Effects of mixtures containing chlordecone and a dechlorinated by-product on hydra regeneration capacity: use of experimental design to evaluate the toxicity risk associated with remediation programs in long-lasting polluted areas

Chlordecone (CLD), an obsolete insecticide, used in the French West Indies between 1972 and 1993, is persistent in the environment but can be dechlorinated either chemically or under the action of microorganisms. Therefore, if soil remediation programs based on these processes are implemented in areas still contaminated today, those will see their concentrations of dechlorinated derivatives increase and these compounds will be also found in freshwater by streaming, leaching and erosion processes. The purpose of the present study was to evaluate, at environmental concentrations, the toxic effects of mixtures of chlordecone and a three-chlorine substituted byproduct. A hydra clone, which has been confirmed to be Hydra vulgaris Pallas, 1766 has been retained for bioassays where the toxicity has been evaluated by regeneration capacity during exposure. Exposure to mixtures is complex to investigate by classical methods, therefore, an experimental design associated to a mathematical model has been used to predict the effects of all the mixtures and to detect the toxic influence of each compound. The predictive model is discussed regarding the stochastic “endocrine disruptor effect” of CLD. At probable environmental concentrations of the compounds in the mixture, results show that impairment of regeneration capacity is explained mostly by the presence of CLD in the mixtures and support the implementation of remediation programs aimed at dechlorination of this persistent organochlorine pesticide.

Prevention of Soil Erosion and Torrential Floods

Climatic conditions, precise relief features, variations of soil, flora cover, socio-economic conditions together lead to torrential flood waves as a result of current soil erosion processes. Erosion and torrential floods are aggravated due to over exploitation of agricultural and forest land along with urbanization. Effects of soil erosion include nutrient loss, land use changes, reduced productivity, siltation of water bodies, among other effects like affecting livelihood of marginal communities dependent on agriculture globally and public health. Nearly 11 million km2 of soil is impacted by erosion precisely by water. Other factors like intensified agriculture and climate change contribute to and aggravate the erosion rate. Contemporary torrential floods are characterized by their increased destruction and frequency unlike the pre-development periods when their occurrence was rare. The focus of this review is to compile and aid as a data base for understanding methods of preventing erosion of soil and torrential floods as put forth by various researchers.

Torrential Floods and Soil Erosion

Floods on large rivers and torrential floods are the most common natural disasters in the Republic of Serbia. Floods on rivers are natural phenomena that go far beyond the framework of water management and hydro-technical measures. Given the distribution of hilly and mountainous areas in the Republic of Serbia and the developed hydrographic network, torrential floods occur very often, almost every year. Torrential floods and soil erosion are inseparable natural phenomena that shaped the relief long before the appearance of living beings on Earth. Erosion processes are difficult to notice and slow and are most often noticed only when large areas are exposed, and then the problem of erosion becomes a difficult-to-solve or unsolvable problem. For the classification of erosion processes in the Republic of Serbia, the EPM method (erosion potential method) is used, which classifies erosion into five categories that have their own quantitative characteristics.

Assessment of Erosion Characteristics in Purple and Yellow Soils Using Simulated Rainfall Experiments

Soil erosion of sloped lands is one of the important sources of substantive sediments in watersheds. In order to investigate erosion characteristics of sloped lands during rainfall events in the Three Gorges Reservoir Area, erosion processes of purple and yellow soils under different slope gradients and rainfall intensities were studied by using a rainfall simulator. The results showed that the sediment concentration in runoff was closely correlated with rainfall intensity. The sediment concentration in runoff gradually rose to a peak with time, and then gradually declined and approach a steady rate during simulation rainfall events. The particle size distribution of surface soils before the rainfall was different from that after the rainfall. Soil erosion mainly resulted in the loss of fine particles of surface soil through runoff, and the fine particles of soil were enriched in sediments. Soil erosion rates were gradually increased with the slope gradient when the slope gradient was less than 10°, and significantly increased when the slope gradient was more than 10°. The slope factor of yellow soil could be fitted well to that calculated by the formula of Universal Soil Loss Equation (USLE). The trend of the slope factor of purple soil was similar to that of the slope factor that was derived from USLE. Therefore, the effect of slope gradients on soil erosion need to be further researched when USLE was applied to predict erosion in purple soil area.

