Evaluation of the Water Quality Status and Pollution Load Carrying Capacity of Way Umpu River, Way Kanan District, Lampung Province, Indonesia, Based on Land Use

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Introduction
Water is the most important component in life, and as a result, people tend to reside around riverine areas. Most human civilizations are located near water streams, especially along big rivers. Tis is because they are important freshwater sources; however, it is the most susceptible to pollution. Moreover, good water quality is essential because it plays a major role in supporting life, food production, energy generation, industry, and environmental support capacities including domestic consumption, agriculture, transportation, tourism, and other required water activities [1,2].
Te river is a meeting point of water coming from various sources such as rainwater and even liquid waste from human activities such as agriculture, transportation, industry, urban, and settlement areas. However, some people think that a river is an ideal place to receive waste from most anthropogenic activities because of its continuous water fow [3]. Te condition of water quality of river in Indonesia is generally determined by the land use. As an example, the source of pollution entering the Cikeas River (West Java) was dominated by housing complexes and the Celeungsi River (West Java) was dominated by industrial sector while the Bekasi River (Wes Java) was dominated by shopping centers, hotels, and restaurants [4]. Tis condition is also widespread in countries with low and middle incomes such as Indonesia, Malaysia, and Myanmar where rapid developments are followed with minimal environmental considerations [2]. Furthermore, the examples of dominant stressors in the lotic system (80% of all water bodies) include hydromorphology degradation, point resource pollution distribution, and water use [5]. Tey commonly afect the water quality in the downstream and upstream areas as a result of the waste that comes from local activities around their surroundings [6]. In addition, stressors were found in the upstream areas due to the efects of anthropocentric activities such as dam building, urbanization, mining, and forestry as well as chemical fertilizers and pesticides from agriculture [7,8].
Water is considered polluted due to the presence of some substances or some conditions that prevent it from being used for a particular purpose [9]. Previous research studies have shown that reduced water quality in some areas such as the Celeungsi, Cikeas, and Bekasi River in West Java, Indonesia, has increased in the last century [4], and this is caused by rapid industrialization, urbanization, other developments/processes, and pollution. Te level of water pollution is assessed based on physical and chemical parameters that infuence the quality of the water body, aquatic habitats, phytoplankton community, and the health of fsh [1,[10][11][12]. Furthermore, the water body is functioned as a habitat for organisms, and responses to the stressors may vary among the producers and consumers. Tese responses afect the nutritional status of the phytoplankton community, and in the long run, it may afect the survival of biodiversity [7].
Te water quality assessment is a complex problem because it involves many factors such as physical, chemical, and biological parameters, and there are difculties in identifying polluting components accurately, which are also infuenced by many factors and processes. Terefore, the knowledge of various causes of pollutants such as sources and impacts of pollution on ecological status is a fundamental prerequisite for efective river management [5].
Te Way Umpu River is one of the main rivers in Way Kanan District, Lampung Province, Indonesia. It has a watershed width of ± 1.179 km 2 , a river length of 100 km, and an average width of 90 to 110 meters. Te Way Umpu River watershed has several land uses, i.e., for forestry, plantation, agriculture, industry, mining, and inhabitant settlement. Besides its main function as macrodrainage into the Java Sea, it serves as a water source for the public. In the dry season, people depend on it for bathing, washing, and fshing [13][14][15]. Moreover, a river is an open ecosystem that is susceptible to stressors coming from its surroundings. Te chief of Environmental Service in Way Kanan District, Dwi Handoyo Retno, S.E., M.M., stated on 27 January, 2021, that illegal mining in Way Kanan, especially gold, severely polluted the Way Umpu River [14]. Te color of the water became brown-yellowish, indicating that the water is not safe to use by the people for many purposes such as washing and bathing. Subsequently, illegal mining also destroys river water fow and mining material waste disposal causes river silting. Tis illegal activity violates the regulation implemented by the Indonesian government for Mineral and Coal Mining Number 4 in 2009, which has been amended to Law Number 3 in 2020 concerning mineral mining [14,15]. Terefore, environment parameter monitoring is the highest priority in water resource environmental status evaluation, environment protection and management, and policy implementation. Furthermore, polluted rivers are important challenges that require intervention from various stakeholders [1,2].
