Evaluation Of Water Quality At River Bian In Merauke Papua

River Bian in Merauke Regency has been utilized by local people in Papua (the Marind) who live along the river for fulfilling their daily needs, such as shower, cloth and dish washing, and even defecation, waste disposal, including domestic waste, as well as for ceremonial activities related to the locally traditional culture. Change in land use for other necessities and domestic activities of the local people have mounted pressures on the status of the River Bian, thus decreasing the quality of the river. This study had objectives to find out and to analyze river water quality and water quality status of the River Bian, and its compliance with water quality standards for ideal use. The study determined sample point by a purposive sampling method, taking the water samples with a grab method. The analysis of the water quality was performed by standard and pollution index methods. The study revealed that the water quality of River Bian, concerning BOD, at the station 3 had exceeded quality threshold. COD parameter for all stations had exceeded the quality threshold for class III. At three stations, there was a decreasing value due to increasing PI, as found at the stations 1, 2, and 3. In other words, River Bian had been lightly contaminated.

Download Full-text

ANALISIS KUALITAS AIR DENGAN PENENTUAN STATUS MUTU AIR SUNGAI JAING KABUPATEN TABALONG

Jukung (Jurnal Teknik Lingkungan) ◽

10.20527/jukung.v5i2.7319 ◽

2019 ◽

Vol 5 (2) ◽

Author(s):

Yuniarti Yuniarti ◽

Danang Biyatmoko

Keyword(s):

Water Quality ◽

River Water ◽

Pollution Index ◽

Total Coliform ◽

Run Off ◽

The Status ◽

Water Quality Status ◽

Index Value ◽

Quality Status

Sungai Jaing merupakan salah satu sungai yang melintas di Kabupaten Tabalong dengan panjang 39 km yang bermuara di Sungai Tabalong. DAS Jaing memiliki luas area ± 298 km2bagian dari DAS Barito di Kalimantan Selatan. Sungai Jaing diklasifikasi sebagai sungai kelas I (satu). Alih fungsi lahan cukup besar terjadi disekitar daerah aliran sungai jaing, bagi sektor pertambangan batubara, sektor migas, sektor industri, perkebunan dan pertanian. Banyaknya aktivitas ini menyebabkan sungai jaing berpotensi cukup besar mengalami penurunan kualitas. Pengamatan lapangan menunjukkan bahwa beberapa kegiatan berpotensi memasukkan unsur pencemar ke Sungai Jaing yang mana kemungkinan membuang limbah produksi secara langsung ataupun run off (limpasan) limbah produksi kedalam sungai. Tujuan penelitian ini adalah menganalisis kualitas Sungai Jaing melalui penentuan Status Mutu Air dari Sungai Jaing. Wilayah penelitian dilaksanakan di Sungai Jaing sejauh 39 Km di Kabupaten Tabalong, Kualitas air sungai diukur dan diamati pada 3 titik pengambilan sampel terhadap parameter fisika, kimia dan biologi. Analisis kualitas dan penentuan status mutu air menggunakan metode STORET dan metode indeks pencemaran. Hasilnya adalah (1) parameter DO, BOD, COD, Fecal coliform dan Total Coliform telah melebihi baku mutu air sungai Kelas I menurut Peraturan Gubernur Kalimantan Selatan No. 5 Tahun 2007 sehingga menyatakan kualitas air sungai jaing menurun ( 2) Terjadi pergeseran status mutu air sungai jaing dari hulu ke hilir yang ditandai dengan nilai STORET dan nilai indeks pencemaran (IP) yang cenderung semakin meningkat berdasarkan kriteria sungai menurut PP nomor 82 Tahun 2001. Nilai STORET sungai jaing adalah antara -108 sampai dengan -110 dengan status mutu Cemar Berat dan nilai indeks pencemaran (IP) berkisar antara 4,027 sampai dengan 4,173 yang menyatakan bahwa status mutu air sungai jaing adalah cemar ringan. Kata Kunci: Indeks polusi, kualitas air, metode STORET, status kualitas. Sungai Jaing is one of the rivers that flows in Tabalong District which has length of 39 km and empties into the Tabalong River. The Jaing watershed has an area of ± 298 km2 of the Barito watershed in South Kalimantan. This river is classified as class I (one) river. Several activities for the coal mining sector, oil and gas sector, industrial sector, plantation and agriculture considered to take over the land function widely surrounding the river. Those activities actually have a potential to reduce the water quality of the river. Field observations found pollutants which are likely to dispose of production waste directly or run off (run off) of production waste into the river. Hence, the purpose of this study was to analyze the quality of Sungai Jaing through determining the status of water quality from Sungai Jaing. The research area was carried out in Sungai Jaing as far as 39 Km in Tabalong District where river water quality was measured and observed at 3 sampling points based on physical, chemical and biological parameters. Quality analysis and determination of water quality status using the STORET method and pollution index method. The results are (1) the parameters of DO, BOD, COD, Fecal coliform and Total Coliform have exceeded Class I river water quality standards according to Governor of South Kalimantan Regulation No. 5 of 2007 stating that the quality of river water is decreasing (2) There is a shift of the water quality status of the Sungai Jaing from upstream to downstream which is characterized by the STORET value and pollution index value which tends to increase based on a river criteria according to PP number 82 of 2001. In addition, STORET value of river jaing is between -108 to -110 with the status of Heavy Pollution quality and the pollution index value (IP) ranges from 4,027 to 4,173 which states that water quality status of the Sungai Jaing is mild pollution. Keywords : Water Quality, Quality Status, STORET Method, Pollution Index

