesocosm approach to test the effects of a salt effluent coming from a potash mine on algal and aquatic invertebrate communities at different concentrations and release modes (i.e. press versus pulse releases). Algal biomass was higher in salt treatments than in control (i.e. river water), with an increase in salt-tolerant diatom species. Salt addition had an effect on invertebrate community composition that was mainly related with changes in the abundance of certain taxa. Short (i.e. 48 h long) salt pulses had no significant effect on the algal and invertebrate communities. The biotic indices showed a weak response to treatment, with only the treatment with the highest salt concentration causing a consistent (i.e. according to all indices) reduction in the ecological quality of the streams and only by the end of the study. Overall, the treatment's effects were time-dependent, being more clear by the end of the study. Our results suggest that potash mining has the potential to significantly alter biological communities of surrounding rivers and streams, and that specific biotic indices to detect salt pollution should be developed.

Salt pollution of surface water in oil fields of Khanty-Mansi Autonomous Area-Yugra

The article gives the results of analysis of salt pollution at deposits of Khanty-Mansi Autonomous Area-Yugra (KhMAO-Yugra) based on data of regional hydrochemical monitoring. Data of a twenty-year observation series were used to identify the most polluted water bodies and to determine deposits with the largest salt load. Correlation and regression analyses are used to assess the interrelation between technogenesis characteristics and pollution level. It was found that the current salt pollution in the area is lower than that in the 1990s, though the pollution level has increased at some deposits of the Ob–Irtysh interfluve.

Seawater-driven forward osmosis for direct treatment of municipal wastewater

Direct treatment of municipal wastewater by forward osmosis (FO) process was evaluated in terms of water flux decline, reverse salt diffusion, pollutants rejection and concentration efficiency by using synthetic seawater as the draw solution. It was found that when operating in PRO mode (active layer facing the draw solution), although the FO membrane exhibited higher osmotic water flux, more severe flux decline and reverse salt diffusion was also observed due to the more severe fouling of pollutants in the membrane support layer and accompanied fouling enhanced concentration polarization. In addition, although the water flux decline was shown to be lower for the FO mode (active layer facing the feed solution), irreversible membrane fouling was identified in both PRO and FO modes as the water flux cannot be restored to the initial value by physical flushing, highlighting the necessity of chemical cleaning in long-term operation. During the 7 cycles of filtration conducted in the experiments, the FO membrane exhibited considerably high rejection for TOC, COD, TP and NH4 +-N present in the wastewater. By optimizing the volume ratio of seawater draw solution/wastewater feed solution, a concentration factor of 3.1 and 3.7 was obtained for the FO and PRO modes, respectively. The results demonstrated the validity of the FO process for direct treatment of municipal wastewater by using seawater as the draw solution, while facilitating the subsequent utilization of concentrated wastewater for bioenergy production, which may have special implications for the coastline areas.

Impact of potash mining in streams: the Llobregat basin (northeast Spain) as a case study

Potash mining is significantly increasing the salt concentration of rivers and streams due to lixiviates coming from the mine tailings. In the present study, we have focused on the middle Llobregat basin (northeast Spain), where an important potash mining activity exists from the beginning of the XX century. Up to 50 million tonnes of saline waste have been disposed in the area, mainly composed of sodium chloride. We assessed the ecological status of streams adjacent to the mines by studying different physicochemical and hydromorphological variables, as well as aquatic macroinvertebrates. We found extraordinary high values of salinity in the studied streams, reaching conductivities up to 132.4 mS/cm. Salt-polluted streams were characterized by a deterioration of the riparian vegetation and the fluvial habitat. Both macroinvertebrate richness and abundance decreased with increasing salinity. In the most polluted stream only two families of macroinvertebrates were found: Ephydridae and Ceratopogonidae. According to the biotic indices IBMWP and IMMi-T, none of the sites met the requirements of the Water Framework Directive (WFD; i.e., good ecological status). Overall, we can conclude that potash-mining activities have the potential to cause severe ecological damage to their surrounding streams. This is mainly related to an inadequate management of the mine tailings, leading to highly saline runoff and percolates entering surface waters. Thus, we urge water managers and policy makers to take action to prevent, detect and remediate salt pollution of rivers and streams in potash mining areas.