Based on the information above, the objective of this research was to measure the level of pollution by analyzing the river water quality, calculating the pollution load capacity and plankton community structure in the Way Umpu River based on land use.

Sampling Location and Sample Collection. Te Way
Umpu River is geographically located between 04°28′41.4″ south latitude and 104°42′34.9″ east longitude. Te research location includes 7 (seven) stations for sample collection representing several land uses such as forestry, plantation, agriculture, mining, and inhabitant settlement. Te sampling location is presented in Table 1. Sampling locations to predict the water pollutant carrying load capacity are presented in Table 1 and Figure 1.
Te water samples were taken during the wet season (October-April) with the monthly average rainfall data for the last 5 years are 376.83 mm, the data are obtained from the Meteorology, Climatology, and Geophysics Agency of Kota Bumi Lampung, Indonesia. Furthermore, they were collected from 7 stations selected based on the land use in watershed areas. Samples were taken from the right and left banks at each station. Te water parameter was measured directly in situ (pH, temperature, and DO) and the other parameters were analyzed in Seameo Biotrop Service Department Environment Laboratory, in Bogor, Indonesia, which is LP-221-IDN nationally accredited. Te physical and microbiology parameters include temperature, total dissolved solids (TDS), total suspended solids (TSS), water color, turbidity, fecal, and total coliforms. Furthermore, the chemical parameters include pH, salinity, biological oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total phosphate (P), nitrate (NO 3 -N), cadmium (Cd), total chromium (Cr), copper (Cu), lead (Pb), mercury (Hg), nitrite (NO 2 -N), and cyanide (CN).
Water debit is the volume of water that fows per time unit through a river cross-section, and it is expressed in meters cubic per second (m 3 /sec). Te data were obtained by multiplying the speed measurement using the current meter and river width and a trapezoidal width approach. Te width of the river cross-section was also measured with a tape meter [3]. Te 50 L water of the plankton sample was taken quantitatively and compositely using a bucket and fltered with a 50 μm plankton net. Plankton samples were taken from the right and left banks at each station. Furthermore, the collected sample was poured into a 30 mL plastic container and fxated with 5 drops of a 4% formalin solution [18]. Te sample was then observed in an Ecological Laboratory in the Biology Department of the Faculty of Mathematics and Natural Sciences at the University of Lampung, Indonesia.

Data
Analysis. Te Nemerow index (PI) was used to evaluate water quality with the maximum and average scores of a single factor index afecting the composite index [16]. PI has been used widely to evaluate water bodies and is determined based on the ratio of environment standard parameters for specifc purposes with parameter scores from various measurement results [19]. Subsequently, the standard scores for this research were purposed for Class III, which makes up the categories of water used for freshwater fsh culture, animal husbandry, crop irrigation, and for other purposes based on the Local Regulation of Lampung Province (2012) [20]. Te PI equation is presented in the following equation [16]: where PI = Nemerow Index, Ci = measured concentration from evaluation factor class i, and Sij = standard concentration of evaluation factor for water purpose class j. Te correlation between PI value and water classifcation includes PI < 1.0: clean, 1 < PI < 2: mild pollution, 2 < PI < 3: moderate pollution, 3 < PI < 5: polluted, and PI > 5: extremely polluted categories [16,21]. Te diferences between each station were evaluated with the method of analysis of variance (ANOVA). Values were considered signifcant at p < 0.05 level.
Te analysis for load capacity based on Minister Environment Decree of Indonesia Number 110 years 2003 [17] was carried out in Station 7, in the downstream area of the Way Umpu River which receives water fow from some tributaries, namely, the Way Kasui Kiri River where its water fowed through the registered 24 forests of Bukit Punggur and plantation (ST-1) and ST-2 Upstream Way Umpu, the Way Ojolali River (ST-4), where the water fowed through inhabitant settlement, manganese, and gold mining, and the Way Neki River (ST-6), where its water fowed through gold mining and inhabitant settlement.  Figure 1: Map sampling location. Note: PI < 1.0: clean, 1 < PI < 2: mild pollution, 2 < PI < 3: moderate pollution, 3 < PI < 5: polluted, and PI > 5: extremely pollution categories [16]. Te results obtained are based on the calculation of the pollution load capacity according to KepmenLH no. 110 of 2003 [17]. 4 International Journal of Ecology Te load capacity was estimated using the mass balance method (equation (2)) based on the Regulation of the Indonesian Ministry of Environment Decree No. 110 for the year 2003 [17].
with CR � average concentration of composite fow (mg/L or°C ), Ci � constituent concentration of fow-i (mg/L or°C), Qi � debit of fow-i (m 3 /s), and Mi � constituent mass of fow-i (kg 3 /s).
