Drivers of Long-Term Land-Use Pressure in the Merguellil Wadi, Tunisia, Using DPSIR Approach and Remote Sensing

Increasing land use pressure is a primary force for degradation of agricultural areas. The drivers for these pressures are initiated by a series of interconnected processes. This study presents a novel methodology to analyze drivers of changing land use pressure and the effects on society and landscape. The focus was on characterizing these drivers and relate them to land use statistics obtained from geospatial data from the important semiarid Merguellil Wadi between 1976 and 2016. Cause-and-effect relationships between different drivers of land use change were analyzed using the DPSIR approach. Results show that during the 40-year period cultivated land increased and wetland areas decreased substantially. Drivers for change were pressure from economic development, cultivation practices, and hydro-agricultural techniques. This leads to stress on water and soil resulting in soil erosion, poverty increase, and rural exodus. We show that hydro-agricultural techniques adapted to the semiarid climate, allocation of land property rights, resource allocation, and improved marketing of agricultural products can help rural residents to diversify their economy, and thus better preserve the fragile semiarid landscape. Results of this study can be used to ensure sustainable management of water and soil resources in areas with similar climate and socio-economic conditions.

Evaluation of Salinity by Using Wavelet Modeling

Every year, due to the salinity resulting from improper irrigation practices, almost 10 billion ha of agricultural lands across the world cannot be used. Among the main elements (cations) for salinity in regions with dry or semi-dry climate are potassium (K+), sodium (Na+), calcium (Ca+2) and magnesium (Mg+’2). Using proper irrigation methods as well as ensuring the quality of irrigation water are of great importance in terms of the salinity of agricultural soils. In this study, laboratory analyses of ground water resources for salinity parameters were conducted in the province of Yalova (Taşköprü, Çiftlikköy, and Altınova regions). In the explanation of the analysis results, variations and effects based on the level of salinity were taken into account and the role of small, meso and large scale factors were determined through the use of the wavelet model. The study results would be of use in the estimation of salinity contents of soils with respect to groundwater irrigation in agricultural areas.

Trace elements characterization of soils and rocks in Agricultural areas of Labunwa, Near Idanre, Southwestern Nigeria

Trace elements (TE) concentrations of subsoil and the underlying parent rocks of Labunwa – Odele area were determined in other to ascertain the enrichment level, distribution and sources of these TEs in the subsoil in the study area. Twenty-one (21) subsoil (at depth of 30 -100 cm) and thirteen (13) rock samples were collected, pulverised and digested using aqua regia for soil samples and near total digestion of HClO4, HF, HCl and HNO3of different proportions for the rocks. The samples were analysed using Inductively Coupled Plasma- Mass Spectrometry, (ICP-MS). The mean TE concentrations in ppm for subsoil showed Cu (40.0), Pb, (24.2), Zn (56.3), As (0.9) and U (2.7) among other elements as against the mean concentrations of granite gneiss (GGN) with Cu (22.9), Pb (61.4), Zn (64.6), As (1.0), U (2.6) and Pegmatite, (PGM) Cu(128.4), Pb(17.0), Zn(108.8), As (1.1), U (1.3) among other TEs. The relatively low concentrations of the TEs in the subsoil compared to the underlying parent rocks suggests that TEs in the subsoil may have been influenced by geogenic factors, such as weathering of the underlying rocks. TEs source apportionments in the subsoil using Bivariant plots, correlation coefficient, Bi-polar and dendogram analyses showed that these TEs are essentially from the underlying GGN and PGM in the area. Pollution status indices, I-geo, Contamination factor and PLI showed that the study area is practically unpolluted. This suggests that locations with relatively higher concentrations of some TEs are probably due to mineralisation and since most of the subsoil TEs are significantly lower in concentrations compared to the underlying bedrock, the area is safe for agricultural activities.

Preliminary Investigation of Microplastics in Sediments from Industrial Manufacturing Waste Sources

Microplastics (particles with a size of less than 5 mm) are a rising environmental problem. Microplastics can disseminate in the air and accumulate in sediments as well as in microorganisms and humans, due to their small size. Sediment is considered to be the major repository of microplastics, particularly those of the PE type. Microplastics in massive amounts accumulated in sediments, perhaps as a result of point sources or diffuse contamination. Microplastic contamination can spread from industrial production facilities, urban areas, agricultural areas, or the air. The current study was carried out to explore the occurrence of MPs in sediments at discharge sources by evaluating 27 sediment samples taken from 9 distinct waste sources from industrial activity locations to determine the amount of microplastic contamination in sediments at discharge sources. Microplastics with relatively high density were found in all sediment samples in this research, ranging from 2,900 to 238,200 particles/kg dw. The most prevalent microplastics detected in sediment samples at these sites were fibers and fragments, accounting for 59-94% and 6-41%, respectively. Fiber microplastics ranged in size from 1000 to 9,000 µm, whereas fragment microplastics ranged from 200,000 to 2,100,000 µm2. Microplastics with < 1000 µm and 1000-2000 µm sizes accounted for a significant portion of the total, reaching 21.05-37.84% and 39.74-61.17%, respectively. The hue of microplastic particles in sediment samples obtained was highly varied.