GEODESY, CARTOGRAPHY AND AERIAL PHOTOGRAPHY

The development of exogenous processes on the Earth's surface is a large-scale problem. Due to the development of exogenous processes there are changes in the composition and structure of the earth's crust and its surface. The destruction of streets, houses and public buildings, roads and railways leads to enormous losses. To predict the development of soil degradation, erosion processes on agricultural lands, which lose annual production areas, leads to the formation of a ravine-beam system and reduces the productive amount of land owned by citizens – is a solution. The use of GIS technologies, remote sensing of the Earth and modern programming can partially solve the problem, as it is a rapid identification of areas that have undergone the process of soil degradation and possible prediction of the development of negative phenomena. The use of geodetic software, GIS, information layers of the Public cadastral map can help in the fastest finding of territories, development of the forecast of the further destructive action, development of the corresponding protective methods and their introduction. The areas with manifestations of exogenous processes - soil degradation in agricultural enterprises, where every year the area of highly fertile chernozems is lost, which leads to large losses and landslides in the forest-steppe and steppe settlements of Kharkiv region have been subject of our study. We investigated destructive processes by geodetic measurements in the territories of their manifestations, observations were carried out for 8 years. The development of exogenous processes on the Earth's surface was revealed, which was manifested in landslides in the settlements of the forest-steppe zone and degradation of agricultural lands in the steppe and forest-steppe part of Kharkiv region. The cause of the destruction of the earth's surface were factors independent of human activity. We built 3-D models of development of exogenous processes manifested in soil erosion and growth of the ravine-beam system and determined the degree of erosion after surveying and processing the results of geodetic measurements in the software Digitals. For 8 years, we made changes to the software, surveying the area and building a monitoring line. Also in the settlements on the territory of the two zones, we observed the development of landslides on the streets of the village. Milova and s. Nova Vasylivka, where there is an intensive development of exogenous processes. The use of GIS technologies and remote sensing of the Earth to monitor the development of exogenous processes simplifies the solution.

Assessment of soil erosion hazard and its mapping using GIS technologies

The article presents a method for creating a territory erosion hazard integrated map using RUSLE integral model, Earth remote sensing data and GIS technologies. The studies carried out on this topic are presented, the analysis of which has shown a more active use of integral indicators of water-erosion processes in foreign scientific works. Urgency of updating methodology for studying erosion processes has been substantiated. Theoretical foundations of the application of integral models of soil erosion are given, the application of the RUSLE model is substantiated, and the optimal way of using this model is proposed. The research methodology has been developed, consisting of primary processing of remote sensing data, calculation of the factors of erosion development and creation of a territory erosion hazard integrated map. Based on the processing of aerial photography materials, a point cloud, a digital elevation model and an orthomosaic map of the study area were created. The results of the geoinformation analysis of the remote sensing data, which included calculation of the soil erodibility factor and the topographic factor, are presented. Based on the integral indicator of watererosion hazard, a complex map of the erosion hazard of the territory has been created. Main patterns of geographical distribution of the values of the integral indicator of the water-erosion hazard of the territory are revealed, devised methodology is assessed. It was found that the schematic map reflects the general pattern of water erosion processes: they are more active in places where more dissected relief is spread. Influence of the soil factor on the pattern of the schematic map is shown: the pattern in the territories occupied by sod-podzolic loamy soils qualitatively differs from the pattern on the lands where sod-podzolic sandy loam soils are widespread. Patterns on the schematic map of different parts of the developed linear forms of relief, formed by temporary streams, are described. It is shown that the proposed method can be used to assess the water-erosion hazard of the territory. The need to take into account a larger number of factors and to refine the assessment of existing ones is concluded.

Beach and Dune Erosion: Causes and Interventions, Case Study: Kaulon Archaeological Site

The dune systems are very important from an environmental, landscape, and coastal defense point of view within coastal areas. Currently, dune systems are significantly reduced compared to a few decades ago and, in Europe alone, dune systems have decreased by 70%. During the same period, intense beach erosion processes have often been observed, and, currently, 30% of the world’s coasts are eroding. These processes have various causes, both natural and anthropogenic, and the knowledge of the causes of the erosive processes are very important for an effective planning and management of coastal areas and to correctly plan any interventions on dunes and beaches. The paper, through a case study, analyzes the beach and dune erosive processes, their causes, and the possible interventions. The case study concerns the archaeological site of Kaulon, located on a dune in the Ionian coast of Calabria (Italy). The beach near the site was affected by erosive processes and during the winter of 2013–2014, the site was damaged by two sea storms. To identify the causes of these processes, three erosive factors were analyzed. These factors are anthropogenic pressure, wave climate and sea storms, and river transport. The effects produced by these factors were assessed in terms of shoreline changes and of damage to the beach–dune system, also evaluating the effectiveness of the defense interventions. The main causes of the erosive processes were identified through the cross analysis of erosive factors and their effects. This analysis highlighted that in the second half of the last century the erosive processes are mainly correlated to anthropogenic pressure while, recently, natural factors prevail, especially sea storms. Regarding the interventions, the effects produced by two interventions carried out during the winter of 2013–2014, one built in urgency between the first and second sea storm and the other built a few years after the second sea storm were analyzed. This analysis highlighted that the latter intervention was more effective in defending the site.