Plankton community structure was determined based on plankton density and expressed as the numbers of individual plankton per liter. Abundance Index (individual per liter or dm 3 ). Plankton abundance estimation is based on the following equation: with N � number of plankters per liter of river water, a � average of plankter number counted from 1 cc of fltered water, b � volume of fltered sample water (mL), and L � volume of fltered river water (L) [18]. Te diversity (H) and evenness of plankton were determined based on the Shannon-Wiener diversity and evenness index [22]. Furthermore, based on the H score, the water condition was evaluated as follows: H < 1.0: heavy pollution, 1 < H < 3: moderate pollution, and H > 3: clean according to Mason [23].

Results and Discussion
Te results of the physical, chemical, and biological parameter analysis are presented in Table 1 the measurement results for all water quality parameters at all stations were below the quality standard for Class III, except for Station 4, where its TSS, color, and BOD exceed the standard. Te estimation result of the water PI score for all stations showed the water quality status was clean and in good condition (PI < 1). However, ST-4 showed moderate water polluted quality status (PI � 2.05) which exceeded the standard for Class III water use. Te PI scores are presented in Figure 2. Te results from the analysis of the pollution load capacity of Way Umpu River using the mass balance method for all parameters are shown in ST-7. Tese results were compared with the standards for Class III water use according to the Local Regulation of Lampung Province [20], as shown in Table 2. Table 3 shows that the load capacity of Way Umpu River at ST-7 for all parameters did not exceed the standard for Class III water purpose according to this Local Regulation of Lampung Province [20]. Tis means that at ST-7 the pollution load capacity for all designation parameters for Class III has not exceeded the quality standard, so Way Umpu still has a capacity for all parameters [17].
Furthermore, the analysis of the plankton community structure consisting of the values of density, diversity, dominance, and evenness of plankton is presented in Table 4. Based on Table 4, it was found that the structure of the plankton community n land use in the form of forests, plantations, and settlements (ST-1, ST-2, and ST-3) which shows the number of species, individuals, and the diversity index were relatively high compared to the areas those were in the form of mining and settlements (ST-4, ST-5, ST-6, and ST-7). Te plankton diversity index indicated that all locations belong to moderate community stability or moderate polluted water quality (1 < H < 3) [17]. In addition, the structure of the plankton community based on the evenness index showed that planktons were evenly distributed (0.41 < E < 0.60 and 0.61 <E < 0.80) with low dominance (0 < D ≤ 0.5) at each station [22]. Tere are several species of plankton used as indicators of pollution, namely, Anabaena sp., Closterium sp., Euglena sp., Microsystis sp., and Nitzchia sp. [7]. Te existence of Euglena sp., Nitzchia sp., Navicula, and Synedra is an indication of pollution by organic matter originating from organic waste, agricultural runofs, and anthropogenic inputs [7].
Te Ojolali River fow at ST-4 receives waste from illegal gold mining activities that resulted in polluted water conditions, especially in TSS, BOD, and color parameters which are 235 ± 2.8 mg/L, 9.7 ± 0.2 mg/L, and 181 ± 7.1 Pt-Co, respectively. Gold mining is performed by striping soil using a diesel machine-driven soil suction with a big-size hose to suck and dispose of soil in big capacity. Furthermore, this method requires thousands of liters of water and disposes of thousands of cubic of soil daily (Figure 3), which blocks the water fow of rivers surrounding the mining area [24]. Besides that, illegal gold mining afects the quality of the river by turning it into brown-yellowish muddy water. Tis condition prevents people from relying on the Way Umpu River as a fresh water source, washing, bathing, and fshing, especially during the dry season [14,15].
TSS consists of organic materials such as the debris part of an organism and inorganic materials in the form of fne International Journal of Ecology  sands and mud. Previous research studies show that a high level of TSS in Semporo Strait (Papua, Indonesia) is caused by factors such as erosion, land use, shifting, agriculture, inhabitant settlement, and sand mining [25].