Excavated farmland with plastic mulching as a strategy in saving water and controlling soil salinization in dryland agricultural areas

Water shortage and soil salinization in gully farmland comprising sediment deposited farmland (SF) and excavated farmland (EF) have become a widespread concern in the loess hilly region. A two-year field experiment was conducted to assess the soil water content (SWC) and salt content (SSC) and their effect on the spring maize yield and water use efficiency in SF and EF. Eight treatments comprising flat cropping without mulching (1), ridge planting without mulching (2), ridge planting with plastic mulching (3), and ridge planting with straw mulching (4) were tested in the SF and EF plots, respectively. The results showed that the yield was higher in SF than EF, whereas the water use efficiency was significantly higher in EF because the bottom water flux was 117.4% higher in SF than EF (P < 0.01). A significant positive correlation was found between the average SWC and yield (P < 0.01), thereby indicating that the yield was severely limited by the SWC. Thus, the higher water use efficiency in EF has important implications for alleviating water scarcity during agricultural production in this region. The risk of soil salinization was decreased greatly by treatment 3 where the SSC was decreased in EF and SF were 0.09 g kg–1 and 0.08 g kg–1, respectively. In addition, treatment 3 had the most significant impacts on the yield and water use efficiency. Our study provided appropriate land type and effective tillage measure for the sustainable development in dryland agricultural areas.

Multitemporal Spatial Analysis of Land Use and Land Cover Changes in the Lower Jaguaribe Hydrographic Sub-Basin, Ceará, Northeast Brazil

Aquaculture is currently one of the fastest growing food production systems globally, and shrimp is considered one of the most highly valued products. Our study area is the lower Jaguaribe River sub-basin (LJRSB), located in the northeastern part of Ceará in Brazil. The aquaculture activity in this area began in the early 1990s and is currently one of the largest shrimp producers in Brazil. This study generated a spatial-temporal analysis of vegetation index and land use and land cover (LULC) using remote sensing images from Landsat satellites processed using geographic information systems (GIS). The findings showed an increase in the water bodies class where shrimp farms are found. In addition, to help us discuss the results, data from the Global Surface Water Explorer was also used to understand this change throughout intra and interannual water variability. Besides shrimp farms’ intensification, agricultural areas in the LJRSB also increased, mainly in the irrigated perimeter lands (IPLs), causing a loss in the Caatinga native vegetation. In summary, over recent years, significant changes have been noticeable in the LJRSB coastal region, caused by an increase in shrimp farms mainly located on the Jaguaribe River margins, destroying the native riparian forest.

Spatiotemporal Evaluation of Water Quality and Hazardous Substances in Small Coastal Streams According to Watershed Characteristics

In this study, spatial and temporal changes of eight water quality indicators and 30 types of hazardous substances including volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), pesticides, and inorganic matters for the small coastal streams along the West Coast of South Korea were investigated. In coastal streams with clear seasonal changes in water quality, larger watershed areas led to greater contamination by particulate matter (i.e., suspended solids, r = 0.89), and smaller watershed areas led to greater contamination by organic matter (i.e., BOD, r = −0.78). The concentration of VOCs and pesticides was higher in agricultural areas, and those of SVOCs and metals were often higher in urban areas. According to the principal component analysis (PCA), during the wet season, the fluctuation in the water quality of coastal streams was higher in urban areas than in agricultural areas. Furthermore, coastal streams in residential areas exhibited higher levels of SVOCs, and those in industrial areas exhibited higher levels of metallic substances. Based on these results, the spatial and temporal trends of water quality and hazardous substances were obtained according to watershed characteristics, thereby clarifying the pollution characteristics of small-scale coastal streams and the major influencing factors.

Erythemal UV Dose and UV Index Measurement at 37th North Latitude and Its Possible Effects on Humans

In this study, UV irradiance and UV erythemal and UV index data of May, June, July and August measured in Adana (longitute=36 E, latitute=37 N altitute=140m) between 2013 and 2019 were analyzed. As a result of the analysis, the average of four months was 14.16 MED (2.9736 J/m2) and the highest value of these four months was calculated as 15.6 MED (3.276 J/m2) in July. The percentage frequency of the total daily UV dose was also calculated and it was determined that the region was under the effect of 70-80% high UV dose. In addition, it was calculated to have a high UV index according to local time (10.00-14.00). It was concluded that this situation poses a great risk for workers working in agricultural areas in the region and for people who spend their summer holidays by the sea. UV Dose-Ozone, UV Dose-temperature, UV Dose-humidity and Ozone-temperature correlations were also calculated. As a result of the comparison, it was found that there was an R= -0.64 correlation between UV-ozone, an R= -1.00 correlation between temperature and ozone, and a direct correlation of R= 0.60 between UV radiation and temperature.

Degradative succession of the insects in small rodents in subtropical systems

We evaluated the insect succession in small rodent carcasses on the soil extracts (surface vs. buried) in two areas (riparian vs. agricultural) and two seasonal periods (spring vs. summer). Daily, the rodent carcasses were weighed and the insects present were collected in them for counting and family level identification. We also measured the air and soil temperature daily, in addition to the physical and chemical characteristics of the soil. The total of 11,059 individuals from 28 taxa was collected. The most abundant taxa were Calliphoridae (70%), Formicidae (20%), Muscidae (2%), and Sarcophagidae (2%). Insect richness was higher in spring in riparian vegetation areas; however, decomposition and insect abundance were greater in spring in agricultural areas by the high temperature measured. Vespidae, Sarcophagidae, Muscidae, and Calliphoridae decreased over time with abundance peaks respectively at 3, 7, 7, and 8 days in riparian vegetation areas. Calliphoridae decreased abundance over time with a peak at five days, but Armadillidiidae increased with peak at 6-9 days in agricultural areas. Decay and insect abundance was high in agricultural areas, mainly on the soil surface. Insect richness was high in riparian vegetation areas, especially on the soil surface. Only the superficial layers of soil presented taxon indicators and all decreased over time with abundance peaks of Calliphoridae, Sarcophagidae, and Muscidae at 5-8, 7, and 7 days, respectively. This abundance peak of insect families help to understand the degradative succession of the insect community in small rodents in subtropical systems of the neotropical region.