Human Agricultural Activities Research Articles

Quantification of the impacts of climate change and human agricultural activities on oasis water requirements in an arid region: a case study of the Heihe River basin, China

Abstract. Ecological deterioration in arid regions caused by agricultural development has become a global issue. Understanding water requirements of the oasis ecosystems and the influences of human agricultural activities and climate change is important for the sustainable development of oasis ecosystems and water resource management in arid regions. In this study, water requirements of the main oasis in Heihe River basin during 1986–2013 were analyzed and the amount showed a sharp increase from 10.8 × 108 m3 in 1986 to 19.0 × 108 m3 in 2013. Both human agricultural activities and climate change could lead to the increase in water requirement. To quantify the contributions of agricultural activities and climate change to the increase in water requirements, partial derivative and slope method were used. Results showed that climate change and human agricultural activities, such as oasis expansion and changes in land cropping structure, has contributed to the increase in water requirement at rates of 6.9, 58.1, and 25.3 %, respectively. Overall, human agricultural activities were the dominant forces driving the increase in water requirement. In addition, the contribution of oasis expanding to the increased water requirement was significantly greater than that of other concerned variables. This reveals that controlling the oasis scale is extremely important and effective for balancing water for agriculture and ecosystems and to achieving a sustainable oasis development in arid regions.

SUBAK LAND INFORMATION SYSTEM BASED ON REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEM IN DENPASAR CITY

Subak is an irrigation system for agricultural land units in Bali. Subak components include palemahan (source of rice field), pawongan (human resources / farmers), and rice farming system. Subak as a typical system and local Bali built since the 7th century, until now subak system still exist in Denpasar. UNESCO, in 2011, designated Subak as a world cultural heritage. Ironically, not one regency / city, and Bali Province has spatial map of Subak, only statistic data. The era of technology and communication development, requires the ease and speed of getting the latest data and information with a high level of spatial accuracy. This paper discusses the use of geo-information technology in subak mapping. This study uses the Worldview satellite image data in Denpasar in 2015, and ArcGIS 10.3 software for mapping of land and area of subak rice fields (spatial data). The supporting data used are land resource data (LR), human resource data (pekaseh) and agricultural activities as attribute data. The result of the analysis is Denpasar City has 41 Subak in 2015, Subak area on satellite image analysis as wide as 2,008.6 ha. This result was smaller 520.4 ha than the data from Central Bureau of Statistics (CSA, Denpasar) that is 2,529 ha with value r2 = 0,8967. Furthermore, the subak information system combined subak spatial map with attribute data. From this research can be concluded that the making of information system subak spatial-based data is very helpful in the identification and analysis of subak areas for irrigation planning.

English

The Eastern flank of Mount Cameroon is made up of human settlement and agricultural activities. Determination of phosphorus (P) fixation characteristics of soils around this region is important for a clean environment and economic fertilizer application. The objectives of this study were to evaluate P-fixation characteristics of soils within the region and identify factors contributing to P-fixation. Composite surface soil samples from five sites (between 36 to 1006 m) were collected and analyzed for physicochemical properties and P-fixation capacity. Fixation data were obtained by equilibrating the five soil samples with 25 ml of KH2PO4 in 0.01 M CaCl2, containing 0, 10, 50, 100, 250 and 500 mg L-1. Phosphorus-fixation data were fitted to Langmuir and Freundlich adsorption models and the relationship between P-fixation and soil properties was determined. The adsorption maximum (KL) for Freundlich model was the highest for Limbe - Man O’War Bay Road (LMR, 174.58 mg P kg-1), followed by SLR (34.12 mg P kg-1), Dibanda-Mutengene Road (DMR, 24.72 mg P kg-1), VAS and UPD (16.87 mg P kg-1). The Langmuir adsorption maximum for Vasingi (VAS), Upper Boduma (UPD), Sasse-Limbe Road (SLR), DMR, and LMR were 0.01, 0.02, 0.01, 0.02 and 0.05 mg P kg-1, respectively. The phosphate adsorption isotherm gave good fit adopting Freundlich (r = 0.98 to 0.99). KF correlated with pH (r = - 0.87), Ca (r = - 0.87), exchange acidity (r = 0.87), and clay (r = 0.67). This study illustrated that P sorption isotherm in relation to soil properties can be used as a tool for P management in sustainable crop production.   Key words: Phosphorus fixation, adsorption isotherms, soil physicochemical properties, volcanic soils, Mount Cameroon.