Download Full-text

STATUS KUALITAS AIR SUNGAI SEKITAR KAWASAN PENAMBANGAN PASIR DI SUNGAI BATANG ALAI DESA WAWAI KALIMANTAN SELATAN

EnviroScienteae ◽

10.20527/es.v12i1.1094 ◽

2016 ◽

Vol 12 (1) ◽

pp. 1

Author(s):

Ahmad Rizqan ◽

Idiannor Mahyudin ◽

Mijani Rahman ◽

Jamzuri Hadie

Keyword(s):

Water Quality ◽

River Water ◽

River Water Quality ◽

Class I ◽

Class Iii ◽

Sand Mining ◽

The Status ◽

Water Quality Status ◽

Quality Status

This study aimed to analyze the water quality of Sungai Batang Alai. Water quality of physics and chemistry properties were analized in location of sand mining and without sand mining. Research conducted at Sungai Batang Alai Village Wawai District of South Batang Alai Hulu Sungai Tengah. Parameters of physical and chemical of water which analyzed were temperature, TSS, TDS, Debit, BOD, COD, DO, pH, Fe, and Mn. The sample were taken at 4 points with 3x replicatation. Status of water water quality were determined by using STORET method, then the results were compared with status of river water quality status of Class I based on South Kalimantan Governor Regulation No. 5 of 2007 on the status of river water quality. The results showed that the sand mining activities negatively impact the water quality of the river Batang Alai than the location there are no sand mining. This can be seen by the river water quality status in the area before the sand mining in the category of Class I to Class III down to the location of the existing sand mining.

Download Full-text

THE STUDY OF WATER QUALITY STATUS IN THE NGEBRONG RIVER WITH PHYSICAL AND CHEMICAL PARAMETERS IN THE TAWANGSARI BARAT REGION, PUJON DISTRICT, MALANG REGENCY

INDONESIAN JOURNAL OF URBAN AND ENVIRONMENTAL TECHNOLOGY ◽

10.25105/urbanenvirotech.v0i0.4361 ◽

2019 ◽

Vol 2 (2) ◽

pp. 164

Author(s):

Bambang Suharto ◽

Liliya Dewi ◽

Aulia Nur Mustaqiman ◽

Tyas Roro Anggraini Kyai Marjo

Keyword(s):

Water Quality ◽

Pollution Index ◽

Quality Standard ◽

Index Method ◽

The Status ◽

Water Quality Status ◽

Almost All ◽

Physical And Chemical ◽

Quality Status

Aim: The purpose of this study was to determine the status of water quality in a river by using the Pollution Index method as stated in the Decree of the Minister of Environment No. 115/2003 regarding Guidelines for Determining the Status of Water Quality and to determine the effect of quality status on development efforts towards ecotourism. Methodology and Results: The measurement of water quality was carried out at two points, namely T1 (upstream) and T2 (downstream) points. The parameters included BOD, COD, DO, TSS, Temperature, pH, Zn, S, P, No3, and No2. From the test results for class I, II, and III criteria, almost all parameters exceeded the quality standard. The status of the river water quality, according to the Pollution Index, has increased from moderate polluted upstream and heavily polluted to certain parameters downstream. Conclusion, significance and impact study: The quality standards that are met for the river are criteria for class IV. The increase in pollution is indicated by human activity around the river which is characterized by increasing population and land use in agriculture and plantations. The increasing pollution reduces the quality of the river if it is developed into an ecotourism area due to its low water quality status.