Te Ojolali River fow at ST-4 receives waste from illegal gold mining activities that resulted in polluted water conditions, especially in TSS, BOD, and color parameters where the values are higher the standard, thus also much higher compared to other stations. Gold mining is performed by striping soil using a diesel machine-driven soil suction with a big-size hose to suck and dispose of soil in big capacity. Furthermore, this method requires thousands of liters of water and disposes of thousands of cubic of soil daily (Figure 3), which blocks the water fow of rivers surrounding the mining area. Besides that, illegal gold mining afects the quality of the river by turning it into brown-yellowish muddy water. Tis condition prevents people from relying on the Way Umpu River for fresh water sources, washing, bathing, and fshing, especially during the dry season.
Subsequently, water bodies are said to be polluted when the TSS level is more than 50 mg/L [26] and our result indicated that the TSS in ST-4 is 235 ± 2.8 mg/L. Te same result was found in the Brantas River of Samaan district (East Java, Indonesia), Batang Kuranji River (Padang of West Sumatra, Indonesia) with TSS levels of 70 mL/L [3] and 165 mg/L to 734 mg/L [27]. Te high TSS levels are also reportedly caused by land erosion, surface water fow from agriculture area, and industrial waste [28] as well as sand and stone mining [27]. Although TSS is a nontoxic pollutant material, its excessive level prevents sun ray penetration, afecting phytoplankton, or covers water plants [29,30].
Furthermore, it obstructs the gills of fshes and other aquatic habitats, thereby causing asphyxiation [29].
BOD describes the organic matter that may be decomposed biologically (biodegradable) and the decomposition result of dead plants and animals from industrial waste or domestic waste disposal. Moreover, water bodies are believed to be polluted when the BOD level is more than 2 mg/L. Te high BOD level in Station 4 was due to domestic waste fow from the inhabitant settlements in Ojolali Village and the degradation of leaves along the river sides. Furthermore, the following results on BOD levels were obtained by some researchers, namely, 1.60 to 18.36 mg/L, 5.7 to 53 mg/L, and 8.46 to 18.48 mg/L BOD levels in Batang Kuranji in Padang of West Sumatra, Indonesia [27]. Te same condition was also found in developed countries such as the Tobol River and basin in Chelyabinsk, Russia, where there is continuous waste disposal from the city, industrial factories, agribusiness, and food water [31].
TSS comes from suspended materials such as mud, sand, organic and inorganic materials, plankton, and other microscopic organisms that cause water pollution and muddiness [30]. It was also found that the TSS from soil particle deposits into the sediment and dissolves when river water debit increases. Tis was proved by the reduced concentration and color in the river downstream of ST-5. Te analysis of pollutant carrying load capacity in ST-7 (Table 2) for TSS and color parameters showed that they were below the standard of Class III water use.
Furthermore, the BOD levels in downstream river areas in ST-5 and ST-7 were low due to decomposed organic materials, changes in the physical and chemical water quality   Note. Species with asterisks are pollution indicator based on references [1,7].
parameters, and the plankton community structure. Tis was indicated by increased numbers of species and individuals and the plankton diversity index in ST-5 and ST-7.
Tis is in line with the research by Ma [32], which states that human activities play important roles in catchment area disturbance worldwide in terms of the physical and chemical parameters of rivers. Terefore, most aquatic species are under big threat because of human infuences.

Conclusions
Te results of this work clearly indicate that anthropogenic activities in aquatic ecosystems can be evaluated using water quality parameters and plankton community structure. Te fnding for the ST-4 area, which is used for illegal mining and residential areas, indicates that this specifc location moderately polluted conditions as demonstrated by TSS, color, and BOD which exceed Class III water use standards. On the other hand, the river in the area of plantation and forestry was found to meet the water quality standard. Te pollution load-carrying capacity of the downstream Way Umpu River (ST-7) is still in the range of standard for Class III water use. Te condition of the plankton community structure in each study location was found to be evenly distributed (0.41 <E < 0.60 and 0.61 <E < 0.80) with low dominance (0 < D ≤ 0.5) and a moderate diversity index (1 < H < 3). It should be noted that several species of plankton as an indicator of organic pollution was observed.

Data Availability
Te data used to support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that there are no conficts of interest regarding the publication of this paper.