The contribution of human agricultural activities to increasing evapotranspiration is significantly greater than climate change effect over Heihe agricultural region

Evapotranspiration (ET) is a major component linking the water, energy, and carbon cycles. Understanding changes in ET and the relative contribution rates of human activity and of climate change at the basin scale is important for sound water resources management. In this study, changes in ET in the Heihe agricultural region in northwest China during 1984–2014 were examined using remotely-sensed ET data with the Soil and Water Assessment Tool (SWAT). Correlation analysis identified the dominant factors that influence change in ET per unit area and those that influence change in total ET. Factor analysis identified the relative contribution rates of the dominant factors in each case. The results show that human activity, which includes factors for agronomy and irrigation, and climate change, including factors for precipitation and relative humidity, both contribute to increases in ET per unit area at rates of 60.93% and 28.01%, respectively. Human activity, including the same factors, and climate change, including factors for relative humidity and wind speed, contribute to increases in total ET at rates of 53.86% and 35.68%, respectively. Overall, in the Heihe agricultural region, the contribution of human agricultural activities to increased ET was significantly greater than that of climate change.

Ancient mtDNA diversity reveals specific population development of wild horses in Switzerland after the Last Glacial Maximum.

On large geographical scales, changes in animal population distribution and abundance are driven by environmental change due to climatic and anthropogenic processes. However, so far, little is known about population dynamics on a regional scale. We have investigated 92 archaeological horse remains from nine sites mainly adjacent to the Swiss Jura Mountains dating from c. 41,000–5,000 years BP. The time frame includes major environmental turning points such as the Last Glacial Maximum (LGM), followed by steppe vegetation, afforestation and initial re-opening of the landscape by human agricultural activities. To investigate matrilinear population dynamics, we assembled 240 base pairs of the mitochondrial d-loop. FST values indicate large genetic differentiation of the horse populations that were present during and directly after the LGM. After the retreat of the ice, a highly diverse population expanded as demonstrated by significantly negative results for Tajima’s D, Fu’s FS and mismatch analyses. At the same time, a different development took place in Asia where populations declined after the LGM. This first comprehensive investigation of wild horse remains on a regional scale reveals a discontinuous colonisation of succeeding populations, a pattern that diverges from the larger Eurasian trend.

Diversity and community patterns of testate amoebae in Bau Sen and Bau Trang lakes in Binh Thuan Province, Vietnam

The species composition and distribution of testate amoebae in Bau Sen and Bau Trang lakes (Binh Thuan Province, Vietnam) were investigated. Fifty-three species, varieties and forms have been identified from the water column and sediments. Twenty-seven species, varieties and forms from the genera Arcella, Centropyxis, Cyclopyxis, Difflugia and Pyxidicula were found in Vietnam for the first time. The updated list of testate amoebae in Vietnam now includes 286 taxa. The genera Arcella, Centropyxis and Difflugia are characterized by the highest frequency of occurrence. The species diversity of Arcella, Centropyxis, Difflugia was the highest. Centropyxis aculeata, Arcella discoides, Difflugia schurmanni, Netzelia oviformis and Difflugia limnetica were the most common species. Many species have shown restricted distribution, some species have been found only in one lake and not been found in another lake. The number of observed species, varieties, and forms in each lake is 34. The average number of the species per sample on the shores of the lakes subjected to human agricultural activity was significantly higher than in the samples from the shores of the lakes with less anthropogenic disturbance. The curves of “cumulative species number vs. sampling effort” are well fitted by equations S = 7.60 N 0.69 for Bau Sen lake and S = 12.52 N 0.46 for Bau Trang. The curves are unsaturated, which indicates that more intensive investigations of testate amoebae should be expected to reveal more species.

