Drainage Water Research Articles

Ecological and Geochemical Characteristics of Potassium Industry Waste

The analysis of the ecological and geochemical characteristics of waste from the extraction and processing of potash salts, which determine the ecological state of the areas of development of these deposits, is carried out. Objects are salt dumps, sludge storages, drainage waters formed on the territory of the Verkhnekamskoye potassium-magnesium salt deposit. Under research of chemical composition of waste and the drainage waters of the sludge storage it was determine that high concentrations of mobile forms of chemical elements in drainage sodium chloride waters of waste storage facilities, an increase in the concentration of nitrogen compounds in filtration waters have been established. The active role of salt solutions in the leaching of clay minerals of salt dumps and sludge dumps, clay protective screens is determined, which leads to active filtration of salt solutions through the bed of the sludge dump, salt dump, migration of microelements in a readily soluble form into the environment.

Remote Sensing and GIS Aided Land and Water Management Plan Preparation of Watershed - A Case Study

Remote Sensing and GIS techniques were applied for the integrated watershed planning of Bajpur watershed in Khurda sadar block of Khurda district (Orissa). IRS ID, LISS III F.c.c. satellite images and toposheet number 73H/12 together with verification were used as the data source. Thematic maps like land use/ land cover map, hydrogeomorphology map, soil map, slope map, drainage and surface water body maps were prepared by using both satellite imageries and survey ofIndia toposheet. By integrating all these maps in GIS, water and land resource management plans were developed. The water resources development plan indicates the sites for groundwater exploitation and sites for surface water development including sites for different soil and water conservation structures. Eleven action items were suggested under land resource action plan with specific sites, aerial locations and maps. Thus remote sensing technology demonstrates the usefulness for providing up-to-date, reliable and accurate information on different natural resources of the watershed which is a pre-requisite for an integrated approach to identify the suitable sites for water harvesting structures, check dams, farm ponds, percolation tanks, nala bunds etc. The GIS technique is helpful to integrate the information into a composite land unit development map to generate alternate land use system for sustainable development of the watershed.

[Effects of Pesticides Use on Pesticides Residues and Its Environmental Risk Assessment in Xingkai Lake（China）].

Xingkai Lake, located in Heilongjiang Province, is an important fishery and agricultural base and is seriously polluted by agricultural non-point sources. To clarify the residual status of many pesticides in the surface water of Xingkai Lake, 27 types of pesticides, herbicides, and their degradation products were analyzed in rice paddy, drainage, and surface water around Xingkai Lake (China) during the rice heading and maturity periods. The results showed that all 27 types of pesticides, herbicides, and their degradation products were detected during the rice heading period, and the total concentration ranged from 247.97 to 6 094.49 ng·L-1. Additionally, 25 species were detected during the rice maturity period, and the total concentration ranged from 485.36 to 796.23 ng·L-1. In comparison, more pesticides, herbicides, and derived degradation products were detected during the heading period, and their total concentration was higher as well. During the rice heading period, atrazine, simetryn, and paclobutrazol were the main detected pesticides, atrazine and isoprothiolane were the main pesticides detected during the maturity period. The distribution characteristics of pesticides and herbicides in the surface water around Xingkai Lake (China) was similar to that in drainage, so they were probably imported from the drainage and rice paddy. The average risk quotient (RQ) values of atrazine, simetryn, prometryn, butachlor, isoprothiolane, and oxadiazon were higher than 0.1 in drainage and Xingkai Lake (China), which showed a potential risk to aquatic organisms.

Denitrifying bioreactors and dissolved phosphorus: Net source or sink?

Understanding the world through a lens of phosphorus (P), as Dr. Andrew Sharpley aimed to do, adds a deeper dimension for water quality work in the heavily tile-drained US Midwest where nitrate is often the nutrient of biggest concern. Denitrifying woodchip bioreactors reduce nitrate pollution in drainage water, but dissolved phosphorus leached from the organic fill is a possible pollution tradeoff. Recent work by Dr. Sharpley and others defined such tradeoffs as strategic decisions in which a negative outcome is accepted with prior knowledge of the risk. In this vein, we assessed 23 site-years from full-size bioreactors in Illinois to determine if bioreactors were a net dissolved reactive phosphorus (DRP) source and, if so, to determine flow-related correlation agents (1904 sample events; 10 bioreactors). DRP was removed across the bioreactors in 15 of 23 site-years. The 23 site-years provided a median annual DRP removal efficiency of 12% and a median annual DRP removal rate of 7.1mg DRP/m3 bioreactor per day, but the ranges of all removal metrics overlapped zero. The highest daily bioreactor DRP removal rates occurred with high inflow concentrations and under low hydraulic retention times (i.e., under higher loading). Dr. Sharpley was one of the first to explore losses of DRP in subsurface drainage and performed decades of useful applied studies that inspired approaches to management of P loss on both drained and undrained land. We seek to honor this legacy with this practical study of the DRP benefits and tradeoffs of denitrifying bioreactors.