Download Full-text

Water quality status of an urban lake in the dry season from 2017 to 2020 (Situ Gintung, Banten Province, Indonesia)

E3S Web of Conferences ◽

10.1051/e3sconf/202021103008 ◽

2020 ◽

Vol 211 ◽

pp. 03008

Author(s):

Sinta Ramadhania Putri Maresi ◽

Tri Edhi Budhi Soesilo ◽

Ami Aminah Meutia

Keyword(s):

Water Quality ◽

Sampling Method ◽

Anthropogenic Activities ◽

General Information ◽

Dry Season ◽

Domestic Waste ◽

Water Quality Status ◽

Quality Status

Urban lakes are experiencing various kinds of problems because of the anthropocentrism of environmental management. This also happens in Situ Gintung, Indonesia. This lake is polluted by many pollutants from urban activities, such as the entry of domestic waste into waters due to anthropogenic activities and the amount of leftover food not consumed by fisheries. These problems can be solved by observing the water quality of Situ Gintung to provide information about parameters that have exceeded environmental quality standards and provide general information about the water quality in the dry season from 2017 to 2020. The research is done using a purposive sampling method and determining water quality status with the STORET method based on the Indonesian standard with parameters less than ten. As a result, Situ Gintung water is neither classified as class I, II, III, and IV nor be utilized for consumption, recreation, fisheries, and irrigation because the quality status is mostly in the heavily polluted category. Furthermore, the three highest polluters from each class are BOD5, COD, and a total of Coliform.

Download Full-text

Analyses of Water Quality Status Based Domestic Waste Parameters By Using Pollutant Index Method At Tabuk River Barito Selatan Central Kalimantan Province

TROPICAL WETLAND JOURNAL ◽

10.20527/twj.v4i1.61 ◽

2018 ◽

Vol 4 (1) ◽

pp. 25-29

Author(s):

Nora Forina ◽

Emmy Sri Mahreda ◽

Mijani Rahman ◽

Mahmud Mahmud

Keyword(s):

Water Quality ◽

Human Health ◽

Pollution Index ◽

Faecal Coliform ◽

Domestic Waste ◽

Index Method ◽

Central Kalimantan ◽

Quality Of Water ◽

Pollution Impact

The study aims to analyze the quality of water at Tabuk River Status by using pollution index method and domestic waste pollution impact to human health. The experiment was conducted in Tabuk River at Barito Selatan Regency Central Kalimantan Province. The samples of water with physical, chemical and biological parameters were taken at 3 points in the morning in the withdraw and flood. After wards, they were compared with the standard quality of water class II based on Government Regulation Number 82 of 2001 and domestic waste pollution impact to human health description. The results of study revealed that the water quality of Tabuk River exceeding criteria based on BOD at 48 mg/L in the withdraw and 22,52 mg/L in the flood, COD at 61,4 mg/L in the withdraw and 47,47 mg/L in the flood, TSS at 338,3 mg/L in the withdraw and 157,4 mg/L in the flood and Faecal Coliform at ≥ 1898 MPN. Whereas based on the index value of pollutants, Tabuk River by the light polluted status of 3,33-3,97, except downstream of withdrawing is medium (pollution index 5,2). The domestic waste pollution negative impact to human health. Increased faecal coliform in Tabuk River at ≥1898 jml/100 mL (MPN) and 58,33% society coastal river area have diarrhea and itch.