Gully Erosion Mapping and Monitoring at Multiple Scales Based on Multi-Source Remote Sensing Data of the Sancha River Catchment, Northeast China

This research is focused on gully erosion mapping and monitoring at multiple spatial scales using multi-source remote sensing data of the Sancha River catchment in Northeast China, where gullies extend over a vast area. A high resolution satellite image (Pleiades 1A, 0.7 m) was used to obtain the spatial distribution of the gullies of the overall basin. Image visual interpretation with field verification was employed to map the geometric gully features and evaluate gully erosion as well as the topographic differentiation characteristics. Unmanned Aerial Vehicle (UAV) remote sensing data and the 3D photo-reconstruction method were employed for detailed gully mapping at a site scale. The results showed that: (1) the sub-meter image showed a strong ability in the recognition of various gully types and obtained satisfactory results, and the topographic factors of elevation, slope and slope aspects exerted significant influence on the gully spatial distribution at the catchment scale; and (2) at a more detailed site scale, UAV imagery combined with 3D photo-reconstruction provided a Digital Surface Model (DSM) and ortho-image at the centimeter level as well as a detailed 3D model. The resulting products revealed the area of agricultural utilization and its shaping by human agricultural activities and water erosion in detail, and also provided the gully volume. The present study indicates that using multi-source remote sensing data, including satellite and UAV imagery simultaneously, results in an effective assessment of gully erosion over multiple spatial scales. The combined approach should be continued to regularly monitor gully erosion to understand the erosion process and its relationship with the environment from a comprehensive perspective.

The impact of natural and anthropogenic processes on the evolution of closed depressions in loess areas. A multi-proxy case study from Nałęczów Plateau, Eastern Poland

Closed depressions are reported in loess landscapes in various parts of Europe. The anthropogenic and natural origin of closed depressions is highly debated in literature. Closed depressions are an important component of the landscape in loess areas of the Lublin Upland. Furthermore, they perform the role of local closed sediment basins, creating unique conditions for the preservation of soils and colluvial sediments, along with the record of the evolution of the Holocene landscape, occurring under the influence of climate changes and human activity.The study objective was to evaluate the contribution of natural and anthropogenic processes influencing the origin and evolution of closed depressions. The Nałęczów Plateau is composed of loess, whose thickness varies from a few meters to >30m. 1761 closed depressions have been documented within the Nałęczów Plateau (493km2). A detailed investigation was conducted within selected closed depression, dissected by a deep and long road trench. The studied form was 40m long, 26m wide and 0.7m deep. The analyzed exposure; 20m long and 7m high, presents a cross-section of the closed depression. Fieldwork and subsequent laboratory analyses were conducted: morphological, micromorphological, microstructural, geochemical, physico-chemical, OSL and 14C dating. Archaeological and historical correlations were also performed.The primary bottom and slopes of the studied depression are composed of loess in situ, overlain by Late Glacial-Holocene fossil soil. Periglacial structures, such as deformed ice-wedge pseudomorphs, cracks and lenses macro-structures were documented in the loess and palaeosol at the bottom of the closed depression. The depression is filled with Neoholocene soil-sediment sequences consisting of 2 layers of colluvial sediments, separated by Neoholocene subfossil soil. They constitute a record of the two stages of CD infillings in the Holocene, connected with human agricultural activity, lasting from the Neolithic up to modern times.A detailed analysis of the loess, Late Glacial-Holocene fossil soil and Holocene colluvial sediments made it possible to distinguish the stages of evolution of closed depression influenced by changing environmental conditions and human activity, during the Late Glacial and Holocene.

Assessment of the natural flow regime in a Mediterranean river impacted from irrigated agriculture

Over the last few decades, the natural flow regime of most rivers has been significantly altered influencing the ecological integrity and functioning of river ecosystems. Especially in the Mediterranean region, irrigated agriculture is considered one of the most important drivers of hydro-morphological modifications in river systems. In this study we employ the Indicators of Hydrologic Alteration (IHA) methodology for the Pinios River and its tributaries, located in a Mediterranean catchment in central Greece, with the purpose to assess the natural flow regime under a simulated no-agriculture scenario and compare with the current situation. The work is based on the use of the SWAT (Soil Water Assessment Tool) model for the simulation of long time series of daily stream flows, which were analyzed under the actual conditions (baseline), and the hypothetical scenario. The key characteristics of the flow regime projected under each model run were assessed through the implementation of the IHA methodology that utilizes a number of indicators to characterize the intra- and inter-annual variability in the hydrologic conditions. The results of this study revealed that without agricultural activities in the catchment, annual and monthly flows would increase, with significant alterations in the flow characteristics of the winter months, and much smaller in summer. However, the analysis showed that the frequency of droughts and low flow summer events would be smaller. The article provides a comprehensive and easy-to-implement methodology that can facilitate the impact assessment of agricultural human activities on river flow variability under the typical Mediterranean conditions, allowing experimentation on setting river flow thresholds required for a good ecological status within the context of the European Water Framework Directive.