Chloride and sulphate toxicity to Hydropsyche exocellata (Trichoptera, Hydropsychidae): Exploring intraspecific variation and sub-lethal endpoints

The rivers and streams of the world are becoming saltier due to human activities. In spite of the potential damage that salt pollution can cause on freshwater ecosystems, this is an issue that is currently poorly managed. Here we explored intraspecific differences in the sensitivity of freshwater fauna to two major ions (Cl− and SO42−) using the net-spinning caddisfly Hydropsyche exocellata Dufour 1841 (Trichoptera, Hydropsychidae) as a model organism. We exposed H. exocellata to saline solutions (reaching a conductivity of 2.5mScm−1) with Cl−:SO42− ratios similar to those occurring in effluents coming from the meat, mining and paper industries, which release dissolved salts to rivers and streams in Spain. We used two different populations, coming from low and high conductivity streams. To assess toxicity, we measured sub-lethal endpoints: locomotion, symmetry of the food-capturing nets and oxidative stress biomarkers. According to biomarkers and net building, the population historically exposed to lower conductivities (B10) showed higher levels of stress than the population historically exposed to higher conductivities (L102). However, the differences between populations were not strong. For example, net symmetry was lower in the B10 than in the L102 only 48h after treatment was applied, and biomarkers showed a variety of responses, with no discernable pattern. Also, treatment effects were rather weak, i.e. only some endpoints, and in most cases only in the B10 population, showed a significant response to treatment. The lack of consistent differences between populations and treatments could be related to the high salt tolerance of H. exocellata, since both populations were collected from streams with relatively high conductivities. The sub-lethal effects tested in this study can offer an interesting and promising tool to monitor freshwater salinization by combining physiological and behavioural bioindicators.

Fuzzy-based wastewater quality indices for pollution classification: a case study in the United Arab Emirates

This paper presents a fuzzy logic-based tool for assessing the pollution concentration of effluents generated by various industrial and commercial activities. The study proposes a fuzzy overall pollution compliance index (FOPCI) (range 0–100) to classify the wastewater discharged from various types of properties present in Ajman, United Arab Emirates. The work mainly focused on three types of pollution that can occur at the inlets of the wastewater treatment plant of Ajman, due to discharge of industrial and commercial effluents, namely pH pollution, salt pollution, and organic pollution. The proposed FOPCI integrates six characteristics, namely pH, Cl−, SO42−, conductivity, chemical oxygen demand (COD), and fats, oils, and greases (FOG) values into a readily understandable scale. The FOPCI is developed by using the Fuzzy Inference System Toolbox available in MATLAB in two steps, in which during the first step, three sub-indices, namely fuzzy pH compliance index, fuzzy salt compliance index, and fuzzy organic compliance index are developed. It is then processed in the second stage to develop the FOPCI. Fuzzy rules are used to classify effluents quality into six categories based on the concentration of pollutant in the effluent, namely “Excellent Quality”, “Good Quality”, “Acceptable Quality”, “Moderately Polluting”, “Highly Polluting”, and “Extremely Polluting”. This linguistic classification using fuzzy logic will be helpful as a decision support system to provide an outline for the prioritization of plans for wastewater management based on the values of the indices developed.

Establishing mussel behavior as a biomarker in ecotoxicology

Most freshwater mussel species of the Unionoida are endangered, presenting a conservation issue as they are keystone species providing essential services for aquatic ecosystems. As filter feeders with limited mobility, mussels are highly susceptible to water pollution. Despite their exposure risk, mussels are underrepresented in standard ecotoxicological methods. This study aimed to demonstrate that mussel behavioral response to a chemical stressor is a suitable biomarker for the advancement of ecotoxicology methods that aids mussel conservation. Modern software and Hall sensor technology enabled mussel filtration behavior to be monitored real-time at very high resolution. With this technology, we present our method using Anodonta anatina and record their response to de-icing salt pollution. The experiment involved an environmentally relevant ‘pulse-exposure’ design simulating three subsequent inflow events. Three sublethal endpoints were investigated, Filtration Activity, Transition Frequency (number of changes from opened to closed, or vice versa) and Avoidance Behavior. The mussels presented a high variation in filtration behavior, behaving asynchronously. At environmentally relevant de-icing salt exposure scenarios, A. anatina behavior patterns were significantly affected. Treated mussels’ Filtration Activity decreased during periods of very high and long de-icing salt exposure (p<0.001), however, increased during short de-icing salt exposure. Treated mussels’ Transition Frequency increased during periods of very high and long de-icing salt exposure (p<0.001), which mirrored the Avoidance Behavior endpoint observed only by mussels under chemical stress. Characteristics of Avoidance Behavior were tighter shell closures with repeated and irregular shell movements which was significantly different to their undisturbed resting behavior (p<0.001). Additionally, we found that mussels were sensitive to a chemical stressor even when the mussel’s valves were closed. Due to the effects of de-icing salt pollution on freshwater mussel behavior, we suggest better management practices for de-icing salt use be implemented. Our experimental method demonstrated that, with the application of current technologies, mussel behavioral response to a chemical stressor can be measured. The tested sublethal endpoints are suitable for mussel ecotoxicology studies. Avoidance Behavior proved to be a potentially suitable endpoint for calculating mussel behavior effect concentration. Therefore we recommend adult mussel behavior as a suitable biomarker for future ecotoxicological research. This method could be applied to other bivalve species and for physical and environmental stressors, such as particulate matter and temperature.