A novel approach for sludge deep-dewatering via flowing-out enhancement but not relying on cell lysis and bound water release

Effective deep-dewatering is crucial for wastewater sludge management. Currently, the dominant methods focus on promoting cell lysis to release intracellular water, but these techniques often lead to secondary pollution and require stringent conditions, limiting their practical use. This study explores an innovative method using a commercially available complex quaternary ammonium salt surfactant, known as G-agent. This agent remarkably reduces the sludge water content from 98.6 % to 56.8 % with a low dosage (50 mg/g DS) and under neutral pH conditions. This approach surpasses Fenton oxidation in terms of dewatering efficiency and avoids the necessity for cell lysis and bound water release, thereby reducing the risk of secondary pollution in the filtrate, including heavy metals, nitrogen, phosphorus, and other contaminants. The G-agent plays a significant role in destabilizing flocs and enhancing flocculation during the conditioning and initial dewatering stages, effectively reducing the solid-liquid interfacial affinity of the sludge. In the compression filtration stage, the agent's solidification effect is crucial in forming a robust skeleton that improves pore connectivity within the filter cake, leading to increased water permeability, drainage performance and water flow-out efficiency. This facilitates deep dewatering of sludge without cell lysis. The study reveals that the G-agent primarily improves water flow-out efficiency rather than water flowability, indicating that cell lysis and bound water release are not indispensable prerequisites for sludge deep-dewatering. Furthermore, it presents an encouraging prospect for overcoming the limitations associated with conventional sludge deep-dewatering processes.

Two-phase flow in the gas diffusion layer with different perforation of proton exchange membrane fuel cell

ABSTRACT Gas diffusion layer (GDL) is an important pathway for water transport in the proton exchange membrane fuel cell. The presence of excessive liquid water in the cathode GDL will cause “water flooding” and block the reactant transport path to catalyst sites. Therefore, it’s critical to understand water transfer mechanism in GDL and propose novel strategy to improve water management. In this study, the effect of GDL with different perforation holes on liquid water transport behavior are investigated by volume of fluid method. The simulation model is validated by comparing with the reported data. The results show that the GDL with perforation holes will accelerate the liquid water breakthrough. Specially, the GDL with cylindrical perforation achieves the lowest breakthrough pressure, and most excellent water drainage capacity under various pressure drops. The gradient hydrophobic distribution in GDL will improve the water breakthrough path and drainage capacity. However, gradient hydrophobic treatment in GDL with conical perforations will result more water leakage along the though-plane direction. The simulation results will provide significant guidance for designing high performance GDL and improving the water management in proton exchange membrane fuel cell.

"Effects of Floating Aquatic Vegetation and Canal Sediment on Phosphorus in Drainage Discharges in Agricultural Canals: A Case Study in the Everglades Agricultural Area, Florida"