Download Full-text

ANALISIS BEBAN PENCEMARAN DAN INDEKS KUALITAS AIR SUNGAI SILANDAK DAN SUNGAI SIANGKER, SEMARANG

Management of Aquatic Resources Journal (MAQUARES) ◽

10.14710/marj.v5i3.14399 ◽

2016 ◽

Vol 5 (3) ◽

pp. 127-134

Author(s):

Tyas Lufiana ◽

Haeruddin Haeruddin ◽

Churun Ain

Keyword(s):

Water Quality ◽

Water Samples ◽

Water Quality Index ◽

Quality Index ◽

Sampling Method ◽

Drainage System ◽

Pollution Load ◽

Domestic Waste ◽

Sampling Points

ABSTRAKSungai Silandak dan Singker merupakan sungai penting dalam sistem drainase Semarang Barat.Sungai tersebut telah dialiri limbah industri dan limbah domestik yang berasal dari pemukiman warga sekitar. Adanya masukan limbah industri dan domestik akan berpengaruh terhadap kualitas air sungai seperti peningkatan unsur hara yang dapat menyebabkan eutrofikasi. Tujuan dari penelitian ini adalah mengetahui beban pencemaran (TSS, Nitrat, Fosfat) yang akan bermuara ke Teluk Semarang serta mengkaji status pencemaran berdasarkan metode Indeks Kualitas Air pada Sungai Silandak dan Sungai Siangker. Materi yang digunakan dalam penelitian ini adalah contoh air yang diambil pada bagian hulu, tengah dan hilir.Metode penelitian menggunakan metode survei, teknik penentuan lokasi sampling bersifat purposive pada 6 titik lokasi sempling.Contoh air diambil menggunakan metode komposit sebanyak 500 ml pada pagi dan sore hari dengan interval waktu 1 minggu. Hasil yang diperoleh berdasarkan analisis beban pencemaran yang berasal dari Sungai Silandak yaitu TSS 838,31 mg/detik, nitrat 5,44 mg/detik dan fosfat 5,08 mg/detik dan Sungai Siangker TSS 417,76 mg/detik, nitrat 4,18 mg/detik dan fosfat 3,42 mg/detik. Kualitas air Sungai Silandak bagian hulu, tegah dan hilir secara berturut-turut termasuk dalam kelas tercemar berat, tercemar sedang dan tercemar sangat berat. Sedangkan kualitas air Sungai Siangker bagian hulu, tengah dan hilir secara berturut-turut termasuk dalam kelas tercemar berat, tercemar berat dan tercemar sangat berat. Kata kunci: Beban Pencemaran, Indeks Kualitas Air, Sungai Silandak, Sungai Siangker ABSTRACTSilandak and Siangker were the important rivers in drainage system on West Semarang. The rivers drained industrial and the domestic waste from around the residential. The industrial and domestic wastes influenced the quality of the waters as the improvement of nutriens that made eutrophication. The purpose of this study was to know the pollution load (TSS, nitrate, phosphate) that flew to bay of Semarang and to review status of pollution from Silandak and Siangker rivers based on the Water Quality Index. Samples of water from Silandak and Siangker rives were taken from the upstream, midstream and downstream. The method used in this study a purposive sampling method to determine on 6 sampling points. Water samples were taken 500 ml by composite in the morning and afternoon in a week. The ammount of pollution load from Silandak river was TSS 838.31 mg/second, nitrate 5.44 mg/second and phosphate 5.08 mg/second and the ammount from Siangker river was TSS 417.76 mg/second, nitrate 4.18 mg/second and phosphate 3.42 mg/second. The water quality of Silandak river from the upstream, midstream and downstream in a row classified as heavily polluted, moderately polluted and very heavily polluted class while Siangker river from the upstream, midstresm and downstream rin a row classified heavily polluted, heavily polluted and very heavily polluted class. Key word:Pollution Load, Water Quality Index, Silandak River, Siangker River

Download Full-text

Analysis of Water Quality in Batujai Reservoir Due to Community and Business Activities in Central Lombok Regency

Journal of Environmental Management and Tourism ◽

10.14505/jemt.v12.1(49).03 ◽

2021 ◽

Vol 12 (1) ◽

pp. 30

Author(s):

Supardiono SUPARDIONO ◽

Wayan ARTHANA ◽

Wayan Sandi ADNYANA ◽

Wayan Budiarsa SUYASA ◽

Nyoman SUDIPA

Keyword(s):

