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Although the impacts of climate change are long-term in nature, the transformation in climate regime can lead to an ecosystem change from one stable to another stable state through intermediate bistable or metastable states. Such state transition or resilience to change in ecosystems is seldom sharp and therefore difficult to quantify with a single tipping point. Rather, the change can be understood through a tipping point range (tipping zone) across hysteresis loop(s). This study uses a satellite data-derived actual vegetation cover map of India and categorizes it into different vegetation types: forest, scrubland, grassland, and vegetation-less. We used high-resolution long-term average precipitation data to develop moisture-driven hysteresis curves and predict various tipping point ranges for vegetation-type regime shifts. Our results reveal that the forest and vegetation-less states could have one-way, while scrubland and grassland have two-way transition probabilities with a probable shift in precipitation regime. In the dry conditions, the precipitation tipping zone predicted between 154 and 452 mm for the forest to scrubland transitions, while the reverse transition (from scrubland to forest) could occur in wet conditions between 1080 and 1400 mm. Similarly, the transition between scrubland and grassland, between grassland and vegetation-less state, may occur in contrasting dry and wet conditions, creating a hysteresis loop. The results indicate that the reversal of state change requires differential energy spent during the onward and reverse transitions. The study proposes a novel characteristic curve demonstrating the varied precipitation tipping points/zones, precipitation overlaps and distribution of the various vegetation types, and co-existence zones, which has huge implications for understanding the climate change impacts. [ABSTRACT FROM AUTHOR]

Several theoretical and empirical models are available to correlate experimental breakthrough curves of water pollutants, one of which is the two-parameter Belter model. Although not as well known as the century-old Bohart–Adams model, the Belter model is being used with sufficient frequency to merit wider awareness of its strengths and weaknesses. Through a systematic analysis, it is shown that the two adjustable parameters of the Belter model are analogous to the equilibrium capacity and rate parameters of the Bohart–Adams model. Breakthrough curves predicted by the Belter model are perfectly symmetric because their inflection points are invariant and always correspond to the midpoint of the curves. As a consequence, the Belter model provides poor fits to asymmetric breakthrough curves. In this work, an improved version of the Belter model is introduced. The new model with a floating inflection point manifests excellent conformity with mildly and, more importantly, severely asymmetric breakthrough curves. [ABSTRACT FROM AUTHOR]

The acute ecotoxicity of a set of mixture samples (washing powders, wastes, fuel extracts etc.) was assessed using four acute ecotoxicity assays with aquatic organisms (Daphnia magna, Poecilia reticulata, Artemia salina and Desmodesmus subspicatus). The experimental concentration-response curves were fitted by seven two-parameter sigmoid equations using non-linear regression. The regression performance of the equations was compared in three categories (overall fit, mid-range fit, and low-effect fit) using non-parametric statistics. The best overall fit was achieved by Weibüll, Bolztman (i.e. logistic), modified Gompertz and log- Weibüll equations. The best low-effect fit was achieved by a modified Gompertz curve. Those equations transforming concentrations to log c fitted significantly worse than those not transforming them. The obtained EC50 values calculated by all of the equations were comparable to those calculated by the probit model. The results show that regardless of the knowledge of the susceptibility distribution or the mechanisms of toxic action simple two-parameter equations fit the data from acute ecotoxicity assays well and might be used for their evaluation. Key words: Acute eco [ABSTRACT FROM AUTHOR]

The kinetics on the growth of T. ferroxidans in the presence of Cu(II) was studied using of series piezoelectric quartz crystal (SPQC). Arsenic ion inhibits the growth of T. ferrooxidans, which is consistent with the previous results by other measuring methods. This further demonstrates that the SPQC can monitor the chemical activity of T. ferrooxidans growth. Cupric ion accelerates the growth of T. ferrooxidans. The mechanism was discussed, i. e., copper promotes the protein enzyme of T. ferrooxidans, rusticyanin, to form over the range of cupric ion concentration studied. The reaction order of cupric ion in accelerating the bacterial growth is 0.067. The growth of T. ferrooxidans is dependent on temperature, the apparent reaction activation energy decreases from 25.56 kJ/mol to 18.32 kJ/mol because of the addition of 10 mg/L Cu(II) to the bacterial growth solution of pH 2.0 at initial inoculum of 10%. [ABSTRACT FROM AUTHOR]