Phosphorus (P) discharge from agricultural and urban drainage is known for causing downstream eutrophication worldwide. Agricultural best management practices that are designed to reduce P load out of farms target different P species from various sources such as fertilizers leaching and farm soil and canal sediment erosion, however, few studies have assessed the impact of floating aquatic vegetation (FAV) on canal sediment and farm drainage water quality. This study evaluated the impact of FAVs on canal sediment properties and P water quality in drainage canals in the Everglades Agricultural Area in south Florida, USA. Non-parametric statistical methods, correlation analysis, trend analysis and principal component analysis (PCA) were used to determine the relationship between FAV coverage with sediment properties and P water quality parameters. Results showed that FAV coverage was correlated with the highly recalcitrant and most stable form of P in the sediment layer (Residual P Pool). FAV coverage also correlated with the dissolved organic P (DOP) which was the smallest P pool (7%) of total P concentration in drainage water, therefore FAV coverage had no correlation with farm P load. The trend analysis showed no trend in farm P loads, despite a decline in FAV coverage at farm canals over an 8-year period. Phosphorus content in the sediment surface layer was strongly associated with farm P load and had a significant correlation with particulate P (PP) and soluble reactive P (SRP) which constituted 47% and 46% of the total P concentration in the drainage water, respectively. Equilibrium P concentration assays also showed the potential to release SRP from the sediment layer. The P budget established for this study reveals that sediment stores the largest P mass (333 kg P), while FAVs store the smallest P mass (8 kg P) in a farm canal, highlighting the significant contribution of canal sediment to farm P discharges. Further research is required to evaluate the impact of sediment removal and canal maintenance practices that help reduce farm P discharges.

Numerical investigation and experimental verification of liquid water dynamic transfer characteristics in the flow field of PEMFC with dead-ended anode during gas purging

Water accumulation in the anode during the operation of a proton exchange membrane fuel cell with the dead-ended anode (DEA) has a significant impact on its performance. In this study, numerical simulation and experimental verification were combined to investigate the water accumulation and water dynamic transfer characteristics in the anode flow field during dead-ended operation and gas purging, respectively. The effects of placement orientation, surface wettability, and purge time on the water dynamic transfer characteristics are investigated. The results show that the placement orientation has significant effects on the water distribution characteristics and drainage for PEMFC. When placed vertically and with a purging time of 50 ms, the liquid water saturation in the channel is 5.52 %, which drains 14.91 % more water than that of horizontal placement. Besides, Water discharge velocity and water removal ratio should be considered comprehensively in the development of the purge strategy, the optimal purging time is 70 ms with the water discharge velocity and water removal rate are 0.39 μl/ms and 97.34 %, respectively. Finally, the transfer process of liquid water in the flow field with DEA mode is observed by visual experiment, and the results of the numerical simulation are verified.

Seasonal Dynamics and Ecological Risks of Organochlorine Pesticides in Kafrelsheikh-Egypt: Implications for Aquatic Ecosystems and Public Health

Kafrelsheikh, situated in the middle of the Nile Delta, significantly contributes to Egypt's aquaculture and agriculture sectors. However, the local use of organochlorine pesticides (OCPs) in agriculture is often a source of OCP residues in associated drainage waters, which may threaten aquatic ecosystems. These pesticides persist in local water bodies, jeopardizing aquatic ecosystems and potentially impacting human health. This comprehensive study assessed the seasonal variations of 17 OCPs in both water sources and Nile tilapia across eight fish farming locations in Kafrelsheikh. Using gas chromatography coupled with mass spectrometry (GC-MS), we detected OCP concentrations in water that varied seasonally: winter recorded the highest levels at 22.5 ng/mL. In comparison, summer showed the lowest levels at 6.2 ng/mL. Despite water samples occasionally showing risk quotients (RQs) greater than 1, indicating a potential threat to aquatic life, the OCP levels in Nile tilapia were sufficiently low, with target hazard quotients (THQ) below 1, suggesting no significant risk to human consumers. The research highlights a pressing need for regular environmental monitoring and stricter regulatory control over pesticide use to protect aquatic life and ensure the safety of aquaculture products. These findings provide a critical basis for policy-making, aimed at balancing agricultural productivity with environmental sustainability in regions heavily dependent on both.

Analysis of rainwater utilization technology and current situation in the roof garden

The urban water environment has been deteriorating over the last decade due to land development and climate change, increasing the pressure on urban stormwater drainage systems. With economic development, the value of buildings has also been challenged at a higher level. Roof garden, as a new form of roof treatment, can effectively increase the urban greening area and compensate for the ecological and water environments that have been damaged by building development and utilization. This paper analyzes the advancement of roof garden by comparing it with the traditional sloped roof. The analysis finds that roof gardens can store water and control drainage, and have significant advantages in reducing rainwater discharge, reducing building water demand, and improving the urban water cycle. Roof gardens not only have the ability to utilize rainwater efficiently, but also come with a series of economic, ecological, and social benefits, such as improving the urban heat island effect, saving the amount of water demanded by buildings, and energy consumption. By analyzing domestic and international cases of roof gardens, it is verified that roof gardens are designed as a combination of utility and aesthetics.

