Title Analisis Kandungan, Fosfor dan Karbon Organik di Danau Sentani - Papua (Analysis of Nitrogen, Phosphor and Organic Carbon Content at Sentani Lake-Papua)
Journal Jurnal Manusia dan Lingkungan Jurnal Manusia dan Lingkungan Volume dan Pages 22(2): 217-225 Vol 22,
Year of Publication 20152015
Author Ervina Indrayani, Kamiso Handoyo Nitimulyo, Suwarno Hadisusanto, dan Rustadi
Group
Group 7
1. Zahra Warda Sari Harahap 235100901111039 2. Diannida’ Halimah Az-Zahra 235100901111006
3. Filza Nabilla Nasution 235100907111012
4. Samuel Krisetya Sinaga 235100900111027
5. Natasha Katarina Widada 235100901111042
6. Sakhi Aqsa Raditya 235100907141001
Abstract
This study aims to analyze the content of nitrogen (N), phosphorus (P), and organic carbon (OC) in Lake Sentani, Papua. The research method used is a stratified sampling method with the Composite Sampling technique. The research area was divided into 4 zones: inlet, net cage culture (KJA), middle of the lake, and outlet. Data analysis used Microsoft Excel 2007 and Analysis of Variance (ANOVA) at a 90% confidence level.
The results showed that the N:P ratio of the lake water was 10.248 mg/L/month at the inlet; 2.417 mg/L/month in the KJA; 0.683 mg/L/month in the middle of the lake; and 8.351 mg/L/month at the outlet. Meanwhile, the C:N ratio was 15.008 mg/L/month at the inlet; 47.647 mg/L/month in the KJA; 90.884 mg/L/month in the middle of the lake; and 6.777 mg/L/month at the outlet. The varying N:P and C:N ratios in each zone indicate differences in the content of nitrogen, phosphorus, and organic carbon in the waters of Lake Sentani. This can be an indication of pollution in the lake.
Introduction
This study aims to analyze the nitrogen, phosphorus and organic carbon content in Lake Sentani, Papua. Nutrient content in waters is strongly influenced by human activities, erosion and atmospheric nutrient inputs. Phosphorus plays an important role in biological metabolism and aquatic fertility. Lake Sentani is moderately polluted due to feed waste, household activities, and residential areas close to the lake, so pollution control needs to be done to preserve the lake. The research method used was a purposive stratified survey, which divided the study area into four zones: inlet, KJA, mid-lake, and outlet. The analysis showed that the N:P ratio in the lake waters varied in each zone, with the highest value in the inlet and the lowest in the middle of the lake. Meanwhile, the C:N ratio was highest in the middle of the lake, indicating high dissolved organic matter influenced by
activities on the land around the lake. Water quality conditions were tested using the Pollution Index (IP) method on nine parameters, showing moderately polluted conditions in all study zones. Therefore, water pollution control measures are needed to maintain the environmental sustainability of Lake Sentani.
Method
This research was conducted at Lake Sentani, Papua, over 12 months with sampling every two months in four different zones. Stratified survey methods (stratified sampling) and purposive sampling were used to collect water and sediment samples from various depths. Laboratory analysis was performed at Cenderawasih University and Intertek Utama Service Jakarta, using spectrophotometry for nitrate and phosphate, and NDIR-SCWO for organic carbon. Sediment analysis included spectrophotometry for total nitrogen, Bray I for total phosphorus, and Walkley and Black for organic carbon.
Data were analyzed using Microsoft Excel 2007 and ANOVA with a 90% confidence level.
Pollution source
Lake Sentani has a number of significant roles, including supporting the aquaculture and capture fisheries sectors, providing water for agriculture, and serving as a transit hub for nearby settlements and a tourist destination. However, these functions have environmental repercussions, including increased nitrogen, phosphorus, and carbon inputs into lake waters. These sources of pollution are caused by a variety of human activities, including fertilizer-intensive agriculture, home and industrial trash, and unregulated tourism.
Chemical Process
Chemical processes in lakes involve various reactions and interactions of compounds that are important to the ecosystem. Nitrate is formed from the oxidation of ammonia through microbial activity and is important in the formation of phytoplankton biomass.