Effects of salinity gradients on benthic invertebrate and diatom communities in a German lowland river

The Lippe is a lowland river located in the Western part of Germany and has been heavily impacted by coal mining activities ever since. Although mining activities significantly decreased during the last decades, the associated discharge of salt-enriched mine water into the river still poses a persistent threat to the local benthic invertebrate and diatom communities. To analyze the effect of salt pollution on invertebrate and diatom species, biological and chemical data were compiled for this study from a publicly available database. Changes in the community composition due to increased salt concentrations were explored by Non-Metrical-Multidimensional Scaling. Indicator species and salinity thresholds for single species and communities were identified using the method TITAN (Threshold Indicator Taxa Analysis). The method is an analytical approach to detect changes in frequency and abundance of species along an environmental gradient by combining the methods of change point analysis (nCPA) and indicator species analysis. The obtained salinity preferences and individual and community thresholds were compared to the literature and existing salinity classifications. For both diatoms and benthic invertebrates, Non-Metrical-Multidimensional Scaling showed a clear split between samples of high and low salinities. Significant salinity thresholds were determined for 50 invertebrate and 58 diatom species of which 23 respectively 18 species were described as ‘reliable’ indicators according to the specifications given by Baker and King (2010). A majority of salt-tolerant indicator organisms were invasive species. For both organism groups, major changes in community composition were detected at a conductivity value exceeding 900μS/cm. A reduction of the average salinity to below this threshold may have positive effects on the overall species richness and the persistence of sensitive taxa in the river Lippe. Individual and community thresholds may however be data-dependent to a certain degree and subjected to fluctuations considering the potential interdependencies between salinity and additional physico-chemical and environmental parameters (e.g. water temperature, lime content).

The environmental requirements of Crunoecia irrorata (Curtis, 1834) (Trichoptera: Lepidostomatidae) and the potential of the species for use as an indicator: an example from the Vistulian glaciation area

The caddisfly Crunoecia irrorata is a wide-spread species in Europe and inhabits permanent spring areas with pristine or moderately disturbed habitat conditions. However, the pattern of its distribution on the national scale as well as detailed preferences toward water properties are still insufficiently known. To complete this knowledge we analysed at first the distribution of this species in Poland which showed that its extent involves the whole territory, however, with sparse occurrence in most regions and with large areas where the species has not been observed yet. The data compilation also showed that the species’ frequency of occurrence is highest in the central-western region of Poland. Furthermore, its frequency of occurrence decreased towards the east and the northeast. Because the highest frequency of occurrence of this species was found in central-western Poland, the spring sites in this region were used as a model area for the analysis of the hydrochemical conditions associated with the species (25 parameters). The results of the study showed that C. irrorata strongly prefers habitats with low nitrate (NO3) and chloride (Cl) concentrations. In detail, a regression model showed that the probability of occurrence of C. irrorata was only 5 % at concentrations of 32 mg L-1 NO3 and 35 mg L-1 Cl. In contrast, high concentrations of heavy metals (zinc, lead, cooper, chromium, and cadmium) as well as of total iron and manganese did not significantly influence the presence of this species. In conclusion, environmental assessments relating to human health and landscape health can use C. irrorata as an indicator species for biogenic and salt pollution, but the species is not a potential indicator of heavy metals in spring water. Therefore, information on the presence of C. irrorata can serve to preserve crenic ecosystems and their assemblages and can be used to prevent anthropogenic contamination of these ecosystems.

Noninvasive monitoring of moisture uptake in Ca(NO3)2 -polluted calcareous stones by 1H-NMR relaxometry.

NMR transverse relaxation time (T(2)) distribution of (1)H nuclei of water has been used to monitor the moisture condensation kinetics in Ca(NO(3))(2) · (4)H(2)O-polluted Lecce stone, a calcareous stone with highly regular porous structure often utilized as basic material in Baroque buildings. Polluted samples have been exposed to water vapor adsorption at controlled relative humidity to mimic environmental conditions. In presence of pollutants, the T(2) distributions of water in stone exhibit a range of relaxation time values and amplitudes not observed in the unpolluted case. These characteristics could be exploited for in situ noninvasive detection of salt pollution in Lecce stone or as damage precursors in architectural buildings of cultural heritage interest.

Numerical Investigation of Nitrate Leakage and Migration in the Soil after Rainfall

Nitrate salt is important heat transfer and storage medium in solar thermal power system, but nitrate salt leakage and pollution in groundwater is seldom investigated. In this paper, the nitrate salt leakage and migration in the soil after rainfall are simulated and analyzed. During the nitrate leakage process, the liquid nitrate will solidify, and then a thin solidification layer of nitrate forms. According to the simulation result, the radius of the leakage opening mainly affects the radius of nitrate solidification layer, while the leakage velocity will influence the radius and thickness of salt layer. During the nitrate migration process after rainfall, the nitrate will gradually migrate to the groundwater, and the final migration domain of nitrate in the soil will be mainly determined by the radius of nitrate solidification layer.