Riparian protection and on‐farm best management practices for restoration of a lowland stream in an intensive dairy farming catchment: A case study

Abstract

Poor water quality (high concentrations of nitrogen (N), phosphorus (P), suspended solids (SS), and faecal bacteria) in Waiokura Stream, southern Taranaki, New Zealand, is attributed to diffuse and point source (PS) inputs from dairy farming. Trend analysis of concentration time‐series data (2001–2008) and annual yields (i.e., stream load divided by catchment area) showed that significant improvements occurring since 2001 may be attributed to changes in farming practices and riparian management. Yields of filterable reactive P, total P and SS declined by 25–40% as a result of increased riparian protection, a reduction in dairy shed effluent (DSE) pond discharges from 8 to 6 with conversion to land irrigation, and a 25% reduction in the average application rate of P fertiliser. Median annual Escherichia coli concentrations declined at a rate of 116 per 100 ml per year, as a result of fewer PS discharges and improved riparian management. Thus, improvements in stream water quality were attributed to adoption of on‐farm best management practices, fewer DSE discharges and riparian management involving permanent livestock exclusion from stream banks and riparian planting to mitigate runoff from pasture. During 2001–06, N fertiliser use increased by 30% and, with a 130% increase in supplementary cattle feed during 2003–08, led to an increase in average milk solids production 1021 to 1262 kg ha^?1 during 2001–06 with the increased production likely associated with increased N leaching losses. Total N and nitrate‐N concentrations and yields increased during 2001–07 as a result of the intensification in land use and increased N cycling. Stream invertebrate surveys using the macroinvertebrate community index (MCI) metric showed little improvement in MCI during 2002–07, probably because of the relatively short timeframe of this study and because water temperatures were not a limiting factor for invertebrate communities. The absence of native forest streams in the proximity of Waiokura Stream that might act as sources of sensitive species to recolonise the restored stream should also be considered as a constraint to improvements in biological community structure.     

Faecal microbial contamination of watercress (Nasturtium officinale) gathered by a Maori protocol in New Zealand streams

A study was carried out to determine the food safety status of watercress (Nasturtium officinale) harvested from rural streams under Maori protocol. Sixty‐five sample bunches (c. 500 g) were collected from four streams in the Waikato region of New Zealand each summer from 2005 to 2007. Two streams, Southern Enclosure and Te Waihou, were within reserves and the other two, Mangapiko and Piopio, flowed through pastoral farms. To assess faecal contamination status, Escherichia coli and thermotolerant Campylobacter were measured on watercress as collected and E. coli counts assessed against the New Zealand guideline for ready‐to‐eat foods (satisfactory: <3 E. coli per g). To determine whether washing would ensure the watercress met food safety standards, an additional 6 bunches were collected and washed in running tap water (household regime). A further 15 bunches were washed by a simulated commercial triple washing regime. At harvest, 16 of 17 watercress samples collected from the Southern Enclosure and 11 of 22 from Te Waihou met the satisfactory criterion for ready‐to‐eat food, but only 1 of 17 from Mangapiko and none of 9 from Piopio were satisfactory. No Campylobacter was recovered from any sample of watercress collected from the four sites. After washing in running tap water, E. coli numbers still exceeded the satisfactory criterion. Commercial triple washing was more effective in ensuring satisfactory watercress, but of the 15 samples subjected to this regime, only 6 met the satisfactory criterion. Escherichia coli remained firmly attached to watercress leaves after both washing regimes (presumably in biofilms). Overall, these findings suggest that it is not advisable to use watercress harvested from rural streams as a raw salad vegetable, particularly from those affected by pastoral farming.     