Synthetic salt water desalination by electrodialysis using reinforced ion exchange membranes for acid–base production

The demand for clean water is vast, whether it is used for human consumption, agricultural activities or industrial applications. To find a solution for this important issue, a small attempt has been made in the present work towards developing reinforced monopolar and bipolar membranes based on functionalized polysulfone and evaluated for electrodialysis of salt water. Polyvinyl pyrrollidone was used as the intermediate layer for the preparation of the bipolar membrane. The concentration of salt water taken for the bipolar membrane electrodialysis (BPMED) process ranged from 5 to 25 g/L. A commercially procured monopolar and bipolar membranes made of polystyrene divinyl benzene was also evaluated for the purpose of comparison. The BPMED performance reached a highest current efficiency of 75.8 and 53.6 % with the energy consumption of 0.36 and 1.39 Wh for the synthesized and commercial membranes respectively. Also the performance of the fabricated unit was assessed in terms of electrical conductivity, salinity and ion (sodium and chloride) concentrations in the feed solution after 8 h duration. The reproducibility performance of the membranes was also analyzed for various concentrations of the synthetic salt solution.

Occurrences and toxicological risk assessment of eight heavy metals in agricultural soils from Kenya, Eastern Africa.

The concentration distribution and toxicological assessment of eight heavy metals including lead (Pb), cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), mercury (Hg), arsenic (As), and zinc (Zn) in agricultural soils from Kenya, Eastern Africa, were investigated in this study. The results showed mean concentrations of eight heavy metals of Zn, Pb, Cr, Cu, As, Ni, Hg, and Cd in agricultural soils as 247.39, 26.87, 59.69, 88.59, 8.93, 12.56, 8.06, and 0.42mgkg(-1), respectively. These mean values of eight heavy metals were close to the toxicity threshold limit of USEPA standard values of agricultural soils, indicating potential toxicological risk to the food chain. Pollution index values revealed that eight heavy metals severely decreased in the order Hg > Cd > As > Cu > Pb > Zn > Ni > Cr and the mean value of the overall pollution index of Hg and Cd was 20.31, indicating severe agriculture ecological risk. Potential pollution sources of eight heavy metals in agricultural soils were mainly from anthropogenic activities and natural dissolution. The intensification of human agricultural activities, the growing industrialization, and the rapid urbanization largely influenced the concentration levels of heavy metals in Kenya, Eastern Africa. Moreover, the lack of agricultural normalization management and poor enforcement of environmental laws and regulations further intensified the widespread pollution of agricultural soils in Kenya.

The Legal Challenges of Transboundary Wildlife Management at the Population Level: The Case of a Trilateral Elephant Population in Southern Africa

More than 80% of the African elephant (Loxodonta africana) range in Africa still exists outside of formal protected areas, and sits across many administrative and political boundaries. These ranges comprise a matrix of multi-use landscapes of potentially divergent administrative, legal and political systems. It is further recognised that the evolution of the various human focused administrative systems, from an elephant conservation perspective, has been ad hoc and without integration. This has resulted in or facilitated a progressive encroachment on the natural range by human settlement and agricultural activities. The movement of elephant across international boundaries results in a parochial approach to their management, particularly within a context of increasing human-wildlife conflict, and an inconsistent consideration of ecological requirements of the elephant at a trans-boundary level, leading to a mismanagement of these populations, at a trans-boundary level. This study investigates the conservation and management of the Central Limpopo River Valley (CLRV) elephant population roaming between Botswana, South Africa and Zimbabwe, and utilizing the trilateral Greater Mapungubwe Transfrontier Conservation Area (GMTFCA). The desirability of conserving and managing wildlife at the level of the biological unit of the trans-boundary population is taken as a starting-point, following insights from trans-boundary large carnivore and waterbird species in Europe. The many legal and policy frameworks applicable to the CLRV elephant population are identified and tested against this approach. The current approach taken in respect of the CRLV elephant population meets the benchmark to a substantial degree, although some essential steps remain to be taken. We discuss potential adjustments to laws and policies that are required to ensure the ecological stability of trans-boundary elephant populations, and to provide for their collective management.

