Organochlorine is a synthetic pesticide that has been banned in many countries because of its high persistence in the environment and can accumulate in animals. The goal of our study was to determine the level of organochlorine residues in surface water and in the mussel Corbicula sumatrana of Lake Singkarak. Water and mussel samples were collected from 10 sampling sites of Lake Singkarak, Batu Taba, Sumpur, Guguk Malalo, Ombilin, Tikalak, Sumani, Saniang Baka, Muaro Pingai, Paninggahan, and Tanjung Mutuih, respectively in June 2021. Water and mussel samples were extracted and analyzed with gas chromatography. The result of our study revealed the occurrence of Lindan (7 μg/L) in the surface water of Tikalak, and also Aldrin (3 μg/L) in the surface water of Tikalak, Sumani, and Ombilin. Organochlorine residue compounds were also detected in mussels of five sampling sites (Tikalak, Sumani, Muaro Pingai, Paninggahan, and Tanjung Mutuih). Mussels of Tikalak contain compounds namely Dieldrin, Dichlorodiphenyltrichloroethane (DDT), and Endosulfan with levels of 2 μg/kg, 6 μg/kg, and 3 μg/kg, respectively. Dieldrin was also detected at Sumani (2 μg/kg), Muaro Pingai (4 μg/kg), and Paninggahan (10 μg/kg). DDT was also detected at Tanjung Mutuih at a level of 3 μg/kg. Other compounds such as Heptachlor and Endrin were not detected both in surface water and in mussel from all sampling sites studied. The results indicate that organochlorine residue can still be found in the environment, with its level in mussels being higher than in surface water.

High-rank coal reserves continue to decrease, while what is widely available is in the form of low-rank coal with low calorific value and high sulfur. Biomass can be a solution for providing fuel to replace low-rank coal (4,000 kcal/kg). To ensure the sustainability of the supply of biomass cofiring, it is necessary to have sufficient land available for energy plantations/forestry plantations (HTE). This research is aimed at assessing the availability of land in forest areas in Perum Perhutani for energy crop activities by using the right types of plants to supply biomass cofiring. Perhutani has entered into a cooperation agreement with PT. PLN to meet the need for cofiring-biomass PLTU. Currently on the island of Java, there are 11 PLTUs with a total electricity capacity of 14,645 MW. For 5% biomass cofiring, 189,849 ha of HTE land is required. Perum Perhutani has established a business portfolio of Biomass Plants covering an area of 67,356 ha. This area is equivalent to the effective area of 48,496 ha of HTE which supplies 3,756 MW of electricity (26% of the total capacity of the Java PLTU). The types of plant biomass used were Gamal (Gliricidia sepium) and Kaliandra (Calliandra callothyrsus).

Organophosphate pesticide is a pesticide derivate that is used widely by farmers because it has a high killing power against insects and easily disappears from plants. Organophosphate pesticide residues can accumulate in the environment and also cause acute and chronic poisoning in humans. Singkarak Lake in West Sumatra Province is surrounded by many agricultural and farming areas. One of fisheries resources that can be affected by activities at those areas is Bilih fish (Mystacoleucus padangensis). The study aims to determine the levels of organophosphate pesticide residues in Singkarak Lake’s water and Bilih fish. Seven organophosphate pesticide compounds: Diazinon, Fenitrothion, Methidathion, Malathion, Chlorpyrifos, Parathion, and Profenofos were analyzed. In June 2021, surface water and Bilih fish samples were collected from 10 sampling locations in Singkarak Lake. The organophosphate pesticide in the samples was determined using gas chromatography. The results showed that residues were detected in water samples of four locations (Ombilin, Tikalak, Sumani, and Paninggahan), but not in the other six locations (Batu Taba, Sumpur, Guguak Malalo, Saniang Baka, Muaro Pingai, and Tanjung Mutuih) as well as below 1 ppb. Methidathion, Malathion, Chlorpyrifos, and Parathion were detected in lake water at range 2 to 8 ppb. Except for the Bilih fish sample from Ombilin, the majority of the samples contained organophosphate residues. Diazinon, Fenitrothion, Methidathion, Chlorpyrifos, Parathion, and Profenofos were the organophosphate derivate found in the fish samples. Malathion compound was not found. The organophosphate residue concentration in Bilih fish ranged from 2 to 70 ppb.

Population of Soil Nematodes in The Treatment of Brassicaceae Plant Waste Brassicaceae plants are known to contain glucosinolates which can be hydrolyzed into biofumigant compounds. This research was conducted to examine the effect of biofumigant derived from Brassicaceae plants waste on soil nematode population dynamics. Greenhouse experiment was carried out on 4 types of Brassicaceae plants waste, consisting of leaf waste of radish (Raphanus sativus), broccoli (Brassica oleracea var. italica), cabbage (Brassica oleracea var. capitata), and whole parts kamanilan weed (Roripa indica) in polybags containing 5 L of nematode infested soil. Plant waste was chopped ± 1 cm in size, then as much as 117 g per polybag was mixed in nematode infested soil, doused with water until wet and tightly closed for the biofumigation process for 14 days. At the end of biofumigation step, the polybags were opened for 3-5 days, then 7 day - old cucumber seedlings of var. Roberto 92 were planted and the plants were maintained in greenhouse for up to 8 weeks. Observation of the type and population of soil nematodes was carried out three times, i.e. before treatment, after treatment, and 8 weeks after planting. This experiment was designed in a completely randomized design with 6 treatments and 5 replications. The results of the study showed that the population of free-living nematodes (bacteriovorous nematodes and fungivorous nematodes) was increased in all treatment of Brassicaceae plants waste. On the other hand, there was a significant decrease in the phytonematodes population in the treatment of broccoli leaf waste. All Brassicaceae wastes was able to suppress population of Helicotylenchus sp., Rotylenchulus sp., and Xiphinema sp., significantly. Leaf waste of broccoli leaves showed the highest inhibition value against all phytonematodes genera with inhibition reached 100%.

Brassicaceae are known to contain compounds that are biofumigants. This study aimed to determine the effect of Brassicaceae waste application on soil nematode community. Broccoli leaves and stems (Brassica oleracea var. italic), cabbage leaves and stems (B. oleracea var. capitate), kailan stems (B. oleracea var. alboglabra), radish leaves (Raphanus sativus), and leaves of kamanilan weed (Rorippa indica) were tested in this study. The total glucosinolate content of Brassicaceae waste was estimated using the palladium method with a modified spectrophotometer. The experiment was carried out in polybags containing 500 grams of soil-infested nematodes. Brassicaceae waste (15 grams/polybag) was chopped and mixed into the soil, watered, and polybags were tightly closed for 14 days. The experiment was arranged in a completely randomized design with nine treatments and five replications. The results of the total glucosinolate analysis showed that broccoli, radish, and kamanilan leaves fall into the high category (144.7-185.2 µmol/g); cabbage leaves, cabbage stems, and kailan stems fall into the medium category (52.0-56.0 µmol/g); and broccoli stems fall into the low category (35.4 µmol/g). There was no correlation between total glucosinolate contents and their effect on suppressing soil nematode communities at the applied effluent dose. The population of bacterivorous nematodes increased in each waste treatment, especially in kamanilan leaf treatment (R. indica) which reached 13,008 individuals. These results indicate that kamanilan weed has good potential to improve soil health. The treatment of Brassicaceae waste against soil nematode communities showed a low diversity index, an uneven evenness index, and a high dominance index.