Water Pollution ◽

Water Quality ◽

Quality Standard ◽

Water Bodies ◽

Class Iii ◽

Domestic Waste ◽

Reservoir Water ◽

Water Quality Standard ◽

The People

The development of an area must be accompanied by an ever-increasing population growth which will also increase the waste produced. Waste production will put pressure on the environment if it is not managed properly which will eventually end up in water bodies. The increased pollution load is also caused by the habit of people disposing of domestic waste, both liquid waste and solid waste directly into the water. Batujai Reservoir is one of the vital objects for the survival of the people of Central Lombok in particular, and the people of Lombok Island in general. Because of its vital role, the Batujai Reservoir needs to be saved so that the reservoir ecosystem can carry out its functions and benefits in improving the welfare of the people of Central Lombok. There are several community activities that are a source of direct reservoir water pollution (point source) such as fishing activities using floating net cages and disposal of domestic waste by the community which is directly channeled to water bodies. Pollutants collected in the Batujai Reservoir will reduce the water quality of the Batujai Reservoir. This research aims to analyze the water quality of the Batujai Reservoir which is caused by business activities and the community based on Government Regulation Number 82 of 2001 and to determine the water pollution index of the Batujai Reservoir. This study uses a quantitative approach by collecting primary data from direct observations in the field and secondary data based on previous research reports and government reports. The results showed that the average physical parameters were above the water quality standard threshold for class II water quality, the average chemical parameters were above the water quality standard for class III and class IV water quality, while the biological parameters were above the threshold. Water quality limits for class II and class III. The decline in water quality in the Batujai Reservoir is caused by various wastes entering the Batujai Reservoir water bodies. The analysis result with storet system shows that the water quality of Batujai Reservoir is in bad condition or heavily polluted.

Download Full-text

Kajian Kualitas Air Laut dan Indeks Pencemaran Berdasarkan Parameter Fisika-Kimia di Perairan Distrik Depapre, Jayapura

Jurnal Ilmu Lingkungan ◽

10.14710/jil.16.1.35-43 ◽

2018 ◽

Vol 16 (1) ◽

pp. 35 ◽

Cited By ~ 9

Author(s):

Baigo Hamuna ◽

Rosye H.R. Tanjung ◽

Suwito Suwito ◽

Hendra Kurniawan Maury ◽

Alianto Alianto

Keyword(s):

Water Quality ◽

Pollution Index ◽

Quality Standards ◽

Water Quality Standards ◽

Chemical Parameters ◽

Physical Chemical ◽

The Status ◽

Total Ammonia ◽

Water Quality Status

ABSTRAKKondisi kualitas air suatu perairan yang baik sangat penting untuk mendukung kelulushidupan organisme yang hidup di dalamnya. Penentuan status mutu air perlu dilakukan sebagai acuan dalam melakukan pemantauan pencemaran kualitas air. Penelitian ini bertujuan untuk mengkaji status mutu air dan menentukan indeks pencemaran berdasarkan parameter fisika-kimia di perairan Distrik Depapre, Kabupaten Jayapura. Pengambilan sampel kualitas air dilakukan pada bulan Oktober 2017 di lima stasiun penelitian, kemudian hasilnya dibandingkan dengan baku mutu air laut untuk biota laut berdasarkan KEPMEN-LH No. 51 Tahun 2004. Hasil penelitian menunjukkan bahwa parameter yang masih sesuai baku mutu antara lain suhu, salinitas, sulfida dan kecerahan perairan, sedangkan parameter yang telah melampaui baku mutu antara lain pH, ammonia total, nitrat dan fosfat. Berdasarkan hasil perhitungan indeks pencemaran menunjukkan bahwa perairan Distrik Depapre berada dalam kategori tercemar ringan hingga tercemar sedang.Kata kunci: Baku Mutu, Indeks Pencemaran, Kualitas Air, Parameter Fisika-Kimia, Distrik DepapreABSTRACTGood water quality is extremely important to support life of organisms. The determination of water quality status was needed as reference to monitor water pollution. This study aimed to assess the status of water quality and determine pollution index based on physical-chemical parameters in the Depapre District waters, Jayapura Regency. Sampling was carried out in October 2017 across five research stations, then the results were compared with water quality standards based on KEPMEN-LH No. 51 Tahun 2004 for marine biotas. The results showed that the parameters in according to the quality standards are temperature, salinity, sulphide and water transparency, while those that have exceeded the quality standards are pH, total ammonia, nitrate and phosphate. Based on the calculation of pollution index indicates that the Depapre District waters was in light pollution to medium categories.Keywords: Depapre District, Physical-Chemical Parameters, Pollution Index, Standards, Water QualityCitation: Hamuna, B., Tanjung, H.H.R, Suwito and Maury H.K. (2018).Kajian Kualitas Air Laut dan Indeks Pencemaran Berdasarkan Parameter Fisika-Kimia Di Perairan Distrik Depapre, Jayapura. Judul. Jurnal Ilmu Lingkungan, 16(1), 35-43, doi:10.14710/jil.16.135-43

