fg
Volume XXII |

Major and minor elements contribution to discriminate between karst drainage watersheds and to outline underground hydrological connections. An example from Sohodol Valley (Vâlcan Mountains, Romania)

Abstract: Water samples for chemical analyses have been collected from impenetrable karst springs and from water flows intercepted by caves within the area of Sohodol valley. The analyzed inorganic constituents were noticed to belong to two distinct categories. One category included solutes of variable concentrations, likely related to local allochtonous inputs (Al, NO3) and to local occurrences of decaying organic matter (PO4, NO3), such solutes being hence irrelevant in terms of regional patterns of rock weathering. The other category of solutes (Ca, Mg, Na, K, Sr, Ba, Rb, Fe, HCO3 and SiO2) proved to have concentrations that did not differ between two interconnected water flows (e.g., impenetrable karst springs that discharged from a common water body; a cave stream connected to an impenetrable karst spring). Accordingly, the concentrations of this second group of constituents represented reliable chemical fingerprints of a particular karst watershed. And implicitly, water flows having contrasting concentrations of such solutes were conjectured to belong to distinct karst watersheds, which likely differed in terms of chemical composition of the karstifiable rocks, and/or of the impervious rocks which provided allochtonous recharge to the concerned karst drainage systems.

Volume XXII |

Influence of climate conditions on maize yield in Oltenia (1990-2021)

Abstract: Maize, the most important cereal crop at global level, is a climate-sensitive plant. Consequently, the changes of the key meteorological parameters, namely temperature and precipitation amount, determine low yields, especially in rain-fed regions. The dependency of maize yield on climate conditions was assessed based on monthly values of the considered meteorological parameters (data from 14 meteorological stations for the period 1990-2021). The mean values of the analysed interval generally reveal proper conditions for the development of maize. However, starting with June until September, mean temperatures are 1 to 2°C above the optimum thermal threshold, as mentioned in the specialized literature. The growth degree days index (GDD) emphasizes Oltenia as a region with a very good thermal potential for maize, all mean values exceeding 1600°C, but the southwestern sector of the plain area has already exceeded 2000°C, underlining the increase in heat stress. The water deficit generates dry conditions, especially in Mehedinți, Dolj, and Olt, mainly in the interval July-August, which also corresponds to the maximum water requirements of maize. Drought prone areas were determined based on Selyaninov’s hydrothermal coefficient (HTC), which indicates slightly dry conditions in the growing season in the plain area, while northwards, in the piedmont and Subcarpathians, the climate is slightly humid, respectively moderately humid, drought risk decreasing gradually in this direction. At monthly level, August is the most problematic period as, except the northeastern part (Polovragi and Râmnicu Vâlcea), the entire region displays dry, moderately dry, and slightly dry conditions. The lowest maize yields correspond to the years 1993, 2000, 2002, 2007, and 2012. If in the first three years, the drastic yield reduction was mostly determined by a severe water deficit registered during the entire life cycle of the plant, in the last two years, the main restrictive factor was represented by temperature, mean monthly values exceeding 27°C and mean maximum values 35°C, especially in the plain area. Taking into account the projected increase in temperature and water deficit, the impact of climate conditions on maize crops may also be gradually higher in Oltenia and certain adaptation measures should be taken.

Volume XXII |

Evaluation of water contamination in a crossborder river catchment affected by mining activities (a case study between Republics of Serbia and Bulgaria)

Abstract: The current article aims to evaluate water contamination in the crossborder section of the Timok River in terms of metalloids and heavy metals. Water pollution comes due to the unregulated discharges of untreated effluents from the Bor mining area (Eastern Serbia) and surrounding ore-smelting plants, dressing and processing factories. Input data includes information concerning the values of eight chemical parameters (As, Cd, Cu, Fe, Mn, Ni, Pb, and Zn), measured at one water sampling site from 2015 until 2020. The analysis follows the Environmental Quality Standards (EQS) for priority substances and some other pollutants recommended in Directive 2013/39/EC and their equivalent criteria transposed into Ordinance H-4/2012. The Heavy Metal Pollution Indеx (HPI) to assess the suitability of water resources for various human needs is calculated. Results obtained show the content of Cd, Cu, Fe, Mn, Ni, and Zn does not fulfill the EQS. The contamination with Cd and Cu is the most severe, the highest concentrations exceeding the normatively determined standards by more than 20 times. The HPI achieves scores ranging from 200.58 (2015) up to 1163.65 (2019), indicating “High pollution” and suggesting the water resources are inappropriate for human consumption. This work complements past studies with findings for a recent period.

Volume XXII |

Structure and composition of mangrove vegetation in the Lakkang Delta and Lantebung, Makassar City, South Sulawesi, Indonesia

Abstract: As a type of coastal vegetation, mangroves are valuable, unique, and vulnerable. Mangrove ecosystems have a distinctive vegetation structure, which consists of several characteristics sequentially, such as trees, saplings, poles, and seedlings. This study aims to assess and monitor the structure and composition of mangrove vegetation in Makassar City, South Sulawesi. Field surveys were conducted to measure and monitor mangroves in two different areas, namely coastal areas and small islands. The highest mangrove density is at Station 2, which is 0.59 ind/m2, which is a river area. The station with the lowest density is at Station 1, which has a value of 0.23 ind/m2, which is a coastal area. Avicennia marina, Rhizophora apiculata and Acanthus ilicifolius were found to have the highest importance value index. Location 1 is the least stable because it only has the Avicennia marina mangrove species. Meanwhile, at location 3 (Lakkang Island, a small island), there are variations in the value of each index, although it is still in the low category. This means that in general, each research location has a less stable ecosystem. Furthermore, this study can contribute to conservation, biodiversity assessment, and sustainable mangrove ecosystem management strategies.

Volume XXII |

Assessing potential habitat suitability of vulnerable endemic species: a case study of Diospyros celebica Bakh and Rhyticeros cassidix

Abstract: Diospyros celebica Bakh and Rhyticeros cassidix are known to be associated in several locations in Sulawesi. Both of these species are endemic to Indonesia that live throughout the island of Sulawesi. Species Distribution Modeling using Maximum Entropy (MaxEnt) is considered an alternative way to understand the potential area suitable for a species. Model predictions from MaxEnt for all species have an AUC value of 0.887 and 0.837. Suitable habitat for D. celebica Bakh in Central Sulawesi (Morowali Utara, and The southern coast of Banggai) and South Sulawesi (Luwu Timur, Luwu Utara, Toraja Utara, Barru, Pangkep, Maros, Sidrap, Wajo, Sidenreng Rappang, and Gowa). However, the suitable habitat for D. celebica Bakh and R. cassidix in the association is much smaller. Environmental variables that are considered important that influence the occurrence of D. celebica Bakh are Soil Types, especially soil types Dystric Fluvisols, Eutric Fluvisols, Or-thic Luvisols, Orthic Acrisols, Eutric Cambisols, rainfall, and bio13. While R. cassidix is affected by distance from roads, distance from settlements, and distance from rivers, based on actual data points and habitat predictions. Most of the suitable habitat for D. celebica Bakh and R. cassidix is estimated to be outside the conservation area, but the suitable habitat is estimated in 8 functional status conservation areas. These results can be used by the Government of the Republic of Indonesia, and the Ministry of Environment and Forestry for determination.