Simulation of the Fate of Faecal Bacteria in Estuarine and Coastal Waters Based on A Fractionated Sediment Transport Model

A two-dimensional depth-integrated numerical model is refined in this paper to simulate the hydrodynamics, graded sediment transport process and the fate of faecal bacteria in estuarine and coastal waters. The sediment mixture is divided into several fractions according to the grain size. A bed evolution model is adopted to simulate the processes of the bed elevation change and sediment grain size sorting. The faecal bacteria transport equation includes enhanced source and sink terms to represent bacterial kinetic transformation and disappearance or reappearance due to sediment deposition or re-suspension. A novel partition ratio and dynamic decay rates of faecal bacteria are adopted in the numerical model. The model has been applied to the turbid water environment in the Bristol Channel and Severn estuary, UK. The predictions by the present model are compared with field data and those by non-fractionated model.     

土著微生物参与下河套平原地下水中砷的还原作用

为查明土著微生物活动对高砷地下水形成的影响,利用河套平原高砷地下水中分离出的土著微生物(YH002)进行了微宇宙实验研究.实验结果表明: 高砷地下水中加入的葡萄糖提供了微生物生长所需要的碳源,微生物大量繁殖,分泌的有机酸使溶液的pH值降低.在缺氧条件下,溶液中的OD值最高达到了0.189,pH值最低为6.22;在有氧条件下,OD值最高达到了0.286,pH值最低为6.04.溶液中As(III)的初始质量浓度为74 μg/L,占总砷质量浓度的11.2%,在加入微生物和葡萄糖后,在缺氧和有氧条件下,As(III)的质量浓度分别为278 μg/L和310 μg/L,占总砷质量浓度的42%和47%.微宇宙实验说明地下水中的土著微生物能将As(V)还原成As(III).      

垃圾和粪便快速除臭方法研究

研究了城市生活垃圾及粪便混合物中恶臭气体的脱除方法。利用所筛选的高效除臭菌种配成不同比例的菌剂,在自然通气的条件下脱臭,８～１２ｈ便可完全脱臭。脱臭后的干燥混合物经加工可用于制备高效生物有机肥料,具有较高的经济价值和应用价值。     

Chemical and Biological Studies of Particulate Organic Matter in the Ocean

This paper presents a review of the past decade's highlights of research on the isolation and characterisation of particulate organic matter (POM) in the world's oceans. The emphasis is on chemical studies but, in keeping with the growing interdisciplinary nature of marine science, advances in other disciplines are also discussed, particularly those in biological sciences. Increasing evidence for the importance of picoplankton, bacteria and viruses as POM constituents is highlighted, including the recent recognition of large populations of autotrophic bacteria able to harvest light for energy. The transport of POM to bottom waters was thought to be largely confined to large, rapidly sinking faecal pellets. However, recent studies have highlighted the importance of organic aggregates and flocs formed by diatoms such as Rhizosolenia and other microalgae. Ascending particles have also been discovered, many of which are lipid-rich. Several studies have shown that resuspension of bottom sediments and lateral advection of material from continental shelves can lead to anomalously high particle fluxes measured in sediment traps moored in deep water. Many new approaches for characterizing POM have emerged, such as pyrolysis gas chromatography-mass spectrometry and direct temperature-resolved mass spectrometry for analysis of higher molecular weight materials and biopolymers. Lipid biomarker techniques have also advanced, exciting new possibilities being raised by the ability to measure stable and radioactive carbon isotopes for individual compounds. The techniques of molecular biology, such as the polymerase chain reaction (PCR), are being increasingly applied to provide complementary information to more conventional microscopy and flow cytometry on the identity of organisms in the sea. The combination of these techniques with advanced chemical analysis methods promises to greatly increase our knowledge of the origins, transport and fate of organic matter in the oceans. This revised version was published online in August 2006 with corrections to the Cover Date.     

厦门浔江湾牡蛎养殖区弧菌研究

利用ＭＰＮ法及ＡＰＩ２０Ｅ系统对厦门浔江湾牡蛎养殖区的特牡蛎体、水体及底质三类榈进行弧菌分析。结果表明，三类榈的弧菌密度随季节呈春，夏〉秋，冬趋而变化。牡蛎体弧菌密度与水样、底质样弧菌密度之间的相关数值分别为０．８１４３和０．５９５５，二者都高于０．３２５，因此呈显著相关，而且前两者相关关系更密切。