Download Full-text

THE RELATIONSHIP WATER QUALITY STATUS METHODS POLLUTION INDEX WITH ACTIVITIES OF FLOATING NET CAGE IN THE RIAM KANAN DAM

Fish Scientiae ◽

10.20527/fs.v1i1.4174 ◽

2017 ◽

Vol 7 (1) ◽

pp. 1

Author(s):

Nida Nida ◽

Mijani Rahman ◽

Abdur Rahman

Keyword(s):

Water Quality ◽

Pollution Index ◽

Class I ◽

Physical Parameters ◽

Fertility Level ◽

Total Phosphate ◽

The Status ◽

Water Quality Status ◽

Net Cage ◽

Quality Status

This study aims to determine the status of water quality in the Riam Kanan Reservoir seen from the physical parameters (Temperature and Brightness) and chemical parameters (pH, DO, Total Phosphate, Nitrate and Ammonia) using Pollution Index (IP) method, knowing trophic level in Riam Kanan reservoir seen from the parameter of Brightness, Total Phosphate and Total Nitrogen and know the influence of floating net cage activity to water quality status of Riam Kanan reservoir.Of the result on measurement of IP method water quality which based on the, the status of water quality in station 1, 2, and 3 was complied with water quality standard (good condition), either for class I, II, III, or IV. Based on the regulation of the state minister for environment Number 28 Year 2009 was found that the fertility level in station 1, 2, and 3 was in the same trophic status, which was oligotrophic. The value of thit nitrate (X1), total P (X2) and ammonia (X3) either for class I, II, III, or IV was lower than ttabel for significance in 5% or sig/.probability > 0,05 which meant that H0 was accepted; KJA activities did not affect the water quality status of Riam Kanan dam.

Download Full-text

Morfometri dan Daya Tampung Beban Pencemaran Danau Pondok Lapan, Kabupaten Langkat Provinsi Sumatera Utara

Oseanologi dan Limnologi di Indonesia ◽

10.14203/oldi.2017.v2i2.51 ◽

2017 ◽

Vol 2 (2) ◽

pp. 49 ◽

Cited By ~ 2

Author(s):

Ahmad Muhtadi ◽

Yunasfi Yunasfi ◽

M. Ma'rufi ◽

A. Rizki

Keyword(s):

Water Quality ◽

Coming Out ◽

Load Capacity ◽

Water Discharge ◽

Pollution Index ◽

Pollution Load ◽

Index Method ◽

The Status ◽

Closed Water ◽

Water Quality Status

Morphometry and Pollution Load Capacity of Lake Pondok Lapan in Langkat Regency, North Sumatra. Morphometry is necessary to know the physical characteristics of a lake and how much the ability of the lake to receive pollutant loads. Determination of water quality status and pollution load capacity of lake water is very important to do with the utilization of lake by the community for cultivation activity of floating net cage (KJA). This study aimed to determine the characteristics of morphometry and bathymetry of the lake, determine the status of water quality and the capacity of lake pollution load. The study was conducted in January–March 2015. Mapping was done by making a path of 100 trajectories which was then processed with ArcView. The observation station for water quality consisted of 4 stations. The status of water quality was determined by the Pollution and Storage Index method based on PerMen LH. No. 115 of 2003. The capacity of lake pollution loud refers to PerMen LH. 28 of 2009. The results showed that Lake Pondok Lapan area reached 63,472.78 m2 (6.35 ha) with a maximum depth of 4.15 m. This lake is classified as a closed water, aerobic, with a residence time of 11–12 days. The depth of compensation is at a depth of 2.61–2.85 m. The water discharge coming out of the lake ranges 12,963.45–14,111.71 m³ per day. The status of water quality of Lake Pondok Lapan is categorized as uncontaminated with score 0 for the Storet method and 0.46–0.86 for Pollution Index method. Lake pollution load capacity is of 1.98 kg of phosphorus per year.

Download Full-text