Performance of surface, subsurface and trench‐type drainage systems in paddy fields for non‐rice farming

AbstractEffective drainage is a crucial factor in paddy fields, especially in regions with waterlogging or heavy clay soils. Identifying an effective drainage system is essential for the successful removal of excess soil water from paddy fields to prepare them for subsequent crops. This study aimed to evaluate three different drainage systems, shallow surface drainage (shallow ditch), conventional subsurface pipe drainage and trench‐type subsurface drainage (French drain), in paddy fields in terms of drainage water volume, water table depth, drainage intensity, soil moisture and cracks. Experiments were carried out in a physical model capable of simulation with a 7.5 m drain spacing. The findings indicated that trench‐type drainage was more effective in reducing soil moisture due to its higher drainage water volume compared to other systems. The time required for the topsoil to reach its lower plastic limit in the subsurface, trench‐type and shallow surface drainage systems was 14, 11 and 15 h after the depletion of excess water over the soil surface, respectively. Although shallow surface drainage represented faster depletion of excess water, trench‐type drainage eventually proved to be the most effective alternative for providing appropriate qualifications for secondary cultivation. Crack areas on the soil surface were twice as extensive in trench‐type and subsurface drainage systems as in shallow surface drainage systems, indicating their superior performance.

Assessing the Efficiency of Municipal Infrastructure - Case study in Vaaniyambadi Municipality, Tamilnadu, India

Abstract: This document discusses the evaluation of infrastructure facilities in Vaniyambadi, with the aim of improving the quality of life by addressing the issues and suggesting ways to enhance these facilities. The study focuses on physical infrastructure, including water supply, sewage and drainage, solid waste management, and electricity supply. It highlights the need for alternate water sources, additional pumping stations, and proper distribution of overhead water tanks to ensure equal access to water. It also emphasizes the importance of covering open drains, installing sewage treatment plants, and raising awareness about proper waste management to create a cleaner and healthier environment. Furthermore, the document addresses social infrastructure, particularly healthcare facilities and educational institutions. It suggests improvements such as increasing the number of beds and water supply in government hospitals, enhancing security systems in schools, and promoting collaboration between the community and municipal workers to maintain cleanliness. The document concludes by emphasizing the significance of infrastructure in driving economic and social development and the need for continuous improvement and modernization. Keywords: Municipal infrastructure, Physical infrastructure, Social infrastructure, Solid waste management , water supply

Isolating Indigenous Metal Resistant Gram-Positive Bacteria: Assessing Their Selenite Reduction Potential

The objective of this study is to isolate gram-positive bacilli from soil and to study the effects of physiological parameters on their heavy metal resistance. High levels of metals in the soil can have major toxic effects on soil microorganisms and may cause a great change in the species diversity and population sizes of soil microbes. In current study soil samples were collected from the agriculture drainage water and soil in Lahore. After the selection of sixty gram-positive strains, their biochemical and metabolic profile was structured and all were auxin producing. The isolates were resistant to multiple heavy metals including Ni. Pb, Cr, Li and Hg. Their selenite reduction was estimated at varyingpH, Temperature and concentrations of selenite and all were resistant upto 3000 ?g/ml, However, their efficacy of reducing selenite was majorly affected by set physiological parameters.

Study on Effect of Bio Control Agent Trichoderma viride and Neem Cake on Rhizome Rot of Turmeric

Turmeric (Curcuma longa) is one of the major spice crops in Andhra Pradesh, which is severely affected by rhizome rot (soil borne disease) and leaf spots (foliar diseases). There was drastic reduction in yield, which is majorly affected by soil borne fungus. So, the present study mainly intends to evaluate the performance of Trichoderma viride along with neem cake against rhizome rot disease. The experiment was conducted in three successive years at 10 villages and 30 locations of Krishna district as a Front-Line Demonstration of Krishi Vigyan Kendra, Ghantasala, Acarya N G Ranga Agricultural University. The treatment (TO1) consists of seed treatment, ridge sowing, excess water drainage and soil application of T viride culture 2 kg multiplied in 90 kg Farm Yard Manure and 10 kg neem cake at the last ploughing time and use of neem cake 300 kg/acre at 60 and 120 DAP at plant base. Whereas, the farmer’s practice (TO2) was drenching of copper oxy chloride @ 3g /l of water only to control rhizome rot. In comparing the average data of both the treatments for three consecutive years, TO1 recorded highest yield of 49.12 t/ha of fresh turmeric with a yield improvement of 32.43 % over control. In case of rhizome rot incidence, the average percent incidence for the three consecutive years was reported as 3.37 % in demo and 10.72% in control. In case of net returns, Rs. 2,08,743/- per ha was obtained with a B:C ratio of 1.99:1 in demo and Rs. 93,428.17/- of per ha with 1.43:1 B:C ratio in control. It can be concluded that apart from using only chemicals, integrated management practices fetch better yield and returns too.