Ammonia itself, which is the result of organic matter decomposition, is soluble in water and affects the fertility of the waters. Phosphate, which acts as a limiting factor, comes from nutrient intake, human activities and decomposition in sediments. Research in Lake Sentani shows that nitrite, nitrate and ammonia concentrations vary across zones and are influenced by rainfall and human activities around the lake. The inlet zone has the highest concentrations for nitrate and ammonia, while nitrite and nitrate concentrations are lower in the middle of the lake and outlet due to oxidation processes and utilization by organisms. The high N:P ratio indicates that nitrogen or phosphorus could act as a limiting factor, depending on the conditions. Overall, the fertility and productivity of waters are strongly influenced by the availability and interaction of these chemical compounds. The highest nitrate concentrations in Lake Sentani were found in the inlet zone (1.00 mg/L), indicating that incoming water sources carry a lot of nitrate-rich nutrients, possibly from agricultural soil run-off or rainfall runoff. This
concentration decreases in the middle of the lake to 0.50 mg/L due to uptake by phytoplankton and aquatic plants, and is even lower in the outlet zone (0.20 mg/L) due to utilization by organisms and natural dilution. Ammonia was also highest in the inlet zone (0.50 mg/L) due to organic matter decomposition, decreased in the middle of the lake (0.30 mg/L) due to nitrification processes, and was lowest in the outlet zone (0.10 mg/L) due to oxidation and utilization by organisms. Nitrite concentrations remained low in all zones (0.01-0.02 mg/L) because it is rapidly oxidized to nitrate under sufficient oxygen conditions.
Impact
Nitrogen and phosphorus have a major influence on aquatic ecosystems, especially in biomass formation and species variation. Water fertility parameters such as nitrite and nitrate are very important in the biological processes of aquatic organisms. In Lake Sentani, nitrite concentrations are generally low, especially in the middle, due to the oxidation process that converts them to nitrate in the presence of dissolved oxygen.
Increases in nitrite and nitrate usually occur when rainfall is low and human activity around the lake increases. Ammonia, which is a product of fish metabolism, also affects water fertility and is found in the highest concentrations in the outlet zone. Phosphate, which increases when rainfall is low, originates from population activity and sediment runoff, and influences phytoplankton composition. The highest total nitrogen and phosphorus contents were found in the inlet and outlet zones, indicating the influence of human activities and river flow. This causes Lake Sentani to be in a eutrophic condition, so the water quality needs to be controlled to prevent further pollution.
Chemical Technology Application
Based on the analysis of nitrogen, phosphorus, and organic carbon content in Lake Sentani reported in the journal, there are several chemical technology applications that can be considered to address the existing problems. One of the technologies that can be used is wastewater treatment technology, such as the utilization of biological methods such as activated sludge or constructed wetlands to reduce nitrogen and phosphorus levels, as well as the use of physico-chemical methods such as coagulation, sedimentation, or adsorption to remove nutrients and organic carbon. In addition, nutrient recovery technologies can also be applied, such as utilizing struvite precipitation technology to recover phosphorus from wastewater, and using nitrification-denitrification technology to recover nitrogen. Sediment treatment technologies, such as extraction or stabilization, can also be used to reduce the levels of nutrients and organic matter in the lake sediments. To monitor water quality in real-time, technologies such as online sensors can be utilized to monitor water quality parameters such as nitrogen, phosphorus, and organic carbon. In addition, the development of water quality prediction models can also help in planning lake management. The selection of the appropriate technology must
consider the characteristics of the lake, the sources of pollution, and the management objectives to be achieved, so collaboration between chemists, environmental experts, and other related fields is necessary.
Countermeasure
1. Restrictions on Household Waste Disposal :
One of the main sources of pollution in Lake Sentani is household waste discharged into the water. Reducing or banning the direct discharge of household waste into the lake can reduce the nitrogen and phosphorus content that pollutes the waters.
2. Erosion Control :
Soil erosion around the lake caused by human activities, such as road construction, increases the amount of sediment and nutrients entering the lake. Erosion control through planting of soil-retaining vegetation and terracing can help reduce the rate of erosion and sedimentation.
3. Management of KJA (Floating Net Cages) :
Reorganizing floating net cages (KJAs) can help reduce fish feed waste that pollutes the water. One proposed strategy is the use of double nets, where fish in the outer net can utilize natural food from the phytoplankton present, which will also reduce phosphorus content in the water.
4. Increased Capture Fisheries Activities :
Enhancing capture fisheries activities by utilizing the phytoplankton and zooplankton biomass present in the lake as a natural food source for fish. This will not only help reduce excessive phytoplankton biomass, but also increase local fish catches, which can support local economies.
5. Not Disposing of Mountain Trimming Stockpiles :
Mountain trimming piles used for infrastructure development should not be dumped into lake waters. This will reduce the influx of sediment and excess nutrients into the lake.
6. Monitoring and Education :
Increased monitoring of activities that have the potential to pollute the lake as well as education to the surrounding community on the importance of keeping the lake clean and sustainable is essential. The community needs to be involved in environmental conservation programs through campaigns and socialization.
By implementing these measures, it is hoped that pollution in Lake Sentani can be controlled, so that water conditions can be better maintained and the lake's potential can be utilized sustainably without damaging the existing ecosystem.