Detecting long-term valley fill evolution and rice paddy land use: Ageoarcheological investigation of the Baeksuk valley and the Bronze Age settlement, South Korea

This study investigates paleoenvironmental changes over time and ancient land use related to agriculture at the Bronze Age settlement of Baeksuk, Cheonan, South Korea. Geoarcheological analytic methods including soil micromorphological, physical and multi-element analyses were employed to examine the alluvial valley fill between hills occupied by a large-scale Bronze Age settlement with abundant crop remains including rice, but which was scarcely inhabited in later periods. The location of the cultivation fields remains as yet undetermined despite a full excavation. This research reveals that there were four phases in the build-up of the valley fill from wetland to periodically dry wetland and, eventually, to the present day rice paddy, forming a cumulic A horizon. In particular, the lower buried horizon may have served as the earliest location for growing rice with surface disturbance noted by textural pedofeature formation, while the upper part of the soil profile exhibits features typical of paddysol with high iron and manganese accumulations. The analyses of the valley soil profile suggest plausible interactions between human agricultural activities and environment through rice paddy cultivation.

Groundwater Quality Investigation Using Multivariate Analysis — Case Study: Western Nile Delta Aquifer, Egypt

DOI: 10.7763/IJESD.2016.V7.732  Abstract—Groundwater is an important source of drinking water in Egypt. Therefore, it is very important to assess the quality of drinking water. The present study presents the multivariate statistical analysis of groundwater quality of western Nile Delta aquifer in order to investigate the factors controlling the groundwater quality. Nineteen Physicochemical parameters viz., Electrical conductivity (EC), Total dissolved solids (TDS), Total Hardness (TH), pH, Calcium (Ca), Magnesium (Mg), Sodium (Na), Potassium (K), Chloride (Cl), Sulphate (SO4), Bicarbonate (HCO3), Carbonate (CO3), Iron (Fe), Manganese (Mn), Zinc (Zn), Cupper (Cu), Nickel (Ni), Nitrate (NO3) and Ammonium (NH4) are analyzed. From the correlation matrix analysis of groundwater quality parameters, strong correlation is observed among K, Ca and CL versus EC. The same relations between Mg, Ca, CL versus TDS, as well as weak and negative correlation are found among HCO3, Fe, Mn, Zn, Cu, NH4, NO3 with EC, TDS. Factor analysis is applied on the 19 parameters to investigate the origin of the water pollution sources. Multivariate analysis showed the existence of up to four significant factors which account for 77.0 % of the total variance of hydrochemistry data. The first two factors can be initially assigned to mineralization, mining and salinity due to saltwater intrusion whereas the others originate as a result of industrial wastes, domestic wastes and wastes from agriculture activities. This work will provide policy makers and land use managers with knowledge of precise groundwater quality problems affecting the aquifer. It is recommended that concerned authorities should take the necessary actions to control the pollution sources of groundwater such as human activities, agricultural activities, and other industrial units.

Driving mechanisms of nitrogen transport and transformation in lacustrine wetlands

As an essential component of proteins and genetic material for all organisms, nitrogen (N) is one of the major limiting factors that control the dynamics, biodiversity and functioning of lacustrine wetlands, in which intensified N biogeochemical activities take place. Reactive N loaded into wetland ecosystems has been doubled due to various human activities, including industrial, agricultural activities and urbanization. The main driving mechanisms of N transport and transformation in lacustrine wetlands are categorized to pushing forces and pulling forces in this study. Geomorphology, wetland age, N concentrations, and temperature are the main pushing forces (passive forces); whereas water table variation, oxygen concentration, other elements availability, oxidation-reduction potential (Eh) and pH, and microorganisms are the predominant pulling forces (active forces). The direction and kinetic energy of reactions are determined by pulling forces and then are stimulated by pushing forces. These two types of forces are analyzed and discussed separately. Based on the analysis of driving mechanisms, possible solutions to wetland N pollutions are proposed at individual, regional and global scales, respectively. Additional research needs are addressed to obtain a thorough understanding of N transport and transformations in wetlands and to reduce detrimental impacts of excessive N on such fragile ecosystems.

