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1.
Terrace-contouring systems with on-site water detention cannot be installed in areas of complex topography, small parceling and multi-blade moldboard plow use. However, field borders at the downslope end may be raised at the deepest part where runoff overtops to create detention ponds, which can be drained by subsurface tile outlets and act similar to terrace-contouring systems. Four of such detention ponds were monitored over 8 years. Monitored effects included the prevention of linear erosion down slope, the sediment trapping from upslope, the enrichment of major nutrients in the trapped and delivered sediments, the amount of runoff retained temporarily, the amount of runoff reduced by infiltration, the decrease in peak runoff rate and the decrease in peak concentrations of agrochemicals due to the mixing of different volumes of water within the detention ponds. The detention ponds had a volume of 30–260 m3 ha−1 and trapped 54–85% of the incoming sediment, which was insignificantly to slightly depleted (5–25%) in organic carbon, phosphorus, nitrogen and clay as compared to the eroding topsoil, while the delivered sediment was strongly enriched (+70–270%) but part of this enrichment already resulted from the enrichment of soil loss. The detention ponds temporarily stored 200–500 m3 of runoff. A failure was never experienced. Due to the siltation of the pond bottom, the short filled time (1–5 days) and the small water covered area, infiltration and evaporation reduced runoff by less than 10% for large events. Peak runoff during heavy rains was lowered by a factor of three. Peak concentrations of agrochemicals (Terbutylazin) were lowered by a factor of two. The detention ponds created by raising the downslope field borders at the pour point efficiently reduced adverse erosion effects downslope the eroding site. They are cheap and can easily be created with on-farm machinery. Their efficiency is improved where they are combined with an on-site erosion control like mulch tillage because sediment and runoff input are reduced. Ponds had to be dredged only after the first year when on-site erosion control was not fully effective. 相似文献
2.
从城市工业固体废物消纳和废弃采石场作为填埋处置场地的角度出发,对利用废弃采石场作为第Ⅰ类一般工业固体废物填埋场场址条件进行探讨,通过广州市地区实例说明利用废弃采石场选址作为第Ⅰ类一般工业固废填埋场址的可用性,这对未来废弃采石场的综合利用具有一定的借鉴意义。 相似文献
3.
Reduction of dissolved organic matter in terms of DOC, UV-254, SUVA and THMFP in industrial estate wastewater treated by stabilization ponds 总被引:1,自引:0,他引:1
The aim of this research was to monitor the influent and effluent water quality of the aeration, facultative and oxidation
water treatment ponds of an industrial estate. This industrial estate, the largest in northern Thailand, has proposed to utilization
of reclaimed treated wastewater in their raw water supply so as to cope with the yearly water shortage during the dry season.
Water samples were collected four times from four sampling points and evaluated for their dissolved organic matter (DOM) content
in terms of dissolved organic carbon (DOC), ultraviolet light absorbance at 254 nm (UV-254), specific ultraviolet absorption
(SUVA), trihalomethane formation potential (THMFP) and trihalomethane (THM) species. Average values of DOC, UV-254, SUVA and
THMFP in the influent wastewater of 12.9 mg L−1, 0.165 cm−1, 1.29 L mg−1m−1 and 1.24 mg L−1, respectively, were observed. The aeration ponds produced the best results: a 54% reduction of DOC, a 33% reduction of UV-254,
and a 57% reduction of THMFP. However, SUVA in the aeration pond effluent showed a moderate increase. The facultative ponds
and oxidation ponds did not take part in the reduction of DOC, UV-254, SUVA and THMFP. Average DOC, UV-254, SUVA and THMFP
value of the treated wastewater were 5.8 mg L−1, 0.107 cm−1, 1.85 L mg−1m−1 and 468 μg L−1, respectively. Chloroform, at 72.6% of total THMFP, was found to be the predominant THM species. 相似文献
4.
5.
Veeriah Jegatheesan Nevelina Pachova Perlie Velasco Mohamed Ismail Mohammed Mowjood Sujithra Kaushaliya Weragoda Madhubhashini Makehelwala Ngo Thuy Diem Trang Bao-Trong Dang Cong-Sac Tran Thi-Kim-Quyen Vo Nguyen Thi Thu Trang Huy Pham Ma. Catriona Devanadera Antonina Torrens Xuan-Thanh Bui Phuoc-Dan Nguyen Amy Lecciones Kristhombu Baduge Shameen Nishantha Jinadasa 《环境质量管理》2023,32(3):335-365
Water quality is a critical challenge in Asia in the context of growing industrialization, urbanization, and climate change. Nature-based solutions (NbS) could play an important role in reducing urban water pollution, while generating multiple co-benefits that could make cities more liveable and resilient. In this regard, a number of pilot and demonstration projects have been set up to explore their potential across cities in Asia. Their effectiveness and impacts, however, have not been adequately documented, thus how they can be sustained, replicated and up-scaled remain poorly understood. This study aims to contribute to addressing this challenge by co-developing an integrated assessment framework and employing it to understand how existing evaluations of NbS in the region can be improved. It focuses specifically on a set of nature-based solutions that have been employed for water treatment across six cities in Southeast Asia (two in each Sri Lanka, the Philippines, and Vietnam), namely, floating wetlands, constructed wetlands and maturation ponds. The study also suggests specific methodologies for capturing a set of core indicators considered relevant for assessing the effectiveness and capturing the multi-faceted impacts of the examined NbS. 相似文献
6.