A Room‐Temperature Curing Plant Protein‐Based Adhesive with High Strength and Flame Retardancy for Heat‐Free Adhesion

AbstractPlant protein‐based adhesives are gaining traction owing to their low cost and eco‐friendliness. However, achieving flame retardancy and long‐term water resistance in them under room‐temperature curing conditions remains a challenge due to the hydrophilicity and low reactivity of plant proteins. Herein, a novel adhesive synthesized from soybean meal (SM), activated sodium alginate (aSA), nano‐hydroxyapatite (nHA), and polyamidoamine‐epichlorohydrin (PAE) resin addresses this challenge. aSA as a reactive bio‐based cross‐linker formed covalent cross‐linking structures with SM matrix at room temperature, while the nHA‐induced biomineralization and PAE‐constructed supramolecular cross‐linking promote water drainage from the adhesive, preventing water erosion of the adhesive structure. The developed adhesive shows versatility across multiple substrates, with its wet shear strength on wood reaching 0.76 MPa, surpassing that of the commercial aldehyde‐based adhesive. The adhesive is effective over a wide temperature range from room temperature to 150 °C due to the reactivity of the PAE resin above 60 °C. Moreover, it exhibits excellent flame retardancy (limiting oxygen index of 31.2%) owing to its dense structure and the abundance of N‐containing and P‐containing components. This work is expected to break the monopoly of petroleum‐based adhesives in the realm of room‐temperature adhesives.

Spatial Analysis of Environmental Factors in the Dengue Hemorrhagic Fever Incident at Soe City District

Introduction: In 2022, there was a large increase in cases resulting in extraordinary events cases in the TTS district with the number 226 cases. Half of the percentage of outbreak cases that occurred in Soe City with a number of cases is 134 cases. Spatial analysis can be used to see patterns of disease distribution in certain areas.Methods: This research is a type of descriptive research with a case study approach. This descriptive research was carried out using a survey method where there was no intervention on variables but simply observing natural phenomena or looking for relationships between these phenomena and other variables.Results:  The research of dengue case data is divided into univariate analysis and spatial analysis, for example, classification, buffering and Moran index. Environmental factors in the form of the existence and condition of water reservoirs with dengue fever incidents can be seen in data related to the number of water reservoirs used by the community which are left open and the number is >3, making it easier for mosquitoes to breed. In the Spatial Classification Analysis, Nonohonis Village has the highest level of risk, but Autocorrelation Analysis states that the Oekefan area has larger cluster points than Nonohonis Village. Furthermore, environmental factors include the existence and condition of dug wells. at a depth of ≤15m with open conditions makes it easier for mosquitoes to breed. Apart from that, based on the buffer data above, it can be seen that at a radius of <100m it is 3 times larger than a radius of 100 to 300m and 2.7 times larger than a radius of 300m to 500m. Environmental factors include the existence and condition of waste water drainage channels (SPAL) with dengue fever incidents. Based on the buffer data above, it can be seen that at a radius of <100m it is 0.6 times greater than the radius from 100 to 300m and 0.8 times greater than the radius from 300m to 500m.Conclusion: It is necessary to control mosquito breeding in water reservoirs and dug wells through education regarding malaria risk factors in Soe City.