Geographical boundary and climatic analysis of Pinus tabulaeformis in China: Insights on its afforestation

Pinus tabulaeformis, as an endemic species in China, is one of the main tree species for afforestation. For rational cultivation planning and conservation, it is necessary to understand the geographical boundaries and the ecological characteristics of P. tabulaeformis, and to explore its priority afforestation areas. In this study, maximum entropy modeling (MaxEnt) was used to identify and prioritize suitable habitats of P. tabulaeformis, based on 13 climatic variables and GlobCover 2009 data. The results show that the MaxEnt model performs better than random prediction, with an average test area under the curve (AUC) value of 0.93 (0.91–0.94). Precipitation of wettest month (PWM), annual biotemperature (ABT), mean temperature of the coldest month (MTCM), annual mean temperature (AMT), precipitation of driest month (PDM), coldness index (CI), annual precipitation (AP), and mean temperature of the warmest month (MTWM) are identified as dominant variables which explain 94.6% of variability the geographical distribution of P. tabulaeformis. Climatic conditions of P. tabulaeformis in the core area of its distribution are as follows: PWM, 100–246mm; ABT, 3.0–4.7°C; MTCM, −20.2 to −1.1°C; AMT, 2.9–14.7°C; PDM, 2–11mm; CI, −49.4–0°C; AP, 431–1122mm; and MTWM, 19.6–31.2°C. The suitable areas for afforestation are 2.6×104km2 (patches with an area >1km2), 1.6×104km2 (patches with an area >10km2), and 1.2×104km2 (patches with an area >100km2), which are mainly located in north Shaanxi, south Ningxia, and the middle of Gansu and Liaoning provinces with serious landscape fragmentation caused by human agricultural activities. Our simulation results can improve our understanding of the geographical and ecological characteristics of P. tabulaeformis and provide prediction of priority areas for afforestation of this species under current and future climate change scenarios in China.

Effect of anthropogenic activities on the water quality of Amala and Nyangores tributaries of River Mara in Kenya.

Mau Forest in the upper reaches of the Mara River basin has recently undergone increased forest destruction followed by human settlement and agricultural activities. These anthropogenic activities may be contributing nutrients and heavy metals, ultimately polluting the river water and eventually Lake Victoria water hence damaging these aquatic ecosystems. This study sought to establish the effect of anthropogenic activities and season on the water quality of the Amala and Nyangores tributaries of the River Mara in Kenya. Pristine springs in the Mau Forest were used as reference sites. Water samples were analyzed for pH, temperature, conductivity, nutrients, selected heavy metals, and selenium. The mean range of the parameters measured from sites along the tributaries was pH 5.44-7.48 and that for conductivity was 20-99 μS/cm while the mean range of nutrient levels (μg/L) was 80-443 (NO3--N), 21.7-82.7 (NH4+-N), 11.9-65.0 (soluble reactive phosphorous), and 51-490 (total phosphorous). The mean range for heavy metals and selenium (in μg/L) from sites along the tributaries were 6.56-37.6 (Cu), 0.26-4.97 (Cd), 13.9-213 (Zn), 0.35-3.14 (Cr), 0.19-5.53 (Mn), 1.90-9.62 (Pb), and 0.21-4.50 (Se). The results indicated a significant difference (p≤0.05) between the reference sites and the different sampling sites, indicating that anthropogenic activities were impacting the quality of water in the two tributaries. Although most of the parameters were within the WHO (2004), USEPA (2014) and NEMA (2006) acceptable limits for surface waters, they were above the permissible levels for domestic use. Moreover, the levels of nutrients, heavy metals, and selenium were significantly higher in the wet season than in the dry season, further indicating that anthropogenic activities are causing a disturbance in the aquatic system. Therefore, further anthropogenic activities should be checked and limited so as to conserve the ecosystem.