从气候、淡水资源和海洋资源等方面简要介绍了山东省的水产资源自然条件,概述了主要淡水虾和海水虾的资源及其分布。从养殖规模和养殖模式两方面总结了主要经济虾类的养殖现状,指出了优质虾苗繁殖困难、病害防治水平低、产品质量差、销售渠道狭窄等制约虾类养殖业发展的主要问题,并据此提出了相应的对策。 相似文献
7.
Saber A. El-Shafai Fatma A. El-Gohary Fayza A. Naser P. van der Steen Huub J. Gijzen 《The Environmentalist》2007,27(2):287-302
An integrated system, consisting of Up-flow Anaerobic Sludge Blanket (UASB)-duckweed-tilapia ponds was used for recovery of
sewage nutrients and water recycling. A UASB reactor with 40 liter working volume was used as pre-treatment unit followed
by a series of three duckweed ponds for nitrogen recovery. The treated effluent and duckweed biomass was used to feed fishponds
stocked with Nile tilapia (Oreochromis niloticus). The UASB reactor was fed with raw, domestic sewage at 6 h hydraulic retention time. The three duckweed ponds were stocked
with Lemna gibba and fed with UASB effluent at 15 days hydraulic retention time. Nitrogen recovery from UASB effluent via duckweed biomass
represented 81% of total nitrogen removal and 46.5% from the total nitrogen input to the system. In subsequent fishponds the
nitrogen recovery from duckweed as fish feed was in the range of 13.4–20%. This nitrogen in fish biomass represented 10.6–11.5
g N from the total nitrogen in the raw sewage fed to the UASB reactor. The growth performance of tilapia (Oreochromis niloticus) showed specific growth rates (SGR) in the range of 0.53–0.97. The range of feed conversion ratio (FCR) and protein efficiency
ratio (PER) were 1.2–2.2 and 2.1–2.28, respectively. The results of the experiments showed total fish yield and net fish yield
in the range of 17–22.8 ton/ha/y and 11.8–15.7 ton/ha/y respectively. In conclusion UASB-duckweed-tilapia ponds provide marketable
by-products in the form of duckweed and fish protein, which represent a cost recovery for sewage treatment. 相似文献
8.
Thórólfur Matthíasson 《Natural resources forum》2003,27(1):1-18
The article outlines the development of Iceland's fishery rights and the extension of its territorial waters between the 1950s and the mid‐1970s, whereby Iceland gained exclusive control and use of the marine resources of the waters within 12, later 50, and ultimately 200 nautical miles around the island. The article concentrates on four of Iceland's main fisheries: shrimp, herring, capelin and cod. These four fisheries are discussed separately and in depth, presenting the beginnings and growth of the industry and detailing the development of management practices and the corresponding legislation and regulatory measures. Iceland's initial concern was to gain control over the marine resources surrounding the island, but once this was achieved, the focus of attention shifted to managing first the economic and soon also the ecological aspects of its tremendous resource. Informed mainly by indigenous expertise, Iceland's concern was to limit overfishing, manage its fisheries sustainably both from the economic and ecological points of view, and find the best ways to distribute the revenues from the marine harvest. The article looks at each of the four fisheries to clarify how the individual transferable quota (ITQ) system came into being, how initial quota holdings were allotted, and analyses the circumstances under which the ITQ system became the management tool of choice. For each fishery, the process of regulatory evolution was quite unique. At the same time, there is a common pattern to all the fisheries, which may be summarized as follows. Firstly, serious attempts to reform management practices only got underway when the fishery had collapsed or was close to collapse. Secondly, stakeholders invariably started the process of regulation by limiting access to the fishery. Thirdly, a variety of rules were implemented to allocate rights to participate in the fishery to additional entrants once membership had been closed. Finally, prior to the invention of the ITQ system, prices were used to manage fisheries in Iceland. It may be concluded that the management of fisheries by ITQs may be a historical accident, rather than the end point of a logical evolution. 相似文献
9.
翟琳 《辽宁城乡环境科技》2006,26(3):4-5,12
对比分析了国内外废旧轮胎回收利用技术和现状,从法规、制度、管理、技术等方面分析了我国废旧轮胎资源综合利用产业发展中存在的主要问题,建议应尽快完善法律法规体系,建设具有法律保障的回收利用体系,促进废旧轮胎回收利用产业的可持续发展。 相似文献
10.
Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH4) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH4 emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH4 emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18–0.80 Tg CH4 year−1 (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500–42 000 km2 of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH4 emissions.