Reusing drainage water for leaching of saline and sodic soils in the Khuzestan province, Iran

Abstract A substantial amount of drainage water is generated in the irrigation and drainage networks of the Khuzestan province, located in the southwest of Iran, and it requires effective management. One low-risk strategy for repurposing this drainage water involves its utilization for the reclamation of saline lands. In this study, we investigated the reclamation of saline and sodic soils within the Dosalagh plain. The experimental tests employed the double-ring method, focusing on leaching at depths ranging from 0 to 150 cm in the soil. The treatments encompassed four distinct water qualities (characterized by electrical conductivities of 2.12, 7, 25, and 40 dS m−1) and four different water depths (0, 25, 50, and 75 cm). The soil underwent examination using the intermittent leaching method, which involved a 2-day interruption, and this process was repeated three times. The incorporation of drainage water resulted in a reduction of the electrical conductivity at the 0–25 cm soil depth, decreasing from 117.7 to 29 dS m−1. Furthermore, this addition contributed to a decline in the sodium content within this layer, dropping from 1415.9 to 39.83 meq l−1.

Morphometric Analysis Using Remote Sensing and Geographical Information System: A Case Study of Nawagarh Watershed of Chhattisgarh, India

The study highlights the suitability of a GIS-based approach for evaluating morphometric parameters. It focuses on the quantitative analysis of morphometric characteristics within thirteen sub-watersheds of the Nawagarh watershed, which originates from the Seonath river catchment in the Mahanadi basin in Chhattisgarh, India. The Nawagarh watershed spans an area of 2647.27 km2. Its outlet is located at 21°46'10" N Latitude and 81° 48’43” E Longitude. The Nawagarh watershed covers four districts in Chhattisgarh - Kabirdham, Bemetara, Baloda Bazar, and Mungeli. The analysis reveals the relative qualities of the sub-watersheds in terms of hydrological response. The Nawagarh watershed features a dendritic drainage network with 2760 streams of different orders. The slope of the land directly affects water absorption and drainage. High relief ratio 0.032 in SWD1 and SWD3 indicates rapid concentration, rapid stream flow, and greater susceptibility to erosion than other sub watersheds. The drainage density is 0.80 km-1, which is close to 1 km-1, indicating that the basin has a nearly high drainage density, which demonstrate that the location with impermeable weak subsurface material and has high relief. The elongated shape with the values of form factor (0.39), circulatory ratio (0.28) and elongation ratio (0.69), indicated that the Nawagarh watershed is more elongated with lower peak flow of long duration having low permeability. The drainage density in the basin is relatively high, suggesting a significant drainage network. The study emphasizes the need for effective erosion control methods in the Nawagarh watershed to protect the land.

Flooded architecture as an adaptation tool for climate change impact—a case study of possible interpretation in Egypt

In light of the current global environmental issues, such as floods, underground water problems, and soil salinity, there is a growing need for sustainable architectural and housing solutions that can effectively address the impact of these challenges on food and security (Nation 2002). In Egypt, frequent incidents of flooding and sinking roads and cities are observed, particularly after rainfall or in projects that involve underground water drainage (UN-Habitat 2022). This paper explores the concept of flooded architecture, which involves designing buildings and spaces that are intentionally flooded with water. Through a review of relevant literature and case studies, the paper investigates the potential benefits and drawbacks of this approach nationally inside Egypt, structure, and construction used materials, including its impact on energy efficiency, sustainability, and resilience to natural disasters. The findings suggest that flooded architecture has the potential to offer innovative solutions for a range of environmental and social challenges but also raises important questions around safety, maintenance, and cultural acceptance in Egypt.

Chemical and microbiological assessment of house-filtered water produced by household water filtration systems

Chemical characteristics and microbiological quality of filtered water generated from municipal water using mono-, di- and penta-stage (5-stage) filters, as well as disposed drain water were investigated. With the application of the household water penta filters, the total dissolved solids (TDS) of the filtered water were highly reduced (0.04–0.07 g/L) and, consequently, electrical conductivity also decreased. Furthermore, total hardness was completely removed (0–2 mg CaCO3/L), as well as the chloride content. In the same manner, the nitrate content in the filtered water resulted from the household water penta filters decreased significantly (0.5–0.9 mg/L). Cations, such as Na+ and K+, in the filtered water were greatly affected and were 18–28 and 2 mg/L, respectively. Filtered water generated from the house-water penta filters was not in compliance with the daily amounts of F, Na and K necessary for teenagers and kids, and it might cause a risk of deficiencies. From the microbiological point of view, the penta-stage filter effectively removed total bacterial counts and total coliforms from water making it completely safe for potable and other domestic uses. The home water mono- and di- filters had low effectiveness of contaminant removal.