The Efficacy of Water Transfer on Nutrients Removal in the Tianjing Lake, Tiacang City, China

Water pollution is a key environmental problem affecting modern day China. Increased human population, agricultural and advanced industrial activities present a complex multiple problems impacting water resource across China. This situation is more pronounced in Tianjing Lake, Tiacang City. Engineered in April 2012, the lake exemplifies severe eutrophication problems. Constructed for recreational uses, the lake plays a vital role in the economic and sociopolitical development of Tiacang City. As a result, the Tianjing Lake water transfer project was carried out in order to improve water quality and alleviate eutrophication. The project considered major field observations that monitored the lake’s nutrients concentrations (TN, TP, NH4, COD Mn) before and after water diversions. Results showed that the effects of water transfer on the overall water quality improvement in the lake seemed heterogeneous. The observed heterogeneity is as a result of the lake’s hydrodynamic conditions influenced by inflow tributaries. However, poor water movement resulting from the lack of outlet to actively expel pollutants may be a key factor compounding the lake’s internal nutrients management. This, however, dictates the engineering of additional flow directions in order to ensure better exchanges and additional nutrients removal through the expulsion via the outlet to improve water quality and sustain ecosystem health. Hence, this study provides useful information necessary to better understand the complex hydrodynamic and mass transport processes in the Tianjing Lake and present a road-map for future management decision-making.

ZMIANY ŚRODOWISKA NIECKI NIDZIAŃSKIEJ (POŁUDNIOWA POLSKA) W ŚWIETLE ANALIZY MALAKOLOGICZNEJ MARTWIC WAPIENNYCH W PIŃCZOWIE

ENVIRONMENTAL CHANGES OF THE NIDA BASIN (SOUTH POLAND) IN THE LIGHT OF MALACOLOGICAL ANALYSIS OF CALCAREOUS TUFA IN PIŃCZOW Abstract. Malacological researches was conducted in an outcrop of calcareous tufa and loess diluvium found in Pinczow, in the Nida Basin. Rich and varied mollusc assemblages were described in detail. The species composition and structure indicates changes in the sedimentary environment during the late Holocene. Calcareous tufa accumulated in a small reservoir formed at the back of travertine dam. The uppermost part of the profile composed of loess diluvium, point out to the development of slope processes induced by human agricultural activity. This sediment accumulated in the Middle Ages as determined from radiocarbon dating and numerous findings of pottery. The sussession of the faunal assemblages enables to define the major phases of changes in the sedimentary environment, determine the human impact on the sedimentation and describe the malacofauna diversity. The tufa profile from Pinczow can serve as a model section presenting the carbonate sedimentation process in small lakes and anthropogenic environmental changes.

Antimicrobial Susceptibility Profiles among <i>Escherichia coli</i> Strains Isolated from Athi River Water in Machakos County, Kenya

Antimicrobial use in agriculture, livestock and human health has increased over the years leading to the increase in antimicrobial resistance that can also find its way to the aquatic environment. Rivers can act as reservoirs of highly resistant strains and facilitate the dissemination of multidrug resistant (MDR) strains to animals and humans using water. A total of 318 water samples were collected from six different sampling points along Athi River and E. coli isolates were subjected to Kirby-Bauer diffusion method for antimicrobial susceptibility testing. The total mean coliform count of the sampled sites was 2.7 × 104 (cfu/mL). E. coli isolates were most resistant to ampicillin (63.8%) and most susceptible to gentamicin (99.4%). MDR strains (resistance to ≥3 classes of antibiotics) accounted for 65.4% of all the isolates. The site recorded to have human industrial and agricultural zone activities had strains that were significantly more resistant to ampicillin, cefoxitin, amoxicillin/clavulanic acid (P ≤ 0.05) than isolates from the section of the river traversing virgin land and land with minimum human activities. This study indicates that E. coli strains isolated from Athi River were highly MDR and most resistant to some antimicrobial classes (ampicillin and cefoxitin) which constitute a potential risk to human and animal health.